2001 GP SE 3.1 slowly Losing Coolant - From Where?

Update - I've been continually adding makeup coolant to the overflow tank about a quart or so a week, and still no indications of any oil contamination or coolant in the exhaust. The leak appears to be limited to a slow leak from the front cylinder bank on the lower left (driver side ) corner that is vaporizing, on a few occasions I have seen and smelled hot coolant vapor over there, and some small wetting of the area on and adjacent to the starter, which appears to be drippage from above. Recently I started seeing the temp gauge spike up to about 210 degrees on initial warm up, and then settle down to maintain about 185 degrees where it usually sits. I did a level check in the radiator itself, and added quite a bit of coolant back in there, now the temp gauge is back to a stable heatup without any big overshoots, and when warm the rad hoses are a lot firmer than they were lately. I suspect that some air may have gotten into the system on one or two occasions where I let the expansion tanks level get too low.

I am going to get an estimate from my indie mechanic on the LIM replacement, however in the mean time I'm thinking of trying out using either Bar's Leaks or Blue Devil gasket sealer treatment of the coolant. I'm figuring that for a relatively slow leak like mine, it might work pretty well. A co-worker had a similar problem on a Mercury Grand Marquis that he fixed with Blue Devil and that fix has held up for about two years now. Anyone here tried these out? I realize that the best way to go will be the gasket replacement, but if I can resolve this with the sealer, I'm figuring why not? After all, they put Bar's Leaks tablets in the coolant right at the factory, at least that's what the techs at my local GM dealership told me.

Another question - at what point do the 3.1 SE (with A/C) radiator cooling fans come on? Most of my other cars have had the fans kick in and run continuously whenever the A/C mode is selected, and if the A/C is off, they will kick on if the coolant temp gets to a certain (usually a good bit higher) temp above the T stat setpoint. In the past I have turned on the A/C mode to start the fans to knock down the coolant temp if I've seen it creep up, typically if I'm stuck in traffic. When I tried that the other day when there was some temp spiking before I refilled the radiator, the fans did not come on. Perhaps because the outside air temp (about 20 degrees) was too cold? Before I put in the sealer and let the car sit at idle for about an hour afterward while the stuff sets up, I want to be sure the fans are in fact working properly . Will do a extended idle warm up test beforehand of course, but still would like to know the normal fan on and off setpoints.

if your a/c works, the fans come on with the a/c and stay on the whole time. till the a/c is turned off.

if the a/c is not working, aka no cold air, the fans will not come on at all when the a/c is turned on.

fans wont come on till the temp reaches 212 in a 3800 not sure if thats the same for a 3100 or not.

I am not a fan of "stop-Leaks" added to the coolant. They are generally a band-aid fix that can cause other problems, like plugging radiators and heater cores. Keep an eye on your coolant level(as you are) and your temp gauge. All a 3100 has to do is overheat once and it will blow the head gasket and most of the time the head cracks.

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if the a/c is not working, aka no cold air, the fans will not come on at all when the a/c is turned on.
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What about being in defrost mode with the temp set to max heat when I manually turn on the AC with the push button switch, and the AC mode light comes on, shouldn't the fans come on then?

only if the a/c actually woks.

if the a/c works the fans should come on with defrost on.

[QUOTE All a 3100 has to do is overheat once and it will blow the head gasket and most of the time the head cracks.[/QUOTE]

Define overheat _ I have never seen the gauge go over about 200. It has only has gone there for a few seconds at a time on a few spikes on heatup when the t stat apparently opened

over heating is when the temp hits the red, then engine fights to run and may even ping like mad before it stalls out. and then there would be steam as well cause most of the time the leak is forced to leak.

The ac compressor will only run is it's above 37-38* or something like that. So your fans won't come on if the compressor doesn't run.

my a/c compressor turns on with any heat setting at any outside temp. this is why i pull the relay every winter.

Quote:

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Originally Posted by Scottydoggs

my a/c compressor turns on with any heat setting at any outside temp. this is why i pull the relay every winter.

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Well, I did an extended idle test with the A/C on, set to max cold output, outside temp was about 27 F. Compressor would occasionally cycle, both fans ended up cycling along with compressor, and/or between on at about 185 degrees indicated on the temp gauge, and off at around 172 F. I checked the temp of the T stat outlet housing next to the engine side end of the upper radiator hose with my Ryobi IR/laser temperature scanner and the temps there tracked very close to what was indicated on the dash gauge. Car appears like it can idle forever at about 175 degrees like this. I didnt try a run without the A/C turned off yet to see where the fans cycle in the A/C off modes.

I would not pull the A/C relay like you do, the compressor should be run every once in a while even in winter to prevent its shaft seals from leaking. That's why many cars turn on the A/C mode automatically whenever you go to straight full windshield defrost mode (At least most Fords do). On my GP SE, it looks like you have the option to run full defrost with or without A/C, i.e. you have to press the A/C mode button to allow the compressor to run. Not clear why yours would run all the time in A/C mode unless the A/C mode push button was stuck on...I believe it only is forced on in the MAX A/C position, the other positions require using the A/C mode on off button.

