Good Head

Post Sun Jul 10, 2005 9:43 pm

I took my head off again today after just 1500 miles seeing as it was turning it's coolant into mayonnaise.
Thinking I had not fitted the HG carefully enough (I thought some oil had contaminated the mating surface on reassembly) I though I would see where the water was finding it's way to the oil, but no.

The gasket was perfect (the head was stuck fast to the block and needed a fair bit of persuasion) I can't see any evidence of the 2 meeting.
There was no oil in the coolant, just thick mayonnaise around the top of the metal spring tube in the inlet manifold, on the underside of the rocker cover and in the breather hose from the TB to the RC.
I'm stumped, as the car was driving fine, not overheating even in traffic, just the coolant not pressurising properly and drinking it's coolant.

It wasn't losing coolant before I put the new (standard) cam in and I can't think of anything else which would make the problem happen so soon after a top end rebuild.

I'm about to dismantle the head and look for clues before I send it for a pressure and crack test.

I'm presuming it needs to be stripped for the test?
How much should I expext to pay for the test?
What the fook am I gonna do if the head is indeed good?

Cheers guys, once again!!

Dan
(hopefully some pics to follow)

Post Sun Jul 10, 2005 9:47 pm

dont need to strip it mate to bet it cracked tested

Post Sun Jul 10, 2005 10:00 pm

If the coolant is turning into mayo, then pull your cam out and check the bottom of the cam bearings for a thin grey line running across them. Especially no 3. This is where M20B25 heads crack I'm afraid. If you'd taken the cam cover off with the engine running and up to temp, you would have seen beads of water emmerging from the cam bearing, if it is cracked here.