Cooling issues

Hi,

My 1997 Lumina's 3.1 engine is having some issues. I suspect stuck open thermostat, but would like some other opinions cause they are not the easiest things to change and I wouldn't want to do it for nothing.

The temp gauge used to slowly rise till about half way, then drop to a bit below half (after the thermostat opens/fans come on I assume). Now it just continues to rise until it is slightly past half, then I worry and shut it down. I notice that the fans are not running when it gets this hot. If I unplug the coolant temp sensor, the fans come on and then when I plug it back in the temp reads the proper temp.

I have just replaced the sensor, and to my knowledge, the thermostat wouldn't cause the fans to not come on, but I could be wrong. If it was a fan relay, would the fans come on at all ever?

Anyone possibly know anything about this?

Also, after I unplug/plug in the sensor, the fans seem to work properly. Even after I shut the car off and re-start it. It just seems that at some point during the drive after that they stop working. Is there some default run time when the sensor is unplugged or something?

Thanks for any help, much appreciated.

I suspect stuck open thermostat,

How about a stuck closed thermostat? Are you losing any coolant, causing an air pocket?

But seriously, at this time of year, cars tend run at a higher temp......your coolant fan will not come on until 220-228F.......

Yeah, that could very well be, I am just a little paranoid given this engines history of head gasket issues.

Especially since about half a year ago, I changed the thermostat (with the fail safe kind which I thought was supposed to never get stuck closed) because it was stuck closed, then had issues with the heater core hoses. They were really soft and gummy, which was leaving oily deposits in the coolant (which I assumed must be the dreaded head gaskets). Then all was well for a few months, then we noticed the temp gauge was barely registering anything even after long drives.

I assumed that this must be a stuck open thermostat, but figured I just changed that and looked at the coolant temp sensor. Somehow the plastic part where the wire connects was broken, so I changed that. That takes me to where I am now with the tem gauge running hot.

Could the oily deposits from the worn hoses possibly have plugged up the new thermostat?

Oh, and not leaking coolant anymore either, not that we ever were leaking lots, but I guess it only takes a small amount for air to get in. While all this was going on I noticed the water pump leaking a bit, so I changed it too. I have also bled the system as well.

Head gaskets really not an issue on these...lower intake manifold gaskets are.

My '97 has been through a shitstorm of cooling system problems in the last year. Started with the thermostat not being able to close and no heat last winter. Replaced that, then the radiator developed a leak, the tank on the side receiving water from the motor got brittle and cracked. Then it blew a small throttle body bypass coolant hose. Then the lower intake started seeping, then gushing coolant one day. Took the motor apart for that pain in the ass, then it blew a heater hose, so I did what I shoulda done before and replaced all the hoses. Now I've got a slight leak back by the firewall, suspect the heater core. Oddly enough the water pump I replaced at 70,000 miles and have added another 110,000+ since, and still not leaking. But easy as it is, I'll probably put another one on soon...it's gotta go sometime.

I don't know how uniform the temp gauges are on these...probably not very...but mine has always run rock solid at 1/3, and will go up over half if idling on a hot day without the A/C on (no constant radiator fan operation)...fans kick on just before 2/3, and it settles quickly back to 1/3. Takes a long time to build high enough to start the fans again.

My first impression on hearing your story is you've got trapped air and it's preventing the fans from cycling properly, this is common on this motor. That would be where I'd start...and if air was found, next I'd wanna know why it was there....

PS, your gummy heater hoses sounds like intake manifold gasket oil contaminated coolant, actually...I hate to say it...I noticed all of mine were like that when they started blowing around the time the LIM gaskets failed...got spongy and weird...

Did find some oil in the radiator core when I removed the tanks from it after putting the new one in. Was in denial at that point, wanting to believe that it was just residue from the failure that must have occurred before I owned the car, and was fixed under warranty...I bought it a year old, and saw that in the service records...

Just did not want to believe that it was the LIM again...didn't wanna do it. You may have that happening...sounds awful similar...

