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Discussion Starter #21
So, for anyone also interested in following my coolant problems, I had a new issue come up with my engine getting really hot now. The leak is gone, so I don't want to continue putting it in this thread and I found a thread that will hopefully be a better place to explain the issues. You can read my update here as well as hopefully, if you have the time, leaving your advice because I am just lost now... I am glad the leak is stopped, but now i'm a bit upset because I don't know what I did wrong.
 

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Not sure if replying to that old thread will work so I'll also post here.

Don't mean to insult but, is it possible that you installed the thermostat backwards ? The side with the spring needs to point towards the engine.
 

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Discussion Starter #23
So, for everyone here that had helped me before i swapped it over to the other forum listing for a related but different issue, I would like you to see this. I made the final posting on the other page, but i wanted all of you who helped me get to where I am now to be able to see it too. Thank you all!
 

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I think I’m having the same problem. Coolant leaks every where, all the time. Replaced hoses and T joint coming from the reservoir, then found a hole in the T joint a week later. Fixed that again, next it was a leak in the brand new hose. Ugh.
One thing I’ve been having trouble with is that occasionally, my car will shift super hard, almost like if you were driving a stick and hadn’t let the clutch out all the way... it jerks a bit. Additionally, all my warning lights come on (including low fuel), all the gauges drop to 0, and the speedometer reads “error”. Please tell me this is a related issue and not electrical. I can’t really afford to fix both the coolant crossover and the computer right now. I’ve suggested to my shop and my mechanically inclined assistant that I worry there could be a head gasket leak, but both insist that the car wouldn’t be drivable at all then.
Has anyone else had the gauges/warnings/shifting issues with the coolant stuff?
 

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The hard shifting often indicates the transmission has gone into limp mode. When it happened on mine, restarting the car would usually clear the issue and it might re-occur less than once a month. I decided to put in some Seafoam Trans Tune and about a week later I changed the transmission fluid and filter. In my case the problem has not re-occurred. I believe the transmission can also throw diagnostic codes. I am not certain of this but I believe some of them require a more advanced scanner to retrieve them. If you know someone or if you local auto parts store has one, they may be able to read it for you and this may provide more of a clue.

The gauges and transmission limp mode may be related if you are having communication issues with the various control modules. There are a number of people who have had some success adding dielectric grease to the large connectors on the Body Control Module under the plastic panel in front of the passenger seat. More info mentioned in this thread

Hope you get it fixed.
 

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Discussion Starter #26
could be a head gasket leak
So, downside to my success story above, turns out it's having issues again. I drove it to work and then on the way home, I checked the fluid levels to make sure it had coolant, and I realized I had never put the coolant cap back on. It drove all the way to work just fine, so i shrugged it off and drove home, but less than 2 miles down the road, it shot up to hot temps again and I decided to pull over and limp it all the way home. It seems like the exact same issue came back where air had entered the system, likely from the coolant cap being open obviously, but when i did the vacuum test again, I saw more damn bubbles, so I decided to replace the tee fitting below the coolant tank that everyone mentions. Mine seemed fine, but i replaced it anyway and then retried the vacuum with no degree of success. Still pulling bubbles up from the bottom of the tank somewhere. The first test did that too, so i tested it again and it still got hot. Unless anyone else has any great Ideas, I am considering taking it somewhere and doing a coolant pressure test or a cylinder leak down test to see if the headgasket is leaking.
 

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If you could rent, borrow or build a smoke tester you might be able to identify the source of the leak in conjunction with the vacuum test. I would not recommend anything flammable, just to be safe. Otherwise a pressure tester and some spray soapy water may well work (if the water squirts out it may be even easier to identify with this method). Hope you find it.
 

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If you could rent, borrow or build a smoke tester you might be able to identify the source of the leak in conjunction with the vacuum test. I would not recommend anything flammable, just to be safe. Otherwise a pressure tester and some spray soapy water may well work (if the water squirts out it may be even easier to identify with this method). Hope you find it.
 

