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TR2/3/3A Knock knock... what's this?

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HighAltitudeTR3 said:
I do not think any work has been done to the engine before my work has started (so unless they put a different piston in at the factory, which I can't imagine would have happened) then I would assume they are stock.
Click to expand...

Someone worked on that engine or replaced it with a late TR4A engine before you got the car, out of the factory the connecting rod bolts on a TR3 would have lock tab washers installed and I don't see them on the picture you posted.
See item #56 in this Moss catalog page.
https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=36459

M.
 
Merlin63Tr4 said:
Piston/rod come out from the top, they cannot be taken out from the bottom.
Sounds like you need a workshop manual, download the following free PDF to your hard drive, it is big file so be patient ....
https://tecb.eu/onewebmedia/Triumph TR2, TR3, TR3A factory service manual.pdf

M.
Click to expand...


Thanks for the advice. This is my 23 vehicle. 1st triumph though. Usually try and get vehicles that are running so I can avoid knocks, like I mentioned above. Not in my pay grade to mess with pistons. I have three manuals on this car, but the reason I join forums is for first hand knowledge from people who work on these daily. Like the comment you made below... they don't mention that in the catalog!! ��
 
Merlin63Tr4 said:
Someone worked on that engine or replaced it with a late TR4A engine before you got the car, out of the factory the connecting rod bolts on a TR3 would have lock tab washers installed and I don't see them on the picture you posted.
See item #56 in this Moss catalog page.
https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=36459

M.
Click to expand...
Well Merlin, I guess I should buy you a beer or something! Looks like I have a CT engine. Now just to quickly go back and recheck everything I've done so far to make sure I'm compliant. Ugh.

*the surprises you run in to with barn finds.
 
I depends which bolt was used to put the con rod caps on.
Look at item #57 on the link I sent you, they changed at engine number CT34071E.
But with the age of the car and prior mechanic/owners doing whatever, you can't depend on just the engine number for guidance.
At this stage of the game it would be hard to determine which bolts you have.

I believe the safest approach would be to put the lock tab washers on.

I don't have the two different bolts on hand to do a side by side comparison of length, etc. So you might want to call Moss or the RoadsterFactory tech support guys to verify.

M.
 
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I'm guessing the locking bolts will have fins on the bottom. I will check when I get home. Does the bearing on the Tr4 engine have different tolerances than the TR3?
 
Merlin63Tr4 said:
I depends which bolt was used to put the con rod caps on.
Look at item #57 on the link I sent you, they changed at engine number CT34071E.
But with the age of the car and prior mechanic/owners doing whatever, you can't depend on just the engine number for guidance.
At this stage of the game since it would be hard to determine which bolts you have.

I believe the safest approach would be to put the lock tab washers on.

I don't have the two different bolts on hand to do a side by side comparison of length, etc. So you might want to call Moss or the RoadsterFactory tech support guys to verify.

M.
Click to expand...

Hold the phone! I think I'm catching up, Merlin.

If the wrong bolts are used could the bolt bottom in the rod, but the cap still be loose?
 
Let's not loose sight of the fact, like CJD posted, that we still don't know the cause of the knocking.
I personally would not use this engine until the origin of the knocking sound is found.
No, the self-locking bolts have a normal hex head.
The bearing dimensions are the same for the TR3 and the TR4/4A
You did check the plug on number 4 cylinder for a loose ceramic insulator or electrode, right?
Question, when the knocking sound is occurring and you gun the engine and then snap the throttle closed, does the knocking change to a rattle?

M.
 
CJD said:
Hold the phone! I think I'm catching up, Merlin.

If the wrong bolts are used could the bolt bottom in the rod, but the cap still be loose?
Click to expand...
I guess it's possible if the unthreaded shank of the bolt that requires the lock tab washer is longer.
But, I don't know for sure, Since I don't have the two bolts available to do a side by side comparison.

M.
 
If you had a problem with the bolts not pulling the cap down, the insert in your picture would probably be paper thin in the middle sections.
Bob
 
bobhustead said:
If you had a problem with the bolts not pulling the cap down, the insert in your picture would probably be paper thin in the middle sections.
Bob
Click to expand...
Very true, also the rod bolts would have failed a while back from metal fatigue.

M.
 
Those would be true if the engine ran for a while. But he just got the car and has no history. It may not have run at all before he first started it.
 
I didn't try throttling up and backing it off (if I did, I don't remember the result). But I do know the knocking goes away once the engine warms up a bit. Usually about 5-10 mins. I am going to attach another.video or two or the engine running and the engine driving. They are old videos. I don't have everything back together.
 
I don't know what steps you took to locate the sound along the length of the engine. I had a disappears-when-warm knock from a loose timing chain. To rule out the rod big ends, you might plastigauge each journal.
Bob

Didn't see Martex's post to same effect. If your crank measurement is near right, you're going to need thicker bearing inserts.
 
Phew, information overload. No indication of bottom end problem. Rod bolts sans locktabs consistent with later engine. Wear seems normal and new std. shells will bring it closer to acceptable tolerance. Problem is elsewhere. Tom
 
Thanks Tom, that about sums it up!! ��
I was a little bummed to find out it was a later engine, but I am well aware I'm not working on a pristine gem (although it's getting there!!) releieved to find it was not the crank or piston.
New bearings will be here Monday.

My plan is to recheck the top end meticulously and locate anything that rattles.

And Bob to quickly answer your question, I pinpointed the sound (which I could hear was coming from the rear of the engine) by taking the load off each cylinder. The 4th cylinder without load remedied the noise. (Video in the 4th post, 1st page).
 
I will say, when I was checking the top end after not finding anything too telling on the bottom end... I was pulling the pushrods up and down checking for any plan and the pushrod on the 4th cylinder, had a lot of play. Now I have to recheck when the engine is back together, because I do not know if having the rod off the crank would effect that (I imagine it would, but I'm also not 100% sure what was going on with too many variables). The pushrod appeared to be slightly stuck and once I jiggled it loose the clearance under the tappet was way off. (I did check these before, but did not excessively shake the pushrod). I might order up a set of pushrods... does this sound like it could be the issue?!
 
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