SeanB23

The holes on mine were totally clean and dry, and I used plain Rotella on the head bolt threads before I put them in. All passed the "ring test." Thus far, it's held...

I should mention that I had to cold re-torque a number of the head bolts after a few weeks, as they had loosened up a bunch, down under 90 in a few cases. Too much oil on the threads maybe ?

This was kinda disturbing...but like I said, it's held thus far.

To the OP: Yeah, be absolutely sure to use the Cummins brand HG. I could tell that the one I had to replace was a cheap off-brand one someone had stupidly slapped in there, thus creating work for me on down the road...night and day difference between the two gaskets. The Cummins one is so over-engineered and heavy duty comparatively it's just amazing.

It was a time-consuming task, but if you have more time than money, hey, it's not all that bad.

wannadiesel

No, just the gasket taking a set. "Tightness" is really not what we are after when we torque head bolts. We are trying to achieve a certain amount of clamping force, torque is just a convenient way to get repeatable clamping force. Lubrication is needed to maintain consistency. Measuring stretch is a better way to measure clamping force but it's obviously impossible on our head bolts.

jimbo486

yes. that's what i was getting at. hydro-lock did come to mind. i made sure mine were clean and dry before i installed the bolts WITH engine oil on the threads and under the cap. i had to run the tap through mine a number of times to get the threads completely clean.

M12x1.75

SOOT4BRAINS

Ok, I torqued the head bolts to 125 ft lbs. A few bolts took 1/4 turn, most of them were already close to 125. The ones by the leak turned a very slight amount. I put the overflow bottle at max, and am watching it closely and also watching engine oil. With the engine running the oil on the dipstick had a few really small bubble on it, but the oil is not milky at all. What else should I watch for? Thanks guys!

93flatbed

What else should I watch for?
A sale at Rocky Mountain Cummins!
But really, sounds like you got it. Just watch for temps and make sure the coolant dosen't get too low. And if it starts to get real hot and then all of a sudden the temp drops to cold. Then the sensor is no longer submerged in coolant and is really low on coolant.

Riflemanusmc

Had to laugh on that one...I'm laughing with you, not at you. I could see that with a large increase in boost pressure along with it. Cummins intended use of THAT head gasket was for block that had been surfaced to that service limit. If you were going to Oring the head with it, then I could see tha use of it at that point. Without written, unbiased test, and not just what someone said. I stand....Even with the head Oringed, if the blocks not flat. Its not going to hold.

wannadiesel

The oil is going to foam while the engine is running. Watch for mayonnaise under the fill cap and on the upper end of the dipstick.

Riflemanusmc

The light tan color of the oil will also be produced from short run times. IE store and back. You'll have it with every engine. If its not brought to full temp, it leaves that light tan color under the oil fill cap as well as the dipstick.

Crossy's son

Condensation ,correct?

jimbo486

more than likely so. the beginning of water blending with the oil, then it turns into mayonnaise if there's enough water in it.

Riflemanusmc

Yes...

SOOT4BRAINS

OK so I drove it over to my friends house to grill up some steaks, and popped the hood. No signs of water in the oil and no coolant loss and wouldn't you know it, there is no wet marks where it was leaking either. Oil pressure is normal. Was a 15 mile trip, definitely reached operating temperature. Plus to top it all off my transmission and front crank seal appear to not be leaking as well. I feel better but won't be happy till I yank it all apart and look at it. But at least for the moment I can still drive it. What could cause it to just leak a little and then stop? The bolts next to the leak were all at 120 ft lbs already. It has seen a little high speed action over 100 mph on the dyno last week. Maybe I should put a stock fuel filter where the oil filter goes and hook up the "water in fuel" light to be a "water in oil" light Thanks for the help guys!!

SeanB23

Could be the rubber seal around the thermostat causing the water leak. You could replace that for next to nothing.

You could also do a compression test on the cylinders to see what's going on there...

Replacing the HG isn't that terrible, though, all you need is a good torque wrench and an engine hoist. That and a bunch of spare time...

I did mine by myself this spring, first time I ever replaced a HG, and it's held so far.

SOOT4BRAINS

I looked between the thermostat housing and block since it is so close to the head where it looked like it was leaking. Got my little mirror out and it looks like the coolant could have come from there. The motor is slanted down towards the back so if it did leak it would drain back, then down next to the head and oil cooler. Could the cooling system make more than 16 psi if the thermostat was still closed or partially closed and the motor was at 3k? It was wrapped up to about 3100 rpm on the dyno last week, and the truck sat about an hour and a half before we actually got it on the rollers. The temp was around operating temp, but this thermostat has a tendancy to open and close.... Could have been at operating temp, but thermostat was still closed. Maybe it pushed a little coolant out the housing. I need to get a cummins thermostat and put in there....

dzl_damon

So the tightening of the head bolts helped? I just noticed a small bubbling leak just under the intake plenum around the injection pump area. I noticed the insulation on the side of the engine was peeling from moisture when I took the inj. pump off. So I'm guessing it was doing this before I put on the new pump with 1 turn to the fuel screw.