First off I hope everyone had a merry Christmas! Mine was eventful blowing the head gasket on the truck, and then finding out the head had cracks in 5 of the 6 cyls of the head. Replaced head and now it runs great. No external leaks but it sucks air and looses prime within a few hours. being this weekend was Christmas/eve  I couldn’t get injector orings or connector tube orings. Could these be a source of the air leak? I changed the banjo washers on the back of the head with no results.

Double check also the return rail of the head make sure the banjo bolt and sealing washers are good then also check your return on the p-pump I've seen the overflow valve create issues with prime when it's wore out.

 

Your biggest issue is your final ratio is too low you should not be running 35 inch tires on 3.55 gears this is why your head cracked. Your best off switching to 4.10 gears.

I forgot to update my sig that I went to 4.10’s last month. I’ll check that t fitting on the return side, overflow valve is only a few months old it would be a weird coincidence that it went bad the same time the head gasket did maybe tonight I’ll pinch the return and see if it starts in the morning 

One thing you can do in the interim is to park the truck on a fairly steep incline overnight (nose pointing downhill) and see how the engine starts in the morning.  Make sure the fuel tank is at least half full.  If it starts easily, I would suspect a leak somewhere between the tank and the injection pump inlet. 

 

1 hour ago, HitCast said:

I couldn’t get injector orings or connector tube orings. Could these be a source of the air leak? I changed the banjo washers on the back of the head with no results.

 

You may get some differing opinions here, but I don't think this is the source of your problem. 

 

Is it possible that you are having a problem with the fuel shutoff solenoid?

 

- John

 

Good at least the final ratio is good. It won't hurt to do all the o-rings on injectors and crossover tubes just to make sure you didn't nick a o-ring.

Update: replaced o rings on injectors and crossover tubes, starts in the morning now. Took it for a drive today hit lockup and blew the head gasket at 40psi…. Same place on the back of the head.

Most likely too much timing on the P-Pump. I had to learn with my VP44 and Quadzilla you can't have high timing while building boost. Cylinder pressures rise and the head gasket will fail. You should have a good deep retard on launch and building boost then once cruise state is reached the hop back to high timing. Sadly this is a huge limitation of the P-Pump.

 

Yeah I'm running about 24 to 25 degrees BTDC at 2,000 RPMs in a cruise state. Now squeeze in the throttle and timing drops to 18 BTDC at 2k RPMs.

 

Yeah I'm even running ARP 425 studs but being I miss tuned and was using too much timing while building boost it lifted the head. 

 

The other thing after a second Cummins gasket delaminated too I'll never use a Cummins head gasket any longer being Cummins does NOT manufacture the gasket but a company in China called BLK that makes Cummins head gaskets.

That’s what I was thinking because when it popped is when it hit lockup and pulled the motor down and high timing + lower rpm + boost = no good. 
 

What do you recommend for a headgasket? The  one that just blew was a mahle and was the only thing I could get on Christmas Eve.

Local Cummins doesn’t have factory gasket and it’s back ordered so I don’t think that’s much of an option. Local parts stores all have mahle composite p# 54174 and felpro MLS 9522pt don’t the newer common rails run an mls would this be an upgrade over a conventional gasket?

Either would be good. Sadly after see a Cummins head gasket de-lamination of the fiber material that peeled away from the steel gasket plate. 

 

Kind of like I never suggest Cummins thermostat either being Cummins doesn't make those either. 

Just curious what is your timing set at and which method did you use to set it.

Lift measurement or fuel spill port closing? Or a shop pre set it.

Well, that’s where things get a little messy when I did the p pump swap I used a degree wheel on the crank. But accidentally retarded it and I advanced it till it ran good. I might have went a little crazy with it but it ran great since May with no issues. I bought a dial indicator to time it with lift on the chart do you know where a 912 180hp ca pump would fall?

Sadly I don't have any of the charts. I always wished someone would build an article and provide the information for that. I understand how to set factory timing but custom timing requires special tools. Problem is with no way to retard you always have to balance your timing so you can launch without huge clouds of smoke and still efficient at highway speeds.

Here’s the chart I found, I don’t have a cpl for the engine this pump came off of so it’s hard to tell. All I know it’s a 912

I have a cpl 2174 on a 97? Auto California with catalyst 180 hp 14 degrees I don't know what the pump number is someone rebuilt it and scribbled 31837 at the end of the number.

Most likely the same then I’ll find out this weekend what the timing was set at and let y’all know I feel like it’s gonna be pretty high….

Here’s the failed head gasket, going to check timing in the morning and see what it looks like!

Headgasket all installed timing reset! It was at 42 degrees… reset to 19. Now when I put it into gear it immediately dies. Would retarding the timing cause this without resetting the idle?

On 1/20/2024 at 9:16 PM, HitCast said:

Would retarding the timing cause this without resetting the idle?

 

Yes. Just like a gasoline engine if you advance the timing it will idle higher so if you retard the timing the the idle will be too low. When timing changes you have to reset idle speed which should be close to 800 RPM.

I bumped the idle and so far so good! During this process I put some new 7x.012 sacs that are set to p pump pop pressures as well. Truck spools way faster than before and seems to start easier, I seen a guy selling H pump swap kits and apparently those are like p pumps but have electronic timing advance? I thought that’d be pretty slick if a guy could get the programming done

I could school you up in what I know for the 24V programming I do. Timing is a neat animal to work with. 

 

Quick tidbit just remember more you retard easier to build boost. More you advance the more you burn the fuel in the cylinder but you have to be careful. I monitor my oil temp being that if your over advanced you will gain heat in the oil because you flood the cylinder jacket with heat with fire burning on the cylinder walls. Optimally you should be about -30°F cooler than coolant temperature. This will provide the best bang for the buck for daily drivers.