Low coolant-Leaking head gasket update

[Maverick]

My 3500 has 85,400 miles so far and so far this week I have added 3 quarters of a gallon of Dex-cool. I can't see any visible leaks. The fan seems to run more often than it should. The coolant tank reads low and if I crack the cap it comes up to normal. The light doesn't come on then. I have lost coolant though. Don't know if I overfilled and it blew out or what. It seems there is a vaccum on the system. The coolant will be sucked down in the tank in the morning. The light will come on. I'll shut it off, burp the tank and the level comes up about 2 inches in the tank and restart and everthing is fine.

Question...does it sound like a thermostat problem or some kind of a injector seal thing More Power was talking about? Need help on this one.

[ 08-12-2002: Message edited by: Maverick ]</p>

[Maverick]

Well you can make the mileage to over 86,000.

Come on anybody. I'll take any info. Anybody ever have a coolant leak on their Dmax? Anybody know why my cooling system has a vaccum and not pressure? Why does the coolant go down in the resevoir 2-3 inches when its hot? When its cold it still stays down till I crack the cap. Need help.

[SoMnDMAX]

Jeff, I guess I'd try testing the pressure cap. Sounds like it's malfunctioning, and not allowing the system to vent as it should. Some vacuum build up is normal due to expansion and contraction within the system, and the cap should be able to vent this pressure.

While pressure testing the cap, I would also test the system to see if it will hold pressure for an extended period of time. You may have a waterpump or a hose leaking you may not be able to see. Has the engine oil level stayed consistant? Any milky crud in there?

Any dealer or reputable repair shop (if they have them in AK ) should have the proper equipment to test the system.

[Maverick]

SoMn,
Oil looks good visually and level has not gone up. I'll have them test the cap also. The dealer thinks its a thermostat problem. They are changing both of them tomorrow morn. The system holds a vaccum so I would think it would hold pressure also. You would think anyway. I'll update tomorrow. Thanks.

[ 07-30-2002: Message edited by: Maverick ]</p>

[Maverick]

You can make that mileage 87,720.

The new T-stats did NOT work. Still losing coolant somewhere. Go in Monday again. I hope its not (dare I say it) a head gasket. Maybe I'll get a new engine, eh. Still runs great, just losing some coolant.

[Kennedy]

Oil analysis would be my first course of action, then adding a dye to the coolant would be next. Pumping up with a pressure tester SHOULD show where the leak is. Having water going through that goofy aluminum bellhousing kinda scares me...

Lotsa orings and such to weep!

[Maverick]

They did put dye in it when they changed the T-stats. They use a black light to sweep for leaks. 88K will be my oil change so I guess I could do it Monday also.

[More Power]

A leaky injector cup seal is a possibility, if there are no visible leaks (got to really look hard everywhere on the engine).

If an injector cup seal is leaking, it should be easier for combustion pressure to find its way into the cooling system than for coolant to make its way into a combustion chamber. So, a check for the presense of combustion gases (CO2, CO, etc.) in the cooling system would help determine this. Any well-equipped radiator shop, GM dealership or other garage should have the correct equipment.

As John mentioned, an oil analysis may show a presense of coolant in the oil, if its getting into the combustion chamber. A tiny percentage could get past the rings.

In any event, I would try to get this resolved soon. Even a small quantity of coolant in a combustion chamber during a startup could wreak havoc with the affected piston and rod due to the hydrolock effect.

MP

[BradL]

Maverick,

When I first took delivery of my truck in Nov '00 I had a "mystery" coolant leak coming off/through the aluminum casting off the back of the block that circulates coolant from one side of the engine to the other. I would see coolant dripping off the bottom of the flywheel cover.

When the technicians dropped the tranny, everything looked fine on the back of the motor and the aluminum casting, but when bolt torque was re-checked, 1 bolt out of 14 (?) needed another 1/4 turn. Since then I have had no leaks.

This was a very obvious leak - although I thought it was transmission fluid at first.

[Kennedy]

AVlube (George) has some quick/esy field testing kits available through Mobil.


Another thing to consider, (gulp) is dropping in a couple of "Cadillac tablets" to see if you can stop the leak. Not the proper solution, but an idea nonethless. If it gets to the oil, it can send wear metals through the roof!


I've been chasing weeping head studs on my '96 for some time now, and HOPEFULLY have them stopped...