BTW, during the extended idle check, I held a paper towel in the exhaust stream at the tailpipe for a few minutes, it got barely damp from the very light exhaust water vapor present in the cold air, absoulutely no indication of anti freeze smell or carryover into the exhaust there.

Quote:

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Originally Posted by AJ1G

BTW, during the extended idle check, I held a paper towel in the exhaust stream at the tailpipe for a few minutes, it got barely damp from the very light exhaust water vapor present in the cold air, absoulutely no indication of anti freeze smell or carryover into the exhaust there.

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Stonington.......Isn't that the home of Foxwoods? I used to visit that years ago. Beautiful place.......sorry for the sidetrack.

Foxwoods is the Mashantucket Pequot Indian Tribal Nation's Resort and Casino, located on their lands about 8 miles north of Stonington.

8 miles.....I knew it was close.......

Well, I rolled the dice and put a bottle of Blue Devil White Label Pour-N-Go Head Gasket Sealer in this afternoon. Followed the directions to the letter, actually took more like three minutes vs. one to slowly empty the bottle contents into the radiator, gave it an additional half hour or so at idle beyond the recommended 50 minutes. No indications of any heater core or rad clogging, all temperatures totally normal during the post fill idle session and a later (after letting things cool off and topping off the system) half hour test run on I-95, including a "hot soak" after a high speed run on the interstate going through a drive in at the Dunky's in Mystic. Ran in A/C mode during the post fill extended idle, the fans cycled between 185 and 175, maybe a 50% on duty cycle. Ran with the A/C off on the test drive, again, all temps totally stable and normal. One thing I have noticed is that the rad hoses are a LOT firmer now after the treatment, more like I would expect from a tight system than I have been observing lately. Also don't smell any significant amount of coolant in the engine bay like I have been noticing of late. Keeping my fingers crossed that the fix has actually "taken" and holds.

On an emergency 30 mile high speed run tonight from my son's house to the nearest Veterinary Emergency Clinic with my wife, son and a very sick beagle, the car ran great. The pooch is now OK too!

Engine temps and heater function were totally normal.. So far so good on the expansion tank level too.

Well, its been two weeks, and while I can't say I am losing NO coolant...its WAY better than previously, I have only had to add maybe a half pint of so once or twice. Expansion tank level generally staying right where it should be as long as I do my daily commute, where I start up, get on the highway quickly, and then park. Whee I lose some it is when I am driving around town with frequent startup and shut offs. Still see a little wetting above the starter, but the rad hoses are VERY firm now, no significant hot coolant smell under the hood any more, and notably less white exhaust vapor, even though there never was any coolant smell there in the first place.

But I am going to pull the trigger on the gasket repair. Not sure how long the band-aid from a bottle fix will last. My local indie mechanic will be doing the LIM replacement gaskets in a week or so, he's done a lot of them and has given me a reasonable estimate for the work. Will also have him do new plugs, I suspect I am still on the originals at 94K now. Whats the preferred plug for these engines? What one are to be avoided?

BTW, for whatever reason, ever since I put in the Blue Devil stuff, my COOLANT LOW warning light has cleared, and its not just due to an improper coolant level in the radiator. That has always been full, and the light started acting up way before I was actually losing coolant. Maybe some of the Blue Devil sodium silicate is now deposited on the sensor, and it's going to indicate OK regardless of the level.

Well, the Blue Devil lasted about 7 months, until shortly after I replaced the water pump due to a small leak I had noticed that was causing coolant scum to collect on the lower radiator hose after being flung off the pump, it was causing me to lose about a pint of coolant a week. After I replaced the pump there was a notable increase in system pressure, based on the how tight the rad hoses felt after warmup, apparently due to getting rid of the slow leak on the pump. All was well for about a week and then the floodgates let loose from the LIM, same leak as before, off the left side of the engine down onto the starter motor. Curiously, after a few days the leak tightened up again, no leakage for a few days and then back to Grand Prix Valdez. Finally had my mechanic do the LIM gasket replacement and all is well. It never leaked anywhere except out of the engine, never got into the oil or as far as I can tell, into the exhaust. I did end up replacing a clogged cat in April, which brought back all sorts of power I never knew the engine had, but it's not obvious that the clogged CAT was due to coolant, there has been no indication of any of that with the new cat after about 10K miles. While the car was in the shop for the repairs, I rented a new 2014 Dodge Charger SXT with a 3.6 V6 from Hertz for a few days. Great car, really fast, and nearly 33 MPG average at highway speeds, simply amazing from a 300HP 2 ton car, must have been the 8 speed auto tranny! Anyway, after I got the GP SE back, I was impressed how favorably it drove compared to the SXT. Obviously not as smooth shifting, but almost as quick on acceleration!

So its been almost 6 months now since the LIM gaskets were replaced. All is well, just added a few ounces of coolant to the expansion tank to bring the level back to where it was six months and about 7K miles ago! Car has run really well ever since. Next project - replace the rotted rocker panels when it gets a bit warmer.

Not clear if it was related to the LIM gaskets, but I have not had to add a drop of oil between changes since the gaskets were replaced. Used to go through a quart every 2K or so.