TR2/3/3A Knock knock... what's this?

[CJD]

Probably std then.

Crank journal should then be 2.4805-2.4815". If it is less, that could be the problem. I.e. A turned crank with a std bearing.

 

[HighAltitudeTR3]

This is what I pulled out. STD bearing. Not even sure what that means....

 

[HighAltitudeTR3]

This is the inside of the bearing... doesn't look warm, but I'm noticing some wear on the edges...

 

[HighAltitudeTR3]

Probably std then.

Crank journal should then be 2.4805-2.4815". If it is less, that could be the problem. I.e. A turned crank with a std bearing.

i will check the journals tomorrow. I doubt the crank has been tuned before, the car only has 7286 miles. But I'll update when I find a micrometer.

Thanks!!

 

[HighAltitudeTR3]

I'm showing 2.0825.... that's a far cry from 2.4805 is there a chance this is off a smidgen?

 

[martx-5]

That 2.4805" number is for the mains, and the internal diameter of the bearings, not the journals. The con rod journal diameter is 2.0860"-2.0866" for STD.

 

[HighAltitudeTR3]

I ordered new STD bearings. I don't think the wear is off enough to have them tuned (nor do I want to go through that if I don't have to). i am open to comments on that. If anyone thinks this is a terrible idea, let me know why, please.

Also, should I replace all of the bearings or just the one I know is an issue?

Anyone have torque ratings for con rod screws? Any other info that would help me out?

 

[CJD]

Yep, my mistake on the journal!

That still shows somewhere in the range of .003-.004" clearance. That is higher than recommended, but should not cause a knock that loud. There is a chance the bearing inserts are the wrong size from the factory. Otherwise you still don't have a cause for the knock.

The insert in your pic is a bit scored, but doesn't appear worn out.

Can you get a feeler gage up to the piston skirt? There is a chance the wrong size piston was installed in the bore. See if you can slip a feeler between the piston and cylinder, and if you can, see how large a feeler will fit.

 

[HighAltitudeTR3]

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. I checked the pistons and con rods. They all look good. I will install new bearings; still unsure if I should do all 4 or just the one in question... I will put everything back together and adjust the tappits again. If I still have knocking I will start looking from the top down.

 

[Merlin63Tr4]

Grasping at straws here, but I wonder if the piston was assembled to the connecting rod the wrong way around. The piston is offset toward the thrust side and if not assembled correctly might cause a lot of piston slap.
If I recall the expansion slot on the piston skirt faces the camshaft.

M.

 

[HighAltitudeTR3]

I will pop my head under there and see. I should be able to see that from the bottom correct?

 

[Merlin63Tr4]

The slot should be visible looking up from the bottom of the engine.
Have you also checked the connecting rod small end/piston pin for excessive looseness/free movement, you should compare piston 4 to other pistons and see if there is a difference.
And yes you should replace all the bearing shells not just number 4.

M.

 

[HighAltitudeTR3]

I did check pistons and wrist pins, they are tight and feel good. No play. Any chance you know the torque setting on the screws?

 

[sp53]

So you have the head off or did you pull the piston out from the bottom? Never tried it, but it should be doable--- getting it back might be a challenge, but do not know. I have taken tr3 motors and pull the pistons out, then had the connecting rods and had the holes trued for roundness, put all new bearing on, put knew rings on and ball honed the cylinders and had that work out great for years.

How is the wrist pin or could the noise been from the top all a long.
steve

 

[HighAltitudeTR3]

I did not pull the piston. Trying to avoid it. I would guess you could pull it from the bottom, but it would be tough. Not 100% are there is room. As mentioned the engine has less than 7300 miles on it, so I hope the pistons are in order. If the knocking doesn't go away with this, I will check everything else before I pull the engine. We're in prime Triumph Season!!

and the wrist pin is tight, no play.

 

[martx-5]

When you get the new bearings, Plastigage them to see how much clearance you really do have. It's the easiest way to find out what the clearances are. The Plastigage comes in three "sizes" for different clearances. Most auto parts stores should have it.

https://www.plastigaugeusa.com/how.html

 

[Merlin63Tr4]

The torque spec for the con rod bolts is 55-60 lbs/ft.
Use new lock tabs.
Do plastic gauge the new bearings like matrix-5 posted. The wear limit (max clearance) for the big end bearing is 0.005 per the manual.

M.

 

[HighAltitudeTR3]

Ok, I'll pick them up when I get some assembly grease.

 

[TomMull]

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. I checked the pistons and con rods. They all look good. I will install new bearings; still unsure if I should do all 4 or just the one in question... I will put everything back together and adjust the tappits again. If I still have knocking I will start looking from the top down.

Couple of things. You will gain very little by replacing all the shells but they are relatively cheap and as they say it wouldn't hurt. I would look at the top end before you button up the bottom because I'm quite sure it is impossible to get the piston rod assembly out from the bottom with the crank in place. You'll need to get the piston and rod out to properly measure everything.
Tom

 

[HighAltitudeTR3]

yeah, it would be quite a squeeze to get those out. Also a little out of my pay range. I am going to button everything up after I install the wheel bears because if the sound remains, then I will have to ship the engine to a builder. I don't have the tools or places nearby that would to get the job to the next level. (Probably have to send it to Denver). Fingers crossed with the engine buttoned back up the knock is gone.

Am am I right to assume if it's not anything above the pistons, the engine will need to come out?