No heat after washing engine

I used a car wash's high pressure water hose to clean my 1994 Taurus's engine and the surrounding parts, and right after that (in the car wash's parking lot, when I started up the car after the wash), the heater no longer worked, except sometimes, when I'm driving on the freeway, it puts out a little heat for about a minute out of every 10 minutes or so, but it's not consistent. Could I have knocked a hose loose somewhere, or gotten water somewhere it shouldn't have gotten? I checked carefully under the hood, and to my uneducated eyes, it looks like everything is still in place. I've been given the lecture by my brother that I did a dumb thing, though I already knew that. I've seen mention of backflushing the heater core to clear out any junk that might be in it that might cause this problem--how specifically do I do that (where are the hoses, etc)? The coolant level is good, so that's not the problem. And, when I turn the temperature control knob on the dashboard, I can hear the blend door's motor humming appropriately, so it appears to be OK, though I can't vouch for the blend door itself since I can't see it without removing the dashboard, which I'd rather not do unless necessary.

I dont think the heater problem had anything to do with your washing. It was just your time to enter heater hell with the rest of us. Most likely junk in the core . . . maybe a worn pump.
You can flush out the core and it will most likely work . . . for about a month!
Wash out . . drain some coolent out then remove the hose on the water pump. (passanger side 3/4" black rubber hose, goes back and over to the firewall to a "T" the t is a bypass hose which i think, by design, is where the problem is. Follow the bypass hose to the other end (another T) disconnect the other end at the engine. Here what I did . . . use a air hose at either end of the hose ends and blow out the water and some junk. now pinch off the bypass hose and blow it out again. Buy a can of coolent cleaner fill the open ended hose until it begains to run out the other end. Let that sit over night then use a garden hose on either end of the hoses then reverse the garden hose to the other end (back flushing) DONT use to much garden hose presure you dont want to damage the core. Then in about a month you get to do it all over again or until summer. What might help is in stall a filter in the "in" line. theres a cheep filter on the internet somewere . . . Itt or TII industuries ??? Good luck . . Have a happy Holiday.

Check your vaccum lines. You may have blown a line off that controls the blend door.

Mike
:smokin:

Thanks for the replies. I haven't had a chance to try flushing the heater core, and I haven't found any hoses not plugged in, but another problem is happening now that's more serious, and probably related: the engine is overheating pretty badly. At first it overheated only occasionally, and only when the car wasn't moving faster than about 40 MPH--when I was on the freeway recently, the engine didn't overheat, though it did on the city streets leading up to the freeway, when I was traveling slower. I suspect the engine didn't overheat on the freeway because the winter air was traveling faster over the engine, cooling it.

Now, I'm not traveling on the freeway, but only around town, and the engine overheats after I've driven only about a mile at 25 MPH. The coolant seems to me to also be under higher than normal pressure, since it's squirting out of a fitting on the radiator where a metal tube enters the left side of the radiator, about three inches below the radiator cap. I keep having to fill the radiator with coolant due to this leak. It's as if the coolant isn't flowing due to some blockage, or something that's not opening up to allow the coolant to flow.

I've bought a replacement thermostat, but I haven't installed it yet, both because I haven't had time, and because now I'm doubtful that the problem is the thermostat, because of a new symptom that happened today: while the engine was cold, I tried to start it up. It wouldn't start the first time, but ran rough instead, so I turned the key again, and it sounded even rougher, far rougher than I'd ever heard it, so I turned it off. I heard hissing from under the hood, and found that the leaky fitting on the side of the radiator was leaking again, even though the engine hadn't had time to get hot. I felt the leaking coolant; it was cold. So now, as soon as I start the engine, it seems that it's creating a lot of pressure in the coolant system, causing the leak--is this further confirmation of a blockage of some sort, or a valve in the coolant system that's not opening up, that should open even when the engine is cold?

Right after I looked under the hood this time, I also opened the coolant recovery reservoir, and saw it was lower than it had been the prior day--it had been high, about three inches from the top, just barely out of reach of my finger, but today it was almost at the normal fill line, indicating the cooling system is generating pressure when warm, and a vacuum when cool, as it's supposed to. As I watched inside the coolant recovery reservoir, coolant blurped from the radiator, into the tank, due to pressure in the coolant system; there were about five or ten blurps, spaced about 10 seconds apart on average, then this stopped. The fill level was still almost the same, though, so not much had gone back into the tank.

