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noise from bottom of engine...

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6969ronin6969

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I fired up the TR3 a couple of days ago (it's got a later TR3A engine in it) and was letting it idle to warm up a bit. After a short period of time I started hearing a tapping/knocking noise and ran over to shut it off. Engine ran less than 30 seconds with the noise.

I pulled the valve cover and everything felt alright. I pulled it up on ramps (with a come-along) and today got a chance to drop the oil pan and see what was going on. I immediately found a couple of pieces of a tab washer, for the bolts holding the big end of the connecting rod to the crank, in the bottom of the pan. Then I grabbed a flashlight and rolled under the car. The first piston (closest to the front of the car) had 1 bolt starting to come out (the other was tight) and obviously missing some tab washer parts.

The engine has been rebuilt at some time in the past (not sure when) and has run very strong since I've had it (~2 years). I started looking at the other con-rods to see what was going on. Here's what I found: all the other cylinders were tight, the 2nd cyl. had the tab washer installed, the 3rd and 4th had regular lock washers, not tab washers. I took out the 2 bolts for the 1st cyl. and the con-rod bearing had a couple of small pits in it. The crank passed the visual and fingernail test.

My thoughts are, since the previous engine builder was inconsistent enough to use locking tabs on 2 cylinders and lock washers on the other 2, is to drop all the half moon parts of the con-rods (cyl.1~4) and replace the bearings, replace the bolts and put locking tabs on all 4 cyl. I'd use Plastigauge when doing this.

Looking for opinions on if others agree or disagree.
Also, should I use locktite of any kind?
Does the bearing just pop out of the half moon part of the con-rod?
How do I get the bearing out of the upper half of the big end of the con-rod?
Anyone have a preference on rod bolts?


A few other items I noticed while in there:

The bolt heads for the rod big ends have "Auto 75" on them, does that mean anything to anyone?
The crankshaft has "010" hand stamped on a flat spot on the forward end, would you assume this means I need .010 over bearings?
Up on the camshaft, between the first and second lobes (again from the front of the car) are the numbers "MC21434" or "M021434". Does this mean something to someone? Factory camshaft or aftermarket?
Any way I can tell the size of the engine while looking from the underside? I rough measured the rods and they appear to be in the 6+" range.

Thanks for reading this far and any advice/info you can offer.

Eric
 
I just noticed Moss lists a self locking bolt that was used on the TR4s. Could I use this instead of the bots and tabs? Anyone have experience with these good or bad?

Thanks again,

Eric
 
Eric, you may get lucky fixing it with the parts you have, but who knows for sure? Since its a TR3 and not something exotic you may get by with just installing new locktabs and tightening everything up properly. If the bearings look good why replace them? Could be just fine . If not it needed to be rebuilt anyways. I've got some spare innards if you need them... Kevin
 
If you use the locktabs, they have to be replaced every time. Otherwise they tend to break off (as you found).

I believe it was Kas Kastner who recommended just leaving out the locktabs (even new ones can have problems under racing conditions, apparently) and using Loctite instead. Ever since my own experience with broken locktabs, that is what I do.

I forget the Loctite number offhand, but there is a "medium strength, oil resistant" formula that I use. Also a good idea, IMO, to check that the bolts are not too long. I have never seen the problem myself, but at least in theory there may be rods that aren't tapped quite deep enough to work with the early bolts and without the locktabs. To check, turn the bolt in lightly by hand without the cap, then set the cap next to the bolt. The bolt should clearly be in farther than the top of the cap. This is also a good test for stretched bolts.

The upper insert just pops out. Look for the locating tab, then push on the other end of the insert with your thumbnail (or similar soft, blunt instrument).

Sorry, I don't recognize any of those numbers. Look at the back of the inserts you removed for the legend 010 (or 020 or 030). If present, that will be the undersize. If not present, chances are that they are standard.

My preference would be to either reuse the original bolts (assuming there is no damage), or replace with ARP bolts. Just too many defective new parts coming through the usual LBC channels to take a chance, IMO.

You should be able to measure the bore if you push a piston up so it is entirely inside the liner. Unless there have been some very unusual modifications, that will tell you the displacement.

Don't forget the plastigage, as a final check you got the right inserts.
 
Thanks for the replies. There was some pitting on the bearing surface so I will replace that one, and since I am in there already, I figure it's good insurance to go ahead and swap them all out. I know I'll feel more confident.

I like the idea of the ARP bolts, as a precaution. Any recommended place to procure the correct ones? Is that something a local NAPA would have?

I didn't try, but can I just push the piston up by hand (after removing the spark plug I assume), so that I can access the upper bearing?

Thanks again,

Eric
 
Between pushing the top of the connecting rod & piston upward and rotating the crankshaft you should have enough room to remove and replace the bearing upper halfs.
Be aware of what you are doing when you rotate the crank so as not to let one of the rods that are hanging down snag on a journal and gouge a groove in it.
 
Sorry, I don't have the ARP number handy. But they fit a Ford or something, so there's at least some chance you can find them locally. Likely a lot cheaper by mail order, though.

You should be able to push the piston up by hand, although it may take a fair amount of force. But generally I just rotate the crank so the journal is out of the way. You don't want the piston too high as it's hard to get your hand up there.
 
OK, the latest, I pushed out the bottom bearing as suggested and it came right out. As mentioned there is some identification stamped on the inside face. It reads as follows, one on top of the other:

A circle with "Fm" inside it
2295-RA
030US
XK

Based on this I assume .030" undersize. Not sure what the US means. I know there is left or right hand steering, do the engines turn different directions if it's UK or US? (just kidding)

Any idea what the other id marks mean?

Thanks again for the help. I've turned plenty of wrenches over the years, but, honestly, this is my first time to mess with the bottom end hence the basic questions.

Eric
 
Just a guess that "030US" refers to .030 inches undersize (as you guessed, and as opposed to millimeter measurement)? And I'd also guess that the "circle with 'Fm' inside" is a Federal Mogul branding? Generally, that's a very well-regarded brand, although I don't know about their bearings for Triumphs. "2295-RA is probably F-M's part number?
 
Andrew Mace said:
Just a guess that "030US" refers to .030 inches undersize (as you guessed, and as opposed to millimeter measurement)?
Click to expand...

I realize this is how they are sized, but it just seems backward to me. The journal is undersized, but the bearing is oversized. At least that is how my brain thinks about it!
 
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