MTFCA Forum

On the way to dinner yesterday, the T started running rough. Parked and removed the plug. The ground electrode was bent flat. UH OH.

Changed it just to be sure. Yup, I have a broken #3 exhaust valve.

So, I've got some work to do. Not entirely sure how to go about it, but I should be fine. How difficult could it be, right?

Are they the original style 2 pc. valves ? If so, you might consider full replacement.

I do not remember what they are, as the head's only been off a couple of times in the last ten years

Will, I’ve done it. #4 cylinder can be a challenge but can be done regarding grinding the seats. If you’re putting in new valves I’d grind the seats. Replacing 1 valve will be a temporary repair as they probably are the 2 peice and others will fail. You need to find a buddy with a seat cutter or buy one.

Will. I wish I could remember if they were two piece valve or not, but I don't. Replacing the broken one is nothing that you can't handle. The main thing to see in there for now is whether they are adjustable lifters. If so, the task is little easier. Valve seat cutters are available online and all you're going to do is take a little lick off the surface by turning the cutter by hand.

You have to get it apart and have a looksee.
You could check compression on the other 3 first, wet and dry to see if there's any ring issues.
I would recommend all new valves, if one broke, they must be cast.
If the seats aren't very bad, you MIGHT be able to get away with hand lapping the new valves in.
None of it is super difficult, adjustable lifters would be nice !!
Take pictures when you get it apart.

From your description of the problem, my money is on the valves being original two piece cast iron valves. After 100 years, there is just so much hard work these valves can stand befor the head, or parts of the head, break off.

Before removing the cylinder head, follow the advice of Ruxstel24 above and check the compression on the other three cylinders. Remove the cylinder head and prepair to remove at least #3 exhaust valve and replace it with a new steel valve. New steel valves do not break, at least not in your lifetime. Check the other 7 valves to see how they are doing and if any of those need replacement. It may be that a complete valve job is in your future.

Respectfully submitted,

Trent Boggess

In my OP, this is not the time to do compression check, you have a broken valve floating around in the cylinder or part of one. Pull the head and have a look see, replace or repair as needed. If you pull the head off without damaging the gasket, I would repair as needed then do the compression check.

Pull the head off and see what is in there. Do not do a compression test, do not rotate the crank, no scopes, no x-rays...just pull the head and let us know what you find.

on removing the head first. You already know how it was running before the valve let go.

Well, the T is back on the road.

It did have two piece valves in it. For want of a more permanent fix, I only replaced the exhaust valves as they were the most severe. I left the intakes alone.

As far as the half of the valve head that broke, it was not in the combustion chamber. Must have blown it out the manifold.

Still runs a little rough, but I'm hoping that will go away. If not, I'll tear back into it. I know it has a manifold leak as the exhaust manifold is warped on both ends.