What do used but healthy valves look like?

[sacrileger]

I have some used valves (see pics) and am completely uncertain which can/not be re/used. Gentlemen, your esteemed opinion would be much appreciated.

Here are exhaust valves that were polished lightly with sand paper just to get carbon and other gunk off. The black rings are actually low spots that did not clean up (never mind the broken valve):

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here's a close-up of valves that actually have dents in them

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these are intake valves that were not touched (polished). The silver ring is actually worn in:

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here is a close-up of the same intake valves to zoom-in on some of the imperfections and worn in ring:

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Here's a different set of exhaust valves with similar microscopic low spots in the black ring as well as some surface deposits that did not clean-up

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and here's a close-up on the exhaust valves above for better view and illustration

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thank you

 

[Mello]

Some might be okay. Most are bad or need refurbished to remove the pitting on the seat area. It may be about the same cost to just buy new ones.

 

[sacrileger]

Some might be okay. Most are bad or need refurbished to remove the pitting on the seat area. It may be about the same cost to just buy new ones.

I do realize some might be okay and some need refurbishing...but which ones?? I am thinking that all of the intake valves might be fine...perhaps they need more polishing with sandpaper. The exhaust valves will definitely need closer examination.
What I am trying to find out is what exactly does a used but healthy valve look like...one that could be reused. I have no reference. Perhaps somebody could post a picture.

 

[motomattx]

Most machine shops only charge a few dollars per valve to touch them up, the ones that cant be touched up they usually just give back with no charge on them, they all need to go to a machine shop period any way you slice it, they are too worn to be put back in service with any measure or cleaning that you can do, they arent dirty they are worn.

 

[sacrileger]

Most machine shops only charge a few dollars per valve to touch them up, the ones that cant be touched up they usually just give back with no charge on them, they all need to go to a machine shop period any way you slice it, they are too worn to be put back in service with any measure or cleaning that you can do, they arent dirty they are worn.

What is the criteria one would use to decide if a valve can be re-used or should be taken to a machine shop for a touch-up? For example, the intake valves above have a ring around the valve head where they were seated but they did not leak. I would imagine that if I put each valve where they came from and lapped them in a bit, they would still seal and work, would they not?
Or is there a general rule that valves after a certain number of miles, let's say 100K, should be replaced/touched up if the head is off?

 

[Mello]

In all your pictures I see only 1 which may be okay. You need to do more than just looking. If the valves are pitted then the mating valve seats are also pitted. You really need to just take the head to a qualified machine shop & get a valve job if you're interested in doing this proper.

 

[sacrileger]

In all your pictures I see only 1 which may be okay. You need to do more than just looking. If the valves are pitted then the mating valve seats are also pitted. You really need to just take the head to a qualified machine shop & get a valve job if you're interested in doing this proper.

thanks. Just for the sake of my own reference and future comparison which of the valves appear to be reusable in your opinion?

 

[1990TSIAWDTALON]

Pitting also makes the stem area weak. I wouldn't run the exhaust valves at all because of that. If the pitted area fatigues, it will snap and guess what happens next? I have had it happen is why I mention this. When a pitted area gets red hot is when it will give out and you sure don't want that to happen.

 

[curt-s]

+1 just get new valves, have new seats cut, and lap them for a nice tight seal.
If any part of a valve is pitted, its too worn to reuse and, depending on age, I would begin to look at the combustion cycle (fuel, timing, etc) for contributing factors.

 

[sacrileger]

Pitting also makes the stem area weak. I wouldn't run the exhaust valves at all because of that. If the pitted area fatigues, it will snap and guess what happens next? I have had it happen is why I mention this. When a pitted area gets red hot is when it will give out and you sure don't want that to happen.

in other words, you would not even get the machine shop to touch up and clean up the exhaust valves....you would just buy new ones and be done with it, correct?

 

[1990TSIAWDTALON]

Yes. You are putting a lot on the line as far as the rest of the motor, if just one let go. I consider it cheap insurance. Take a good look at the springs also and make sure they don't have any pitting on them, they do A LOT of work.

 

[sacrileger]

+1 just get new valves, have new seats cut, and lap them for a nice tight seal.
If any part of a valve is pitted, its too worn to reuse and, depending on age, I would begin to look at the combustion cycle (fuel, timing, etc) for contributing factors.

Exhaust valves are the only ones that are pitted. The intake valves just have a very even ring around their seats as can be seen. I have not polished them at all.
In addition to the pitted exhaust valves, would you also replace the intake valves as well? If yes, what would used valves have to look like to be reusable? Obviously not pitted, but what else?

 

[sacrileger]

Yes. You are putting a lot on the line as far as the rest of the motor, if just one let go. I consider it cheap insurance. Take a good look at the springs also and make sure they don't have any pitting on them, they do A LOT of work.

That makes a lot of sense; especially for engines that run turbo or are raced. Would you say this also is essential for a daily non-turbo driver that will probably never see its redline?

