Valve seal replacement

thekidd · 03-07-2011, 07:51 AM

I am going through the head gasket replacement and in the kit I got valve stem seals. I do not know how to go about replacing them (just did a slight search). Haynes says you need a special tool and doesnt tell you how to do the job- take it the dealer- no. The search I did says you need a spring compressor, but others used a c- clamp. Not exactly ire what that is. Is is nesecary to change the valve seals? How do you tell if they are bad with themstill in the car? How would you go about changing them out? Will toy with it in a little bit, but should be receiving a head today and putting her back together.

krystar · 03-07-2011, 08:01 AM

valve spring compressor. either 2 prong kind or a giant C clamp (like....12in opening...to go all way around the side of the head)

u pretty much have to remove the valve to do the seals. so..yea.

i believe the standard diagnosis for a bad valve seal is if when you start the car, there's initial oil burnoff, but after car warms up, there's nothing.

HondaDustR · 08:48 AM

If it were me, I would just replace them regardless since you're in there already, especially if they are over 100K miles old. I used one of those 2 prong screw type compressors and I hated it, but it was cheap, readily available, and it works with the head still installed. These springs are very strong and it could only just barely reach the inner spring and compress far enough. A standard overhead lever compressor for rocker valvetrain can also work quite well with some extra scrap bits.
It's a 928 head, but it's nearly identical to a 8v 944 head.

I believe there is a tool to push the seals on with, but if you are careful, a deep socket works. It is important to get them on straight and they do fit very tightly, so a bit of assembly lube helps them go on. You also have to be careful to stop when the end of the guide reaches the step molded into the seal inside. It is possible to go past if you push hard enough and the seals are nearly impossible to pull back off intact.

krystar · 03-07-2011, 09:06 AM

nice pix hondadustr

Rasta Monsta · Rasta Monsta's Garage

Does this mean you aren't taking the head in for a valve job?

89-944NA · 89-944NA's Garage

Save yourself some future problems, and get a valve job done now....how would you like to install the head, and a month or so away have to pull it again because of a leaking valve? Spend the money for the peace of mind. The key here is Preventive Maintenance

thekidd · 03-07-2011, 11:50 AM

am going to take the head in, but thought that I may save myself some money and do the valves myself a couple of bucks. On the new head I got it looks like one valve is a little crooked. First one is the 3rd valve to left, second picture it is the 3rd valve from the right (one with the shinny metal showing on the valve) old and newer heads. Is the valve bent?

krystar · 03-07-2011, 01:05 PM

yup that sucker's bent. looks from the reflection like a solid impact with the piston. yer also missing an exhaust stud.

and...i think someone's done a valve job on this head already. second pic top head #2 from the left's intake valve doesn't have the same dish as the other valves.

Rasta Monsta · Rasta Monsta's Garage

Which one? The one with the shiny hammered spot?

ROFL!

HondaDustR · 03-07-2011, 01:26 PM

So why do you have a second head? Was the first one warped or cracked? Or just preparing for the worst?

That exhaust valve is definitely finished, and it will need a new valve guide as well, which then means the valve seat needs to be re-cut. If you can afford it, get a good exhaust valve and have the shop replace the guides and re-cut the seats. Then you can lap the valves in and the head will be good for a long time. If you can't do the whole thing, check that the valves don't fit loosely in the guides. You may need to at least replace the exhaust guides depending on the mileage. They wear out much sooner than the intakes, but guides are cheap. Worn guides will wear the valve seats and stem seals much faster meaning more problems down the road sooner than you would like for all the trouble you are going through.

bebbetufs · bebbetufs's Garage

One tip wen installing valve stem seals is to make a spacer for the stem to avoid pushing them on too far. I made mine of a piece of pvc tubing of the kind they route electrical wires through. It turned out to be a perfect fit.

Measure the distance from the block to the botttom of the valve stem. Cut a piece of the end of the tubing slightly longer, you will have to sand it to make it smooth anyway. Make sure it is absolutely square. When done cut out a 2 mm gap in one side. That way you can snap it on an off the stem from the side. Makes fitting the seals very easy and saves you the hassle of pushing them on too far.