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Newly rebuilt motor, new problem...

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Draegon Tim Barrick
Hamilton, ON, Canada   CAN
Well my professionally rebuilt motor for my 82 TR7 has a different problem than first described to me.

Turns out all the hassle with the coil/igniter wasn’t the problem, $340 down the tubes.

Mechanic removed the distributor cap, and it wasn’t turning. So removed the distributor altogether and said the gear inside the motor wasn’t turning when the motor cranked either.

Isn’t that the jackshaft? It’s got a sprocket that the timing belt is running on right? It would make a hell of a lot of noise anyone could hear if the new timing belt broke, wouldn’t it?

This is turning into another nightmare.

Any ideas?

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Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1512161 by Draegon Well my professionally rebuilt motor for my 82 TR7 has a different problem than first described to me.

Turns out all the hassle with the coil/igniter wasn’t the problem, $340 down the tubes.

Mechanic removed the distributor cap, and it wasn’t turning. So removed the distributor altogether and said the gear inside the motor wasn’t turning when the motor cranked either.

Isn’t that the jackshaft? It’s got a sprocket that the timing belt is running on right? It would make a hell of a lot of noise anyone could hear if the new timing belt broke, wouldn’t it?

If it is any consolation, I too have flushed copious quantities of green down the toilet by chasing the wrong problem. That is when I walk away from the car for a few days and remind myself it is a hobby that I ultimately enjoy, despite wanting occasionally to set fire to the car and take the insurance money. So take heart, you learn along the way, and not every project is a success. We have all been there. If it wasn't a challenge it would not be nearly as satisfying in the end.

Yes, it is the jackshaft. You may get lucky and it is merely a loose or broken timing chain, or perhaps the timing gear has come loose from the jackshaft.

A pessimistic guess would be that the dowel on the end of the jackshaft has broken (or fallen out), and the jackshaft drive gear is turning but the jackshaft is not.

It is not an engine teardown if that is the case though. If you get the timing cover off the front of the motor, you can drill the end of the jackshaft for another dowel or a roll pin, and then reassemble. You would probably need to pull the radiator, but it is not a horrible job, and could be done without removing the head.

Of course if the timing set has failed or the gear is loose, it would be even simpler.

Chin up, and carry on! We are rooting for your success. Keep us posted.

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

sliproc Avatar
sliproc Kevin Quistberg E
Long Beach, CA, USA   USA
Well, if it's one thing I've learned about owning Brit cars is when you begin to flush money down the toilet start with the small bills. Also, it sounds like you can probably delete the word "professional" when referring to your rebuild.

I agree with Vance, the dowel was either forgotten or the sprocket bolt wasn't tightened which caused the dowel to get sheared off, either one would explain why it ran for 20min. then wouldn't start.

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Draegon Tim Barrick
Hamilton, ON, Canada   CAN
Thanks for the advice.

I have a 78 Triumph Spitfire I bought when I was 16, still have it at the age of 53. No Triumph will ever outright surprise me, ever... lmao

This is my first TR7, 2 years now, and it’s definitely a Triumph.

So, from what I’ve read here, it sounds like the rebuilder is 100% accountable for this, going to enforce my warranty.

This guy rebuilds all the motors for the big auction houses like Southeby’s too.

They even forgot a frost plug on the block when I picked it up.

I’ll let you know when it works out.

Thanks

Draegon Tim Barrick
Hamilton, ON, Canada   CAN
By the way, where is the dowel located in the jackshaft?

Is it just a holder for the sprocket, or does it join parts of the shaft together?

My manual is with the car at the mechanics.

Thanks

sliproc Avatar
sliproc Kevin Quistberg E
Long Beach, CA, USA   USA
The dowel fits into the end of the jackshaft right next to the sprocket bolt hole. Moss has them for about a buck and a half. You'll need to remove the front cover to replace it, make sure you know where the old one is. You'll have to remove the belts and crank pulley(and maybe some other components) to pull the front cover, if you can retrieve the dowel with the jackshaft in place you should be able to leave the radiator in place but if you have to remove the jackshaft to get the dowel you'll probably have to pull the radiator.

Rover827 Avatar
Rover827 Rich Truett
Berkley, MI, USA   USA
What's happened here is that the water pump was installed improperly and the gears on the front of the jackshaft have been stripped.
This is going to cause massive problems.
Now there are are metal flakes in the oil.