 

[curt-s]

You dont polish valves, you ensure that they have a (nearest makes no difference) perfect seal between the conical section and the seat. If you polish the valve and leave the seat untouched you will have leakage, guaranteed. Leave the sand paper alone.

Get a competent machine shop to give their opinion on intake valves. Sometimes handling them, spinning them in hand, etc., is more descriptive than a pic or two.
If the intakes are pristine, you should be ok putting them back in the exact guide you took them from. Also inspect the stems and guides for wear and ovalling.

 

[sacrileger]

You dont polish valves, you ensure that they have a (nearest makes no difference) perfect seal between the conical section and the seat. If you polish the valve and leave the seat untouched you will have leakage, guaranteed. Leave the sand paper alone.

Get a competent machine shop to give their opinion on intake valves. Sometimes handling them, spinning them in hand, etc., is more descriptive than a pic or two.
If the intakes are pristine, you should be ok putting them back in the exact guide you took them from. Also inspect the stems and guides for wear and ovalling.

To clarify, the intake valves were not touched. The exhaust valves were cleaned up with a wire brush and then spun in a drill against sandpaper to get all carbon and baked-on deposits off. My intent was to get an opinion here on the condition of the valves before I lap them in until I get perfect sealing on all of them.

The consensus here is that the entire head assembly should be taken to the machine shop....which makes sense. However, from past experiences, machine shops I dealt with always went for overkill and wanted to do and replace everything to maximize their revenue rather than sticking to what was absolutely necessary for the head to work properly. That's why I was hoping to get a better picture here of what is and what is not necessary.

 

[bastarddsm]

The serviceability is generally determined by the condition of the stem, and the thickness of the margin.

If the stem is worn too much it's junk. 4g valves are nitrided so they barely wear the stems, but the guides go away quickly

If the margin is thin there isn't enough meat to grind off the faces to get them straight.

If the valve job is good it should take minimal lapping to seat them, in fact if it's a really nice job, lapping isn't even needed. The seats were not lapped from the factory.

Also keep in find that lapping a used valve job generally doesn't do shit. The seating surfaces should be straight/flat/round. As they wear you round over the valve seat, and concave the valve face. Lapping a valve does the same thing.

Last point, just because a shop has a serdi or newnan or other new style carbide cutter machine for cutting seats doesn't mean they do a good job. I'm only marginally experienced, and I can guarantee I can do a better job on old school stone based equipment than an an idiot on a new machine.
Personally I look for the old timer with experience that uses stones, and has a good feel for the equipment, vs. a young shop that thinks a big machine is the best way to do it.

 

[Mello]

Thread stats: 15 posts, 8 are yours. 7 remaining, & 5 of these 7 say "get new valve" minimum along with "you need a valve job".

Valve jobs on a 16 valve head is not cheap. No respectable shop would ever reuse old wornout parts. I would want new valves, guides, seals, springs on my head. Also I'd have the head check for flatness & cracks, have the seats cut, lap the valves in, ensure the valve tips are the correct height; etc. Nothing in a head rebuild is cheap. I'll stop here.

 

[sacrileger]

Thread stats: 15 posts, 8 are yours. 7 remaining, & 5 of these 7 say "get new valve" minimum along with "you need a valve job".

Valve jobs on a 16 valve head is not cheap. No respectable shop would ever reuse old wornout parts. I would want new valves, guides, seals, springs on my head. Also I'd have the head check for flatness & cracks, have the seats cut, lap the valves in, ensure the valve tips are the correct height; etc. Nothing in a head rebuild is cheap. I'll stop here.

It's always helpful to run into a self-appointed statistician such as yourself whose only default advice is to post "take everything to a machine shop and opt for the most expensive and least practical solution". Unless you have a reading comprehension problem (in which case I apologize) or simply have not been paying attention, I am not building a turbo charged race car here. I watched this video where the guy at @9:30 minute mark was able to do a visual examination of his 60K valves and determine that the valves were in perfect condition. How the hell did he do that??? Obviously you are the wrong member here to ask...so never mind.

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All I was asking for was a guideline how to determine what can or cannot be DIY type of solution. If everybody was acting on your useless "get everything done in the machine shop" advice, there would be no need for this forum. So yeah, no need for the unimaginative, broken record "machine shop" advice. Thank you for your input and have a nice day.

 

[Mello]

Rebuilding a head on any car is not a DIY project & I'm very familar with Jafro's video, have been for numerous years. Sorry that you are not getting to answers you want to hear but this does not change the facts to any of your questions. Head work is head work & it makes no difference if it's for a turbo, race car, or non-turbo. Only an idiot would try to continue on the path you are trying to pursue.

 

[1990TSIAWDTALON]

On your turbo car, make sure that, as others have said, the valve guides are good also or you will get blow by that can't be fixed by replacing valve stem seals. It was a good thing that bastard and curt brought up. I always check the guides for ANY play and if there is some I have them replaced while I am servicing a head.

