Do I need new intake + exhaust valves?

[Vwspen3310]

I am in the process of doing the valve stem seals and just cleaning up the head in general from my 85 8v. The head is currently off. After pulling all of the valves out, I noticed that at least one of the valves has some extensive pitting up the shaft, and several other valves have some less worrisome pitting on them. Should I just replace the valve that looks pretty bad? or should I just get all new intake and exhaust valves?

And if I get new ones, is there a proper way to get them to seat?


Also while trying to get the first valve stem seal out, I grabbed the valve stem seal on the inside and put a little scratch into it. I'm wondering if I should get new valve guides.

[euroteknique]

for the price of all new valves you can buy a good used head people sell these all the time fairly cheap. I see 16v heads for sale often for like 150.

[Vwspen3310]

I can get a set (4 intake vales and 4 exhaust valves) for right around 50 bucks. with the guides makes it 60 bucks. Worth it?

[euroteknique]

you might as well do seals and guides to do that it takes a machine shop.

[sciroccohal]

I am in the process of doing the valve stem seals and just cleaning up the head in general from my 85 8v. The head is currently off. After pulling all of the valves out, I noticed that at least one of the valves has some extensive pitting up the shaft, and several other valves have some less worrisome pitting on them. Should I just replace the valve that looks pretty bad? or should I just get all new intake and exhaust valves?

And if I get new ones, is there a proper way to get them to seat?


Also while trying to get the first valve stem seal out, I grabbed the valve stem seal on the inside and put a little scratch into it. I'm wondering if I should get new valve guides.

First...The BENTLEY BOOK!

You need to MATCH the valves to the seats. You need to measure and lap them by hand.
You need to do a run-out measurement on the valve guides...wiggle back and forth. Replace anyway. New valves, guides, seals and clean up the head SURGICALLY.
Hopefully you will mark your buckets and springs and keepers and put them back into their respective places.

If you fail to do any of that properly you will burn the exhaust valves and have the chance of the intakes not sealing either.

[TBerk]

For sixty bucks, I say replace 'em. Mr Hal, he of the good word, speaks truly in that even if you keep good serviceable, valves have a good valve job, a proper valve job is a long term key to happiness.

[sciroccohal]

For sixty bucks, I say replace 'em. Mr Hal, he of the good word, speaks truly in that even if you keep good serviceable, valves have a good valve job, a proper valve job is a long term key to happiness.

I guess I didn't actually say it...replace the valves etc and get a machine shop to do it.

This is no job for beginners. No insult here.

[Vwspen3310]

Yes I am measuring all of my intake and exhaust valves and figuring out the tolerances.

Beginners have to learn somewhere. What i am trying to get at is, several of the intake and exhaust valve shank pieces are worn and some are pitted. This makes me want to get new ones. If I get new ones, do I HAVE to take it to a machine shop? The valve seats in the head are all still in great shape. This leads me to think that I can just lap the new valves in place. correct?

The bently that I looked at only said that if the valve seats were damaged they had to be machined, and that when installing new exhaust valves that they are NEVER to be machined only lapped. It did not say that when installing new intake valves that they should be machined. This is why I am asking. If I do have to machine the head, I am just going to buy a used one. And not to say that if I buy a used one, that the valves will still be pitted along the shank and I get the same darn problem and have to put new valves in anyways.

I can do guides. I have access to a press and reamers.

I just want to know (basically): repair the head, get a used head, or go extreme and drain my pocket book on a eurospec head (pretty much out of the question).

[polov8]

Taking it to a machine shop is only really vital if you replace the valve guides. If those are OK and you fit new valves, the alignment with the valve seat should be retained, and you'll be OK to just grind them in.

Are the valve seats pitted at all? If so they may well need cutting, and then you'll need a machine shop.

Heads are quite fun to work on so long as you have the right tools, a bit of patience, and an eye for detail. Cleanliness is key to all engine work, make sure it's all spotless!

[DUBSfightinRUST]

Seems like you have a good understanding of the process. Repair the head according to the manual. Do not be afraid to spend $60 on parts. I know guys willing to spend in excess of $2000.00 on a cylinder head.

The most important things are : follow the service information and have fun!

Wrenching are what Sciroccos are all about.

[MacGruber]

My 2 cents: I was reworking a 8v head, with the valve play right at the specified limit. After buying the guides and paying the VW specialist to press them in, now 4 of the guides extend right up to the valve head taper. A call to the specialist reveals the OEM VW guides are high quality designed to last forever, while the replacements, with the correct Vw part # are still just aftermarket. Those guides now need to be reamed.

He essentially stated I just wasted my money replacing the guides, and correct reaming still to be done.

I just bought a much better looking head (with block attached) instead.

[jdek]

Taking it to a machine shop is only really vital if you replace the valve guides. If those are OK and you fit new valves, the alignment with the valve seat should be retained, and you'll be OK to just grind them in.

+1
If you replace the guides, you need to work the seats every time.
If the tolerances between the guides and the new valves is within spec, confirm your seat width and its location on the valve face while lapping and you should be ok.

[Vwspen3310]

After more research I took it to a local machinist and he is going to do new guides, most likely new valves, resurface the head and seats and adjust the shims for me.

Not as cheap as I had wanted it, but: Do it once, do it right.