99' intrigue overheating 3.5L 6Cyl 109,000 miles

[portland99intrigue]

Excellent forum here. Thanks in advance for reading my post.

I've read the other threads here about this overheating condition and they were somewhat helpful BUT my problem continues.....please read on.

We have a 99' Intrigue with the 3.5 liter 6cyl engine and 109,000 miles on it. It gets regular 3000 mile oil changes, has had one tranny fluid change in the 2 years we've had it. Both front wheel bearings and outer tie-rod ends were replaced last year. Never had any other problems until now.

WHILE DRIVING, the temp gauge has been floating between 1/2 and 3/4's for about 3 months now and a few days ago it went all the way to the top and the red light came on in the gauge and there was a light clunking or popping sound coming from the engine compartment or center area as heard from the inside. There has been no coolant loss at any time from this car. No oil loss either. No oil in the coolant. No coolant in the oil. No white cloud from the exhaust pipe. And plenty of power! My girlfriend loves this car!

Anyways, after listening to a few local sources including reading posts from this forum, i've changed the coolant temperature sensor (oh, that was fun) and completely flushed and filled the cooling system with a 50/50 mix of Halvoline Dex-Cool. After doing only those two things I still have the same exact problem.

During the coolant change and sensor install there was plenty of orange coolant coming out when I opened the cooling system but only 5 quarts went back in and the reservoir is between the cold and hot mark just like before the overheat problem ever started.

Still have the same conditions WHILE DRIVING: temp fluctuates between 1/2 and 3/4's or slightly more (no red light); same popping/clunking coming from under the hood after driving 10 minutes or so. No coolant leaks anywhere. Upper radiator hose was firm and only slightly squeezable after 40 minutes of city/freeway/neighborhood driving. Both fans coming on and running both high and low at intervals of about 2 to 5 minutes. Opened coolant reservoir very slowly after turning motor off and the coolant came flooding up to almost the top then leveled out at the full hot mark. Then upper hose was soft/normal. Lower hose felt medium, not firm not soft. Reservoir cap rubber seal looks good, is clean, and cap maintains pressure in reservoir.

The engine runs fine, always has.

My questions: Could the popping/clunking be air making its way out of the system?

Could the system have had air in it before and if so, why would it be in there all of a sudden?

How can one be sure all the air is out of the cooling system if there is indeed air pockets/bubbles in there? (i'm singing the "no radiator cap blues")

Could this be the water pump?

Fan/Radiator switch?

Temperature switch?

What are the other possibilities?

I have a new thermostat in my hot little hands and by the time most of you read this, it will be in. (doing this Thanksgiving morning of all times).

Thanks for your help on this. We have no other car and no means to take her into the shop so this is it.

Thanks much for your help.

[kmohr3]

Good luck with your thermostat replacement, I hope it cures your problem. One piece of advice, however - My service manual mentions opening coolant bleeder screws before filling the engine with coolant. I would highly recommend finding the screws and opening them before adding fluid. Some engines can have problems getting the cooling system properly bled, (ie older VW Rabbits and Golfs, Hondas, etc).

I haven't really done anything to this engine yet, so I don't know much else. One other thing, maybe the water pump vanes are rusted down to nothing, or very little. I've seen this happen, but not very often. Can you tell if the coolant has good flow?

Good luck, and report back!

[portland99intrigue]

Where are the bleeder screws? Does your manual show them? I didn't replace the thermostat today because, after removing it, the thermostat is integral with the housing and the parts store sold me the wrong part yesterday. Today being Thanksgiving, it'll be tomorrow until I can git r' done.

Thanks for your help and i'll be sure to report back with my results.

[edit/added on] In answer to your question: I don't think there is any flow and after talking more about this whole thing with friends, we think it probably IS the thermostat seeings how the upper hose was fairly firm, the clunking(clucking actually)/popping sound under the hood was probably coolant boiling and then after I opened the reservoir and saw the coolant rush back in real quick: stuck thermostat, no flow or severely restricted flow.