 

[sacrileger]

Rebuilding a head on any car is not a DIY project & I'm very familar with Jafro's video, have been for numerous years. Sorry that you are not getting to answers you want to hear but this does not change the facts to any of your questions. Head work is head work & it makes no difference if it's for a turbo, race car, or non-turbo. Only an idiot would try to continue on the path you are trying to pursue.

Since there's nothing that Jafro has done that I myself could not "DIY", I guess Jafro is an idiot, based on your being the in-house expert, for re-using valves and not taking his cylinder head to a machine shop for an expensive valve job:

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[bastarddsm]

Mello, I don't want to be a dick, but nothing wrong with reusing used parts. The valves in my car have over 200k on them and seem to work just fine being that I make oh ya know north of 700whp, and turn it 9000 regularly.

OP, if the valve faces have any visible wear they should be reground.

Typically the process I would use is to first clean all the carbon off the valves using a wire wheel in a bench grinder. You have to be careful doing this because the wire wheel wants to grab the valve repair on your hand and throw it on the ground.typically when that happens it bends the valve and it is now junk.
I would then measure the stems in several places with a micrometer, a good stem typically measures about .260 inches.

If they measure good I would then generally lap them just a little bit to see how the seat looks. If it is nice and consistent and the valve face is not concave it all, they are probably in good condition and can be reused without being ground.

However most used valves have at least 50 to 100,000 miles and are worn concave some, and will need ground.

The valves in your pictures need ground several of them are junk and will need to be thrown away.

The factory valves are a very good heavy duty valve they hold up very well and in no case I would throw away a factory valve just to put a cheaper aftermarket valve in. Most aftermarket valves may look nicer and flow better but they are probably not as durable.

One Caveat to this is that the factory valves will break in many cases if they are bent due to the timing belt slipped, most aftermarket valves will not break they will bend.

 

[lasthope05]

You are not going to be able to lap those pits out of the valve faces without destroying them. Also chances are since the valve faces are chewed up, your valves seats would also be the same. Fully lapping in valves is old school and is fine on small weed wacker engines or cars you're just looking to run real quick to flip. On a car you plan to keep and make good power on, no F'in way. On a proper valve job you dont even need to lap the valves. Let me guess, you're they type of person who thinks they can bore out a block at home with a stone hone too right? Some thing are best left for the professionals and machine work is one of them.

As for jafro....he actually takes the head to get it properly cut in future videos. Also dont look at him as some kind of dsm guru. Hes gets plenty of things wrong.

 

[sacrileger]

OP, if the valve faces have any visible wear they should be reground.

Thank you for taking the time to address my question. The statement above applies to my case. The exhaust valves are pitted and in bad shape. I will need to purchase new ones. I checked the intake valves with a micrometer and the stems are a tiny tiny bit out of round but none of them .260". Mostly around .258 - .259". The margin on all intakes is original...the black hardened surface has no wear on it and I measured .039-.042" (difficult to measure as there's no surface to grab).
However, the silver ring on intakes is where the valve contacts the valve seats and that area is worn right through the original hardened finish. But the seating is fine. I checked using a black marker and the valve seats properly and smears the ink away. Since these are 1g valves, and based on your previous post, it is the stems on these valves that wear down so the guides must be ok. I dont have a good way to measure the 'stem to guide' clearance. They are not cracked.

So I am thinking I could reuse the intakes. However, as one of the previous posters mentioned, the exhaust valves are pitted and the exhaust valve seats also have tiny (nearly microscopic) pitting on them. Using valve grinding paste, would you try to lap the new exhaust valves until the surface on both sides is perfectly smooth? No visible pitting? Again, these are very small imperfections I am talking about...not some big dents or gouges.

 

[sacrileger]

You are not going to be able to lap those pits out of the valve faces without destroying them. Also chances are since the valve faces are chewed up, your valves seats would also be the same. Fully lapping in valves is old school and is fine on small weed wacker engines or cars you're just looking to run real quick to flip. On a car you plan to keep and make good power on, no F'in way. On a proper valve job you dont even need to lap the valves. Let me guess, you're they type of person who thinks they can bore out a block at home with a stone hone too right? Some thing are best left for the professionals and machine work is one of them.

As for jafro....he actually takes the head to get it properly cut in future videos. Also dont look at him as some kind of dsm guru. Hes gets plenty of things wrong.

Point well taken...see my post #24. And yes, you're right, I am that kinda guy. I just put new compression rings on and used a stone hone to prep the cylinders for the new rings at home. I did not take it to a machine shop. Now I am working on the cylinder head, DIY type of 'jafro' style. I dont look to make more power on this car than what the non-turbo factory car gets out of this motor. I am just trying to keep the car on the road and get more life out of it at the least cost.