LB7 pressure in cooling system

Snedge

Snedge

Comp Diesel Sponsor
Joined
Sep 1, 2006
Messages
18,886
Have a truck (01 LB7). It builds a huge amount of pressure in the cooling system. Is this a no brainer for head gasket failure? I was thinking these earlier DMAX's had an injector cup issue. Any help.
This truck will build pressure cold at an idle. No Coolant in oil.
Any help would be, well........... helpful.
 
Okay lets try this

If you wanted to talk to a Duromax expert, who would it be?
 
partsguy662 said:
It sure sounds like a head gasket issue to me...
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Well parts guy. Looks like your the expert. Does Napa supply a complete head gasket set for the chevy?
 
Calling me an expert on something may be dangerous to both you and I...:hehe:

There are at least 3 different head gaskets for the Duramax engine, depending on the thickness you need. I have access to the head gaskets, but we'll need to know what thickness you need.
 
I'll look you up then, we haven't gotten that far yet. Really busy with heavy duty repairs now.
This is gonna be a side job and its on the backburner for now.
 
Snedge said:
I'll look you up then, we haven't gotten that far yet. Really busy with heavy duty repairs now.
This is gonna be a side job and its on the backburner for now.
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it's more than likely a headgasket failure. the injector sleeves are installed with a high temp locktite to keep that fom happening, and with them torqued to specs i doubt that the 15 or so psi in the cooling system could lift the injector sleeve up because they are pretty close to being a lapped surface.
 
01 seem to have more common head gaskets go bad. scott, just give him the thickest and be done with it!
 
If the injectors have been replace then it could be the cups. I have seen quite a few leak after the injectors got replaced, seems some dealership guys like to just yank up on the injector when doing the change out with a warm engine. This disturbes the cup and once the loctite seal is cracked it's all downhill from there.
 
Thanks all for the help everyone.
Diesel Tech. I am suspecting the tubes for that very reason. This truck has an injector history. I'll update.
 
I would drain the cooling system then pull all the injector cups making sure to get down in the head where they seal and clean the mating surface well. Then clean the seal surface on the cups or get replacement ones. When it's time to install have everything clean and ready then put the new loctite on the cup seal push into place and install the injector right away and tighten the hold down bolt. Do them one at a time till there all in place. I would leave the coolant out of the motor until the last thing to add and make sure there has been enough time for the Loctite to dry before adding any coolant.
 
Well we popped the tubes out after pinpointing pressure to drivers side. We found no obvious signs of compression past cup. Looks like we're pulling the head(s).
 
Mr. partsguy662 looks like we'll be contacting you. You say you ship direct to our door? Can you save us money too?
 
Snedge said:
Mr. partsguy662 looks like we'll be contacting you. You say you ship direct to our door? Can you save us money too?
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There's a reason they call me the parts jockey...:hehe:

Let me know what you need..Like I said, there are some things that aren't available through me, but I have a few good GM parts connections....
 
Blown gasket

Let me first say that this engine sucks to work on.
We found a bad gasket. Only going to do that side. Did I mention the engine sucks to work on?
I noticed some minor pitting in the cylinders that were running some coolant. I guess the plan is patching it up so the guy can trade it.
Thanks for all the info from the members.
Dieselson, to answer your question. It was not leaking coolant, untill it blew the expansion tank apart.
 
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