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Duratec/mx5 mk3 valve stem seals
cliftyhanger - 26/4/22 at 01:45 PM

Just bought a cheap MX5 mk3 for my daughter, nice and resonably priced with no corrosion issues. However, we knew the engine is a little smokey. Mainly on startup, and lift off/throttle produces a plume. Typical valve stem symptoms.

Is it feasible to do without taking the head off? I guess chain tensioner is an issue, and use the rope trick to retain the valves? Any special tool recommendations to remove the valve springs/buckets?

TIA

nick205 - 27/4/22 at 01:43 PM

Interested in any answers here myself - a job I've contemplated on a 205 1.9 GTI engine. Never had the guts to try it for the fear of dropping a valve, but if done with care it must be possible. That said if the valve stem seals need doing the enfine would probably benefit a fresh head gasket and timing belt anyway.

cliftyhanger - 27/4/22 at 04:18 PM

There is teh rope down the bore trick, or even a compressor to keep the valves up. But is there a special tool for compressing the valve springs?
It must be a common job, there are zillions of duratecs out there.

If I end up taking the head off, I may as well drop the sump, pop teh pistons out and hone the bores. A set of rings, and possibly bearings wouldn't be a lot, but I doubt will be necessary. And the duratec has a cam chain, another issue to overcome...

obfripper - 27/4/22 at 05:02 PM

I have a draper kit similar to the following link, i''ve used it on all sorts of engines but not a duratec/mzr engine.

https://www.ebay.co.uk/itm/372623561731

At a quick glance, you would have to reset the timing/chain tensioner as each cam has to be fully removed to swap out the seals, some engines you can slip the chain off and not disturb the timing, but the tools are needed to confirm this anyway.

I would say the 1.8 ford versions do have a tendency to use oil and it is often the rings, however i have not noticed the same with the mazda versions.

Dave

cliftyhanger - 27/4/22 at 08:40 PM

quote:
Originally posted by obfripper
I have a draper kit similar to the following link, i''ve used it on all sorts of engines but not a duratec/mzr engine.

https://www.ebay.co.uk/itm/372623561731

At a quick glance, you would have to reset the timing/chain tensioner as each cam has to be fully removed to swap out the seals, some engines you can slip the chain off and not disturb the timing, but the tools are needed to confirm this anyway.

I would say the 1.8 ford versions do have a tendency to use oil and it is often the rings, however i have not noticed the same with the mazda versions.

Dave


Thanks, that is useful.
I "think" there is a way of keeping the timing chain tensioned correctly, but the MX5 forums are inhabited by people a wide variety of skill levels and getting decent info is almost impossible.

Pretty sure the seals are poor, the smoking on startup is a give-away. Possible rings are a bit worn too, but one thing at a time!

Cheers
Clive

[Edited on 27/4/22 by cliftyhanger]

pewe - 30/4/22 at 11:12 AM

I've used this one my Mk1 MX5 head a couple of times (don't ask!) combined with the rope method - use polypropylene rope as it isn't hairy, about 8mm diam IIRC inserted into the bore with the turned over and taped up end of a wire coat-hanger so it goes well into the barrel, before turning the engine over to squash the rope firmly inside the head.
It then seems counter intuitive to hit the tool with a lump hammer when both dismantling then re-assembling but it does work.
I bought some 6mm diam plastic straws to use as stem sleeves when fitting the new seals, plus plenty of oil of course, then a light tap with a suitably long 1/4" drive socket to ensure they are seated properly.
Valve collet removal tool
PS it smoked a lot before - doesn't smoke now - result!
[Edited on 30/4/22 by pewe]

[Edited on 30/4/22 by pewe]