Crank oil hole bevel

[telphoto]

I'm  rebuilding the engine in my T3 just for the hell of it, it was running quite well but I had little idea of the condition of the bottom end as I'd never ventured there before, but I bought the bike as a fixer upper a couple of years ago and rehabilitated the rest of it from a pretty poor condition so it was time to have a look over the winter.

This is what I've found: The big end shells on one rod have large linear score marks the run through the oil hole, which is puzzling. I noticed that the oil holes in the face of the crank do not have any kind of bevel or chamfer and wonder if this has caught on the oil hole in the shell, is that a feasible theory? Did the crank originally have a chamfer and is this an indication that this has been reground? Is there a home remedy to chamfer the crank or is the a machine shop only (ie: a have a countersink bit.....only kidding!)

I ordered new shells but these turned up with three oil holes instead of one, and none of them align with the oil hole in the rod. My understanding is that the oil hole into the shoulder of the rod is some sort of oil jet of questionable value to lubricate the cam, is it safe to use these or return for the much more expensive item. Some Guzzi's with the same crank have the hole in the rod, others don't and I've read conflicting information on it's worth so just throwing it out there.

[Wayne Orwig]

If it were a burr on the oil feed hole, wouldn't the 'gouge' go 360 degrees? It looks like the damage goes part way, then stops, like contamination that spun around there a bit, then stopped.

No idea on the oil hole alignment.

[Triple Jim]

I ordered new shells but these turned up with three oil holes instead of one, and none of them align with the oil hole in the rod.

Right, not good.  If the bearing halves arrived with no holes, I'd be OK with drilling them in the right place if I had to, but having three that don't align is wrong.  I'd return them and explain why, and give the seller a chance to make it right.

edit:  There isn't a groove that connects the three holes on the back side, is there?  That would allow oil to get to the rod hole.

[Vasco DG]

Can you feel that ridge on the crankpin with your finger? Looks big enough. If you can you need a regrind.

As for the oil feed holes? These have always been a bit of a non event. Over the years it has been experimented with one, two, none (With reliefs in the flanks of the big end castings of the rods to throw oil out *Somewhere*!) or, if you decided for whatever reason to upgrade to aftermarket rods Carillos were usually the rod of choice and these used no drillings or reliefs at all! And you know what? They all seemed to work equally well!

Regardless of the theory behind the drillings the fact is as long as the rod side clearance is adequate the thrashing of the crank will be quite sufficient to distribute the oil everywhere it needs to go as there is a lot of throughput. On the modern 8V engines with very truncated skirts on the pistons I still honestly query the necessity of the under-crown sprays but they certainly can't do any harm and the Pistons do have substantially less surface area to dump heat to the cylinder walls.

Anyway I'm sure someone will come up with some other wonderfully complex, if slightly barmy, theory to explain why I'm wrong but let's face it. That's half the fun.

Pete

[Triple Jim]

I haven't held one of these rods in my hands.  I thought the hole in the rod went all the way up to the wrist pin bore.  If not, then disregard my previous post.

[Mike Tashjian]

Wow, take apart a good running engine to find ways to spend money.  I am sure you can buy new parts and the engine will run fine again.  But how do you expect to buy new parts when you don't know what parts you have?  Are you measuring as you go?  Pete mentions running a fingernail across the crank to check for wear. If you notice any, the next step would be to measure it.  That will determine if it needs servicing.  The rod shells you took out look pretty normal for a used motor besides the lines.  The lines are a mystery for sure.  Holes in the crank would have less stress champhered, but that is not an indicator that the crank was ground.  How did you determine what shells to buy if you don't know if the crank was ground?  Any good service manual will get you pointed in the right direction.  And I am sure between everyone on this site who has rebuilt motors you will get plenty of good advise.   Mike

[acogoff]

      Similar scored conn. rod bearing appeared on my old lump when the original chrome bores started to flake, but could be from anything passing through. Make sure your cam followers are in good shape as they tend to give off chunks when going south.

[Dick]

I haven't held one of these rods in my hands.  I thought the hole in the rod went all the way up to the wrist pin bore.  If not, then disregard my previous post.

Hole exits right above the big end of rod.

