//www.minimania.com/part/LJQ101160/Valve-Stem-Seal-Late-Mpi-Type-Dupont-Viton

 

Sad to hear the state of modern parts.

I ended up using these seals. Hope they hold up.

//www.minimania.com/part/LJQ101160/Valve-Stem-Seal-Late-Mpi-Type-Dupont-Viton

John

Yeah I need seals too after probably 2K mi on the fabulous 1362 Jemal built me.  My fault on the seals!

Sorry i only just saw this and havent read through it all but I can tell you that I had an entire set of seals "go-bad" on me recently. The head was brand new from Calver. He wrote me to see how it was doing and to address some concerns he had on a few things that have been cropping up. Valve seals were one of them. Its not that they are going bad as much as they just were not built correctly in the first place. The springs were too weak from the start and only needed a few hundred miles to basically totally fail. As i have said in other posts, they truly are not making things like they used to. Sad times

Se7en Thank you for the kind words. I have quite a responsibility as the current caretaker of this beast. It was a pleasure to see you as well, and to meet Ray. I hope he has figured out the issues with the Riley.

I don't think I have ever seen such a large quantity of show cars on the golf course. It was massive.

John

And the car looked to be very popular at the PVGP car show last weekend! The car is quite a conversation piece, John...a real slice of Mini history. Good to see you and the family, if only briefly. 

I just wanted to give an update to my valve stem seal problem.

It has been about a month since I put everything back together and on the road. I replaced the valves with the correct taller ones. I also had the new guides fitted a little lower.

So far i have put about 100 miles on the car and has not been smoking.

Thanks for the help, John

Hello, I finally pulled the head off and got to measure a valve. As Jemal suggested, the head has the wrong height valves in it. They are 3.52" Cooper s valves. Not the 3.57" valves.

The guides were set at the proper standard height of 15.2mm or so.

Looks like I will be changing valves now.

I'm curious, if the guides are set low enough to let the seals clear the valve spring retainers, is there a performance loss due to the shorter Cooper S valves? This head was put together in 1979, and functioned for quite a while until the cam was changed.

John

We find that sometimes the valve seats are 'too high' so too much of the valve is too far down in the combustion chamber. This leaves less room at the top for the valve springs and results in the spring retainer smacking the top of the seal and knocking out those little springs.  The fix is to either cut the seats down letting more of the valve length be at the spring end, or machine the tops of the guides a little to let the seal sit lower.

We had one guy use the shorter Cooper S valves thinking "well they must be 'better' because they're for an S", but the .040 shorter valves in the 12g940 (same as the 12G1316 height) resulted in destruction of the seals.  Make sure your valves are 3.57" long! 

Thank you for the replies Doug and Kevin,

I talked to the previous owner and learned it has a Kent 276 cam. Not as aggressive as i thought.

I have not taken anything apart yet, but i feel the guides may be high. I think I will need to have the guides lowered, or different one fitted.

Todd's Viton seals must sit a little higher than the stock metro seals. As seen in Kevin's example. I don't see another way around the issue.

I guess if I get the head off I might as well get a valve job as well.

Thanks, John

I also have Todd's seals on my car's engine which has a big valve 12G940 head.  I have not seen the springs come off the seals on my engine.

If you just want to replace the seals, that can be done with the head still on the engine as long as the rest of the valvetrain components are stock.  See Todd's web page for some information on that. 
//members.tripod.com/austin_america/index.html
(Select "Technical Advice" from the left column, then "Engine" on the next page.  Scroll down to the bottom of the Engine page).

I had that problem on a recent rebuild, running a 276deg Russell Eng cam, 1.5 rockers and Todd Miller's Viton valve seals. Valve caps `just' hit the seals, and the seal springs came off.
I got out of it this time by fitting stock Metro seals, however a better way is press all the guides further in 1.5mm or so. No need to reseat the valves.

[edit] I only fit seals to the intakes, as the exhausts need an oil film for lube and heat transfer, as Vizard said. There's no real vacuum on the exhausts anyway.

Hello, I have a Mini that has been blowing excessive blue smoke at start up, as well as through various driving conditions.

I suspected that something was going on with the valve stem seals. When I removed the rocker cover I saw that two of the little springs that help cinch that seals around the valve stem had broken. I was able to remove them from in between the valve springs with tiny needle nose pliers.

The engine has only a couple hundred miles from when the previous owner had it assembled. I do not know what cam is installed at the moment, but I would describe it as lumpy. I also do not know the lift of the cam, but I feel this may be where the problem is. I feel the valve spring retainers are hitting the top of the seals and causing the failure due to the assemblers lack of accounting for the high lift cam. The seals look to be staying attached to the guides.

My thoughts are that I need to remove the head and have different valve guides and seals fitted. Something that will sit a little lower and not get hit by the valve spring retainers.

The engine is a thin flange 1293cc Coopers S block with a 12G 1316 head. The rockers are standard Cooper S.

My questions are, has anyone seen these springs break? Is the removal of the head necessary? Could I just have defective seals and just need to replace them? Are there any lower profile spring retainers or valve stem seals available that would allow a little extra clearance? I also wonder that if it smoking the guides probably need to be replaced anyway?

Thank you, John