Pontiac G6 Forum banner

Losing a LOT of coolant, no idea how or why. Help?

12K views 37 replies 12 participants last post by  Smiley419 
#1 ·
Nuptup here with a problem...

So, I finally got my big issue fixed with the Driver side window of my '06 GTP Convertible, then fixed my leaking Power steering pump, and now I have noticed that I am putting a LOT of coolant into the car. When I got it back from detail to look for my leak and found the power steering leak, I also noticed it was not at a good level of coolant. So, I put nearly a half-gallon into it to bring it up to the cold fill line (It was really low...). I fixed the power steering leak, then took the car for a test drive. It seemed like it drove fine, so I parked it and called it good.

The next day, I was going out with some friends to take some photos of our cars, and before leaving I checked the engine bay for leaks just to make doubly-sure that my power steering was fixed, and it was, so I was about to close and get ready to go. But then i glanced at the coolant reservoir and it was well below the cold fill line again. So I put even more into it, this time going about an inch over the cold-fill line and taking the bottle with me because I would be out for a much longer time than the previous test drive. I drove it all day and then parked it at home last night.

I checked it before heading to work today and it was back down to just below the cold fill line. I was in a rush, so I didn't fill it back up and am going to check it again tonight before leaving work. (at work currently), but I am just tossing this out there to any of you guys for advice or suggestions on where to look for a leak or if it's burning coolant or anything like that. I feel like in the past 4 days I have had to put entirely too much coolant into it, and I am not seeing a leak anywhere under the car. Like, no puddle or anything. I am stumped and really don't know what to do.

Any advice before I take it somewhere to get looked at would be great!
 
See less See more
#3 ·
So, as a minor update, I drove it to work last night and it ran fine the whole drive, I parked it and went inside, expecting that I might have to put some coolant into it when I get off work. Anyway, I went outside to the car after work and saw a note on my door that pretty much said "Yo, all your coolant is on the ground, good luck." and lo-and-behold, all my coolant was on the ground. I'm hoping it's not a head gasket and is instead just the water pump as some people have said. But, it's currently at the show and they'll be looking into it tomorrow morning to tell me what it is that busted.
 
#4 ·
Another update, the shop did a test for me and found that the "Water cross-over gasket(s) between the heads" blew out and needs to be replaced. Can anyone give me any kind of advice on how big of a task that will be? The shop wants more than I would rather pay, so I am trying to find out what I'd be getting into to tackle it myself.
 
#7 ·
I've done the coolant crossover gaskets. The first time they can be a bear. Almost everything comes off the passenger side of the motor.
Alternator, pulleys, hoses (heater, coolant vent pipe at the top), the whole motor mount, airbox, air intake tube all have to be removed. All the tools are common (a factory hose clamp tool helps a lot) as well as some open ends and some deep sockets for the rear bolts near the alternator. Some bolts go into the back of the engine and hold the alternator on.
If you are good with taking motors apart it's a 4 hour job with about $60 in gaskets and some antifreeze. Also a good time to change the water pump if you have not yet done so, it will be easy to see and access.
If you have specific questions let me know.
The first time the gaskets went bad the dealership changed them under warrantee. A year later the warrantee is up and they leak again. Find out after I am about to remove the crossover tube that the dealership forgot to tighten the bolts, they were all finger tight and that caused leak #2... Just one of many bad dealership stories.. unfortunately.
 
