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Which valve stem seals leak

Old 02-12-2018, 12:49 PM
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Interesting theory. Could be that the viton in the supertech seals is a bit stiffer and doesn't conform to a wobbly valve as much.
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Old 02-12-2018, 01:23 PM
  #162  
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Funny thing Adaindj, (and I am showing my age here); in the past engines have not always had much in the way of guide seals and they didn't smoke... well, much. Some of the mid 1950's-60's era V-8's used nothing more than an O-ring atop the guide to "deflect" excess oil. In going thru a 1960 recently Catalina I ran into a valvetrain design where Pontiac had actually drilled oil galleys to feed oil thru the guide, and they didn't smoke... much.

I can't believe that a well made stem seal of this modern generation could cause so much trouble. If your guides are somewhere in the .0015-.0018" range then I would think that the oil control issues (in the amount that you are describing) would be coming from another source. I believe that you are onto something when you talk about loose guides and wobbely valves.

btw: I did pick up that other car... now how long before I have Gabe turn up the boost? cj
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Old 02-12-2018, 02:24 PM
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Originally Posted by gtred View Post
Funny thing Adaindj, (and I am showing my age here); in the past engines have not always had much in the way of guide seals and they didn't smoke... well, much. Some of the mid 1950's-60's era V-8's used nothing more than an O-ring atop the guide to "deflect" excess oil. In going thru a 1960 recently Catalina I ran into a valvetrain design where Pontiac had actually drilled oil galleys to feed oil thru the guide, and they didn't smoke... much.

I can't believe that a well made stem seal of this modern generation could cause so much trouble. If your guides are somewhere in the .0015-.0018" range then I would think that the oil control issues (in the amount that you are describing) would be coming from another source. I believe that you are onto something when you talk about loose guides and wobbely valves.

btw: I did pick up that other car... now how long before I have Gabe turn up the boost? cj
Well, those old pushrod engines had significantly less oil above the valves, unlike the DOHC motors that have 10+ oil journals to keep lubed entirely above the valve stems...
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Old 02-14-2018, 09:30 PM
  #164  
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I just received feedback from my engine builder. All 16 Supertech valve seals are leaking. All valve guides showed wear, but are within Mazda specification. Right now my plan is 16 new valve guides and Felpro valve seals.
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Old 02-15-2018, 07:30 PM
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Originally Posted by Ken Hill View Post
I just received feedback from my engine builder. All 16 Supertech valve seals are leaking. All valve guides showed wear, but are within Mazda specification. Right now my plan is 16 new valve guides and Felpro valve seals.
That's... impressive!
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Old 04-18-2018, 02:01 AM
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Reposted from the other thread here:
Issues with Supertech Viton Seals

I'm reposting this in order to keep the info on the Sticky.

"OK! I've finished a fairly exhaustive test to evaluate these valve seals. Somehow I've ended up with 7 different seals to test.

I decided to make up some kind of test in order to evaluate actual performance. Measuring the various dimensions is all well and good. But due to the spring, material type and shape/form of the lip, I can't positively establish which is really any better/worse.

So I made up a way to mount each valve seal as mounted on a valve stem. Then I'd simply add weight until the grip on the stem is lost.
Now all of these basically have a 'slip point' at which they whip right out. So I tried to very carefully measure that point. Using engine oil for lube, I put these on and gave them a chance to fall (over and over) in order to establish a repeatable measurement. In most cases I tested 3-5 samples. Unfortunately, some of these only had one or two samples to test (US Seal EOK, Felpro)



The results make perfect sense. Something we already know: DON'T INSTALL SUPERTECH VALVE SEALS.



Overall winner? A seal that I don't even have a new one to test. OEM. I'm going to guess that the seals on this motor are fairly well used. But I have no idea.

The Supermiata are great. Really tight fit and strongest grip overall."
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Old 09-07-2018, 10:42 PM
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I have a fresh rebuilt motor and I'm 90% sure my seals are leaking. I went with the supermiata ones after reading this thread. The engine builder checked the guides and said they were in spec, so didn't replace any of them. They also installed the seals, did a valve job, and built my bottom end. I have ~800 miles on the motor and have noticed that it very slightly smokes, but only after idling for 10+ minutes and then i rev the motor, or engine braking down long (1+ mile) downhills.

Otherwise under WOT, or even normal driving conditions around town it does not smoke at all.

I plan on proving this theory by pulling the intake and/or exhaust manifold to check for leakage, though the smoking is so minor I probably won't bother until the dead of winter. I'll update this thread at that time.

As a data point when I pulled the head for the rebuild, the old valve stem seals were clearly leaking, a lot. I'm now wondering if those should have been replaced as well.

The builder of my engine and head were well known shop that works with spec miatas, so I trust they did things correctly.
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Old 11-01-2018, 01:14 PM
  #168  
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Another data point- I went with 949 viton seals two years ago as part of my rebuild and still no leaking or smoke.
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Old 11-01-2018, 01:22 PM
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Originally Posted by AlwaysBroken View Post
Another data point- I went with 949 viton seals two years ago as part of my rebuild and still no leaking or smoke.
Were your valve guides replaced?
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