I have been getting sludge (mayo) under the radiator cap for awhile - there was no mayo under the oil cap and no water in the oil.

I've since changed the head gasket, flushed the radiator and cleaned it with that alcalyte solution. The car is running fine, is not smoky and all 4 cylinders are working. But the bastard mayo in the radiator has returned.

What could that be gentlemen?

Check temp- the thermostat may be stuck open. That's a maybe..

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Dr I Hate to say this but could it be a crack, Please prove me incorrect.
Otherwise you did say you flushed the system, Did you just flush the Rad or did you give the complete a real good flush, sorry for the water restictions

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Stop Licking the Dog...I Don't Care Who Started It

If it is a crack, it'll blow the water out... ask me how I know this...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Yer come on, on Where

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Stop Licking the Dog...I Don't Care Who Started It

I had a head on the 998 `matic that kept blowing water out. Changed gasket 3 times. Finally found the crack... bang between #1 & 2 chambers, under the gasket line. Bloody head was hollow where it shouldn't be.....
What pissed me off was I had spent about 20 hours porting the bastard.

So I machined a groove in it, put it on the 2 burner camp stove cranked up to full, had a beer- turned head over, had another beer- lit the oxy up and bronze welded the sucker. Then I took it to work next day and planed the head flat. No more leaky..

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

No I flushed the whole system (was driving with the stuff in for a good few hours).

The thermo might be a good idea, I'll check it. Thanks doc.

Dont reckon its a crack, all inspected real well when the head was off.