Crankshaft bearing installation
Main bearings
Thanks Claude, ye something went in ontop of piston 3 and 4, I thought the rings broke and came past the piston but when I took the pistons out all the rings was stil ok. I didn't find anything on top of the pistons either when I took the head off. The head is gone in for repair and I have to replace 4 exhaust valves. I am replacing the pistons, rings, big end bearings and main bearings. I spoke to someone at mitsubishi but he didn't seem to know about these numbers I will try to see the workshop manager. The funny thing is there is a code on the crank shaft and on the engine block and they are different from each other, so it is a bit confusing.
In most cases you can ignore those markings...
In a production line with automated maching equipment in constant use,the tools used to grind the crank journals and align bore the blocks wear at slightly different rates and this creates a situation where each crank journal may have a different finished dimension and the same goes for the bearing shell "seat" in the cylinder block - for this reason, the factory will make available bearing shells with different thicknesses, allowing the engine to be assembled with very close tolerances.
The code on the crank will be based on measurements made at the factory after the crank was machined, the code on the block will be based on measurements made at the factory after the block was align bored - they are not expected to match - they are used to compute the thickness of the required shells, with the thickness being specified as a color.
If you look at third part replacement bearings you will find that they are sold in sets, either standard, or undersized (for use with cranks that have been reground) and that all the shells in those sets are identical.
What you need to do is measure the crank journals to determine whether they are within spec for "roundness" (they wear oval) and size, if they are out of spec. the machinist will tell you how much the crank needs to be "cut" to bring it back into roundness and that will determine what size bearings you need to get. If the journals are within spec you can either get a "standard" third party bearing set which will have identical shells, or you can use the factory manual to determine what color bearings you need - I strongly believe you'll find that you'll be using all the same color.
The other thing to be aware of is that unless the engine has very, very low mileage, the crank journals will have some degree of wear making it impossible to achieve the same close tolerances as when it was originally assembed, which is why the markings can generally be ignored.
Bearings
Thanks for the info Fordem, what you are saying make sense because I have done other engines before and never came across codes like this. I search through all the manuals I have and found another sheet like I posted before but with sizes instead of S1, S2, S3. For some reason I cant attach the sheet to this post.
It might depend on your "background" ...
and by that I mean, the manufacturers on whose product you first gained experience - for me that was the english Austin/Morris conglomerate, just around the time they became British Leyland - their engines were, so to speak, quite agricultural in nature, and had nowhere near the levels of precision that I have come to expect from Japanese manufacturers.
I first came across these "individually sized" bearings working on Suzuki engines and it was a bit of a struggle to understand, but, after you've done it once, it's really not that difficult.
Another approach would be to use "plastigage" or similar - where you tighten the bearing cap assembly down over a plastic "thread" than can then be measured to determine the actual clearance.
Crank bearings
I am not a mechanic or mechanical at all I am an electrical guy but when I was young I helped my father with engines that is where I picked up the mechanical and when I started to drive I did all my cars myself starting with Ford engines and then Volvo and volkswagen and a few others but for these engines if you asked for STD bearings that is what you get. I will go sit with the guys from Mitsubishi this week and see what they say. I will try and get some plastigage to see what clearance I got, I see they show in the workshop manual how to use it. What I found confusing is the code on the crank is 33323 and on the block it is 11111.
Bearings where I am at now
I went to see the workshop manager at Mitsubishi and I was told that they have never done an engine like this and was send to the engineering shop. the guy at the engineering shop measured the journals and said the standard bearing will be ok. I re-assembled the engine last week with new bearings ,pistons, rings, gaskets and seals, fitted the head that was redone by the engineering shop, they replaced 4 exhaust valves welded the head where it was damaged and machined it down again. Saturday I put the engine back into the io, I picked the inlet manifold up to clean and a piece of metal fell out, after close inspection I realized that it was a piece of a valve guide. I had a close look at the head on the inlet side and found that four guides are broken and I am sure that it was these pieces that went on top of the pistons and caused all the damage. I am a bit P@#$%st of with the engineering shop because they should have picked it up when he did the head. Now the head must come off again!!!!. Do you guys think I can use the head gasket again or must I get a new one.
Syndicate
crankshaft bearing
I haven't done this for a long time, and not on the io. This is what I think, but I could be wrong....
The bearing could have identification, colours and number for their location and sizes. no point explaining location, for size...depending of the final machining of the crankshaft at manufacture, they may have different final size, so the green one could be smaller than the black one....example only, and you will need special measuring equipment to see the difference.
Again, check with other, as the wrong bearing size will mean an early engine failure.
Are you rebuilding your engine ?
That will be interesting to know the final word on this one.
Happy io
My io is now SOLD Thankshttp://pajerio.com/forum/claudes-io-2002-zr-built-thread-onlyhappy-io