Desperate need of sound opinion.

[DURAMAN]

I've been struggling to figure out what's wrong with my truck and have come to a conclusion that's not making me happy. Here's the deal - I have an 02 6.6 w/80,000 on it, no mods. I parked the truck one night and noticed antifreeze running out the overflow tube, over heated I assume. Got up the next morning and drove to town. Engine would not heat up past about 165 degrees and no hot air, thermostat I assumed stuck wide open. Replaced both t-stats, flushed cooling system, bled the system. This was good for about a day and then began to notice hot/cold from the heater. Engine temp normal. I thought I may have had some air left in the system so rebled the system. Good again for a day and then hot/cold from heater again. Repeated bleading several times since. Still hot and cold coming from the heater and low coolant light on. All I'm left to conclude is bad head gasket. Could anything else be dumping air into the cooling system? Suggestions please...

Thanks,
Shane Weber

[Mark Rinker]

Sure sounds like a head gasket problem. At least you are well under warranty if it is. However, head gasket problems aren't common, so look for the simple first!

1) Try replacing your overflow tank cap. If it is plugged, the system could be overpressurizing, forcing coolant past the waterpump seals into your engine oil. It is gear driven. They are $8-$12 at the dealership. Are you 'making oil' on the dipstick?

2) Which leads me to the waterpump. Many fail slowly and lose coolant only when under load and while underway. I saw very little coolant leaking from the pump, but had constant coolant loss which had me worried about head gaskets as well.

3) It takes awhile for these coolant systems to eliminate air after being opened up. You may simply be dealing with issues of air introduced into the system from the thermostat replacements. My '01 acted funny for a full week after the waterpump was changed at the dealership - coolant smell, level drop, etc. I was convinced that I had a head gasket problem the whole time, but it worked out to be trapped air and/or a bad cap. I've replaced both caps on both trucks with new OEMs and tossed the originals, which still appeared to be fine.

Good luck, let us know what happens!

[SoTxPollock]

Mark pretty well covered it, just be sure you followed the book about reving the engine to clear the air out of the system, I ran mine at 3000 for about 5 minutes and it blew all kinds of air out before it finally settled down. Once it stopped I tightened the cap and haven't had a problem since.
Sorry to hear that the water pumps tend to fail, even slowely. I'm probably going to regret not putting a coolant filter on one of these days.
I'm changing coolant every 3 years regardless of mileage and using distilled water. Maybe it will last a little longer that way.

[DURAMAN]

Bad news. Dealer is pulling the heads off as I type. I asked them to look close at the injectors while they're in there. I was surprised when he told me the 01 - 03 injectors were warranteed for 7yrs or 200,000 miles.

Two questions - First, what else should I have done while she's torn apart? Second, what are the odds they'll put it all back together right and not cause any additional problems?

Thanks for your help!
Shane

[Mark Rinker]

At 80K - probably nothing that needs proactive replacement.

[DURAMAN]

In case anyone is interested... The dealer said the injectors were all plugged as well. Not sure why. I run injector cleaner thru quite regularly.

[mark45678]

In case anyone is interested... The dealer said the injectors were all plugged as well. Not sure why. I run injector cleaner thru quite regularly.


You should feel lucky the dealer is doing this, most of them would send you on your way only to have a failed injector next week ! Plus the dealer gets paid more labor hours to do the same job so in the end you get a good job and a great running truck. The post ^ hith the nail right on the head dont leave dexcool in any car or truck for more then 2~3 years !Converting to green old school is a good idea if your out of warrenty . Water flush 2 or three time and refill to 50% green/distiled water.NEVER MIX green and dexcool you will end up with a semi solid goop in your cooling system.

[DURAMAN]

Now wondering if I should have the dealer do the glow plugs as well. It may be a little soon, but don't they need to be replaced at 100K anyways??

Shane

[colt49]

I once had a blown head gasket on my Datsun. Similar with aluminum head for the example as Duramax components are aluminum. The antifreeze raised the oil level and it was blowing steam as I ran it into the dealer for a warranty repair situation. The motor was only ran about 20 miles and had the anti freeze/oil mix for 1 day it was drained being radiator and engine at once. The dealer put in new detergent oil afterwards and let it sit overnite and did the removal/repair next day. The mechanic had me look at the bearings and valve train after the short time of exposure and it was already corroding the internal metals in that engine. He said sell this fast unless you replace it and keep it. I just did the fast warranty repair and traded it 2 weeks afterward on a new Jimmy. We could not believe the degree the antifreeze attacked the metals like that. I guess that was our lesson. It was just a bad gasket with a very limited defect actually in that engine line. The engine did have a backfire situation that I could not duplicate for the service manager that is what created the blown gasket from the tremendous internal pressures. What a loss we took on that vehicle in the trade in to get it gone. It was best moved out that way for our replacement as we believed the bearings and crank failure was a real problem and the added expense of another engine was to much to tolerate. The compression of a diesel is double/plus that of the gas motor we had so I would really wonder how much increased compression would hasten bearing fatigue/failure in the diesel after antifreeze got to the internal components of the high tight tolerance areas. It may operate fine if it's repaired quickly in the Duramax situation.

[JoeyD]

After you get it back do a few oil samples on it to see whats going on inside. If the bearings are worn due to the antifreeze it will show it.

[More Power]

I recommend replacing the coolant surge tank cap whenever the water pump has been replaced due to leaking seals.

Overpressurizing the cooling system, due to a head gasket or cup seal problem, puts more stress on the water pump seals. I've heard of a couple water pumps that began leaking not all that long after a head gasket problem. In any case, once the problem has been resolved, replace the coolant surge tank cap...

I recommend keeping Dex-Cool in the cooling system. It lasts longer, transfers heat better, and offers better corrosion resistance as long as there isn't any air in the system. :)

Jim

[madmatt]

A blown head gasket doesn't always equal coolant in the oil. Do you have reason to believe you had coolant in your oil??? If not I'd just change it like should be done after the repair anyway and run it w/o worry. Injector cup seals if failed can also allow combustion gases to pressurize your cooling system. Head gaskets alone are more likely though.