Originally Posted by kmohr3

Good luck with your thermostat replacement, I hope it cures your problem. One piece of advice, however - My service manual mentions opening coolant bleeder screws before filling the engine with coolant. I would highly recommend finding the screws and opening them before adding fluid. Some engines can have problems getting the cooling system properly bled, (ie older VW Rabbits and Golfs, Hondas, etc).

I haven't really done anything to this engine yet, so I don't know much else. One other thing, maybe the water pump vanes are rusted down to nothing, or very little. I've seen this happen, but not very often. Can you tell if the coolant has good flow?

Good luck, and report back!

[kmohr3]

I'll look at the manual again, but I don't think it shows them. they might be up high - like on the intake somewhere, or on a coolant pipe or housing. Take the upper cover that covers the intake and injectors and look around there.

Make sure you don't mistake the fuel pressure release with the coolant bleeder valves!!!!

[portland99intrigue]

Thanks for checking your manuals for me, I appreciate that very much. I noticed the fuel pressure release yesterday and thanks for the warning. I'll look tomorrow for the coolant bleeders under the cover. I called one local 24 hour parts store here today and all they had to say about the thermostat was "dealer part" so its off the dealership tomorrow. I found a few prices online of anywhere between 20.00 and 60.00 which seems reasonable.

Originally Posted by kmohr3

I'll look at the manual again, but I don't think it shows them. they might be up high - like on the intake somewhere, or on a coolant pipe or housing. Take the upper cover that covers the intake and injectors and look around there.

Make sure you don't mistake the fuel pressure release with the coolant bleeder valves!!!!

[portland99intrigue]

*****UPDATE*****PROBLEM NOT FIXED! 11/26 9:51 PM

Well I spoke too soon. Actually, it WAS fixed I thought. After the initial drive today it was fine after replacing the thermostat but now it is back to the popping/clucking sound under the hood but only at speed on the freeway where the temp guage jumps from 1/2 up to 3/4 and above almost to the redline.

What could be causing this problem? Is the popping sound coolant boiling because exhaust is getting into the cooling system from a blown head gasket or cracked head or block even? We really need help with this to at least know what is wrong, though we have no dough to fix it at a shop. I'm almost sure now that we will need to take it in for a diagnosis so we can at least know what we're up against.
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*****UPDATE*****Problem Diagnosed 11/27/8:15 PM

Had a friend diagnose the problem at his friends shop. They say it is a bad water pump. Said there are metal bits around it, not sure where. No coolant loss though but this is the last part it could be besides a bad head gasket or cracked or warped head or block. They also said it is belt driven. 357.00 to fix with a lifetime guaranteed water pump. We found a way to pay for it over time so no problem there. I'll report back after the work is done.

[portland99intrigue]

Originally Posted by portland99intrigue

*****UPDATE*****PROBLEM NOT FIXED! 11/26 9:51 PM

Well I spoke too soon. Actually, it WAS fixed I thought. After the initial drive today it was fine after replacing the thermostat but now it is back to the popping/clucking sound under the hood but only at speed on the freeway where the temp guage jumps from 1/2 up to 3/4 and above almost to the redline.

What could be causing this problem? Is the popping sound coolant boiling because exhaust is getting into the cooling system from a blown head gasket or cracked head or block even? We really need help with this to at least know what is wrong, though we have no dough to fix it at a shop. I'm almost sure now that we will need to take it in for a diagnosis so we can at least know what we're up against.
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*****UPDATE*****Problem Diagnosed 11/27/8:15 PM

Had a friend diagnose the problem at his friends shop. They say it is a bad water pump. Said there are metal bits around it, not sure where. No coolant loss though but this is the last part it could be besides a bad head gasket or cracked or warped head or block. They also said it is belt driven. 357.00 to fix with a lifetime guaranteed water pump. We found a way to pay for it over time so no problem there. I'll report back after the work is done.

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In answer to a pm recieved on 4/26/05

Quote:
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Originally Posted by Brruaaam
I had the same exact problem w/my intrigue (temp gauge going up to red zone when engine at normal temp, soft popping noise, gurgling water noise, etc.). I had thermostat and sensor replaced. Still had the prob!

