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TR2/3/3A Knock knock... what's this?

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And the small cam lobe is for the fuel pump. Which, by the way CAN cause a knock too for certain failure modes.
 
Yes, obviously not valve guides... have too many projects on this car going at once. 😜 Luckily I attached a photo so it was very obvious those were not valve guides. I thought the cylinder walls were scored, but I don't fee anything there. Keep searching. Will test clearance on the old main bearings with plastigauge tomorrow and hopefully pop the new ones in and viola! We'll see.
 
Just a quick update: I ordered the wrong seals so I have a couple more days until I get the right ones in. But I did check the clearence with Plastigage. I am showing .002 on the con bearings. That doesn't seem like that big of a gap. Worth the knock?
 
You have to be careful how you measure clearances with Plastigage. All oil has to be wiped from surfaces to be measured, care must be taken to not rotate the surfaces being measured while the Plastigage is in place, etc, etc.
Is the above measurement with the new bearing shells or the old?
Big end bearing clearances when the TR engines were newly manufactured were in the range of 0.0028 to 0.0040......

M.
 
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Thanks for the reply...

It was wiped and steady ;)

this was the old bearing. I will measure the difference with a micrometer on the new shells vs. the old shells when I receive them. Fingers crossed I can wrap this up with some success, I don't know what else I can check!!

Anything else before I close the bottom?
 
That very well could cause a knock...but the more i think about it, it would not stop by pulling the ignition lead. So, never mind!?!

This is an odd one. Another possibility is carbon in the head combustion chamber. If everything else in the bottom end is tight, then pulling the head would be the next step.
 
My only guess is the little bit of wear that was ok the rod bearings. And I will post my findings when I get the new ones installed. I would like to confirm the passage for oil is clear in the crank, but I don't like the idea of blasting air in there. I am worried it could cause a much worse block as well as leaving a void air in the crank, maybe a block elsewhere? Is there any way to check if there is a block by somehow pushing oil through?
 
By now all the oil is drained from the crank anyway, so adding air is not going to hurt anything. You should see it bubbling out the rear main. You cannot impose a block unless there is already something in there to block it. The oil hole is just a drilling from the rod journal to the rear main journal. .003" bearing clearance is not enough to cause a knock, unless there is no oil reaching the bearing.

An oil blockage is a long shot. I no longer think it's the bearing. It has to be piston related.
 
Yeah, you got a point...

do you blow air from the hole in the crank journal?

What more can I check with the piston with the bottom off? I am going to compression test engine when I get it buttoned back up. Oil pressure was good...
 
Have you checked the small end for clearance? Grab the end of the connecting rod and try to move the piston up and down. The PO may have left the small end bush off the No. 4 rod.

David
 
I have. I actually took a video of it, but it's such a frustrating video because I'm just fumbling around in a really tight spot. The only bit of "play" is at the wrist pin from side to side... nothing lateral.
 
To me, the noise sounds like the double knock from a loose small end bushing. It is especially noticeable when removing and replacing the spark plug wire.
Berry
 
There's no denying it's much better! I still hear a slight knock, but I'd personally wait until it gets more pronounced before digging into it.

Is the consensus that the old bearing shells were out of tolerance?
 
That's kind of what I'm thinking. I think I'll drive it like this for awhile, if the knock comes back, I will probably end up having to get a rebuild. I think the knock is a two fold knock I am going to replace the manifold gasket next and see how that helps.

need to set the timing and get the carbs dialed in. I feel like I'm idling very high~950 rpms
 
It sounds like a typical TR engine with a few miles in it.
You can still hear the knock, but it is not very noticeable.
Still wonder why the excess wear on the No.4 bearing shell and not the other three.

M.
 
Merlin63Tr4 said:
It sounds like a typical TR engine with a few miles in it.
You can still hear the knock, but it is not very noticeable.
Still wonder why the excess wear on the No.4 bearing shell and not the other three.

M.
Click to expand...

i bet there was a clog in the oil at some point. With the score marks running from the oil holes on the bearing, it seems like some grit probably worked its way through there.
 
Yeh much better without the spark waking away, I still do not like the hollowness I hear, and yes the problem does not have to be one thing. Maybe bottom end and valve train together. I hear a typical TR3 valve train and==== yes a little== to a lot=== too loose. Have you slid one of the rockers over and felt the bottom of the rocker shaft. you have too loosen up the adjuster with the piston up..

TR3s chew those shafts up for some reason, but perhaps it is the originals that I have taken out over the years, but what I am saying is the shafts can get very worn deeply and the motor runs fine=== but makes noises and it cannot be fixed without replacing the shaft and usually re-bushing (which I do not recommend) or replacing the rockers. I would seriously think about doing that because it has to be done anyway, does not cost that much and the motor and stuff stays in the car and the access is easy. Wish I was there I would feel more confident about my diagnoses.


Bottom line is you are a TR3 guy now, so now=== you have to fix it, and yes===== I did see a Rabbit run through here.
Steve
 
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