Is the thermostat supposed to always be a little open even when the engine is cool, to allow the coolant to start flowing early, and then when the engine heats up, the thermostat opens even more? Or is the thermostat completely closed until the engine heats up? If it's closed until the engine heats up, I assume there are other parts of the coolant system where coolant flows before the engine gets hot enough to open the thermostat, and that's the part of the system where the blockage might be.

To me, the current symptom implies the thermostat isn't the problem, and that there might be something else blocking the cooling system and causing the pressure. It seems that whatever is blocking the cooling system is getting worse fast, as if there's a partially blocked spot with a small hole remaining, that's quickly getting filled in more and more. Or maybe some sensor (maybe the temperature sensor?) that gates coolant according to some measurement it makes, is bad and getting worse? Could the water pump be involved? And does the water pump actually pump the coolant? I'm new to this, so I don't know if the terms "water" and "coolant" in this case are the same thing. If they are, how do I tell if the water pump is working?

Am I on the right track in any of this? I'm not starting the car until I've done a few things like replacing the thermostat, flushing the cooling system and heater core, etc., and some other things to try would be welcome. I've bought a Chilton manual, and I'm pretty handy, so I'll see how much I can do before taking it to a mechanic. Thanks for any further help.

I bet the T-Stat is the problem. I had similar problems - last winter it started with the heater not working that well. All of my trips were either on the highway (to utica, 15 miles away) or too short for the engine to warm up. Once it warmed up, I didn't have any heat and it would have terrible spark knock.

I would change the thermostat. You did get a thermostat gasket right? Probably your best bet would be change the T-Stat and then just change the coolant.

Thanks, Millermagic. I agree that the simplest thing I can do right now is to replace the thermostat, which I'll be doing soon (I didn't know they were so inexpensive--$5), but the Kragen where I live didn't have a gasket to go with it, so the sales clerk said it would be OK to use the old gasket along with some gasket sealant, which I also bought, but I decided that if I was going to do it right, I'd be better off buying a new gasket, so I'm going to find one at another store. The sales clerk at Kragen said that once I have the old thermostat removed, I could test it by putting it in boiling water, so I'll try that--I suppose the heated fluid is supposed to make the thermostat's spring retract, which pulls back the thermostat's valve, opening up the path for the coolant. I'll also be flushing the coolant system and the heater core--even though I also need to be spending the time doing other things, this will be a useful learning exercise in my ongoing car education.

I'm still wondering: is the thermostat supposed to be open a little, even before the engine heats up? If so, then if my thermostat isn't open at all at first, it might be causing at least some of the overheating, even if it opens more later when the engine is hot. But maybe it's not open at all when the engine is cold, then opens not enough later when the engine is hot, causing initial overheating, and then more overheating later. Good theory I suppose, but I'll know whether this is what's happening only after I've got the new thermostat installed.

I woukdn't be driving if it's overheating, you're going to damage your engine.. what size engine ?? Hopefully the 3.0 ????

Is the cooling fan working? Before tackling the thermostat, make sure the cooling fan works properly. If not, a new thermostat won't fix your issue. When you're traveling at highway speeds, the air is moving through the radiator on its own, keeping the cooling system cool. As you slow and get into city driving, the cooling fan should kick in to pull air through the radiator.

Also, test or replace the radiator cap to make sure it is properly pressurizing the cooling system. Pressure on the system will increase the boiling point (and freezing point) of the coolant. It doesn't really sound like you have a problem with it boiling over, but the pressure cap is often overlooked.

-Rod

Thanks for the replies. TaurusKing, I agree--I stopped driving the car, and won't be driving it until I've done some work on it. The engine is a 3.8L--is it more likely to become damaged due to overheating?

I should have mentioned that the really bad overheating the car is doing now, started only after I filled the radiator with water from a garden hose, on the advice of a mechanic who posted a reply to a post of mine on another forum--he suggested doing this to get rid of air bubbles that might be in the cooling system, to see if this would fix the car's original problem with a nonworking cabin heater. While I was filling it with water, the exhaust pipe put out a lot of billowing white smoke, and I've recently read this can be a sign of a blown head gasket letting coolant/water into the cylinder, so indeed maybe I have damaged the engine. I'm hoping it's something less serious, so I'll be doing the things I describe above and a few more things before I start the engine again, and see if the white smoke returns.

Shorod, the cooling fan is working--I've heard it start up several times, but I haven't taken the time to notice if it starts up every time the engine has overheated--I'll watch for this. I've also thought of replacing the radiator cap due to possible pressurization problems--they were right next to the thermostats at Kragen's, but I didn't get one since at the time I thought the thermostat was more likely. But I'll buy a radiator cap and install it before starting the engine again, since they're pretty inexpensive.