I think you are just tricking it into cycling the fans...when unplugged, it sees no reading...then you plug it back in, it runs them to make sure the circuit is now complete...like I said, if yours is in any way similar to how my gauge works, the fans won't come on until about 2/3 up the gauge...

And if the thermostat is working right, you shouldn't see a lotta gauge swinging up and down, not while running say at speed on the road with minimal stops or slowdowns...if that's what you see in traffic with no A/C on, that would make sense...but if you're swinging up near half and dropping back abruptly constantly while going down the road, there is something wrong...again, air in the system, bad thermostat, cooling system blocked, etc...should run pretty rock steady while moving.

I don't recall what type of thermostat was put in, but its good to know that they can fail quickly so that might be it. But then again, this is the first time we have had the car in such hot weather. It sounds like yours runs the same temp range as mine, but I get worried as soon as it is over half way and shut it down.

Maybe there is nothing wrong with it, I just haven't seen it go that high before and made a bad assumption.

That worries me that what may have cause the hose to go gummy might be a LIM failing. I have been playing with the idea of selling it because I fear something major happening like that. It is still saftied and in pretty good shape with moderate mileage on it.

Well, I will go check for air in the system again this weekend, and maybe now that I know not to panic if it is over half way on the gauge, I will let it warm up a bit further than that and see if the fans come on, that was what I wanted all along.

Thank you both for your helpful input. I guess now I gotta start thinking about what I might want to buy next.....

Yeah I wouldn't worry, long as it trips the fans before/around 2/3, and brings it back down to normal within 2 mins or less....but like I said, with A/C on, mine never budges...that's only A/C off, idling in traffic, hot day...in winter it takes FOREVER for mine to start creeping up off 1/3...like 20 minutes or more...

What about your reservoir? Seeing any brown sludge on the sides in there yet? If so, the LIM is probably a factor here...

Alright. Our A/C actually isn't working. The compressor had to be changed out and it wasn't refilled. If I were to turn it on would it trigger the fan? I know the clutch and all that wouldn't engage because there is no pressure in the system, but at least if we could turn a fan on with the A/C switch when it starts to run hot, that might help.

Damn, there was some brown sludge in the resivoir. I just changed the water pump because it was dripping, so I flushed the system the best I could and took the resivior out and washed it too.... it looks clean so far, but I guess it has only been about 5 days, LOL. I was hoping that all the oily crap and brown sludge in that resivior might just have been from the hoses deteriorating.

Alright, so I guess it is decision time, but one of those retired cop cars that I have been itching to get back, or do the smart thing and take advantage of my girlfriends dealership pricing and get a newer vehicle under warranty so I don't have to spend my weekends fixing cars....

Anyway, thanks again for all the help, you may have just saved me a lot of money by not keeping the car till when the inevitable LIM gasket fails.

Would putting that BARS stop leak in buy me some time, or make things worse do you think? I actually had a 1993 Caprice police car that developed a intake manifold gasket leak and figured there was nothing to loose by giving BARS a try, it actually sealed the leak and gave me another year and a half before I had to take it apart and fix it right. It was a water fall of a leak too.

since it is a 1997 I would replace the temp sender for the guage. also the fan relay. make sure the connectors for the sensors are good. if bad go to scrap yard and find a better one.

thermostats mess up if the coolant is not at the proper mixture. 50-60 % coolant should be used with the distilled water. non distilled water causes corrosion and scale build up restricting the coolant passageways.

also the cooling system needs at least 50 % coolant to protect water pump from damage.

with head gasket failures or oil getting into the coolant the coolant system should be acid flushed , and then the engine drained of all dirty coolant before restoring.

test the thermostats before installing. get the ones that have a warrantee. I have found too many in recent years not working correctly. sticking open slightly.

use solder and heat shrink to replace these connectors .

I have actually just replaced the coolant temp sensor just last weekend too. The connector looked fine. I suppose it might be worth changing the termostat again and the fan relays, they are all cheap.

Thanks for the suggestions.

I have actually just replaced the coolant temp sensor just last weekend too. The connector looked fine. I suppose it might be worth changing the termostat again and the fan relays, they are all cheap.

