ok then,hav already asked this but my oil cap keeps blowing off,

i had a perfectly running 1.6 bog standard rst,

got a full width intercooler on it then replaced the head with a ported/polished and put in a newman cam and vernier also a stage 3 turbo,

now wen i drive along and hit a bit boost it blows th cap off,now i was told to check pipes for blockages but alll seems fine so ive finally bit the bullet and agreed may be the rings,now then,,,,,,

how do i test my rings,using a compersson tester ?

what should they be ?

also any1 think off another reson y its blowing off ??



cheeRS sean

 

have you tried a new cap just incase it's as simple as that or a bailey oil breather tank and if memory serves me right the compression psi should be round the 140 mark but am sure if i'm wrong someone will tell me but they should all be close to each other not 3 at 130 and the other at 110 if i'm making sense

 

aye ano what you meen mate,ive tryed a new cap and still not working,

ill jst have to try the compersion tester

does a oil breather make alot of differance ?

 

did a compression test tonight

cylinder 1 - 122psi
cylinder 2 - 115psi
cylinder 3 - 110psi
cylinder 4 - 110psi

thot was 2 much off a differance so did cylinder 1 again n was around 115 ????


soo since im an electrition(lol) what this mean ?

 

your a spark and i'm a plasterer so between two great minds we'll fuck it up. i do't suppose you.ve got a oil pressure guage in your car. the breather is a good escape for the pressure that builds up i've got one and never had any problems

 

mine kept blowin off aswell. i did a comp test and add no comp on 2 and 3........

i thought it was the head gasket but i had melted 2 pistons....

but if you have comp thats a good thing, sort of......

 

mine was doing exactly the same mine was 15 psi down in 1 cylinder and i turned out to be the piston had broke between the 2 compression ringsand very badly scored the block.hope its not like this in your case
juffer

 

yeah mine was down the side of the pistons, never done anything to the block though................

av had a word with me mate n he say check the breather that comes off the rocket cover... coz the block easily and thats what blows the cap off, if its not missfiring!

 

which breather mate ? the with the wee block on it lol or th one that goes straight to the bottom end ?

 

can it have anything to do with my turbo ???

also any1 2nd that its ment to be 140psi ?? as im around 110-115 which is quite a loss,


when head was off the rings/bores looked fine

 

My rs turbo years a go did precis the same thing, the oil cap keeps flyin off when accelerate the car, the car idles roughly and when i take the pistons off one of the pistons had cracked and the bit fell of when i little bit hit rubber hammer the piston
So i bet there is piston broken.

 

eas there any movement in the pistons??????????????????????????

 

Check the one on the righthand side of the rocker cover (as you look at the engine from the front)

It wont be anything to do with your turbo, anywhere between 140-150+ odd is a good compression

 

have a leak down test done i have found this to be more accurate in the past

 

whats this mate ?

 

o wel looks like the heads coming off it again this weekend and getting treated to new rings/pistons,

how much will it be for rings pistons and new shells ?
cheers guys
also wil i use burton power for th parts ?

 

i got mine from woodford garage motorsport
tel:- 01803 863958

pistons = Ł275 with rings
full set of mains and big ends in heavy duty =Ł99.95

if thats any help!

 

ouch!!!

 

Have you got a one way valve on the vaccum pipe between the inlet manifold and the engine breather and if so is it working?

If the valve is not there or it’s sticking open when the manifold goes to positive pressure (boost pressure) it will pressurise the crankcase via the engine breather and can blow the cap off.

A leak down test is where a metered amount of air is put into a cylinder via the spark plug hole and the amount "leaking" out is shown on a gauge. It is done with the piston on TDC and the end of the compression stroke when both the inlet and exhaust valves are in the closed position.

If the rings are not sealing properly or there is a problem with a piston the air will be herd escaping from the dipstick tube or the oil filler cap. All engines will have some degree of leakage past the rings, the greater the cc the more leakage there will be.

It can also be used to diagnose leaking valves and head gasket failure.

 

B1G_RST
its where each cylinder is filled up with compressed air and a gauge tells you how much each cylinder is leaking but bear in mind you have to turn the engine over by hand to get the valves shut on each one as you do it.

 

MIKEDAF2
cheers for the info,

think im just gona go ahead and put new pistons/rings in the motor,
was on burton power,what pistons do i use ? haha