Morning All

 

A recent conzult power balance test highlighted an issue with No. 6. Despite this, car was running fine. Anyway, decided to change plugs yesterday for the cooler NGK PFR6B-11B's. No 6 plug had some oil on the end and evidence of a burn mark. Other plugs and all coilpacks were fine. Did a dry compression test and cylinders 1-5 showed 165psi but no.6 stopped at 90psi :sad: Re-tested and same readings.

 

As I said, the car seems to run fine - no hesitation, misfire etc but clearly there's a problem as there should only be a 14psi maximum difference between the cylinders. A little research suggests that as there is low compression on a single cylinder, it may be a broken ring, burned valves, or a burned piston.

 

1. If it was any of these items, would the car still run without any notable issues? If not, what symptoms should I be encountering?

2. If left unattended, what potential issues can I expect?

3. Other than a wet compression test, is there anything elseI can do to diagnose the problem?

 

Thanks, any thoughts or comments would be really appreciated.

Hi mate, I'm no expert but I have gone through a similar thing in the past; the recommendation initially is to try dropping a little oil in the cylinder and doing the compression test again this hopefully point to either a worn bore/ring or sticking valve etc. i.e if the result is higher than 90 then the oil is creating a bit of a seal between the piston and the bore.

 

The Zed engine can run on five cylinders or very low compression on a single cylinder and you wouldn't necessarily notice as they are quite a smooth engine. let us know how you get on...

 

cheers

 

Paul

Thanks, Paul. Nice to hear from a fellow SE Londoner.

 

Planning on doing the wet test in a few days. Assume a teaspoon of oil is sufficient? How did you resolve your similar problem?

 

Cheers

Hi mate,

 

No worries... Where abouts are you based in SE london? could run up with my conzult etc. at some point... Any how my issue ended up being slightly different as my compression was ok and the issue in the end was the injector.

 

If you do a search on Cylinder 6 and/or balance test you'll find that a fair few people have issues with cylinder 6 detting due to the way the fuels distributed to the cylinders etc.

 

Yes I believe that a teaspoon of oil is sufficient and will be enough to show what's going on... Let us know how you get on.

 

Cheers

 

Paul

No 6 is the most common cylinder to melt a piston.

I have exactly the same prob on my current engine which is still running fine, but im changing engines anyway, new one has forged internals and new heads so should be much better.

piston 6 is a pain. somthing to do with it being the hotest at the back of the engine :(

Thanks for all the replies, guys.

 

Have been doing more research on No.6 and there are definately known issues for this cylinder (heat + leaness = detonation!!). I don't think it's the piston as I'm not gettling any grey/blue smoke from the exhaust. So could well be the ring or valve but a wet test should help to narrowing the possible issue. Anyway, sounds like the engine may have to be dismantled at some point in the future. In the meantime, it seems to be running fine so I'm just going to enjoy it over summer.

 

Paul - I'm down in South Norwood, near Crystal Palace. Don't really know any other Zed owners around here other than Steve (Cybernet) in Croydon. Our cars seem to be a rare sight in this neck of the woods. Must try and meet up some time to say hello.

 

Cheers guys.

Best thing to do is to take it easy i surrpose, Give you time then etc to save up :)