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TR4/4A "Engine seized after engaging overdrive at low speed.

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Giovanni59

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I took my 1965 Triumph TR4 out for ride to show a friend and I was demonstrating the overdrive. However, I did not realize I was only going about 30 mph and was in 3rd gear. The overdrive engaged and a few seconds later I turned it off, (there is a turn signal type lever on the right side of the steering column that turns the OD on.) A few second later the engine died, it did not seize or lurch. This is typical right after I start it and it has not warmed up yet. So I engaged the clutch while in second to pop start it, I was doing about 15 mph at this point and the car just came to a stop without turning over. When trying to start it it does not turn over, turns hardly at all when looking at the fan.

Does anyone know what I did and how much damage I might have done? I'm hoping there is a simple fix. It seems that the overdrive should not effect what the engine is exhibiting. If it is in neutral and the clutch pedal is pushed down the transmission and all components should be disengaged and should not effect the engine turning over, correct?

Is it possible the engine had an issue already and it failed by coincidence right at the time I engaged the overdrive.

Please help.

Thanks
 
It would be strange for the engine to have catastrophic failure simply because you engaged O/D at a little lower than usual RPM. I would guess simple electrical problem, except it wouldn't turn over when you popped the clutch.

Cranks occasionally break on those engines, hope it is not that. Will the motor turn over manually if you leave it in 4th and push it or turn a wheel like you would do to set the valves?
 
The only way the OD had anything to do with the engine stalling is if it blew a fuse common to both the ignition and OD.

If the crank broke the engine would normally start and run, but would rattle like a banshee. You would have at least heard the rattling before you stopped on the road.

I would remove the plugs to see of the engine turns over easily. If that fixes it, then you managed to build up fuel in the cylinders (hydro-lock), which would mean a carb issue. If the engine still does not turn over with the plugs removed, then there is something else going on.
 
Hydo-lock or flywheel jamming somehow? Anyway, I'm voting this the most intriguing problem posted here in a l-o-o-ng time. Can't wait to find out the answer.
 
Giovanni59 said:
...When trying to start it it does not turn over, turns hardly at all when looking at the fan.
Click to expand...
There is a big difference between 'seized' and 'turns hardly at all' -- the latter is a much better place to be.

Have you confirmed that your battery is good?
 
Yes, the battery is good. As for seized vs turns hardly at all, I put it in 4th gear and the car would not budge.
I have not taken the plugs out, I was working on getting the car jacked up high enough to remove the oil drain plug.
Someone suggested that in another forum to see what comes out with the oil. However, the plug is in bad shape, it is tapered narrower toward the end and I cannot get a good hold on it with several wrenches I have dried. I plan on getting some ramps to get the car higher up so I can manage getting the plug out. Thanks
 
I don't think much harm can come from checking to see if the starter is jammed into the flywheel.

The usual solution for that is to put the gearbox in 4th and rock the car backwards.

It could be jammed pretty good after several attempts to start so you will have to rock it pretty hard - hoping to hear a big clunk that means the starter is free.

This was a known issue when the car was new - indeed the TR3A owners manual contained instructions on how to free a jammed starter. The manual's method was to remove the cap on the starter and use a wrench on the armature to back it off - but I have always found rocking the car to be easier.
 
Okay, I have not tried that.
When I had it in fourth gear I was pushing it forward, I did not know you were supposed to go backwards to unjam the starter from the flywheel.
I'm concerned about pushing it pretty hard and if the problem is something else perhaps I can damage it even more.
However I will try it gently pushing backwards unless I get some more confirmation that I can't do more harm if it is another issue. Then I will push it more aggressively.
I will try tomorrow thank you, thanks.
 
Unless you have Hulk Hogan, the Rock and Mark Wahlberg helping you rock the car backwards I don't believe you have anything to worry about
 
Easiest way to rock/push it backwards is to push on the top of a tire (I always went with the left rear). That gives you a 2:1 advantage.
 
Geo Hahn said:
Easiest way to rock/push it backwards is to push on the top of a tire (I always went with the left rear). That gives you a 2:1 advantage.
Click to expand...
Geo is so right, as usual. My grandson and I just rolled my “engineless” TR4a up a 4 inch high curb incline, three feet long, using that method and it was a surprising breeze. If you are about to say you could do that alone, well . . .
 
KVH said:
Geo is so right, as usual. My grandson and I just rolled my “engineless” TR4a up a 4 inch high curb incline, three feet long, using that method and it was a surprising breeze. If you are about to say you could do that alone, well . . .
Click to expand...
Hi, thank you everyone for all your input, sorry it has been a while since I posted to this thread, I just moved into a new home. I finally found someone local who had time to look at this for me and after taking the oil pan of and looking with a scope he discovered one of the pistons got dislodged. There is slight damage to that cylinder but he says it can be honed, He will replace all the rings, rod bearings and crankshaft.
Parts and labor $2000. I think I am lucky, ( the worst case scenario was a whole new engine rebuild costing 6-7 thousand. and I will have him do the work, he warrantees for 12 months or 12,000 miles.

I have always had a desire add horsepower to the engine and I asked him about boring out the cylinders and replacing the cam. Not sure how much HP will be added but I am concerned about altering this motor and putting unnecessary strain on the rest of the drivetrain. Any thoughts/?
I guess a more import thing to consider it the impact on the originality of this 1965 classic.
Thanks again for all the input.
 
I have some thoughts. At a place like this forum I readily defer to the long-time experts, but I’m concerned about hearing of a jammed piston. Barring some rare pin or circlip issue, or a bent rod, I’ve never heard of such a thing, and if you’re replacing the crank I think, if it were me, I would just do a complete engine rebuild, and I don’t think the difference between what you’re planning and a complete rebuild would be at all prohibitive. Further, with the removable “wet“ liner system in the engine, I don’t believe there is any concept of block boring.
 
He should be talking about a new liner and piston set. If he is suggesting boring the block he may not be aware that it is a wet liner engine so not know what to look for when re fitting the liners and liner protrusion.
Did you mean he would replace main crankshaft bearings or replace the crank shaft?

David
 
I’d look real hard and get some good machine shop advice before allowing anyone to replace my crankshaft. Will it be better? Balanced? Ground to spec? Correct tear main seal? How will you know? This is why there are so many proficient “mechanics” right here on this site.
 
This doesn't make a lot of sense to me. I'm not sure exactly he means by a "dislodged" piston. I can't imagine what could cause a piston to jam in a cylinder and yet be fixed by honing. It also would not require a new crank.

Does it really cost $6K to rebuild one of these engines? If so, I'm in the wrong business.

As for increasing the displacement, the easiest way is to get a little more displacement is to buy an 89mm piston and cylinder set. This won't be a dramatic improvement. These cars had a lot of power, by the standards of their day, and by driving them right, you can get all the performance you need.
 
For the sake of argument, could a piston ring or rings broken on one side cause a piston to go off center and jam in the cylinder? I have no idea.
 
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