I also noticed a couple days ago, while looking under the car, that the bottom front edge of the radiator's fins are somewhat crunched, probably when I or someone else driving the car before me, drove into a concrete parking stop or a curb or something similar, which is something I'd done a couple times prior to the overheating beginning. I haven't looked at this closely to see if any of the radiator's cavity has been crunched, but I'll be doing that tomorrow.

I'm hoping that once I'm finished with this process, I'll have some kind of idea what it was about washing my engine that led to all this, or if something else unrelated happened just after I washed the engine that caused the engine overheating.

"Is the thermostat supposed to always be a little open even when the engine is cool, to allow the coolant to start flowing early, and then when the engine heats up, the thermostat opens even more?" There's a way for coolant to purge/bypass around the t'stat. The, "start to open," temp is the t'stat setting, say 190F, when it cracks open and continues to open until it's fully open at operating temp, usually 200F. Good way to check a t'stat is put it in a pan of water with a thermometer and turn the heat on and see exactly when it cracks open which should be the degrees stamped on the t'stat.

"Or is the thermostat completely closed until the engine heats up?" No, see above.

"I'm new to this, so I don't know if the terms "water" and "coolant" in this case are the same thing." Yes, they're the same. Coolant generally refers to water & anti-freeze mix.

"If it's closed until the engine heats up, I assume there are other parts of the coolant system where coolant flows before the engine gets hot enough to open the thermostat, and that's the part of the system where the blockage might be." The coolant circulates to some degree but not enough to move nearly as much as it does when t'stat is fully open. My 03 Vulcan stone cold and I turn the heater on high temp it takes about two minutes to start making slightly warm air and gradually gets hottter n' hotter like it should. That's with ambient around 40-50F.

At this point you should eliminate the possibility of worn out water pump blades because the bladles and t'stat determine the volume of water moved through the engine & heater. If the blades, t'stat, hot-cold coolant heater valve and the vacuum doors are working properly, then look to a clogged heater core. Oddly enough, with worn blades it will pump enough coolant to keep the engine cool but not enough to keep the heater core hot.

Elsewhere I saw directions for blowing out the heater core which is the best quick fix going, but if the water pump blades are severly worn then you're wee-weeing into the wind for distance. If you do blow out the heater core, TAKE CAUTION because typical garden hose will make 60 PSI and if you over pressurize the core it will start leaking. And, as always, NEVER attempt to work on a hot engine and let it cool down at least an hour first.

Engines run close to boiling point of water 212F so if you make an error and get a face full of coolant it is a painful disaster and/or serious burn that can scar and disfigure the face and/or other parts of the body. Long time ago an old Dude told me, "Treat a hot engine like a Rattlesnake, one error and you're bad hurt." Getting cut is bad enough, but I'd take five cuts instead of one burn.

BTW, good idea to wear safety glasses because if you get a squirt of antifreeze in your eye it will make you call fo' yo' Ma'ma and 'prolly lose half your religion to. AARRGGHH! It Burns!!! (The Exorcist.)

"Now, I'm not traveling on the freeway, but only around town, and the engine overheats after I've driven only about a mile at 25 MPH. The coolant seems to me to also be under higher than normal pressure, since it's squirting out of a fitting on the radiator where a metal tube enters the left side of the radiator, about three inches below the radiator cap. I keep having to fill the radiator with coolant due to this leak. It's as if the coolant isn't flowing due to some blockage, or something that's not opening up to allow the coolant to flow."

Long shot, but here goes. You fill it then get home and park it for the night. coolant runs out then cools off and draws air into the system through the leak. Remember physics 101 hot gases expand - cold gases shrink? Now you have air in the system and fill it up in the morning trapping air in the heater core and there's the problem. Get the leak fixed first then if the heater works good to go. If not check the water pump blades & t'stat and if no go then G E N T L Y blow out the heater core. If it don't work then sit a can of Sterno in a bucket and rock on. (Just kidding). Don't do it! I did that with an old VW once when we were stoned zonked and nearly asphyxiated all of us.

Or you could just be like me and not use the heat at all. The only time I use the heat is when someone is with me. If it's 0 out and the windows fog up, I open a few.

Zero degrees and you ride in a car? Brrr! Haven't done that since I was in Germany in 1961-2 and only reason I did it then is I was on duty and didn't have a choice.

