51 replies to this topic

[slindborg]

I use 10/60 and its "fine" thought the halfords stuff was 15/50?

[NA Jimbo]

I use 10/60 and its "fine"

thought the halfords stuff was 15/50?

I thought that whilst I was typing it! So I did a quick google and it showing as 5w50, the mobil1 they sell is 15/50.

[theolodian]

I'm now more confused with this than before. If the compression test doesn't show anything then I'm stumped. I've bought some more oil to top up with if I need it. I've gone for 5w50 to see if this helps, should this viscosity be safe to use?

Compression rings and oil control rings are separate entities. If the bore is damaged then they are both affected, but otherwise loss of compression and smoke are not necessarily linked. You aren't going to break a ring on a stock NA, so really there is no reason to suspect any issues there.

[slindborg]

if it was the bores properly, then it would smoke under load at any point in the rev range

[techieboy]

if it was the bores properly, then it would smoke under load at any point in the rev range

That'll be what I've got, me thinks. Probably so much oil getting through that the smoke coming out is black and not blue.

[slindborg]

if it was the bores properly, then it would smoke under load at any point in the rev range

That'll be what I've got, me thinks. Probably so much oil getting through that the smoke coming out is black and not blue.

I've been in one car with its bores sooooo shagged the smoke was pure white that was utter comedy test driving it as a red arrows tribute

[techieboy]

Fecked if I can work it out. Black smoke but not overfuelling post-remap. Changed coolant temp sensor, new IAT sensor, new GM lambdas and no difference. Managed 3 litres of oil over the Anglesey weekend but the soot on the tailpipes isn't oily (smells more fuel like). No smoke on start up or at idle but the soon as you give it some beans, a nice cloud of black stuff out of the back. Booked in for an emissions test tomorrow to see if that reveals anything more. Then I guess it's a compression test and then who knows.......

Edited by techieboy, 23 July 2009 - 10:10 PM.

[theolodian]

Fecked if I can work it out. Black smoke but not overfuelling post-remap. Changed coolant temp sensor, new IAT sensor, new GM lambdas and no difference. Managed 3 litres of oil over the Anglesey weekend but the soot on the tailpipes isn't oily (smells more fuel like). No smoke on start up or at idle but the soon as you give it some beans, a nice cloud of black stuff out of the back.

Booked in for an emissions test tomorrow to see if that reveals anything more. Then I guess it's a compression test and then who knows.......

How are you sure it isn't overfuelling? Shove a wideband up the tailpipe.

[techieboy]

How are you sure it isn't overfuelling? Shove a wideband up the tailpipe.

Yep, took it back to Courtenays after dropping the compression with new pistons as that was the obvious thing to do. They ran it up on the dyno and recorded the lambda readings at full load and at 250rpm part load through the range. Was running rich through the middle of the rev range so Klassen did some new part throttle maps for the car to cut back the fuelling and also add back a couple of degrees of advance that the original high compression SC conversion loses for safety. I have an almost straight line for the lambda readings now with almost no change anywhere in the rev range.

[theolodian]

How are you sure it isn't overfuelling? Shove a wideband up the tailpipe.

Yep, took it back to Courtenays after dropping the compression with new pistons as that was the obvious thing to do. They ran it up on the dyno and recorded the lambda readings at full load and at 250rpm part load through the range. Was running rich through the middle of the rev range so Klassen did some new part throttle maps for the car to cut back the fuelling and also add back a couple of degrees of advance that the original high compression SC conversion loses for safety. I have an almost straight line for the lambda readings now with almost no change anywhere in the rev range.

I think that you're on the right track with a gas analyser, but don't rule out the remap just yet.

[NA Jimbo]

I've just been out to the car and had a better look at the breather pipe. Although there's no obvious oil on it there was 'some' fresh oil present when I put a screwdriver in the pipe. I've had another search on the web and it seems that if excessive oil is entering the intake through the PVC that this can be caused by 'blow by' and could still be a symptom of dodgy rings??

[NA Jimbo]

After a bit more reading about rings failing I took my oil filler cap off and put my hand over the opening. I could feel very strong pulses of air coming out from inside the rocker cover and when I put the cap back on the palm of my hand had a good covering of oil all over it. Is this normal on these engines or is this excessive blow-by?