Hi all,

I have uprated my intercooler and ECU to run more boost. I am running the car up to 15PSi at the minute. I took the car out for a run and turned the boost up a bit more and the car popped the oil filler cap off. The car at the minute has a standard breather system on it which is nice and clean. The engine has got new rings in aswell which when pressure tested throws out 125PSi.

Why would this happen over 15PSi.

Any ideas?

Cheers
Dave

 

make sure the seal is ok on the filler cap and fits nice and tight, have u got a chrome rocker cover?, if so the caps never fit properly, normally put some tape around the spout to give it a good seal

 

Check all breather pipes are not blocked up might have loads sh#t stuck in them mine used to blow off but that was due to rings being fcuked

 

Its a standard rocker cover on it at the minute. The oil cap seems to be a nice tight fit

I'll double check the breather system. Shouldn't be the rings as I've only done 1,200 miles so far.

Thanks for the input.

 

could the one way valve be broke on the breather pipe and be pumping the engine full of boost?

just an idea

 

I'd say check your breather pipes...

 

What do you mean by the one way breather pipe?

Cheers
Dave

 

when it had new rings is that the only thing that got changed? simply re-ringing an erst is pretty pointless as any ridge at the top of the bores will cause the new ring to shatter when they come into contact. if so the rings might be at fault again!

 

my mate is having this problem, his rings are fooked!!

good luck matey!

 

there is a valve thats on the breather pipe that only alows vacume and will not alow positive presure past

if thats bolloxed then it would fill your engine full of boost i would presume

 

Does the engine cut out when the cap comes off? if it does the breathers alright, the only other possibility is the rings.

TTFN PaulT

 

I honed the bores till the bores had no lips on the top and checked the new piston ring gaps which were within the tolerences in the Haynes Manual.

When I pull the cap off with the engine running it tries to cut out.

Up to 15 PSi it is fine right they way through the rev range.

Gonna do a compression test at the weekend just to double check everything.

Does anyone know what the standard breather setup can handle?

Cheers
Dave

 

compression test is the only way to be sure. sounds like you will be unlucky if is the rings after doing the bores and everything.

my mates S2 ran 16psi for 4 years without a problem on a standard breather so that shouldnt be a problem!

 

Does it spit oil out of the dump valve or pop the dip stick out ??? Get a uprated breather system see if that helps and run the metering head return to fresh air.......... If still no joy pistons it is

 

I honed the bores till the bores had no lips on the top <---- !!!!!! oh shite!

thats your problem your bores will be 1/4mm bigger than the std set of new rings so u get massive bow past even worse than before! because there will be a big gap between the rings

by using the honing machine you have made the bores bigger than before when already worn and fitted new std rings/pistons so the gas gets past

you should of got a rebore and oversize pistons/rings and everyrhing would of been as good as new

its just a therory but im shure its feasable after 6 stellas at 12.44 at night

 

Very good theory IMO too
You cant just 're-hone' a block and put standard pistons and rings back in.. ESPECIALLY if there was a lip at the top of the bore!

 

I thought if the ring gaps were within the tolerences given in the manual it would be ok. Was I wrong in thinking this. I know a rebore would have been the best way to go but I was waiting on Mahle getting back to me about my pistons that i ran for about 500 miles then cracked between the ring lands. So I got another block and re-ringed it to put me on.

They've only just got back to me saying that the reason was down to too much compression with the head being 0.5mm smaller than a standard head. I don't think that was the cause due the pistons cracking in the same place. This with the pistons has been going on for 3 months now.

Ant thoughts?

Cheers
Dave

 

That should have been any thoughts?

Thanks for the input so far its, good to be able to talk to other people with RST's as not many people/garages know alot about them.

Cheers
Dave

 

No oil comes out of the dump valve. Car runs perfectly. No oil burning or anything. Just doesn't like going over 15PSi without blowing the cap off. Under 15PSi the cap stays on right the way through the rev range.

Cheers
Dave