HJ45 oil in water jacket

[45Dougal]

Reposting here in the hope of a wider audience - I posted in the diesel section but tbf I rarely look in there even myself.

Got my engine a bit warm last year because the rad cap was leaking and my gauge wasn't working at the time. It hadn't lost much coolant, so I topped it up with water to limp home.
Forgot all about it and it sat most of the winter. Ran it for a while today on the drive, and I've got steam pouring out of two core plug holes, while 2 core plugs lie on the ground beneath.

No big deal I thought, just replace them.... but then I discover both holes are full of oil too.
No sign of water in the oil, no emulsification on the stick or at the filler.

Ran a compression test and have nearly 400psi on all except pot 5 which is making at least 340psi. Seems OK for a 1977 H motor.

I'm assuming it's broken through the head gasket between oil and water, but happy to hear any other suggestions before I tear it apart (once I track down a mythical head gasket for a H motor that is...).

 

[charliemeyer007]

That would be my guess - head gasket. Have you tried to retorque the bolts with say a few extra #.

 

[45Dougal]

That would be my guess - head gasket. Have you tried to retorque the bolts with say a few extra #.

Haven't even checked the head bolts yet tbh. I guess if they were really loose then I might have confidence in that, but it's hard to determine if oil is still leaking inside.
Hoping that my top end has actually been getting at least some oil recently.

 

[charliemeyer007]

Things get longer when heated. Cast iron grows at a different rate than steel bolts. The gasket is designed to work in a heat range for a long time without issues. Exceed the range then all bets are off. It cost nothing to check the torque and maybe add a few % to try for a good seal again.

On the gas I6 cylinder 5 gets toasted from leaking brake booster.

 

[45Dougal]

I'll definitely give it a try - doesn't cost anything
Not enough vacuum on the diesel engine to power the booster, so at least I won't suffer from that. I'm running an electric vacuum pump since the original alternator (with mechanical pump attached) got switched out.

 

[45Dougal]

So a quick update on my potential head gasket failure..
I removed the rocker cover to re-torque the head bolts, and discovered 5 more blown core plugs that I didn't even know were there in the top face of the head.

I'm hoping (with everything crossed) that these plugs are the only cause of oil in the water.

Waiting for a new set of 24mm plugs now to go with the 28 and 30mm plugs from behind the intake manifold.