Valve Stem Seals
Traction Owner’s Club › Forums › Technical › Engine › Valve Stem Seals
- This topic has 7 replies, 4 voices, and was last updated 3 years, 7 months ago by Nigel Watling.
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18th April 2022 at 2:04 pm #29830
Nigel Watling
ParticipantHello all,
Has anybody had an issue with a smoking engine after head removal and refit?
Between overhauling the engine a while back and recent head off I found out that I’d fitted the valve stem seals in the wrong place, I’d put them on the stem before assembly of the spring and collar and keeper rather than immediately below the keepers, so as I had a new set to hand put these to where they should be according to the manual. Now I have a smoking engine and piston No 4 has oil laying on it when viewed with a camera down plug hole, I wish now I’d left alone or at least put seals in both locations.
Has anyone ever tried a modern type vale stem seal if these would even fit.
Another thing that’s probably not helping is the fact that I lowered the rear of the engine slightly so as the mounting block was central to the housing and this in turn allows more oil around No 4 valves.
Interested in any thoughts
Regard
Nigel
19th April 2022 at 10:23 am #29831Philippe Allison
ParticipantHi Nigel,
I have done 4 engine rebuilds in the last 10 years including one 6 cylinder. When the heads are being reconditioned I have new valve guides made which take the modern “top hat” seals. None of these engines use a drop of oil. Having said that I have also built engines with the old type seals and these have not used oil.
You have not said if the bottom of the engine has been rebuilt, if not it could be worn bores or a broken oil control ring, a cylinder leakage test may help to identify the cause before a complete strip down.
Good luck Philippe
19th April 2022 at 11:19 am #29832ParticipantHi Philippe
Thank you for replying, apologies I have only given half the story, the engine was rebuilt with new piston and liners, crank regrind, valves, hardened seats and guides, pump etc a while back. and the reason for the strip down was after 100 miles it developed a knock, so sump off big ends checked (all ok) so then removed head, took pistons out looking a bit deeper but nothing found as all measured in tolerance so rebuilt with new shells and seal location change as previously stated after which it started smoking.
I may have jumped the gun a bit because after refitting the head and doing the re-torque no amount of idling or revving would clear the blue smoke but after taking it for a ten mile run yesterday its now very much cleaner.
Will keep you posted.
Regards
Nigel
20th April 2022 at 4:10 pm #29838Bernie
ParticipantNigel,
The original, square section ring vss are designed to stay in a fixed position on the stem and move with the valve, the theory being that oil running down the valve stem is diverted away from the stem at that point. The “umbrella” type is designed to stay in place on the guide and “wipe” the valve stem as it reciprocates. The latter is likely to be more efficient on an old engine with heavy wear on the valve stems/guides but could possible impair valve stem lubrication on a new, tight, assembly.
I have only ever used the original type square section rings and have never had a smoke problem with a rebuilt engine but, in light of Phil’s positive experience, I think the umbrellas are probably equally good.
As your smoking has apparently decreased, perhaps it was simply a function of pistons, ringing and liners all bedding in.
B…..
25th April 2022 at 8:06 pm #29841ParticipantHello Bernie
Many thanks for your reply and comments, the smoking issue has now gone away especially now that I’ve found out that the dipstick had been re-marked sometime in the past to hold an extra one litre of oil.
Whilst I’m on here may I ask if yourself or anyone else has any experience with drive shaft replacement, as in fitting CV type shafts, one downside of the car since being put on the road is that it has a vibration and on inspection this evening have found a outer UJ badly worn and from my readings these don’t seem a nice job to do. I see the club lists either a single CV or a double CV jointed shaft, firstly are these a direct replacement or does the hub/drum require machining?, secondly are these a gearbox out job to fit?and thirdly are CV joints available in the event of a failure?.
I look forward to any comments please
Nigel
25th April 2022 at 9:55 pm #29842ParticipantNigel,
Glad to learn you have stopped smoking.
Original driveshafts can be replaced with “modern” production items with CV joints as a straight swap without having to make any mods to other components.
You will not have to remove the gearbox but you will need to split the lower swivel joint to get clearance to extract/refit the shaft from/to the hub. With the shaft out you can then access the joint at the gearbox to remove the inner yoke.
B…..
15th May 2022 at 3:43 pm #29871Chris
ParticipantNigel, on the question of CV joints. Several years ago I replaced my shafts with CV joints at both ends. I have had the gaiter on the inner CV joint fail twice (same side). I don’t know why it fails, nor why the other one doesn’t. If I was doing the job again, I would probably go for shafts with just the outer CV joints and retain the inner UJ and spline arrangement because it is easier to grease that than change the gaiter.
Chris
15th May 2022 at 4:47 pm #29873ParticipantHello Chris
That is exactly what I did, more by circumstances than choice as the club spares only had one side as did other overseas suppliers so I contacted Robert William at Yellow Box Engineering Ltd and they had a pair in stock which I purchased, more expensive than other sources but these do come with upgraded inner spline and UJ assemblies. Can highly recommend their service, very pleasant to deal with and kept me well informed throughout.
Nigel
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