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Engine Valve seals?

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70herald

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Hi
I seem to have a problem with the valve guides / seals. Yesterday I dumped some oil into the engine, and went to start it. The #4 cyl almost immediately fouled its plug, and the smoke coming out of the tailpipe was something fierce.

When I had the engine apart, the machinist took a look at the valves /guides and said they were fine (not to loose) of course the normal Triumph design doesn't have valve seals. These are probably tight enough for a more "conventional
design with seals. There are valve seals on my engine, but they are all riding on the top of the valve not connected to the valve guide. Whatever is supposed to hold it at the bottom obviously isn't doing the job. Right now they sort of look like little umbrellas about 1 cm above the valve guide. Clearly not doing much good. When I put it all together, the valve seals were pushed onto the guide, but the first time the valves were pushed in the guides slid up and stayed.

Where can I get decent seals that will fit and stay in place?

Kind of annoyed those plugs haven't been in the engine for more than 20 minutes of running time.
 
On my Tr6 I uses a Perkins Diesel ceramic seal #P-33415133 (from a Massey Furguson dealer) I dont know if the Herald has the same guides but they work good on the 6. Machine shop might carry or order these seals also.
 
70herald said:
Hi
I seem to have a problem with the valve guides / seals. Yesterday I dumped some oil into the engine, and went to start it. The #4 cyl almost immediately fouled its plug, and the smoke coming out of the tailpipe was something fierce.
Click to expand...

Given that symptom, I find it difficult to agree with your head machinist that your valve - guide clearance is "OK." A seal might work to minimize the problem for a while, but it's a "band-aid." The root issue will need to be addressed.
 
Moseso said:
Given that symptom, I find it difficult to agree with your head machinist that your valve - guide clearance is "OK."
Click to expand...

That very well might be true.
At the same time, in retrospect, dumping oil into the engine at idle, (high vacuum) may not have been the greatest idea either. I certainly provided it with a good opportunity to suck in oil, and the #4 cyl is directly under the oil fill cap.
 
I would only add oil if the engine were shut off. Some may disagree, but that's just and old habit to avoid making a mess or having the rocker arms hit the old metal spouts that we used to use on metal cans. With plastic bottles, it's not much of an issue.
 
The motor was ON?

I think I tried that once about 40 years ago. My recollection is that a significant portion of the oil I wanted to go in the motor wound up ON the motor -- and on me. I have never tried that since.
 
Faced with a somewhat similar problem on a TR3A, I went to a local "speed shop" with the guide & stem diameters. They found some "Teflon" type seals that fit without machining (and I installed them without pulling the head). Had springs in the rubber skirt to hold them to the guides, so I had to use a long socket to push them down. Strictly a band-aid, though, as Moseco said.

FWIW, some OEM seals do work the way you've described, little more than umbrellas that ride up and down on the stem, only touching when the valve is fully open. Apparently, they keep just enough oil away to reduce oil burning to the desired level. I even had one engine where the 'umbrella' was built into the spring retainer, and the only seal was between the retainer and the valve stem.

It's all a balancing act, since the guides need to have *some* oil for long life.
 
Hello 70 Herald,

how was the car running before you topped up the oil? If this smoking only occurred after you topped up the oil, could you have started the engine before the oil had drained down into the sump. (Or did you overfill the sump significantly and oil is coming up the bores?)
What intrigues me that the machinist said the valves and guides were OK, I would be very surprised if he were mistaken?
However, seeing as you seem to have the engine dismantled, you might as well fit some seals to the inlets.
Even without valve stem seals these engines are not smoky even if only in average condition.

Alec
 
piman said:
Hello 70 Herald,

how was the car running before you topped up the oil? If this smoking only occurred after you topped up the oil, could you have started the engine before the oil had drained down into the sump. (Or did you overfill the sump significantly and oil is coming up the bores?)
What intrigues me that the machinist said the valves and guides were OK, I would be very surprised if he were mistaken?
However, seeing as you seem to have the engine dismantled, you might as well fit some seals to the inlets.
Even without valve stem seals these engines are not smoky even if only in average condition.

Alec
Click to expand...

It is hard to say how the engine was running before. I only have gotten it to run properly for about 40 minutes since rebuilding it. Before rebuilding it, it ran so poorly that troubleshooting really wasn't possible. The cyl bores really were shot.

The first 20 minutes it ran poorly but that was a result of a wobbly dizzy. After I replaced the dizzy and put new plugs in I tunned it up and let it run for about 20 minutes it ran like a champ. Quiet, idled at ~880 rpm no smoke, wasn't missing... Then I shut it off and went away for a few days.

The only thing I did after that was dump some extra oil in since I have an oil leak on the bottom which I haven't yet worked out. When I dumped the oil in, I did so quickly enough that the #4 cyl guided certainly could have been submerged in oil. there is definitely not enough oil to cause it to come up the bores. The other 3 cyl are firing nicely.

My engine guy is not exactly up to building racing engines or even real high performance street engines, but he does have about 40 years experience, and learned on Triumph engines, they were very common here in the 60s/70s. If they really did need replacing, he would have been quite willing to take my money, so at least for the time being, I think I can go with the assumption that they are acceptable (in terms of wiggle space) but not at the tolerance that Triumph originally specified without seals (to keep oil in place)

Well I guess I will just have to clean the plug and see what happens. I don't have any speed shops around here but will most likely be in the US some time this winter so I guess this is just one more thing to put on the buy list.
 
Ok, I just pulled the plugs and they were black, but since it was running at Idle, this is not surprising. certainly no build up of carbon.

Could it just be a marginal coil? I tested the coil last week, and main coil was fine, ~4 ohms, the secondary ~10,000 ohms and no short between the coils and case, so that should be good but then I have spent most of my professional life working with really high voltage stuff (above 60kV)(lasers Electron beams.....) so I know that all heck can break loose when voltages go up. Anyway, I ordered a new coil at a local shop will arrive from the warehouse tomorrow.
If that solves the engine problem I can bring it in for inspection Tuesday or Wednesday Yeah!
 
Hello 70Herald,

Ok, so the cylinders are freshly re-bored? I can't remember if the herald engine is slightly down at the rear making the number 4 the most likely to drown in oil.
I certainly would not panic about it, just run it again. It can take some while for all the oil to be burnt off, but I guess you will find that it all settles down.

Alec
 
If umbrella type seals are installed that move up and down with the valve stem then, the seal will act like a pump forcing oil down between the stem and the guide. When installing seals on a triumph make sure the seal is securely installed on the guide. The Teflon seals that I used required using a special valve seal cutter removing material from the top of the guide. The seals are retained using spring steel around the seal
 
According to my machinist, you cannot "over seal" valves. On my vintage Corvette I have the teflon and spring seals on the valve guides, "O" rings on the valve stems and steel shedders under the valve retainers. Just over 1000 miles on the total rebuild and one quart of oil. Probably less as the engine continues breaking in. Those teflon seals come in two ID's .500 and .531 for different guide sizes and a couple three sizes depending on the valve stem dia. Available from Northern Auto Parts in Iowa. Bob
 
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