#9 ·
I've done the coolant crossover gaskets. The first time they can be a bear. Almost everything comes off the passenger side of the motor.
Alternator, pulleys, hoses (heater, coolant vent pipe at the top), the whole motor mount, airbox, air intake tube all have to be removed. All the tools are common (a factory hose clamp tool helps a lot) as well as some open ends and some deep sockets for the rear bolts near the alternator. Some bolts go into the back of the engine and hold the alternator on.
If you are good with taking motors apart it's a 4 hour job with about $60 in gaskets and some antifreeze. Also a good time to change the water pump if you have not yet done so, it will be easy to see and access.
If you have specific questions let me know.
The first time the gaskets went bad the dealership changed them under warrantee. A year later the warrantee is up and they leak again. Find out after I am about to remove the crossover tube that the dealership forgot to tighten the bolts, they were all finger tight and that caused leak #2... Just one of many bad dealership stories.. unfortunately.
So, I personally am still an automotive novice, but I am learning with each problem while my more experienced friend has been helping me with everything. I am debating on leaving something like this up to the shop though because it seems like a whole lot of work and i really don't want to mess something up. However.., I also really don't want to pay around 400-600 in shop labor, and paying retail+mark-up for parts. So, I might just tough it out and learn the gruelling way what makes it so hard.

Unfortunately that's a very common place for a coolant leak. What engine do you have in that GTP?
It has the 3.9l v6. And, honestly, that really sucks that it's common. But, I figure I may as well try and learn it eventually. Otherwise anytime it repeats itself, I have to shell out the dough again. However, it is pretty nice that the shop offers a 2-year/24k warranty on parts and labor. But, still, that's a lot of money...
 
#10 ·
I, also don't mean to dump on your garage/mechanic, but......????? I had this problem also, and it wound up being the plastic "TEE" right under the resevoir. It was cracked, but you couldn't see it because the crack was actually inside the hose. Just don't want you to spend unnecessary $$$$$ for a $10.00 plastic TEE.
 
#11 ·
This might be a good repair for you to learn on, all of the parts you will be working with are pretty hefty and you are not likely to break anything accidentally. The only part that has a critical torque is the crossover tube which is more like an aluminum engine accessory bracket with a water tube in it.
Buy the Felpro replacement gaskets, I've had better luck with them vs the stock Victor Reinz gaskets.
One of the harder parts is getting the 10+ year old hoses off the crossover tube assembly, go on amazon and buy a factory hose clamp tool and what's called a "hose pick", it will save you from damaging the heater hoses and a lot of time/scraped knuckles.
Also you can leave the heater hoses on, pull the cover an inch away from the block, pop the old gaskets off (they have an aluminum "frame") and slip the new ones in and hold them in place with 2 bolts. The gaskets have little "tabs" that stick out past the crossover tube so you can align them. This will make ZERO sense until you get there and see it. I did this the first time I changed them. Second time was when I did the intake gaskets and the crossover tube had to come out anyway...
 
#12 ·
Good tips in here for replacing the crossover manifold gaskets. Only one I have to add is - make sure you're using a torque wrench for the fasteners. Without one, it is easy to crack the aluminum manifold. Also ensures that you get even distribution across the gaskets, and prevents premature failure. Also very important to ensure that your gasket surfaces are clean and dry. This will make for a much better seal.

Another tip - you will need to remove the water pipe that runs along the front of the engine to the coolant manifold. There is an o-ring seal in there that can tend to leak. I would replace that o-ring while you have it apart. Part number is 98553MP (AC Delco).

It's honestly not a bad job. Take your time and do it right. If you like, I can post the Alldata procedure here for you. Just let me know!

Mike
 
#13 ·
It's honestly not a bad job. Take your time and do it right. If you like, I can post the Alldata procedure here for you. Just let me know!
Yeah, I kind of decided to take it up a level. I've decided to do this, the water pump, the thermostat and the radiator upper and lower hoses all while i'm in there. I have the alldata sheets as well since a friend works with them daily and shared a log in with me. Anyhow, I want to say thanks to everyone who replied. I genuinely appreciate all of the helpful advice and want to thank you all!
 
#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.
 
#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!
 
#24 ·
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?
 
#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.
 
#25 ·
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.
 
#27 ·
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.
 
#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.
 
#28 ·
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.
 
#30 · (Edited)
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
 
#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!
 
#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.
 
#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.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top