Thanks for the suggestions.

the fan relays have to supply a large amount of current to get the fan running. with constant switching the contacts get pitted and this could cause a malfunction that, in the begining , to be intermittent. if these are original then they should be replaced. I would also measure the voltage at the fan to see if you get the full 12volts. a lower voltage would also cause higher temp problems..

sensors can be very erratic and the wiring /connections can esp. on older vericles cause a malfunction.

Alright. Our A/C actually isn't working. The compressor had to be changed out and it wasn't refilled. If I were to turn it on would it trigger the fan? I know the clutch and all that wouldn't engage because there is no pressure in the system, but at least if we could turn a fan on with the A/C switch when it starts to run hot, that might help.

Damn, there was some brown sludge in the resivoir. I just changed the water pump because it was dripping, so I flushed the system the best I could and took the resivior out and washed it too.... it looks clean so far, but I guess it has only been about 5 days, LOL. I was hoping that all the oily crap and brown sludge in that resivior might just have been from the hoses deteriorating.

Alright, so I guess it is decision time, but one of those retired cop cars that I have been itching to get back, or do the smart thing and take advantage of my girlfriends dealership pricing and get a newer vehicle under warranty so I don't have to spend my weekends fixing cars....

Anyway, thanks again for all the help, you may have just saved me a lot of money by not keeping the car till when the inevitable LIM gasket fails.

Would putting that BARS stop leak in buy me some time, or make things worse do you think? I actually had a 1993 Caprice police car that developed a intake manifold gasket leak and figured there was nothing to loose by giving BARS a try, it actually sealed the leak and gave me another year and a half before I had to take it apart and fix it right. It was a water fall of a leak too.

The LIM likes to swap oil into coolant, and coolant into oil...the stop leak usually doesn't do much, because the expansion between the parts is too great across the temp range to form a good seal. And when the gaskets fail, it's some huge holes...I did a thread on it a while back, if you dig it up you can see a pic of my failed gasket (one of 'em)...pretty pathetic. It didn't catch my attention until it got bad enough to start flowing off the back of the motor, until then my only evidence was a few red drops of Dexcool here and there in odd places...and the crud in the cooling system.

I also found upon taking it apart that the two bolts on either end of the manifold that hold it down were loose as all hell...I'm sure that figured into the problem...the torque spec on them is surprisingly low, so any gasket shrinkage or thermal changes in bolts and intake is gonna slowly loosen things up, I suppose...

If for some reason you do decide to keep it, and it does require a LIM job, for sure go for the Fel-Pro PermaDry gasket set...it's more expensive, but has some extras and the gaskets themselves are built to last (silicone over metal carrier), unlike the standard set (plastic carrier with RTV (?)beads).

Watch your oil too. Dexcool in the crankcase oil turns into something unholy and is very destructive to bearings...

http://www.automotiveforums.com/vbulletin/showthread.php?t=1077048

Here's that thread. check out the broken piece.

Well, looks like this may all be for not. I have put a deposit on a Mazda 6 this afternoon. I just need to head back tommorow so my girlfriend can test drive since she will be the one driving it daily.

It should be a good deal with her employee pricing, and it will be nice to have a newer car that should be trouble free...hopefully.

Thanks again to everyone for their help and information. It has probably prevented me from driving the car untill the gasket failed puting me in the position of deciding to take a long weekend to fix it, or just selling it as is for whatever I can get for it.

The 6 is a really good car. The 3 is a lot more fun to drive, in my opinion....corners like it's on rails. But if you like the larger size, the 6 is pretty nimble too.

I've had 3's at speeds on cloverleafs that shoulda put a rear wheel in the air...and they aren't even fazed...pretty cool.

Good to know. I have liked the mazda 3's and 6's for a while now. I haven't found any negative comments or reviews on them and am actually looking forward to it.

I have never owned an import before, but figure why not give it a shot. As good as this car may be as a daily driver however, I can not wait to sell our condo and get some land. Once we have the room, I will be reclaiming my car collection, which will consist mainly of muscle cars and classics. Love those cars.

Thanks again everyone, this forum is great!