m42 high compression figures!?

[Alistair]

hi there,
over a year ago i stripped and rebuilt my m42,
everything was within tolerance so it basically got
a good clean and new gaskets, including profile. ( head was skimmed also)

on the weekend she developed a small oil leak (haven't found it yet) and mayo on the dipstick (mayo was why I stripped in the 1st place)

compression test gave me 218psi in 1,2 and 3, and 210 in 4
thats alot higher than stock,
is that too high - should a fit a thicker head gasket to bring it down a peg?

[TPS]

My IS engine was 180 across all 4 cylinders, don't know if thats good or not.

[Alistair]

the manual says minimum 142-156psi

[capnmchl]

Sure your compression tester is accurate?

[Alistair]

only its second use, how would i check?

does that suggest 218psi should not be possible?

[razler]

I got :
1. 200
2. 215
3. 220
4. 210
before I pulled mine to-bits with a pretty good mac tools comp. tester..

[Alistair]

so I needn't be concerned?

[capnmchl]

Here's my two cents.

You had the head skimmed, so that's raised the compression ratio. These are fairly high compression engines anyway iirc. All the pressures are relatively close to each other.

It's probably fine.

I think your figures in psi threw me a bit, used to working in Bar.

As for your mayo problem, do you only do short journeys?

[HairyScreech]

Around 210 sounds fine to me, they are afterall over 10:1 standard.

How much mayo on the dip stick?

[Alistair]

hi there,
so 14.5 to 15 bar on the other scale.

4 hour round trip to Heathrow in late December, otherwise no more than 35min trips,
I have been driving her a harder than usual.
I guess your suggesting a little condensation - you might be right as there's not a lot of mayo.
(I did my oil change just before Christmas)
I have an oil leak to investigate so that should reveal........something

thanks guys
al

[Brianmoooore]

Water in oil is perfectly normal. Coolant in oil is not.
Concentrate your observations on the level in the coolant bottle. If the level doesn't go down, then it's not leaking into the oil.

[TPS]

Mine is 180, is that Ok?

[Chris_B86]

the manual says minimum 142-156psi

I'd say so

[Alistair]

your all absolutely right of course - cam and timing covers removed, squeaky clean.

oil seems to be leaking from the (exhaust) side of the lower timing cover although
the gaskets look to be in good order (and are only 12months or so old)
o well