[Maverick]

Well the leaks been found. A cross over hose just above the injector pump and....gulp.....the right cylinder head gasket. It is leaking on the front side facing the radiator. They pulled the fan, the shroud, and the alt. and bracket to get a better look. The die they put in on Wed gave the leak away. You can clearly see there is sepage. Why me. Truck has just over 88K on it now. They will have all the parts and pull the head and replace the gasket on Mon and Tues. I will have pics of all this when its being done. I seen the leak for myself and it there. Well there are no....my brother friends cousins uncle story here. I have been here to long for that crap. It sucks but thats the way it goes. Good thing I am not over 100K just yet. Maybe in another couple months. Please pray for my fallen hero as he put up a great fight.

[Paintdude]

Glad they found the problem..

I figured it was the Chevy and not the GMC.. [img]smile.gif[/img]

Hope all goes well and they pay for it all..I am looking forward to the pictures..Good Luck..

[SoCalDMAX]

Sorry to hear the bad news... at least it didn't happen at 105k mi. Sounds like your dealer was diligent and resourceful in finding it.

Make sure the clock starts over with a new 100K mi warranty! It doesn't hurt to ask...

Good luck, Steve

[hoot]

Maverick,

Don't worry, be happy. Could have been an improperly torqued head or a bad gasket to start with.

Or, it just plain failed. Take comfort in knowing it's not a common occurrance and when she's fixed it will be just as if it never happened.

[mackin]

Mav,

Sorry to here ...... Will they pull both sides? At least we now it's not BS,waiting to here the full details once you get it back,As to there determination to what went wrong.......

Mac

[Kennedy]

If I may interject BEFORE they start pulling it apart any further.

I think I would be inclined to repair the hose and clean, then pressure test to make sure that the dyed coolant leaking fronm the hose has not simply "channeled" to this location.

Not wanting to sound like I am second guessing the diagnosis or unwilling to admit that a head gasket could fail, but this does seem like a distinct possibility!

[Maverick]

Kennedy,
That was one of the reasons for pulling the front of the engine apart was to make sure it didn't trail to the head. There is no way it could get there(hose leak to the head). It is dry between these two points and well, I'll take pics on Mon. I am going to steam clean both areas well and run it for the weekend. The small hose almost still looks like its leaking. The leak has slowed as of yesterday though, so maybe its only leaking from the head gasket now. They did put my truck back together so I could haul freight the rest of the week. 88,400 miles. I did find out that there are 3 different head gaskets for a Duramax. They are classed as A:No hole B : one hole (My engine) and C:Two hole----There is a oval casting mark on the front of the head. Inside the oval will have no, 1, or 2 circle(holes). This determines the gasket. There are three different thicknesses. Interesting stuff. Learning more everyday.

[ 08-07-2002: Message edited by: Maverick ]</p>

[Maverick]

You can make that mileage 89,931

Anyway, an update. Dropped the truck off at the dealer this morning. New head gasket and other parts are in. Preliminary test on comression is good at 400 for every cylinder. Did a test for emissions comming from the anti-freeze res. Shows there is combustion gases in the anti-freeze. The cooling system is being pressurized by something. The dye in the dex-cool indicated a leak on the right head(pass side). My guess is the gasket is letting combustion gases into the system, pressurizing it and causing another small hose to leak also. The gasket is also letting coolant go to the outside of the head. I do see a light gray haze from the exhaust when at an idle. Maybe dex-cool burning? The dealer had everything off the engine on that side except the head itself. They are hoping to have it done at close of business tomorrow. We'll see. I looked at my glow plugs and the are black and blistered on the ends. They are all the same length. Is it time for new ones? I took some pics but left the digital camera with the tech to take some pics. Gotta work the 2500HD again tomorrow while the 3500 takes a breather. Gotta haul 18,800 incuding the trailer. We'll see how she does. I'll probably get the head gasket pics up on Wed.

Going to bed.

[Maverick]

Well that 2500HD sure doesn't have the mountain pulling power that the 3500 has. This is comparing stock to stock. 3500 has way more power on the hills. Pulled the 18,800lbs just fine though.

Got the head gasket photos up. Sure was a small space to leak. The gaskets are made of 3 thin pieces of metal with a black coating that makes the seal. The black coating is what deteriorated and cause the leak. Hopefully it is fixed for good. Pick it up tomorrow.

Click on photo link below and go to the head gasket albumn.

[konacat]

Thanks for the pictures! Very interesting.