New engine problem

[Tom and Maria]

I've had my new engine in for about 450 miles now, it runs brilliantly and is a pleasure with the exception of two issues which I'd really appreciate a second or third opinion on.

Firstly, I have an oil leak from between the head and the block. It is definitely not coming from the tappet chest covers. It seems to be leaking from the front right hand corner, just near the bypass hose, and is being blown back above the tappet chest by the fan. Is this something anyone else has ever experienced? I've torqued the head down a few times (45lb ft) but the leak continues. New gasket? Check head for flatness (looked okay when it went on)?

Secondly, compression is low on no.2 cylinder, about 140 psi compared to 170 on the others. This is coupled with exhaust fumes under the rocker cover. Am I right in thinking I messed up grinding in that exhaust valve?

Whatever happens, I'll be building up a spare head over the next few weeks after checking it is flat and with new valves. I do wish I hadn't accidentally left that 12g940 in the broken oven at my last student house... Don't ask.

Tom

[bmcecosse]

Low compression and oil fume suggests piston ring damage - nothing to do with valves. That's the oil feed point to the rockers - so if leaking oil there the gasket (or the head/block surfaces) must be damaged. Lift the head to check - and pop up #2 piston to check the rings.......

[Tom and Maria]

Piston rings were fine luckily, but I did find a very badly burnt exhaust valve on number two. I ground it hard in, which should get me up to dartmoor for a camping trip tomorrow, but will be building up the spare head for a swap over shortly. Stupidly I didn't buy new valves when I rebuilt the block.

Hopefully the thin smear of sealant will sort the oil leak, the head was dead flat, so a new gasket should sort things more permanently. The old gasket was re used as I couldn't get another today. All seamed fine on the test run earlier so fingers crossed.

Thanks,

Tom

[bmcecosse]

Doesn't explain 'oil fume' though... Remember to set exhaust valves to 15 thou gap.

[Tom and Maria]

Yep, all exhaust set to 15 thou.

With the valve ground all psi readings are 170 ish and no fumes, so can only presume that the burn (which was pretty awful) was getting up the valve guide. Would have the new head on in the next couple of weeks.

A little odd I guess, but very glad all the rings were okay!

[bmcecosse]

Indeed! And 170 psi is very good - enjoy.