I've had bad experiences with heat and driving ... and sleeping.

an easy way to check if it is a blown headgasket is:

when the engine is COMPLETLY cooled, not even a slight bit warm, take the cap off and have a friend start the car. Then take a flashlight and look into the radiator and see if you can see little bubbles almost like it is boiling. If you see any bubbles whatsoever, stop driving the car. That is a sure fire blown headgasket, and if you are new or even semi good at cars, bring it to a shop. They are a bitch to repace and damn near impossable for most people. Also what motor is in your car, the 3.0L or the 3.8L, this can help diagnose the problem more than you would think.

Thanks very much for all your suggestions. We were on the right track--it turned out to be a clogged but otherwise OK water pump, and a thermostat that wasn't opening all the way (don't know yet if the heater core is blocked--testing that comes later). I haven't posted my results here for a while, since I was doing a lot of basic coolant system research to decide if I should try doing the repairs, or have a mechanic do it. I finally decided to have a mechanic do the work, since even with the research, I wouldn't know how much I didn’t know, so I wouldn't have been confident enough while doing the work to know if I was missing something. Here are the results--I go into a lot of detail here because it might help someone else finding this thread:

But before I had the mechanic work on the car, I replaced the radiator cap, and the engine didn't overheat quite as much for a week--the dashboard temp gauge stayed about an eighth of an inch above the red, though before I installed the new cap, it was right at the red. Then I fixed the leak on the fitting on the side of the radiator, using JB Weld. Maybe it began to leak due to the higher than normal pressure of the coolant in the radiator (caused by the clogged water pump) that the engine was trying to push through the radiator, but was unable to. But after I fixed this leak, the engine began to overheat a lot worse, with the temperature gauge just reaching the red, so maybe the leak was acting like a safety valve, preventing the coolant from heating up as much since the pressure was lower.

Because of that more extreme overheating, I finally parked the car at home and thought about what to do next. We had a rainstorm during that night, with a single loud thunder strike nearby. I don't see how this could have anything to do with it (I began thinking electromagnetic pulse, but nothing electrical was damaged in my apartment), but some time the next afternoon, I tried to start up the car, but only heard a rapid electrical tick-tick-tick clicking, more like a zapping, and no engine turnover at all. I was worried that the engine had finally seized due to the overheating--I pictured the pistons welded to their chambers. Yes, I know I shouldn't have still been driving the car while it was overheating, but sometimes you just gotta make a trip across town (a couple miles max), and walking or biking it is just a little too far. A friend suggested the battery was low, but I didn’t think so, since the headlights were still at full brightness, or at least so it seemed to me. I charged the battery overnight anyway, but the engine still wouldn't start. But I began to think the battery might really be the problem when I found that pressing the doorlock up/down button caused the car's overhead light to dim a little, which it had never done before. I later found the doorlock motors go through a 40 amp fuse, which is a fair amount of current to draw from a weak battery, which would explain the light dimming when I pressed the doorlock button. I then read that the startup problem could be the usual suspects--the starter, its solenoid, the relay, etc.--but then I realized I might finally be getting in over my head, even with as much as I was learning, since the startup problem might have had some other, weird relation to the overheating that I hadn't read about at all, so about a week later, I called a mobile mechanic, to work on the car a couple days ago. It was great that he came to my home and did the work, since I could ask him questions and do a lot more learning.

He looked at the startup problem first. He jumped my battery from his van, and my car started up right away. So something had happened to the battery, so that it wasn't able to hold enough of a charge any more to start the engine. The mechanic suggested a high-resistance short somewhere in the electrical system might have been draining the battery often enough to finally reduce its ability to deliver enough current to start the engine--he'll check for that next week, since I mainly wanted him to look at the cooling problem first. I do know I accidentally drained the battery fully about three weeks ago, when I left the glove compartment door open overnight; I recharged the battery after that, and it worked fine for another couple weeks, so it's either odd it decided to die two weeks after I had drained and recharged it, or it may have just been on the edge for a while, and finally died. So I bought a new battery. Until the mechanic fixes the battery drain problem, we're leaving out the fuse through which he found the current leakage is flowing, so the new battery doesn't die too--it's fuse #8, under the driver's side, for the lights for the dashboard backlight, overhead lights, glove compartment, engine compartment, and trunk; and power mirrors, chime for key in ignition, and radio memory.

