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MG TD TF 1500 - Valve Stem Oil Seals

My TF only has the simple "O" ring and collet shroud to prevent oil leaking down the valve guides. The car has a smoky exhaust, especially on start up or after idling which I believe are the classic signs of oil down the guides. The guides are new and the stems are a good fit. I know the rubber boots fitted to the stems/guides of a Mini can be fitted to an EXPAG but they do require a groove to be turned near the top of the guide to keep the boot in place. This is an easy job if the guides are pressed out but I would have to recut the seats when the guides are replaced. Has anyone made up a tool to cut the groove without removing the guides? I thought about super glue but it is a bit of a botch.

When I bought the dismantled car the block had been rebored to +20 and nicely honed and there was a set of brand new Hepolite pistons. I should have measured the bores to check they had been machined properly but I didn't. When I lift the head I will check the bore sizes but would poorly sized bores cause oil burning? The compressions are all good.

The issue with this kind of a job isn't the work but the cost of parts. A new gasket set, oil and antifreeze and you will spend over £100.

Jan T
J Targosz

Jan,
I had exactly the same symptoms. It was very embarrassing especially pulling away at traffic lights when cyclists were around.
I replaced the valve guides using the Peter Edney improved ones and the top hat seals.
I fitted them to both the inlet and the outlet valves.
The consensus, at least in the A-Series engine world, is to fit the top hat seals only to the inlet valve guides so as to reduce the amount of oil being sucked down the inlet guide. The exhaust valve guides need a small amount of oil to help lubricate the valve stems therefore the top hat seals can be left off.

It didn't cure my problem which turned out to be the piston rings in the end.

Regards
Declan


Declan Burns

Jan,
run your engine till hot, quickly remove the rocker cover and check the valve spring caps. If any do not have any oil resting around the collets then that is how it is getting down the guides.
You probably know that the "O" ring should be fitted after the caps are in place and form a seal with the collets and cap.
I have renewed the "O" rings with the head in place on a few cars and stopped the smoke.
I made a spring compressor to use with the head in place. Can send photo and dimensions if needed.
Ray TF 2884


Ray Lee

The original system works well if the guides are not worn too much. I agree with Ray, although I would say there is no hurry .... If there is no pool of oil (even next morning) above the collets, it has run through the "O" ring seal.

When assembling valves 1 compress spring assembly, 2 push "O" ring over valve stem, 3 fit collets, 4 release spring. Some people WRONGLY put the "O" ring on the valve stem before compressing the spring assembly.

New original seals could be fitted without removing the head. I am not sure I should recommend it, but (to check guide clearance of sticking valves) I once removed springs by pushing rope down the spark-plug hole, turning the engine (gently) to push the rope up under valves and then compressing the springs. I have heard of compressed air being used to do this too. The rope method is tricky due to the head-face ledge alongside the valves.

Good luck with the project.

Bob Schapel
R L Schapel

Hi All,

Thanks for the replies. My cylinder head came in a box and had been ported and polished by a firm called Mangoletsi in 1969 but had never been fitted to the car. It was well protected with thick grease. Just to be sure I had the seats resurfaced using a state of the art Serdi machine. Here is where I fall down though. I fitted the "O" rings to the stems BEFORE the end caps so that could be my problem. A copy of Ray's compressor would be very useful (jtargosz@hotmail.com). How did you keep the valves closed? I have heard of pieces of string, pushed into the spark plug hole, and compressed air being used.

Declan's response depresses me though. As I mentioned before I should have measured the bores. I think Ray lives in Liverpool and I attach a photo of a receipt from the Liverpool firm who did the machining work. Do you think they overcharged and will their guarantee still be valid. I wonder if they are still on the go.

I will send a further photo of a Liverpool receipt for Ray to comment on.

Thanks

Jan


J Targosz

For Ray's comment

Jan

J Targosz

This was the rig on test, used it in anger and found the handle fouled the carbs before the spring was compressed. Made new bent handle and all OK now.
The old method was pyjama cord down the plughole but compressed air is better as long as you go to TDC with it in gear handbrake on.
As for the bill. In 1969 I worked in the National Health Service and £20 would have been a weeks wages after deductions. I am sure I could not get that done today for a weeks pension.
Ray


Ray Lee

Pic with dimensions.
Ray

Ray Lee

should have said that the 10 mm bolt goes into the rocker post tapping adjacent to both springs on each chamber. By the way it is a two man job you don't want your finger tips trapped in the collets trying to do it one handed.
Much cheaper and easier than head removal.
Ray
Ray Lee

Ray,
Excellent-I will make up one of those as soon as I'm fit again.
Regards
Declan
Declan Burns

I did not install the o-ring or the top hat. No isdues with oil past the guides...
Regards, Tom
tm peterson

Jan,
I unterstand you don't want to read this but your symptoms are very similar to mine. You will have to take off the head anyway. Measuring the bores will not tell you much about the condition of the rings. The bores on my engine looked perfect but number 3 plug was always somewhat oily. I put some petrol in each bore and on number 3 it vanished fairly quickly.
When I removed the pistons this is what I found. New rings solved the problem.