Did replacing the water pump fix the prob?
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Our Intrigue was eventually repaired and runs great now......read on:

Actually, we replaced the water pump, thermostat (one piece integral with the housing type), upper plastic intake manifold, spark plugs, coolant temp sensor, serpentine belt, head gaskets and a few other sensors and things just to round out the work we thought would be more intrusive and be like the stuff that'll never get done otherwise. Cost was 1100 dollars total done by a local mechanic who used to work at a dealership but decided he could do better on his own. We obviously could not have gotten a better price and he has a 12,000 mile/1 year warranty on his work as well (in writing and signed).

The REAL fix? The mechanic ended up taking the whole top side of the engine apart, cleaning down inside the engine coolant ports because they were severely clogged, probably caused by the dex-cool. We use the new stuff in there now, can't remember the name of it. He actually did some trial and error first with the coolant temp sensor, then the water pump and so on before finally coming to the conclusion that he would have to take the motor apart in a major way. We also got new fuel injectors as well.

She runs beautifully now and has that roar like she should when you really push her. 0-60 is just awesome and she goes well over 100 without much more effort. We love our 99' Intrigue, goofy engine set-up and all!

[toyotalover]

Had exactly the same issue, same mileage as yours we also found out exactly what caused it. Bad engine design the popping and crackling noise is the head gasket it blows near cylinder 6 even after we had a head gasket replacement it burnt the gasket out again within a few miles. GM forgot to strengthen the block around the head bolt thread, its weak and even though the bolts torque down its not fully flat between the head and block. After a certain VIN # (way up the production line) they made a change by adding some form of steel inserts around the head bolt threads within the block for strength. The Alero’s are the same up to a certain VIN #. The symptoms first seem to start with faint sloshing noise from the cooling system when you first start up then when up to operating temperature it disappears. Eventually it will get to a point where it over heats, it appears this can take many months after first hearing the faint sloshing noise. Basically GM cut the Northstar motor down to the 6 cylinder called it the Shortstar and messed up.

[portland99intrigue]

Originally Posted by toyotalover

Had exactly the same issue, same mileage as yours we also found out exactly what caused it. Bad engine design the popping and crackling noise is the head gasket it blows near cylinder 6 even after we had a head gasket replacement it burnt the gasket out again within a few miles. GM forgot to strengthen the block around the head bolt thread, its weak and even though the bolts torque down its not fully flat between the head and block. After a certain VIN # (way up the production line) they made a change by adding some form of steel inserts around the head bolt threads within the block for strength. The Alero’s are the same up to a certain VIN #. The symptoms first seem to start with faint sloshing noise from the cooling system when you first start up then when up to operating temperature it disappears. Eventually it will get to a point where it over heats, it appears this can take many months after first hearing the faint sloshing noise. Basically GM cut the Northstar motor down to the 6 cylinder called it the Shortstar and messed up.

Well i'm glad you got everything taken care of on yours too. I USED to love the roar of that car but SOMEONE decided she needed a new car so she traded it in. For a Hyundai of all things and to add insult to injury it's a 4 banger! Oh well, it gets great gas mileage and fits her better.

[Jimmy Olsen]

Well guys, I have a different take on the situation. The 3.5L shortstar is an aluminum engine which means that hot coolant causes aluminum ions to migrate from the engine to the coolant which then deposits it in the form of scale which eventually causes the engine to overheat because the scale interferes with efficient heat transfer.

In other words, preventative maintanence is require to power flush with chemicals the aluminum scale out of the interior coolant cavities. I had mine done at 5.5 years or 63k miles.

[kmohr3]

I had my 2002 done at 47K, just to play it safe! It would be a shame to have to disassemble this engine.

[Jimmy Olsen]

Originally Posted by kmohr3

I had my 2002 done at 47K, just to play it safe! It would be a shame to have to disassemble this engine.

Just to play it safe, I change the coolant mixture in the overflow tank once a year to add some fresh additive to the system.

When I had the power flush done at 5.5 years, a close examination of the coolant in the overflow tank showed an aluminum tint to the dex-cool.

When you consider that the a tune-up is only required every 100K miles and the engine has a timing chain, the Intrigue is a fairly low-maintenance vehicle.