[Ben_Sierra]

In trying to diagnose the lack of power in my G13BA (even more than usual) I've pulled the plugs for a compression test.

The compression was pretty good (185-175-180-190), but the number 1 and number 4 plugs not so much.

They appear to have both pretty bad carbon deposits on the electrodes, as well as a heap of oil on the threads.



This also explains the oil I've been using.

I'm thinking oil rings or valve stem seals. Would you agree?

[JrZook]

They don't look that bad from that angle. Can you get a pic electrodes up as well as maybe a comparison shot between the other 2 cylinders?

How many k's on your engine btw?

[Ben_Sierra]

I only have my phone for pics atm and its not very clear...

The engine has 240+ but I think its been rebuilt before.

I'll see what I can do about better pics...

[Ben_Sierra]

Camera battery is on charge, I'll get some better pics soon.

[alien]

easy to test the difference between stem seals and rings... stem seals should give a big puff of smoke on startup after sitting a while - rings should smoke like buggery under full throttle and lower RPM.

240k is a pretty decent run for a motor though =) rather than dicking around trying all different things to fix/diagnose it, you might be better doing a swap to a fresher reco one.

[Ben_Sierra]

[Ben_Sierra]

alien wrote:

easy to test the difference between stem seals and rings... stem seals should give a big puff of smoke on startup after sitting a while - rings should smoke like buggery under full throttle and lower RPM.

240k is a pretty decent run for a motor though =) rather than dicking around trying all different things to fix/diagnose it, you might be better doing a swap to a fresher reco one.

Or maybe there is another possibility that I haven't considered yet... That's what I'm trying to figure out. If it is time for a fresh motor, I'll (with some help) do the reco myself. Best way to learn

[alien]

what about one of those exhaust probey things they do for emissions tests? could you get that done and see how much oil is coming out the pooper pipe?

have you checked if the carby is running too rich?? that could cause the blackness also couldnt it?

maybe also check the PCV valve?

[Ben_Sierra]

alien wrote:

what about one of those exhaust probey things they do for emissions tests? could you get that done and see how much oil is coming out the pooper pipe?

have you checked if the carby is running too rich?? that could cause the blackness also couldnt it?

maybe also check the PCV valve?

Exhaust probey thing isn't something I can do at home, but when I get time I may take it to someone...

I would have thought if it was running rich I'd have carbon on all 4 plugs...

PCV valve is on the list to check but I ran out of daylight...

[alien]

they look carbony on the pics is all... but you can see oil in the threads... could be a bit of both perhaps? its easy enough to lean out the carby and see what happens.

[fordem]

Oil on the threads is usually an indication that the plugs weren't as tight as they should have been.

[alien]

it'd surely still take a bust pcv valve to have the pressure to force oil up those threads though wouldnt it?