Replacing valve seals

[Bentsdl]

My engine uses oil (1L per 1500km) and the exhaust gases stink.
I've checked the compression and leakage and it is within spec. The engine wasn't used for quite some time so I suspect the valve seals to be dried out, causing oil leakage. They are cheap so I thought id give it a shot. I've heard it's possible to replace them without pulling the head by pressurizing the combustion chambers to hold the valves in.
My question if this is true and what the procedure would be. A how to somewhere maybe?

Any help would be appreciated!

[rbodor3]

Well your exhaust gases stinking I don't think is directly linked to valve seals. I would say this is probably the signs of needing a new catalyst.

Do you have any smoking? If you're leaking oil from the head I can't imagine how it would not smoke somewhere. Run it hot and pop the hood, look for smoking under the hood, and also out the exhaust.

[FernandoBunster]

I don't think you can get to the valve seals without removing the valve springs.

[Bentsdl]

Well your exhaust gases stinking I don't think is directly linked to valve seals. I would say this is probably the signs of needing a new catalyst.

Do you have any smoking? If you're leaking oil from the head I can't imagine how it would not smoke somewhere. Run it hot and pop the hood, look for smoking under the hood, and also out the exhaust.

I don't have a cat as it's a 1979 euro 3.5L. It doesn't really smoke(maybe a little), only after some engine breaking in high revs. Lets say from 5000rpm back to 2000, if I hit the throttle after that I get a nice blue cloud behind me. There's no oil leakage anywhere on the outside of the engine.


I don't think you can get to the valve seals without removing the valve springs.

I'm sure the springs will have to be removed, the question is, can it be done without pulling the entire head?

[Bentsdl]

Oke, it turns out it was possible to replace the valveseals without removing the head. It took me almost 3 days, that includes making all kinds of stuff to compress the valve springs while the rockers are still in place (just slid to the side a little). You have to put the cylinders under pressure to keep the valves in while compressing the spring, and at the same time remove the two valve collets, it was no fun to this with one pair of hands!
On one valve I forgot the rotate the crank, and the valve dropped in the cylinder! Thank God I managed to pull it back up with a magnet on a stick:confused

The good news is that it has solved the smoking and stink issue, and with that hopefully the oil consumption. The old seals were cracked and hardened to the point that they broke to pieces when you touched them, so the high oil consumption was no surprise after seeing them.
But the entire process of replacing all 12 seals was such a major PITA that I will never do this again, and I strongly recommend anyone with the same problem to just pull the head. Though, the results are good, and it cost me only $15 for the seals. So I did save $150+ on a new headgasket and and other gaskets that need replacing if you pull the head..

[alpinacsi]

I missed this post originally but had the same experiance as you. I used compressed air applied thru the spark plug hole to hold the valve in place and used a valve spring compressor that allowed the spring to be compressed while the head was installed. I also came to the conclusion as you had and decided that any time from now on, I will just pull the head. Glad you got it sorted.

I used a tool similiar to this:

http://images.grainger.com/B305_31/images/products/450x450/2ZPG6_AS01.JPG

[Bentsdl]

I have looked at one of those too, but I thought that it was not possible to use it because you can slide the rockers only half an inch to the side, thus not have enough space to get it around the springs properly. Did you use it with the rockers and rockershafts still in place? Could have saved me a lot of trouble if I could have used it after all.

Did you have the same trouble of preventing the engine from turning over after you applied the pressure? I found it almost impossible to get the piston perfectly in the top position. After a while I discovered pressurizing the cylinders was unnecessary if you use magnet to keep the valves up.
In the end I had the most trouble removing the old seals from the valve guides without scratching the valve shafts. Those things were pressed on there really tight!

[alpinacsi]

The last time I did one that way was when I was a teenager and that was...a long time ago. I can not remember the specifics of the job but I will say the tool looks like new and has never been used again since.

[e24wish]

+1 alpinacsi. Just pull the head and have at it. All done and ready for a ton more miles. The basic valve spring compressor is a rental tool that is generic and should be found easily on the side of the road or borrowed from any gearhead. Special tools are a pain in the wallet i.e. MB head bolts, Jag/Aston cam reference tools, and anything Porsche. Ungodly wastes of money for the DIY and any shop that has the gear will look at you like you are some alien if you ask to borrow it...