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Valve stem seal leak

4K views 17 replies 5 participants last post by  EA1191 
#1 ·
Has anyone tried sealing the collets as a fix for leaking valve stem seals?
At this early stage the result is a cure for my engine.
The valve spring retainers and collets are washed a number of times with a small brush and mineral turps. Silicone rubber is forced down onto the collets. A suitable spatula is the back end of a nail file.
A better way may be to mix silicone gasket rubber with mineral turps to a fluid consistency and apply to the collets in the spring retainers. Try this mix on some loose metal bits, such as nails or screws first.
Or there may be a better way.

If you have not removed the rocker cover before.
Lots of bits in the way.
After removing the air filter assembly the large air tube is unclipped and using a bent wire hook is lifted and hooked as high as possible above the engine. The cable conduit fastening on the drivers side is freed by slitting the adhesive tape and the air tube clip removed from the rocker cover can be twisted out of the way and hooked to the water gutter in front of the windscreen and another hook further along. The accelerator cable which is held on a bracket and the plastic nut on the bracket can be loosened on the plastic guide and unscrewed to allow the cable to pivot at an angle and the cable held as high as possible with a cord to the front of the bonnet. The plug leads are numbered with white crayon or labels. After the nuts holding the cover are removed a piece of 2cm by 3cm timber or other lever will lift the buttressed projection on the drivers side at the back of the rocker cover. The cover is lifted, tilted at about 45 degrees and moved sideways to the drivers side to clear the rocker gear and then pulled towards the front of the car to slide under the accelerator cable.
 
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#7 ·
I'd make the voting at least three to one against sealing collets like that. The risk of clogging things up when the silicone comes off is too high.
Change the stem seals and you know its done correctly.
 
#10 ·
So - I may have sacrificed my engine to prove that sealing the collets will replace stem seals. Perhaps someone can find a way to seal them in a safe way.
The engine now idles well and it can be started from cold, run, stopped and restarted without the plug fouling. The idle could be better but the spark is orange and I have been told that orange is not good.
 
#12 ·
How could they be replaced so fast without removing the head?
It may be easy for you but I do not have the tools and I am an old man who does not like playing with motors nowadays. Really do not need a car and it runs well except for a few minor problems which could result in more trouble if not fixed.
In 12 years it has not failed except for a couple of problems due to my neglect. The inspections always pass it as very good.
 
#14 ·
Failure. The engine was running very well - could hardly believe it was the same engine. The computer must have problems adjusting to the oil from leaking stem seals particularly if the leak is not the same in each cylinder.
Decided to check the plug and was surprised to find it black. Removed the rocker cover - only about 10 minutes for me now - and the rubber sealing compound had not stuck to the retainers and oil had penetrated below them to the collets. The rubber was easy to remove and now have some other ideas to seal the collets.
When it worked it was very effective and am wondering just what was happening. If the oil was stopped at the retainers and there was no stem seal would the valve stems have better lubrication? Or does the seal settle to the bottom of the stem and stop too much oil on the stem entering the guides? Stem seals are simple and effective for engine assembly but not for maintenance.
 
#15 ·
Unfortunately EA1191, sorry to say, but you are at the moment epitimising for me the adage "a little knowledge can be dangerous".

If for some reaon there was a better, more economical way to seal the valve stems do you not think that the car manufacturers would have done it?

There are a number of recognised ways to seal, or at least minimise oil loss through the valve stems. They include chamfering the top of the stem to create a 'knife edge' which in essence scrapes oil form the valve stem as it moves, this is what you'd probably find on '50 - '60's era engines.
Then you have the rubber mushroom type seal that may or may not move with the valve, either way it is usually long enough to keep the top of the guide covered and therefore stops excessive oil getting on the stem.
The third, and nowadays most used, seal is the push on teflon type which is pressed onto the top of the stem and acts like a scraper on the stem as the valve moves.
Valves do not need much lubrication and usually the oil that sits in the minute machining marks on the stem is enough to keep them happy.

With all this being said, save yourself a lot of headaches in the future, take your car to a mechanic or head machinist and get them to put new valve stem seals on for you.
 
#16 ·
MLS said:
The third, and nowadays most used, seal is the push on teflon type which is pressed onto the top of the stem and acts like a scraper on the stem as the valve moves.
Should say "The third, and nowadays most used, seal is the push on teflon type which is pressed onto the top of the guide and acts like a scraper on the stem as the valve moves.
 
#17 ·
Thanks for that information. Thought there could be a problem of not enough lubrication for the guides. I feel confident about fitting stem seals but need some more tools and it is more work. Just rotating the engine is a problem. I have owned cars for over 40 years and never had work done - except once when a mechanic did a butchered job.
Have another try at sealing the collets - only involves one cylinder and maybe only the input valve. Probably fit seals later.
 
#18 ·
Sealing the collets has a major effect on the oil flow down the stem into the guides.
Have now sealed the collets on the valves on No 4 cylinder, which fouled the plug, and cleared the others. The engine operates well but the idle is not as good as it should be. When all the collets on all the cylinders had been sealed, the engine was very good.
Does that mean that the normal stem seals are not good enough? Or do they become less effective as the rocker parts wear and more oil is splashing around. Or have all the seals deteriorated.
 
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