After we got the startup/battery problem diagnosed, he looked at the overheating problem, and found at least two causes so far:

-- The thermostat wasn't opening completely. He replaced it with the one I bought, and used a new gasket I also bought later at the same Kragen's where I had been told earlier, at the time I bought the thermostat, that they didn't have any. But after he replaced the thermostat, coolant still wasn't flowing through the system.

-- So, next he looked at the water pump, and found no coolant was coming out of it even when the engine was hot, and the new thermostat was open, allowing hot coolant to flow out of the engine, into the radiator, and into the pump. The cause was a clog in the pump. I thought the mechanic said the clog was in the pump's upper inlet, at the point of the "V" where the two metal tubes on top of the pump join together (coming from the heater core and from the top of the engine). But later I realized that if the clog was at that location, it wouldn't have prevented the coolant from flowing through the pump to the engine, since the outlet for the pump is on the side of the pump that's attached to the engine. The pump's blades and bearing were fine. The clog was some kind of stuff he couldn't identify, but he said it wasn't rust. I wasn't there when he found it, so I don't know what it looked like, and I forgot to ask what color it was. He asked if someone had added any radiator sealant or similar stuff to the coolant in the past, but I didn't know, since I just got the car from my Mom, and my Dad's not around any more to ask. So, little or no coolant was flowing from the pump to the engine.

Once the mechanic replaced the thermostat and unclogged the pump, coolant flowed through the system as it should, the fan came on at the right temperature (it wasn't before), and the engine no longer overheated. There's still coolant billowing from the tailpipe, so probably my driving the car around while it was overheating blew one or both head gaskets (I thought I'd avoid damage like this by continuing to put coolant in whenever it got too hot, until I had a chance for a mechanic to look at it, but I guess that didn't do enough to keep it below the "blowout" temperature). But I wonder why the first time I saw white smoke coming out of the tailpipe was several weeks ago, before the overheating began (or at least before it began to show on the dashboard's temperature gauge), when I used a garden hose to pour a bunch of water into the radiator while the engine was running, on someone's advice (see my post above), to try to fix the heater problem on the theory that this would push air bubbles out of the cooling system that might be blocking flow--before I did that, the engine wasn't overheating. Could adding just water alone have allowed the engine to get hot enough during this "flush", since there was no antifreeze in it to increase the boiling point, to finally blow the gaskets? It's also weird that I wasn't seeing a high reading on the dashboard temp gauge for the first week after the heater stopped working, if the cause for the heater not working was a clogged water pump--maybe the clog first got into just the tube that receives water from the heater core, and later, maybe during the water flush I did, some of it migrated into the outlet that goes into the engine. With all the variations on things that can cause overheating and heaters not working, I can see why some of these problems can be hard to diagnose.

Next week, I'm going to have my mechanic flush the cooling system (I didn't have him do it after he fixed these problems, since it got a little late that night to proceed further), and then try some gasket sealant fluid. He says the head gasket problem doesn't seem severe enough to preclude the use of sealant--just a minor misfiring on one cylinder, and the engine runs smooth after about ten minutes, though it starts up rough, and runs a little rough for those first ten minutes--I wonder why, if the cooling system is now OK (except for the gaskets)?

The day after the mechanic worked on the car, I started it up, and noticed something I didn't expect, but may be normal--anybody know? After ten minutes, the two hoses going into the top of the water pump were still cool. One is the engine coolant bypass hose, and comes from the top of the engine, directly above the thermostat housing, and the other normally comes from the heater core, but the mechanic had pulled both heater hoses out of the firewall and connected them together temporarily, until he can backflush the heater core. The heater inlet hose (on the right, if you're facing the front of the car) runs from the top of the engine, like the hose that goes to the water pump. The big hose going from the thermostat to the top of the radiator was also cool. After another couple minutes, the joined heater hoses got slightly warm, but the engine coolant bypass hose (that runs directly from the engine back into the pump) stayed cool. I felt the top of the engine, and it was only warm for a change, instead of too hot to touch, so that was nice. The radiator hose was starting to warm up a little, but not much. At first I was worried that this might mean there still wasn’t enough coolant flow, but since the engine temperature was OK at this point (at least by feel, and the dashboard temp gauge was in the middle), I thought this was unlikely. But about five minutes later, the dashboard temp gauge climbed up rapidly, while I watched, and stopped just above the red mark, so I turned off the engine. But an odd thing about that: my mechanic told me the temperature gauge on the dashboard is now giving an incorrectly high reading. I could understand that, given that its reading was high now even though the engine was now only warm to the touch, but the gauge was apparently showing a correct reading before he did the work--at least it was showing the engine was overheating when it really was. Why would it still almost get into the red, when the engine is running so much cooler now? Is there a part of the engine that's still overheating, where the temperature sensor for the dashboard gauge is located? Is there a way for me to confirm whether the dash temp gauge reading is wrong? And is the fix to replace the temperature sensor or the dash gauge, or both?

