LB7 Lost Gallon of Coolant
 

My first duramax isn't going well. I have had to add coolant every time I drive it. Lost gallon in 400 miles. Truck has 191K miles 2003.

First off no coolant leaking on the ground or coming out the overflow vent tube.

When it cools the Upper hose has been collapsed some. System holds vacume even with new rad cap.

system will hold 14 psi with gauge for an hour. Cant find leak anywhere.

Then I noticed water droplets in the oil fill and then I pulled pcv hose and its almost clogged with a gooy substance. So some must be getting into the crankcase.

Now the oil deffently hasn't gained a gallon so I think most is being burned off. The upper hose never is rock hard, no bubbles in the overflow tank. Also checked for exhaust gases in the coolant. was none. also oil look good.

Ive spent days reading on this. But still cant make a decision. Can the injector cups leak coolant into the top of the head? where else can the coolant be going.

Love this site by the way.

The two pics are the goo taken from the pcv hose

Well first it not vaccum on the cooling system its pressure, I would start it and drive and see what your pressure builds up to. Your injector cups are not surrounded by water so no, and since you dont have a gallon of water sitting in your sump, its most likely a head gasket which duramaxs are notorious for.. If you put a gauge on the cooling system and start it and it builds 15psi uber fast you have compression in you coolant, you may not see any exhaust gases because there is very little pressure in the cylinder on that cycle, but where it builds is on the compression cycle, it may not be much but enough to put water in your oil.

Ranchhand, I said it would pull a vacuum after cooling and it would pressure test 14 lbs PSI.

Also the system is not building pressure. Upper house stays soft.

well took valve covers off. Not sure what to do. The top of the heads were clean. But a lot on the covers. Couldn't see any evidence of the cups leaking. All glow plugs had some carbon built up so I don't think its burning it. I cleaned the valve covers off and put all back togather. The PCV system was stopped up completely. I have it dumping onto the ground know instead of the oil pan. Going to drive it for a couple more weeks and keep better track of the coolant lost.

Has anybody had good or bad experience with Blue Devil sealant .

the pics

You are getting water into you coolant, and I appologize for your miss understanding, but if that is what is lubricating you engine at this moment, you will end up with a bigger repair bill. You have to have a bad headgasket. If it does not build pressure what so ever. Have you actually put a gauge on the coolant system at the recover tank? If its not the head gaskets its an oil cooler but you would have a coolant system full of oil if that was the case.

well just giving an update. Still loosing coolant. Pulled valve covers back off and they were covered again. Went ahead and took heads off and sent them to the machine shop to get pressurized. But I didn't really see anything wrong with the head gaskets. One piston was lighter than the others. I don't know whats wrong.

Photos of the pistons and gaskets?

Pic