testing piston rings? and testing valve seats and seals?

[Paul Smith]

Hi,

How can I test the piton rings to make sure they are ok?

How acn i test the oil seats and seals to see if they have an issue?

The reason behind this is i am burning oil at the rate of about 2 litres every 3 - 4 weeks. the car blows smoke when at high revs. I am unsure what colour this is exactly as its hard to see whilst driving. She seems to drive fine just a little groggy at times.

I thought the oil loss was from an oil leak i have had but this has been sorted and its stil churning the oil. She has had new oil filter and oil.

She is not losing water, and I think it will be the vale springs/seats this sort of thing rather than the rings but I am paranoid about the rings being ok.

Thanks

Paul

 

[Alexx117]

exactly the same problem as me mate! its deffo not the head gasket as well. im getting a lower mileage engine anyway soon its about time mines done 123k and 27k of that is me ragging it over the last 18months.. lol

 

[Paul Smith]

mine isnt the head gasket as this was done a while a go, i have also checked the compression and this is a little on the low side but still about normal for a micra. Im wondering if the springs are weak and they are floating at high revs??? if its possible

 

[ibrooks]

Are the compressions consistent across the cylinders?

If it's the rings then a couple of teaspoons of oil in the bores will briefly improve the readings on a compression tester.

A head gasket failure doesn't have to result in a loss of water.

A leakdown test is a more definitive way to check. An adaptor is screwed into the spark plug hole similar to when a compression test is done but as well as a pressure gauge this has a comnnection for a compressor. The engine is rotated until both valves on the cylinder being tested are closed and air is pumped into the cylinder to raise the pressure inside. Then the tap to the compressor is turned off and you watch the gauge. It'll always drop gradually but a rapid drop sows a problem and you can get an idea where the problem is by listening to where the hissing is coming from. If you can hear it from the intake (through the carb or throttle-body) then the intake valve is leaking. From the exhaust means the exhaust valve is leaking. From the rocker cover or engine breathers suggests the rings are worn.

Iain

 

[frank]

my money would be on the rings paul (unless the inlet valvestems look coked up with a black treacle type snot around them when you look up the inlet ports)

 

[superls]

rings cause serious oil burnage (is that even a word lol?) stem seals tend to smoke on start up mainly but not constantly while driving, not enough to burn alot of oil.

only thing you can do to test rings is do a compression test, open throttle obviously, if there all low or uneven then you have got something to work on, assuming the valves are sealing, but iirc you've had some head work done recently haven't you?

 

[Paul Smith]

yep, the head was rebuilt as i bent a valve, but i didnt put new springs in which i should have but it didnt cross my mind to change them.

How hard is it to do the rings? do i have to strip the head off again?

 

[frank]

How hard is it to do the rings? do i have to strip the head off again?

fraid so paul fwn and sump, and usually a bore hone too

 

[Paul Smith]

###### - thought so, have you done many bottom end rebuilds frank, any advice you could give? gonna look for a bore hone now.

 

[frank]

it could easily turn into a money pit paul fwn (rings are £100 ) you,re best to invest in a lowmiler replacement engine imo (i was posting up a mint cga engine for months, and they weighed it in in the end :doh