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Discussion Starter #29
in conjunction with the vacuum test
How would the smoke tester work "in conjunction with the vacuum test"? Sorry, I'm not the most knowledgeable, but I'm unsure how that would work. I was under the impression that the best options i currently had were to do a coolant system pressure test to try and pressurize the system (instead of pulling an incomplete vacuum) and see where the leak forms at. But, I'm unsure how exactly I would do that, and what i would be looking for besides the obvious jet of coolant from a split hose etc. Like, if you do a pressure test, wouldn't a leaking head-gasket then cause the coolant to dump into the head with a pressure test? That is why my other thought was a cylinder leak down test because it checks the head gasket from the cylinder side, not the coolant side. Then again, the only real reason i'm focusing so hard on the head-gasket is because it's not leaking any puddle or drops where it's parked, so my thinking is it must be internal somewhere where the leak occurs. It also seems to only "take-in" air into the system now instead of drain coolant out of the system. Before it was draining coolant from crossover pipe, leaving a drop and being mostly obvious to see (after a cleaning), but now it's not "losing" coolant, and is just letting air into the coolant system when I pull a vacuum which I believe is stopping the vacuum from adequately removing the "air dam" that is causing my high temperature spikes.
 

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The vacuum will be pulling air into the system as you mention. The hope is that the smoke will flow to where the air is being pulled as you move it around and thus show you where the air is getting in. The pressure test would be the reverse, air or steam leaving the system.

The coolant you are losing may be evaporating on hot engine parts. Head gasket issues are often accompanied by a white smoke or milky oil cap.

Another area to check is the plastic return hose connector. It sits above the water pump and has an extended diamond shaped base with two bolts and a black metal tube that runs across the front of the engine. Mine leaked here and left a pinkish residue from the evaporated coolant. There is an O Ring on the plastic part that goes into the engine. Replacing the part did not work for me, I still had a leak. In the end I used some radiator gasket seal on the diamond shaped base to seal it to the engine, That solved my leak.

If you want to try the replacement part route, the part number was 12592926 for my 2007 3.5. It is the complete plastic riser with o-ring. I could not find a part number for the o-ring itself, but you may be able to measure it or find one at a hardware store. There is also an o-ring on the metal hose connection - I added some silicone grease to this. The gasket seal may be a cheaper and easier bet.

Found a picture...
17787
 

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Discussion Starter #31
The hope is that the smoke will flow to where the air is being pulled as you move it around
This makes way more sense now that i read it this way. I didn't think to create a vacuum and then just "wash" the engine in smoke to follow it to the leak. This will help with an external leak for sure, but I don't think this would help with a head gasket leak if it's leaking into the cylinder, but, either way, definitely worth the attempt since i have a smoke can already at the house (my mechanically savvy room mate's).

may be evaporating on hot engine parts
Good point, I hadn't considered this...

plastic return hose connector
I had noticed this piece when I was doing the crossover pipe/water pump/thermostat, and I replaced the o-ring for where the metal pipe sockets into it, but I never messed with the larger o-ring, so that's another potential cause of the issue.

I'll show this all to my room mate and see what they think, but I'm not sure when we'll tackle this again. It's kind of just beaten my spirit into submission, so yeah. Who knows, might be something we can do soon, at least the smoke+vacuum combo test.

Thanks for all the help!
 

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Discussion Starter #32
So, I couldn't end up trying the smoke test since I don't have 2 air hoses or a splitter or anything of that nature, and I've kind of just gotten fed up with it. So, I'm sending it to the local dealer Monday to have them take a look at it and tell me what's wrong with it. I'll keep you all up to date with updates when i get them.
 

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Discussion Starter #33
It's finally fixed. I guess, according to the GM guy, I had a "Absolutely massive air pocket in the engine somewhere" and anyway, they pressure tested it and did all the testing, there's no leaks to the system, it just needed to keep sucking air i guess. Anyway, they fixed it and re-did the coolant in the system, so that's good. All seems to be good for now.
 
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