Went to have a clean of the engine bay with the manifold off today and i noticed that one of the valves had a yellow residue round it.

Please see the picture of the valve below. This is the only valve with the yellow residue, all the rest are clean.

It is in position 3 in the picture below.






Is this normal? Is this a sign of something sinister lurking? *panic hat on*

 

Yellow colour residue in the combustion / valves area is usually due to using octane booster.

That may be all that it is.

David APi

Agents for:
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I've never used octain booster Dave, only V-power...

 

Aah well, it won't be that then..............

It may be just one of those things. Keep an eye on temperature and coolant use. Just in case it is a sign of coolant into the cylinder and being burnt.
BUT, if the motor is running smoothly, with no misfires, I wouldn't fuss too much about it.

David

Agents for:
Simtek, the most exciting new Ecu for years
Buddy Club exhausts
Scoobysportexhausts
Eibach suspension
AP Racing brakes and clutches
And of course; the well known APi Performance Exedy organic clutch

www.apiengines.com

01926 614333

 

Someone mentioned it could be a head gasket blowing? would you disagree?

 

Only by one valve? unlikely in my opinion. AND the engine would be shaking all over the engine bay if it is running rough at all. If you have a silky smooth tickover, it ain't that. Silky smooth as a flat four ever is......

Head gasket is a possibility, but unless you have other problems with the running of it, I would discount the idea. Loss/use of coolant ? That'd be a giveaway.

David

 

as far as i am aware there has been no loss of coolant, and tickover is solid at 0.7k so i don't think there is a problem there?

Is there any point in me doing a compression test?

 

I've noticed a slight orange discoloration on the plugs when using V-power.

JohnD

 

on all plugs?

 

My plugs were a strange brown colour ( VPower + booster )

HTH

DunxC

 

bump

 

Its been sugested that it's simply residue of old petrol . and that if you turn the engine off with the valve in a particular cylinder fully closed and then a bit of petrol gets down there for any reason, it can do this?

 

I think you are worrying about nothing..

 

The valves look nice and clean. (Ah - the wonders of modern fuel and oils!) what's the mileage?

JohnD

 

Thanks John...

its a P1 on about 53k at the moment, been on the road since april 2001...

i thought they looked pretty clean, but never seen anyone elses so thought it was just normal lol

 

Inlet valves usually are clean, it is the exhausts that get all crappy and gummy. Doing a compression test is loads of fun for all the family on a Subaru.

Don't think I'd bother, given that nothing is suggesting a compression problem and how much hassle it is to do the test.

David APi

 

Thanks David and co, all your input was gratefully received…