Heat problems, 1994 Bonneville

joeshannallie · #1 11-20-2006, 11:44 PM

It seems the heat does not get hot enough this year. The passenger side vents seem to be fine with good hot heat. But is luke warm at best on the driver vents. The heat gauge does not go to where it should. It use to peg out at 200 but now is it like half between 100 and 200 and stays there unless you are in traffic or something. The radiator has gunky rust like stuff in the neck of it. Coolant level seems to stay fine. Does anyone have any suggestions?

LMP · #2 11-21-2006, 08:08 AM

...of course, I'd be tempted to replace the thermostat in case it is blocked partly opened....but this proves as the wrong diagnostic 9 times out of 10.....but at least, this is inexpensive and it clears the way for more serious investigations..if needed....so, easy moves first.
for more serious cases....check this out
http://www.automotiveforums.com/vbul...d.php?t=298431
...of course a blown head gasket is a frequent cause for heater and gauge going haywire....but it would need more symptoms, like blowing steam, or simply popping bubbles out of radiator, whitish goo under the oil fill cap.....and this occurrence is rare with the 3.8.

ChemMan · #3 11-21-2006, 11:46 AM

Sounds like your thermostat is stuck open. You'll need to replace it. As for the rust like stuff, it sounds like you have the famous red long-life coolant. You need to flush the cooling system out and refill with the regular green coolant. You could use fresh long-life coolant but I've seen too many problems with that stuff. While you're at it replace the radiator cap. If you need more detail let me know.

I'm recommending the thermostat replacement and coolant flush because your temp gauge is reading low. This may not solve the problem with the heat in the car. It could be a stuck mixer door under the dash.

xeroinfinity · #4 11-21-2006, 04:11 PM

If thier is rusty stuff in the neck you should probly use some radiator flush(like prestone).
After you flush it rise well and fill with the proper coolant mix.

After the flush is when I'd change the thermostat.

just my

joeshannallie · #5 11-23-2006, 12:22 AM

Just replaced the thermostat and it seems to have helped some but it is still not like it should be. Could it have air in it somehow? What is the bleeder screw for on the thermostat housing? I will flush it in a few days. It does have the green coolant. Could the heater core be going bad? I have checked the flap door and it seems to work fine. The mix also works fine. You know like turn the heat knob from red to blue and the air cools. Please reply soon.

ChemMan · #6 11-23-2006, 01:53 AM

Was the old thermostat open at all? When cooled down it should be completely closed. The bleeder screw on the housing is to purge the air out of the system after opening it. Once everything is closed up, start the engine and allow it to idle until hot. Open the bleeder screw to allow the air out and once you have a steady stream of antifreeze spurting out you are done.

Since you have green coolant, then that red rust stuff you noticed is definately rust! You need to very throughly flush the engine block, radiator, and heater core out. Once you have drained the old coolant out of the engine(loosening the lower hose on the rad works best), remove the radiator from the car and flush it out with a garden hose until the water comes out clean and debris free. While you are at it spray water through the radiator fins to clean the junk out. Next, remove the thermostat and put the hose into the opening. Allow water to flow into the top of the engine and out of the lower rad hose until clear. Lastly, and possibly most difficult, is to remove one of the heater hoses where it connects to the engine, and push your garden hose into the heater hose and run water through into the heater core. I'm willing to bet that the rust in the engine has collected in your heater core and constricted flow. Keep flushing until the water coming out(probably from the lower rad hose) is clear. Make sure to observe if you get any rusty water coming out. Put everything back together except leave the thermostat and thermostat cover off for now. Fill the radiator with fresh(don't reuse the original stuff) properly diluted antifreeze slowly, until you see the antifreeze blubble up into the thermostat cavity. Now reinstall the thermostat(in the proper direction) and thermostat cover, rad hose, etc. Finish topping off the cooling system including the overflow tank(fill to hot mark). Replace rad cap and purge air out of the cooling system like i described above. Make sure to check the expansion tank for a few trips and add coolant as needed to make up for air being flushed out.