[Dick]

To me, there looks to be a chamfer in the crank oil holes. In my view, the crank looks good. I would guess-do to the location and angle of the rod holes-that there purpose was to spray the cylinder walls?? Installation of the rods is with both holes and both ground flats of big end, (both hole and flat being on the same side of rod), facing towards the right cylinder. I would agree with Wayne, probably some loose swarf dug in. Not the first I've seen looking like yours. 

[Antietam Classic Cycle]

I ordered new shells but these turned up with three oil holes instead of one, and none of them align with the oil hole in the rod.

I don't know where you bought the bearing shells, but MG Cycle offers three different rod shells. Those like yours with three holes (cheapest), some with two holes (most expensive)

and some that have only one hole (priced in between the other two)


IIRC, I always order the two hole version for early engines with the oil squirter hole in the connecting rod.

[telphoto]

Wow, take apart a good running engine to find ways to spend money.  I am sure you can buy new parts and the engine will run fine again.  But how do you expect to buy new parts when you don't know what parts you have?

Well, maybe I was being flippant when I said I was pulling it apart for the hell of it. The bike was a complete mess when I got it a couple of years ago so spent about 6 months stripping it back to the bare frame and rebuilding it, but as I mentioned I didn't get into the bottom end of the motor at the time as it didn't have any obvious problems and there was so much else to do, however given the poor condition of the rest of the bike and mess that the top end was in I always intended get to it  and after two years of riding it the time was right to pull the engine down.  I'm very glad I did, as evidenced by the gouges in the shell bearings, also sent the cam and tappets out to have them ground as well as they were looking a little sad. I was also keen to have a peek at the oil pump and fit a new type cam chain tensioner as it still had the old rubber block type there.

I didn't explain properly. I mic'ed the crank before ordering new shells and it's within spec, nice and smooth with no ridges and as you mentioned the old ones looked in reasonable shape, next week I'll have a plastigague party. I was thinking the lack of chamfer may have been a result of a welded and ground crank.

[telphoto]

    Similar scored conn. rod bearing appeared on my old lump when the original chrome bores started to flake, but could be from anything passing through. Make sure your cam followers are in good shape as they tend to give off chunks when going south.

And you know what, this bike had flaking chrome bores when I got it and first thing I did was replace them with Gilardonis. Perhaps it's suffered from the same fate. Thanks!

[Vasco DG]

Have you cleaned out the sludge trap yet?

[telphoto]

Have you cleaned out the sludge trap yet?

Not yet, it's still in the block but hope to get to it sometime this week. I'm waiting on a puller for the rear main bearing.

[mtiberio]

Race rods do not have oil holes in the rods. Just use the right thickness shells for the diameter of your crankpin.

[lucky phil]

Race rods do not have oil holes in the rods. Just use the right thickness shells for the diameter of your crankpin.

What "race rods" would those be? I can order "race rods" from any number of manufacturers and have whatever I like. Pressure fed gudgeon, oil squirters, standard, whatever.
Ciao

[Mike Tashjian]

Measuring parts is always a time consuming part of any rebuild.  Time spent at this point will pay dividends later on down the road.  I do like Plastigage but hesitate to use it much. Hard to tell if the part is round or egg shaped where you use it.   I prefer to use micrometers and bore gauges.  Figuring an optimum clearance for parts depending on the type of riding you plan will be important too. If a motor is being rebuilt for maximum service life tighter clearances(minimum vs. maximum allowable) would be preferred.  At this point every part you have can be checked in many ways to ensure it is a good part, before you put it back in service.  Any doubts about a part should be answered before it is installed.  Mike

[Chuck in Indiana]

And you know what, this bike had flaking chrome bores when I got it and first thing I did was replace them with Gilardonis. Perhaps it's suffered from the same fate. Thanks!

Well, looking at the bearing shells, *something* nasty went through them..

[CalVin2007]

 Exactly. Any time a groove starts at the oil hole and travels 'round the bearing you can bet some swarf came down the pike and tried to go 'round with the journal. Only the embeddability of the bearing surface prevents disaster.

  Terry

[mtiberio]

What "race rods" would those be? I can order "race rods" from any number of manufacturers and have whatever I like. Pressure fed gudgeon, oil squirters, standard, whatever.
Ciao

Carrillos

[lucky phil]

Carrillos

Yep Carrillo will do whatever you want.
Ciao