I'm also wondering: does the water pump have coolant flowing through it even when the engine is cool, before the thermostat opens? It couldn't have flow from the radiator, since until the thermostat opens, there's no flow out of the engine and into the radiator, and then from the radiator to the pump. If the pump isn't circulating the coolant until the engine gets hot enough to open the thermostat and let hot coolant flow, then apparently the only coolant flowing through the engine until that point, is driven by the mechanical motion of the engine parts, and the amount of it is whatever was in the engine when you last turned off the engine; this seems to mean you really need to keep enough coolant in the system all the time, which raises another of my concerns: the fluid level in the radiator doesn't stay an inch or two below the radiator's fill inlet (which is what I've read is where it should be), even after I add a lot of coolant--it goes a lot further down, almost to where you can't see it; and it seems I can pour in more coolant than I thought would go into the system (I recently read the 94 Taurus holds three gallons of coolant)--should I just keep adding coolant until the level in the fill inlet stays an inch or two below the fill inlet?

I'm also trying to find information on whether the 94 Taurus's heater has a heater valve to gate hot coolant through it. I can't find any mention of this so far, so I assume coolant is always flowing through the heater core in this model, but does anyone know if that's true?

Next week comes the flush of the coolant system and the heater core, and pouring in the head gasket sealant, and other things I'm sure. I'll post back here with the results. Hope all this helps someone else too.

The 3.8 is a notorious for headgasket failure.. I don't know what headgasket sealer is, but I'm betting it ain't gonna work... you need to take it to a reliable repair shop and get a leakdown test done to confirm, or not, that the headgasket(s) have failed.. do that first, all the other stuff is small potatoes, easily fixed after you attend to the possibility of stopping major engine damage in it's tracks... in the future, do not run the car overly hot, newer engines are major-league susceptible to damge from it

Alot of info is right and we 'preciate it. Heed Taurus King's warning. The minute temp gage shows hot you safely get off the road and stop the engine.
Forget messing with the engine or you could be seriously burned. :nono: Let it cool off until its barely warm then slowly pour water in it. If you put cool water on a hot head there is a good chance it will crack then I hope you have deep pockets.

It's like flying where pilots get a case of, "get-home-itis," and do a stupid thing and take off in bad weather at night wind up eating it instead of going to the motel and have a good nights rest and wait for the bad weather to passnd fly in the daylight the next morning VFR. The car will be there, so relax and grab a cab or call wifey to come get you then deal with the engine in the morming when it's cool. Heck, spend the money to have it towed home and it'll be a fraction of the cost of replacing a head or, Lord forbid, TWO heads. AARRGGHH! :2cents:

I'll answer a couple questions for you. "Could the water pump be involved? And does the water pump actually pump the coolant? I'm new to this, so I don't know if the terms "water" and "coolant" in this case are the same thing. If they are, how do I tell if the water pump is working?"

Yes, the water pump pumps the water/coolant circulating it thru the engine, heater and radiator. Water is plain water, coolant is anti freeze mixed with water. Tauri are famous for wearing the blades off the water pump and wierd things happen. Some run cool awhile then run hot, some heaters don't work then they do. If you have substantial miles on yours it would be a good idea to change the pump.

I'll read your whole thread tomorow but right now it's sack out and ZZZZ's time for this old Horse.

To clarify, the water pump will be circulating coolant even before the thermostat opens. The coolant will circulate through the block, then once the thermostat opens, the coolant will flow through the radiator as well.

-Rod

Go to the parts store and tell them you want something that tests for a blown head gasket. There is no such thing as a head gasket that is blown but not blown *that* bad and it'll get worse.

Hot spots in the engine can be caused by the exaust gas escaping through the head gasket into the cooling system thereby making bubbles and where ever the bubbles are the coolant doesn't touch the block or head, hence you get hot spots.

Here it 'tis: If the coolant pump is good, the head gasket is not blown, radiator is doing it's job and there are no restrictions in the cooling system it will NOT run hot. My best guess is the combuistion gases are escaping through the blown head gasket into the cooling system causing the bubble syndrome.