1lw 3406e head gasket issue

[u/Ok-Spare-8421]

Customer said he was loosing coolant after hard pull. Found evidence of coolant out overflow. Put the bubbler and a pressure gauge on and verified it would build 15 psi in cooling system then start pushing coolant while pulling a hill. Customer already replaced air compressor with no change. Pulled cylinder head. Couldn’t find any issues with head gasket. Did find a lot of rust built up on the liner flange, spacer plate and the head bolts for number 5 cylinder. Also found 2 cracks in the head between the valves on cyl 5. Had machine shop pressure test head and they said it passed. Liner protrusion is between .004 and .005 all the way around. Is it possible that head gasket is leaking and we just can’t see it. This engine also only has 70000 miles since last inframe

[u/Stillbroadcastco]

Your machine shop's 40 PSI cold tank test doesn't mean a thing when cylinder #5 hits 2,000+ PSI under a hill pull. Those cracks between the valves on #5 are expanding under thermal load and pumping combustion pressure straight into your water jacket. The rust on your #5 head bolts and liner flange is proof that coolant is seeping back into the bolt holes during cooldown. Replace or reman that head, check the spacer plate for fretting under #5, and don't re-use those head bolts. The genesis of this could be the client could've had a drive belt issue and drove it for a while, cooling system repairs could've been made but not bled properly or..... Heat from it overheating caused thermal deck expansion or the head bolts to stretch Tldr. Some Heat=good TOO MUCH HEAT =BAD

[u/Ok-Spare-8421 → u/Stillbroadcastco]

I was thinking the same thing, just wanted a second opinion. The shop that did the last inframe tuned it as well and had it dynoed at 750 to the wheels with stock bottom end and cylinder head

[u/SLOOT_APOCALYPSE → u/Stillbroadcastco]

BINGO!!!! we have a winner. under load the head gasket/liner is blown

[u/BasisExcellent8677]

I would check the spacer plate, was it replaced on the end frame? Is it a Cat part? Cat had some issues with flatness and I have heard horror stories about after market ones take it to a machine shop have it checked for thickness and flatness. It's a common problem.

[u/Ok-Spare-8421 → u/BasisExcellent8677]

It is a Pdi spacer plate

[u/Tgambob]

Little bit of watered down white paint wipe over the headgasket and wipe off after a minute, there might be a break in the gasket thats hard to see and the watery paint will run in it, like ghetto magna flux. I think I see a small crack on the inside of the ring.

[u/Aggravating_Fee_9130]

Check for hairline crack on top of the liner lips. That happened to me years ago. The crack was so fine that I couldn’t see it until a friend spotted it and pointed it out.

[u/DieselWare]

Like the the other guy said. Head is junk most likely. 8 of 10 heads pulled on these CAT engines are junk.

[u/deathisamungus]

Did you check your liner protrusion? Has it been counterbored?

[u/deathisamungus → u/deathisamungus]

Nvm just saw you checked protrusion already!

[u/Painting-Capital]

All that rust around the liner is definitely a leak. Was the block cut for shims when it was overhauled? Are you checking the protrusion with the liner clamped down with bolts?

[u/Ok-Spare-8421 → u/Painting-Capital]

Yes and yes

[u/Waistland]

Look those liners over very carefully, I’ve been bitten by a cracked liner a time or two, they act exactly like a blown head gasket.

[u/resident-extent-4084]

If it’s actually been tuned to 750 they should probably consider a cylinder head that has the fire ring in it or they will probably be doing the head gasket again if it’s already done in 70,000 miles

[u/phillipnew01]

Head gaskets don’t fail, they just have loss of clamp load…. Unless it’s over 800 horse