Regards
Declan

Declan Burns

Hi Declan,

I started to make up the kit needed to remove the valve springs in situ and got as far as an adaptor to pressurise the combustion chamber. When dismantling the rocker shaft, and despite twisting the pushrods, I pulled out one of the cam followers so I have bitten the bullet and have lifted the head. As I had correctly remembered the seals were in the wrong place and eight new ones are on order. I am going to do as you advise and see if petrol leaks past the rings. After speaking to the owner of the machine shop, who used his pneumatic compressor to remove the springs, I am sticking to the original seals. He has seen significant stem and guide wear with the ones that fit over the guide. Apparently they can starve lubrication to the guide.

Cheers

Jan
J Targosz

Jan,
That is why the A-Series guys only fit top hat seals on the inlets. The outlets need some lubrication.
I installed the Peter Edney guides in Autumn 2013 and have had no problems-at least not that I have noticed.
Did you do a compression test before you lifted the head?
Just before I replaced the rings I did a compression test and no. 3 was the lowest but only by 7 psi which was not a vast amount but enough to cause the smoking. The petrol in the bore trick (all pistons at the same height)was a clear indication of the ring problem. I hope it is not a ring issue in your case as it is not a pleasant job on an XPAG engine.

Regards
Declan
Declan Burns

Hi Declan

Tried the petrol in bores test and no loss after one hour. Enclose a photo of my air compression union. Not as elegant as the one you will make but it appears to work. I used a pneumatic spring compressor to remove the collets. The head is placed on a flat plate and arm that holds the ram can be slid from valve to valve. I was considering something similar for an in situ compressor. I was going to fit pieces of angle iron to the front and rear head studs and fit an old rocker shaft into holes in the vertical faces of the angle iron. A siding tube on the shaft could be the fulcrum for the compression leaver. I will look forwards to seeing what you make up.

Jan


J Targosz

I can't stand by and just watch without adding my input.

On my last rebuild, I installed FelPro Umbrella Valve Stem Seals. In the case of the TD/TF head, it seems that Ford 351 V8 seals were the best choice. FelPro number SS 70373. I believe I paid abt $12 for a set of 8 from Advance Auto.

I've had these in now since 2006 with no sign of smoking.

Gord Clark
Rockburn, Qué

Gord Clark

Hi Gord,

Hope I haven't upset you. What prevents your seals from lifting from the guide as the valve stem rises? Ones from a Mini need a groove turning in the top of the guide to accommodate a ridge in the seal. My guides and valves are in perfect condition and it isn't worth the trouble of pressing them out, turning the grooves and then regrinding the seats. If I was rebuilding the head I would consider modified seals but perhaps only on the inlets.

Cheers

Jan
J Targosz

Wish I could give you an answer Jan, that would suggest that the do indeed, rise. But in fact, they stay in place just fine. I've had no problems with mine.

I have a friend who put them on his Ford Windsor engine (351) where they were standard equipment on certain Windsor and Cleveland 351s, and as far as I know, those neither, came off.

Gord Clark
Rockburn, Qué.



Gord Clark

Used Volvo B 18 umbrella shaped stem seals. Fixed a rod in the lathe and lined up all the seals on it. At the same time the lathe rotated the seals the diameter was reduced to fit using a finger grinder. They now prevent too much oil from entering thru the guides. But if it was vise to put seals also on the exhaust I am not sure. How it is done on the B 18 I don´t know. Together with the modified seal for the rear end of the shaft I have described in another thread and the B 18 seals, it now consumes hardly any oil at all and produces no smoke.
YS Strom

Further to my previous comment regarding B 18 seals.
Bearing in mind how oily the inside of the rocker cover usually is, I believe enough oil will reach the exhaust stem, even if a B 18 seal is fixed. Anyone who knows?
YS Strom

YS,
It is highly debated issue whether the top hat/umbrella seals should be fitted to exhaust valves or not. I have them on the TD and since 10 years on my Morris Minor and have had no issues and no smoke. When I rebuild an engine I always fit them. That is just my opinion.

Regards
Declan
Declan Burns

A good way to check for to much oil goning down the valve guides is to take foot off the gas when going down a steep hill in top gear. Look to see if she ( or he if your car has a male name like Buds Lazarus) smokes. This will increase the vacuum pressure and suck oil down intake guides. Remember the old vacuum operated windscreen wipers that went like hell when goning down hill ( also stopped when going uphill). Same thing. Also the O rings are not valve guides seals at all. With all the oil flying around inside the rocker box they are not doning much of anything. The only thing they do is keep oil on top of caps from running down valve stems when engine is not running. Forrest TD/C 22679
Forrest Rubenstein

Thanks Declan
Pleased to learn from your experience. This makes me feel a lot more comfortable with the seal arrangement I have used.
Y Strom

This thread was discussed between 20/07/2017 and 28/07/2017

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