Not knowing how experienced you are, I'll go into pulling the rad real quick. You'll need to disconnect the rad hoses, along with the transmission cooler lines. Be careful with the cooler lines; spray some WD-40 on the threads and use a backup wrench on the hex on the radiator side of the fittings. They are probably going to be tight and you don't want to damage the plastic(bleh!) radiator tanks. Some transmission fluid will drain out of the lines and cooler, so you might want to put a catch pan underneath and have some plugs handy to seal off the lines. Next, remove the three bolts that attach the cooling fans to the upper radiator mount. Finally remove the four bolts that attach the upper radiator mount to the car. Once that upper radiator mount is out simply and carefully lift the radiator out of the car. Avoid bending fins!

I apologize if all of this is rudimentary for you.

Also, I still recommend replacing the rad cap!

xeroinfinity · #7 11-23-2006, 07:37 AM

With the rusty stuff you are having I'd say your heater core could be pluged.
But First I'd try and purge the air as ChemMan mentioned and see if that doesnt help. Just my

Happey Thanksgiving !!

joeshannallie · #8 12-08-2006, 10:17 AM

Still no heat. Or shall I say nowhere near what it should be. I have flushed the whole system and it seems like that made it worse. What about a intake leak? I don`t think it has one but I heard that could be the problem. Am I right to assume if there was a leak the car would eventually be overheating?
The hoses are hot from the radiator. Also hot going into the heater core. I was going to change the heater core but I see no possible way to get to the squeeze clamps on the firewall side. Does anyone have any solutions on how to remove the core. Or any other suggestions will be greatly appreciated. Please reply soon.

LMP · #9 12-08-2006, 02:59 PM

With all you have said, I really think again you should consider air mix door syndrome using this:

http://www.automotiveforums.com/vbul...d.php?t=298431

xeroinfinity · #10 12-08-2006, 07:04 PM

joeshannallie, are the heater hoses that goto the heater core hot ?

If you cant reach the hoses from the top then you'll have to jack up the car, prop it up on jack stands and crawl under with some plyers

joeshannallie · #11 12-08-2006, 11:36 PM

Yes the heater hoses are hot. One is like hot and the other is like warm. Not hot enough you can`t hold it for awhile. Also the top radiator hose is hot. I can drive it like 15 to 20 miles and the radiator cap is still cold. You used to not be able to hardly touch it let alone take it off as soon as you park up without being burned.
The heat is tolerable on the passenger side vents on the dash but the driver side vents are cool. Not cold just to cool. I put the heat to the floor and the air is cooler than the driver side vents. It just does not make any sense. If the heater core was clogged up there would be no heat or very little anyways, Right?
I can see the actuator thing and when I mix the air from hot to cool it seems to work fine. Maybe it looks like it works when it really isn`t. If that was the problem then I don`t think there would any heat at all.
You just can not get to the clamps next to the firewall that goes into the heater core. The ones coming off the motor are fine to get to.

xeroinfinity · #12 12-09-2006, 08:28 AM

Hum, I guess if the heater cores pluged, the side that has the hot HC hoses could heat up just half of the HC causing heat on one side....

... this almost sounds more like the hvac flap isnt changing the heat to its right spot.
Have you checked out under the dash to see if anythings broken or loose?

markwb · #13 12-09-2006, 12:48 PM

Sounds more like heat exchanger blockage. You checked the air mix doors already, correct?

joeshannallie · #14 12-09-2006, 01:38 PM

I have checked everything their is to check. I would put a new core in but I see no way getting to the clamps next to the firewall. I have tried the flushing kit that Walmart has. You know cut one of the heater hose and insert the tee and hook the water hose to it. And I think it really made it worse. I guess it is time to buy a 12volt heater.

joeshannallie · #15 12-10-2006, 12:26 PM

I may have found the problem. The housing where the blower motor is mounted has a hole near where the blower motor is. It is all brittled up and my bet is that it is sucking cold air in somehow. You can see the insulation(I guess that is what it is). I will get some of that tape like they use on furnace ductwork and tape it up real good and see what happens. Do you think that will work?

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