How to fix:
(1) Get a good used jackshaft.
(2) Replace the water pump and shim it properly. Likely, it was tightened too much and caused it to bind with the jackshaft.
(3) Drain the oil and somehow flush the oil pan.
(4) Change the filter, of course.

Once the car is running...
Don't drive it. Let it idle for a few minutes, then change the oil and filter again.
I'd repeat this procedure several times. Metal flakes in the oil will take out the bearings and crank in no time.

DO NOT use the available Indian-made water pumps available from the normal suppliers. They do not fit properly.

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Rover827 Avatar
Rover827 Rich Truett
Berkley, MI, USA   USA
sliproc Avatar
sliproc Kevin Quistberg E
Long Beach, CA, USA   USA
Rich,

If the water pump is the problem how do you explain the distributor not turning? If the water pump stripped the jackshaft gear and the drive sprocket was properly attached to the jackshaft the distributor rotor would still be turning. In fact the motor might still fire and run in some fashion, although without a water pump the motor would start to overheat fairly quickly.

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Rover827 Avatar
Rover827 Rich Truett
Berkley, MI, USA   USA
Take off the valve cover and confirm the chain is still attached under tension to the sprocket.
Turn the engine over.
If the camshaft is turning, the problem is jackshaft gears, or perhaps the crankshaft gear has sheared the key off or broken.
Either, way if the distributor is intact, the engine is coming apart again.

Draegon Tim Barrick
Hamilton, ON, Canada   CAN
Thanks Rich for that link, saves me from tearing the jackshaft out of one of my other motors.

The engine rebuilder said the pin was indeed sheared off, so we’ll do a shaft switch on it.

Hopefully that will be it, just have to wait for up to 2 weeks for delivery of the shaft, although $46 sure beats the $740 for a new one.

Rover827 Avatar
Rover827 Rich Truett
Berkley, MI, USA   USA
I'd wonder why the dowel sheered off. Important not to repeat that again.
The most important part of this process is the water pump.
(1) Make sure you are using the proper cover for the proper pump. You can't use a 6-vane cover on a 12-vane pump and or vice versa.
(2) Don't force the pump into position. You can put the pump in the freezer to get it to contract just a bit.
(3) Make sure your use the proper combination of gasket and shim the pump properly.
(4) One the pump is installed with the cover tightened to spec, put the distributor in and verify that the jackshaft turns freely in both directions smoothly, with even effort and no binding.
(5) Install the timing chain/tensioner/guides, etc.

sliproc Avatar
sliproc Kevin Quistberg E
Long Beach, CA, USA   USA
Tim,

If your jackshaft is otherwise ok you might be able to extract the pin from the jackshaft and reuse it.

Draegon Tim Barrick
Hamilton, ON, Canada   CAN
Thanks again Rich.

I went through some head warpage issues during the rebuild, so brought them another complete TR7 motor for the head.

When I picked up the motor, it was missing parts, flange, waterpump, oil pump not installed, so they put it all together, we used the waterpump cover off the other motor that was there.

I didn’t realize it would matter, and as I read your post, I remember seeing a waterpump cover at the mechanics when he showed me a bunch of extra parts.

The block the cover came off of has been scrapped out, so no way of knowing if it was a 6 or 12 vane one, my car uses the 12.

So does the pump, which turns freely without the shaft in place, have to be removed and reinstalled before putting the right cover on it? It was a new pump.

Kevin, I just ordered a jackshaft yesterday, rather than get the pin drilled on my own shaft. Thanks anyways.

Rover827 Avatar
Rover827 Rich Truett
Berkley, MI, USA   USA
The water pump is coming out. You have to remove it to replace the jackshaft,
And really, you need to have close look at the gears on the water pump.
What sounds like could have happened is the water pump impeller jammed on the cover and sheered off the jackshaft dowel.
If that's the case, I would replace the jackshaft and the water pump. Those gears are delicate. They must be in good shape.
Now, about the 6 and 12 vane covers.
I am not sure if you can tell which is which by the part number stamped on the cover.
What I would do is post a picture here. I am very sure someone can identify the cover you have.
Realistically, there isn't much difference in performance between the two pumps.
You should be able to look at the old cover and see witness marks if the impeller jammed it. That would indicate the wrong pump/cover combination or possible the cover was installed improperly. The proper combination gaskets must be used to get the factory spacing specs. And the cover must be torqued exactly like the factory recommends.
This is not a job where any corners can be cut and there can be no guesswork.

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