Head Gasket or Injector cup? Once again

[KenZ]

I know this has come up quite often and read a lot of the posts, but just want to see if anyone has any thought on my situation. 2002 Duramax. replaced the heads, (using ARP studs) injectors, head gaskets about 85000 miles ago. Truck smoked at idle before the job and I didn't have an injector problem such as cracked or leaking, but changed them when I put new heads on due to blown head gasket and warped head. I did both sides. The truck ran ok, but the smoke at idle never went away. Didn't use much oil and water level didn't go down for 80000 miles. Then I noticed I had to add a little coolant from time to time. Not much. Took a trip to CO back in October and on the return trip something changed and started to blow out the coolant at highway speed. Couldn't notice any bubbles at idle. Made it back home (after 1500 miles driving and stopping to add coolant quite often), and the next day noticed the dreaded bubbles in the overflow tank at idle, which got more violent and blew a couple of gallons out at idle. I will mention that half way home a leak developed in the oil cooler gasket and coolant was leaking on the ground from that. I believe the pressure in the coolant system blew that out, so I left the radiator cap off to avoid a pressure build up. I did change the oil cooler and and gasket and no leak there now.

So now I'm faced with the decision on direction and cost. I really don't know why a head gasket would have blown and thought the ARP studs would have taken care of that problem. The new heads had the injector cups installed when I got them, so I didn't fool with them. I hate to replace the injectors because I don't feel like I got the life out of them and not having any problems, but If I get into the heads, should I just bite the bullet and replace them again? I'm still not sure of the reason for the smoke in the exhaust. Could I have had a leaking gasket or injector cup all along?

Where do I start? Any way to determine which side the problem is on? Then before I pull a head, or both heads, is there a way to determine if it is the head gasket for sure or an injector cup. If money was no issue, I would just replace the heads, gaskets, injectors etc or get a replacement engine. However don't have the $$ right now to do that.

I'm also wondering if the smoke is related to the rings. This truck did have early injector failure and was leaking diesel into the crankcase. At the time GM couldn't get the injectors and told me to just drive the truck that way. I avoided that as much as possible, but don't know how many miles were put on it with diluted oil.

Everyone says the smoke indicates bad injectors, but it acted the same way after the replacement injectors as before.

Any thoughts? Thanks, in advance.

[More Power]

Ken, The amount of combustion pressure finding its way into the cooling system says to me that a head gasket(s) have failed. An injector cup leak typically produces a lot less over-pressure in the cooling system.

As for determining which side the problem might be on, you could look at injector balance rates to get a hint (weak cylinder = more fuel). And, you could have a compression test performed. If the head gasket leak is as bad as you say, it should show up in a cylinder compression test. The smoke you're seeing could be related to a low combustion pressure for one of the cylinders. Have the injectors tested when you have the head off. Jim



I know this has come up quite often and read a lot of the posts, but just want to see if anyone has any thought on my situation. 2002 Duramax. replaced the heads, (using ARP studs) injectors, head gaskets about 85000 miles ago. Truck smoked at idle before the job and I didn't have an injector problem such as cracked or leaking, but changed them when I put new heads on due to blown head gasket and warped head. I did both sides. The truck ran ok, but the smoke at idle never went away. Didn't use much oil and water level didn't go down for 80000 miles. Then I noticed I had to add a little coolant from time to time. Not much. Took a trip to CO back in October and on the return trip something changed and started to blow out the coolant at highway speed. Couldn't notice any bubbles at idle. Made it back home (after 1500 miles driving and stopping to add coolant quite often), and the next day noticed the dreaded bubbles in the overflow tank at idle, which got more violent and blew a couple of gallons out at idle. I will mention that half way home a leak developed in the oil cooler gasket and coolant was leaking on the ground from that. I believe the pressure in the coolant system blew that out, so I left the radiator cap off to avoid a pressure build up. I did change the oil cooler and and gasket and no leak there now.

So now I'm faced with the decision on direction and cost. I really don't know why a head gasket would have blown and thought the ARP studs would have taken care of that problem. The new heads had the injector cups installed when I got them, so I didn't fool with them. I hate to replace the injectors because I don't feel like I got the life out of them and not having any problems, but If I get into the heads, should I just bite the bullet and replace them again? I'm still not sure of the reason for the smoke in the exhaust. Could I have had a leaking gasket or injector cup all along?

Where do I start? Any way to determine which side the problem is on? Then before I pull a head, or both heads, is there a way to determine if it is the head gasket for sure or an injector cup. If money was no issue, I would just replace the heads, gaskets, injectors etc or get a replacement engine. However don't have the $$ right now to do that.

I'm also wondering if the smoke is related to the rings. This truck did have early injector failure and was leaking diesel into the crankcase. At the time GM couldn't get the injectors and told me to just drive the truck that way. I avoided that as much as possible, but don't know how many miles were put on it with diluted oil.

Everyone says the smoke indicates bad injectors, but it acted the same way after the replacement injectors as before.

Any thoughts? Thanks, in advance.

[Kennedy]

Tough position to be in for sure. In my experience, a properly done head gasket job with studs will not repeat. properly done is skim cut the head surface and hand clean only on the cylinder deck. I also have never seen a cup just start to leak after time.

The unfortunate part of the LB7 head gasket job is that it really is best to include and injector job at the same time unless the injectors are VERY low miles and in many cases the lines and bowls are corroded again anyhow.