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MG TD TF 1500 - Engine examination - lucky man

Sooooooo.....

The pistons are .040, that's why the cylinders are free of a ridge and in perfect condition, the engine's been worked a bit. The crank is std (uncut) and shiny and smooth and is perfect.

The main bearings and all but one of the con rod bearings are perfect. One con rod bearing has just about disintegrated (photo) BUT the journal hasn't got a mark on it.

It looks like I caught this one just in time. I'll be installing new bearings all around just in case any of the others from this batch are also this close to failure.

I'm so glad this one's rebuild-able in my own shop.

MAndrus

Wow, that looks like a lucky escape indeed!

I wonder what could have caused this damage in one bearing?

Willem van der Veer

I don't know, but I'm not thinking a manufacturer's error. Caps are installed out of a pile of them, not packaged as paired sets of 2.
MAndrus

I think fatigue failure or dirt. I would consider there is metal in all of the oil galleys in the block/head/crank. Unless the crank is new manufacture Moss (will have the part # cast into it) or other brand of new crank (IE not an original T-series crank), definitely magniflux it.
George Butz

That is good news. Mag test the crank for cracks and insure it is straight Mic all journals and check the rods for trueness. Check the line bore as well. Then your bottom end should be good to go.

Bill Chasser
TD-4834
W. A. Chasser

That cap and rod are not matching, the factory machined these as a set. You can see that the cap bolt hole bottom left is closer to the bore which would distort it and offset the shells. The cap bolts are all that locate the bearings. I blew the picture up and it is very obvious. I think a new rod and cap are required. With unknown rods always assemble without shells and check there is no step at the faces.
Ray TF 2884
Ray Lee

I feel it is metal fatigue.
John...Sydney
John Walton

I've also seen etching like that from the acids in engine oil sitting for some time in an engine.

Tom Lange
MGT Repair
t lange

Ray, that's the first thing I checked. It's a proper set, the machine marks line up. I tried rotating the cap, not even close, it couldn't have been fitted backwards.

MAndrus

That bolt hole does look very thin to the inside edge. Never seen that before.
Bruce Cunha


New parts coming in a week or so, Bench assembly and measure will be important on this engine. No telling what else I'll find. I'm taking the rods out to a shop to see that they're straight. Also, I don't re-use fasteners. No way to tell what's been done to them.

Had a chance to look at notes from Feb, '12. This cylinder had the best compression, and it's cam lobes were good, unlike the other 3 cylinders. So, I'm figuring this cylinder was doing more than it's share of the work.

A bit off-spec and getting hammered..... I'm glad it was caught before the crank joined in on the party.

Unless the shop tell me the rod is bent, I'm chalking this up to induced fatigue. Has to be, all the bearings had been changed at the same time.
MAndrus

Mate

I dont like the scoring on the face of the big end journal as depicted in your second image. Perhaps material removed from this face migrated into the big end slipper bearings. That engine needs a thorough degrease and flush as George has indicated to ensure there is no swarf floating about.
G Evans

I'm with Tom - that's acid damage from keeping the engine for a long time with well-used oil in it, not wear. Worth checking all other bearings in the engine - cam etc.

David
DavePro

This thread was discussed between 27/11/2016 and 28/11/2016

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