Engine/Transmission (1994 - 1998) Boost and the stock head gasket

[JGheen]

How much boost can the stock head gasket take?? I have heard many different opinions, from max of 40 to max of 50 and even higher and lower than those #'s. I am currently seeing max of 38-40 and was just wondering how much more that stock head gasket can take before it could possibly spring a leak? I may be putting on a PDR HX-40 and 370's sometime since my cash flow has picked up a bit and I know that the HX-40 will put out at least 50 psi. I think I will need to either install a aftermarket marine gasket or just go all the way and send it to Piers for O-ring and porting jobs... ... but wanted some experienced opinions first. Thanks.

 

[mrsmith]

I hit 60-65lbs with my B1 and haven't had any problems yet,I did retorque my headgasket and would suggest doing that. I'm going to go with studs and a O-ring job when it does go.

 

[JGheen]

Originally posted by mrsmith

I hit 60-65lbs with my B1 and haven't had any problems yet,I did retorque my headgasket and would suggest doing that. I'm going to go with studs and a O-ring job when it does go.

You retorqued your head after how many miles?? And the head had never been on the engine before, you just checked the torque for the sake that you were running so much boost? I guess that is something I could do, what is the torque and how many head bolts are there?

 

[Cooker]

Originally posted by JGheen

I know that the HX-40 will put out at least 50 psi.

An HX40 will not live very long at 50 PSI. If I am not mistaken Piers likes to see his HX40's no higher than 38 PSI.



As far as the HG, I think 50PSI is about max. I personally wouls not want to see more than that if I was trying to keep the stock HG alive.

 

[JGheen]

Cool, that's the experienced opinion I wanted to see. Anyone else with some advice? How about the re-torquing of the cylinder head or just checking the torque on the bolts?? I wouldn't think that would be a smart idea being they haven't budged from the original engine builder's torque at the Cummins factory, just my thought, maybe I'm worng.

 

[JohnE]

Boost and/or advanced timing will take miles off the head gasket.

Also luck of draw for bolt torque and head/deck planarity.

Driving style really plays a part too.



No consistent rule of thumb that I can see.



Bad news, I have oil in coolant.

Good news i get o-rings and studs.



edit

It does not appear to be the oil cooler

 

[JGheen]

So does anyone concurr with mrsmiths recommendation of checking the stock torque of the head bolts??

 

[WadePatton]

I'm running a hybrid 35/40 up to 45 psi with DD's UFM timing. Headgasket fine.



A certain truck made pert near 800 hp with stock headgasket--and I think 55 # boost---but lots of VOLUME.



Headbolts. I wouldn't mess with them until time to pull the head. There's 26 of them on a 24v. And the procedure is--torque all to 59, then torque all to 77, then check all at 77, then give 'em a quarter turn more. Maybe the 12v is different. I don't have that book.

 

[BPonci]

Ran 55 and 60psi daily never had a problem.

 

[DSiemens]

If you are going to run more boost than stock, it would not hurt to check headbolt torque. Per 12 valver, Cummins/Dodge uses torque turn method, but for checking purposes 120 ft/lb, motor cold.

 

[Hutchew]

My stock (original) HG popped the first time I hit 48-50 psi.

Stock HX35, wastegate blocked, 370's, 4k GSK, 16*, #10 plate.

Didn't have time to have head o-ringed, but did booty up for a set of studs and full set of 60# springs. Unblocked the wastegate and fiddled with the linkage to hit max 35-36 psi and no more problems.

 

[JGheen]

Thanks guys,



It looks like I am gonna just have to take it easy and expect the unexpected. I guess I am just going to continue to BOMB away until something happens. Not adding any combustion additives at all, but 370s and timing to 15 or 16 is comin' soon, so we'll see.

How many head bolts are there on the 12v's and your sure it's 120 ft. -lbs??

 

[Forrest]

Got some cool pictures on my Readers Rig Gallery ... o-ringing job up @ PDR. Oo.

 

[DSiemens]

Checking bolt torque 120 ft/lb. The sequence to get there on a new installation is 30, 60. 90. 120. Should be 26 bolts. On the short bolts, exhaust manifold side, a 100 ft/lb will do. I used Joe D. posted advise and went up to 120 ft/lb in steps. There is also a numbered sequence to follow. Piers will give you good advise when you get a o-ringed head from him.