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Which valve stem seals leak

Old 05-17-2017, 06:40 PM
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I tried ringing Ford, Suzuki & Toyota.
-Toyota had what they called exhaust valves - listed as inlet valves on the link and were more expensive than Mazda.
-Ford didn't even recognise the part number
-Suzuki weren't open.

I have found a seller on eBay selling genuine Kia intake valves - 8 for all 8... I have bit the bullet and bought the full engine gasket set from Mazda - there's another $350 gone.

Now to decide whether to use the stock HG or buy Cometic.
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Old 05-17-2017, 07:03 PM
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If you look at the link I posted and take a minute you'll see all the cross-references/vehicles/dimensions/part numbers you need and can order whatever you want online. Valve stem seal cross-reference - post #37

Also, for whoever is so inclined, here's a paper (attached) on valve stem seals + design + materials + tips on installation etc.

I have another email into Supertech to get a definitive answer on diameter range their seals can handle. Will post when/if I get a reply.

EDIT: Well I got a reply but nothing of substance. I specifically asked what valve stem diameter the seals were designed to accommodate and the reply was "They're designed for 6mm stems".

Kind of funny especially when they list their exhaust stems @ 5.94 which is 0.025 [.001"] below the factory tolerance (5.965-5.980, 5.915 Min). Oh well.
Attached Files

Last edited by bahurd; 05-18-2017 at 06:29 PM.
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Old 05-22-2017, 09:57 PM
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***** unnerving y0
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Old 06-02-2017, 11:56 PM
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Supertechs installed this winter. A couple hundred miles on them, and I could see the oil pissing out the exhaust manifold.


I'm in the middle of replacing them with felpros. My impression is that it's way easier to feel the double click as the felpros seat.

Also, use this gimmick when you reinstall the keepers

1) seat the keepers so they're started on the valve stem.


2) slip a Ziploc bag over the top of the keepers and under whatever you use to compress the spring. Push it. Push it real good. The plastic guides the keepers into place. Super easy.
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Old 06-03-2017, 12:19 AM
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Very nice post. Have a feeling I'll be doing this soon. Your oil out the exhaust flange just looks like a poorly sealed exhaust flange.
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Old 06-03-2017, 12:24 AM
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Originally Posted by curly View Post
Your oil out the exhaust flange just looks like a poorly sealed exhaust flange.
Yeah, I'm sure that's part of it. The picture doesn't do it justice. It's literally dripping out the bottom of the manifold.
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Old 06-03-2017, 09:28 PM
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poscat for the keeper bag trick. I'll be using that tomorrow
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Old 06-05-2017, 05:09 PM
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Originally Posted by wackbards View Post
The picture doesn't do it justice. It's literally dripping out the bottom of the manifold.
"What are all these black dribbles down the side of the block under the exhaust?"

Its oil, don't worry about it.

"Are you sure?"

Yeah.

I've been having this same conversation since my STs went **** up back in 2015 I hope the felpros work out for you, we definitely need more datapoints on this one.
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Old 06-05-2017, 09:53 PM
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did anyone with leaky ST seals notice that once warmed up they didnt seem to leak? i was stuck at a readlight for a bit today and didnt notice any smoke when i took off. however if i let it sit for any time when cold it will smoke
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Old 06-05-2017, 09:56 PM
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Theoretically there should back pressure in your exhaust manifold when running. Harder to leak?

What about engine off at a red light
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Old 06-05-2017, 10:00 PM
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i dont know about engine off. It will do it when running and getting up to temp before i leave.
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Old 06-05-2017, 10:17 PM
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Originally Posted by aidandj View Post
Theoretically there should back pressure in your exhaust manifold when running. Harder to leak?
Exhaust manifold pressure is basically ambient at idle or even part throttle/off-boost.

--Ian
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Old 06-06-2017, 12:35 AM
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How far back does this problem go? Were ST seals ever any good? Reason being Mobius has some oil in his exhaust, but I put his CNC head on (with ST valve stem seals AFAIK) at least 2 years ago.
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Old 06-06-2017, 12:43 AM
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Supertech never admitted there was an issue. So I doubt well ever find out about any sort of manufacturer change that may have caused this.
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Old 06-06-2017, 01:28 AM
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Fingers crossed, but the Supertechs (that I thought were OEM, but apparently not) in my head (which got installed around the same time as Gordon's) seem to be holding up OK. No smoke or oil drilling down the head, at least.

--Ian
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Old 06-06-2017, 01:29 AM
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Are you running a cat?
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Old 06-06-2017, 02:13 AM
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I do not run a cat on the track, no.

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Old 06-07-2017, 09:59 PM
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Not surprised at super tecks responds. I'm sure they are well aware if their seals are dodgy or not.Who would admit to that. But as far as the specific details of the seals themselves go They might be concerned that you will start havin your own ones mad which may end up better than thiers.

I've just installed the Miata Roadster ones from Bill.
COMP Cams Valve Stem Oil Seals - MiataRoadster - High-performance service...and parts for Mazda Miata Roadsters

not sure what the verdict is for those. Its only been a few weeks.....before I spotted this thread.
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Old 06-07-2017, 10:50 PM
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I have found this on rockauto. Viton seals from engine tech. No idea the quality but it might be something to try.

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Old 06-08-2017, 12:54 PM
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Originally Posted by curly View Post
How far back does this problem go? Were ST seals ever any good? Reason being Mobius has some oil in his exhaust, but I put his CNC head on (with ST valve stem seals AFAIK) at least 2 years ago.
curly, my CNC head was ordered at around the same time as Mobius and they've leaked since the beginning.
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