Unknown Deposits Around Valves

[Beanie D]

Hi all,

I’m currently rebuilding the engine (M16A) on my 2014 ZC32S Swift Sport.

My cylinder head has been rebuilt by my engine specialist with new valve stem guides, de-coked, pressure tested etc. Today I went to fit it to the block and as I was cleaning the mating surfaces, I noticed that there were some greyish looking deposits left around the valve seats/ports.

Now, I’m assuming that this is just left behind carbon deposits, but I would expect it to be a lot darker in colour. Can someone possibly please tell me what this might be? I don’t want to fit the head until I know what this is, because as far as I am concerned, these areas should be perfectly clean.

I can’t currently upload photos for some reason, possibly because I’ve only just signed up to the forum!

Edited by Beanie D on Saturday 10th May 14:43

[GreenV8S]

That's a question for your engine specialist.

[finlo]

Sounds like valve grinding paste.

[stevieturbo]

finlo said:

Sounds like valve grinding paste.

It does, and it absolutely should not have been left there. It should have been thoroughly cleaned off

[JONATHAN_11_80]

Grinding paste take it back needs cleaning off and find another engineer.