So I blew a head gasket, now what to do

[nyford]

So how common are blown headgasket on realitively stock trucks?

I am pushing 30 psi of boost and the gasket gave up between cylinder 5 and 6. I have only done minor tweets to the pump. This is on a 89 truck. Turbo is a h1c with a 12 cm housing running through an intercooler.




Also how common is the cracking between intake and injector holes? It looks like #5 in cracked between them. I now on my VW's it is very common and does not typically effect anything.

Sorry for the newb ?'s Just want to get the truck up and running again.

[nyford]

Forgot to ask, consenses is to use only a cummns brand head gasket correct? Is felpro or victor hinds ok to use for everything else? I have to replace the exhaust manifold gasket as well.

[Tacoclaw]

Cracking is extremely common on the non-IC'd trucks, that's why they dropped the injector diameter to 7mm from 9mm.

Have you bumped your timing up any? That will increase cylinder pressures, and with the 12cm housing may put a strain on the HG. Has the truck been overheated that you know of? I ran a lot of boost through a 12cm housing on my '90 and never had the gasket fail. You may have a warped head/block or it may have just been bad luck from a 23yr old gasket.

Definitely stay Cummins on your HG and valve cover gaskets. My Cummins VC gaskets have been apart countless times and still haven't leaked a drop.

[nyford]

Thanks,

I believe the PO bumped up the timing but never touched the pump otherwise. Still had the tamperproof coller on the fuel screw.

Truck runs very cool all the time. Mind you this is in a f350 with a four core rad.

Will the cracking cause other problems? Can it get so bad it will migrate into a cooling passage or drop a valve seat? or is that not common?

[dazedandconfused]

Usually with the 9mm head cracking people replace it with the newer 7mm head.

[Tacoclaw]

Heh, I learned the hard way that our valve seats are integral to the head, unless it had a valve job and they were so bad they cut them out and replaced them you'll be fine there. The cracks may cause a power loss if it starts leaking air past the valve but otherwise I don't think they can cause any fatal harm.

Keep in mind if you replace your head with a newer one you'll need new/different injectors to fit its smaller holes.

[nyford]

Tacoclaw, that is what I am trying to avoid till winter. Already sourced a rebuilt head from a buddy, just trying to put off the big $$$ (injectors, studs, etc) till winter when the truck is sleeping from the NY salt.

Worst part is I have injectors for the head, but for a p-pump so they won't work and the p pump and etc.

[Tacoclaw]

The tips would, though I have no experience with the nuances of it, you can put the 7mm Ppump tips on your injector bodies and run them.

[PToombs]

The tips would, though I have no experience with the nuances of it, you can put the 7mm Ppump tips on your injector bodies and run them.

But his 9mm injectors still won't fit the new 7mm head.

[Tacoclaw]

The tips are what are 7mm, not the bodies. That's why you "have" to use a bushing on the 7mm ones.

[PToombs]

He has 9mm injectors, from the old head, and a 7mm head with p-pump injectors. Not gonna work Taco.

[Tacoclaw]

Put the P-pump tips on his 1stgen bodies, I'm decently sure that's possible.

[dazedandconfused]

From what I've gathered you can't just swap the nozzles like you can with the 7mm nozzles.

[Tacoclaw]

Oh.

Well, never mind then.

[RCCUMMINS89]

You can, just have to swap the internals over as well...... intermediate plate and what not.