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MG TD TF 1500 - Question about valve seals

I've learned from the archives to use Felpro part #70373 umbrella seals instead of the o-rings and shedders from the factory on my TD. Are they supposed to hold fast to the valve guides? These don't grip and are riding up and down with the valve. They were brand new and in the box as I ordered then from my NAPA dealer. I just had a valve job done with new seats and valves but the machinist said that the guides were just fine but they may have been replaced by a PO. There does not appear to be any ridges on the top of the guide for these new seals to grip onto. Can I leave as is or am I looking for trouble? If this is NG, what can I do to remedy it? Thank you guys. Sandy
smb brainsky

I'm at that crossroad, too. That will probably boil down to each person's own preference.

I don't mind the thought of the umbrella bopping up and down; it'll shed some oil, just like an UMBRELLA (Felpro part #70373 umbrella seals). I'm not racing and not worried about an extra gram for premature valve float. I found some new leftover seals from our Dodge Shadow and some Hondas- I'm not particular.

I emailed one of our resident experts and he seemed a bit neutral but likes the thoughts of valve guides getting some extra oil, even if it might show up as a touch of smoke.

The one thing I learned about the MG head is the O-ring goes directly underneath the keepers supposedly, to keep oil from funneling down the spring retainer. Reference Moss catalog engine internals.

JRN JIM

Hi Jim, those are interesting thoughts about lubing the guides. But everything I have learned on this subject says dump the o-rings. Apparently they hinder the lubrication of the guides. What if we just used them on the intake valves with the umbrella on all?
smb brainsky

Sandy - I'm not sure where you got your anti-o-ring info, but my own experience is that - when properly installed - they last tens of thousands of miles, and work just fine. I replace them as a matter of course every time I rebuild a head, but I have had no sticking of valves in the guides, no excessive valve stem wear, or any other indication that the o-ring is overly or minimally restrictive.

It ain't broke, as far as I am concerned, and there is no need to fix it with umbrella seals or the FELPRO guide seals. Under racing conditions I can understand a different paradigm, but for a street car the o-rings work just fine, assuming the valve guide clearances are appropriate (I suspect this is where many more problems occur).

Tom Lange
MGT Repair
t lange

Hi,
the main thing is to make sure the "O" ring is properly seated under the collets ie not cut or trapped in the collet.When anybody I know complains of overrun smoking I check by letting the engine stand for 5 mins then take off rocker cover. If any "O" rings are broken then there will NOT be a pool of oil on the on the faulty one.
Ray TF2884
Ray Lee

I agree, Ray. In most engines I've worked on that smoked on deceleration the o-rings were assembled all the way down the valve stems to the top of the guides. The o-ring goes into the groove of the valve step just far enough so that the collets can be fitted.

Tom Lange
MGT Repair
t lange

OK, I have been reformed. You've made me a true believer in o-ring valve seals. My info came from reviewing the archives and from Peter Edney's XPAG rebuild video. When I first researched this, I was pointed the other way. So what about using both? Although I am not too excited about those poor fitting umbrella seals bopping up an down like hot air popcorn. Can any harm come from 2 seals per valve? And thanks for everyone participating on this thread. I realize it has been rehashed more than once. Sandy
smb brainsky

When you look at the assembly of the shield and O-ring on the XPAG Engine. You will see how it makes the umbrella effect to stop a lot of oil running down the valve stem. Mine has worked fine for 40 + years.

I did see on a TC in Bielefeld Germany belonging to a friend which was smoking rather well. The shop who had worked on his engine had placed the shield on the bottom of the springs. Which caused the issue of a lot of blue smoke. It was acting like an oil reservoir.

It was an easy fix. Assembled them correctly and it resolved his issue.

Rod



R D Jones

Thanks Rod. That is by far the best diagram of this whole arrangement I have seen so far. Sandy
smb brainsky

I fitted both.

The one on the valve guide is a very snug fit and I believe the are Audi or VW seals. There a thin flat steel spring that holds it on to the guide.

I think the oil shields as in the diagram above are missing on my engine. Where they fitted to all XPAG's?

Willem van der Veer

I found it rather fiddly to get the o-rings onto the valve properly, so in order to fit the o-rings I made a little tool to push them over the stem.

If lubricated liberally it will slide into place against the collets perfectly when the valve spring is released.

Willem van der Veer

Tool in action

Willem van der Veer

and the result

Willem van der Veer

Willem, those shields were a standard feature on the xpag engines but seem to have been collectively omitted by modern practices. That diagram posted above by Rod is the best view I have seen of them. They are not on my engine either. I like that you found better fitting umbrella seals and that you have installed both. I have decided to make my felpro seals fit better and use them only on the intakes and put the o-rings on all 8 valves. I like your simple little installation tool too. Nice job. Sandy
smb brainsky

Willem, those shields were a standard feature on the xpag engines but seem to have been collectively omitted by modern practices. That diagram posted above by Rod is the best view I have seen of them. They are not on my engine either. I like that you found better fitting umbrella seals and that you have installed both. I have decided to make my felpro seals fit better and use them only on the intakes and put the o-rings on all 8 valves. I like your simple little installation tool too. Nice job. Sandy
smb brainsky

Go to Bug Kruegers web site (TTalk) and look at the article and pictures I posted on the replacement process of the Felpro seals.
The seal functions not as a seal, but as an umbrella to stop gobs of oil going down between the guide an the stem. Yes it goes up and down, its supposed too. Some oil is needed as a lube for the valve stem and guide.
colin stafford

That's http://www.ttalk.info/StaffordSeal.htm Bud
Bud Krueger

This thread was discussed between 05/01/2014 and 08/01/2014

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