Thread: 2.25 Petrol Valve Stem Seals

I do this sort of stuff all the time.

What's wrong with using compressed air on TDC and universal umbrella rubber valve stem seals.
Using umbrella seals it doesn't matter if O rings are all ready fitted further in the valve guide.
The only draw back to using compressed air is you need to stick a bar or screw driver in the ring gear to stop the motor moving from TDC.
If you don't have a cylinder leak down adaptor to to add compressed air to the cylinder, one is easily made using a old sparkplug.
While the compressed air is in the cylinder.......ie cylinder leak down test, it is the best way to check ring and valve condition.
Good way to check out the head gasket and other stuff doing it this way, and no oil , no mess.
Umbrella valve steam seals can be purchased from any engine reconditioner very cheaply and one size fits most engines.
Many a time I have made money buying a supposedly stuffed motor in a vehicle and fixed the valve stem seals in situ and resold as the motor stopped burning oil.
Ron

compressed air will work just as well, BUT..

not everyone has an adaptor to get the compressed air reliably on the cylinder through the plug hole and if you tap it just a little bit to hard trying to get the collets in you can drop the valve. against oil with the crank being held in the "apply force" direction the viscosity of the oil means you have a little more wiggle room if you push a little to hard.

you also may not have it on the side of the road.

that said.

Ive used

rope, shoelaces, paper, water, oil, diesel, compressed air, strips of rag, and just to proove it could be done (and we had to pull the head anyway so no loss if I got it wrong) nothing inside the cylinder.

Try using this style of valve spring compressor.

http://pages.ebay.com/link/?nav=item...d=140402538477

Aaron

I'd indian rope it like we do on aircraft engines, lots easier than all that messing with oil and stuff.


but we all have missed the point here, where did his compression go?
on aircraft engines we do not do a battery condition test type compression check, but do a differential test where we set the cylinder on top dead comp stroke and then introduce compressed air and read the leakage on a gauge set,
no need to mess around like that for your car engine, but on the cylinder you think is crook, set it on tdc comp stroke, pump compressed air in through your plug hole and listen at the oil filler cap, exhaust and carby top to hear the air escaping.
this will tell you where the compression leak is.
there will always be air escaping past the rings which you will hear at the oil filler cap, any air at the exhaust or carby indicates a valve leak.
also check your valve /tappet clearances, at tdc, If I remember correctly , you should have .008 in clearance.
if the tappet clearance is nil, that might be a reason for the valve leaking.

Good to see another aircraft man Harry! My valve is not leaking, just letting oil past its stem seal. This was apparent when I removed the manifold to replace broken studs.

BUT! After running this engine a bit and going for a drive the problem is not nearly as bad as it seemed. Sitting around for a decade may have something to do with the leak, using the engine seems to be reducing it so for the time being I am leaving it.

There is a heap of good information in this thread and I thank the contributors. If I do the job I think I will first use clean nylon cord. Air sounds great but I lack the fitting and the resolve to either make one or hunt one down. Oil sounds great to me and would certainly make a strong hydraulic lock, but the mess would **** me off.

Thanks for the link Aaron, that does look like the tool I am after and for the cost, well worth buying.

Just my opinion, but would it not be easier to pull the head for the cost of a head gasket? seems like a lot of effort to go though with the 50% chance of having to pull the head anyway.

Disclaimer: I have no idea whether this actually works. It may fall into the same category as Hiclones and flux capacitors.

I was told years ago that some oil additives have a component that slightly softens seals that have become hardened with time.

If such additives actually exist and if they actually work, your situation might be exactly the sort of problem they are designed to cure.