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glcook01

International D239 Cam Bearing Replacement

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I am rebuilding an International D239 from a 574 Tractor.  When I received the tractor it had leaking sleeve seals allowing coolant into the crankcase.  I have the engine disassembled, and all of the main, rod, cam bearings have extreme wear so I am replacing bearings, sleeves, pistons, rings.  I ordered parts from All States Ag Parts  (Reliance) and just received the parts.  My current confusion is with the cam bearings.  I read that the cam bearings come unfinished and must be line bored so I was expecting an unfinished bearing but the part that arrived is a finished bearing.  The part number sent is a 3055008R2 on the package.  I test fit the bearing and it felt very loose.  I then measured the inside diameter and it is 2.292".  The measurement of the Cam journals is nominally 2.2825.  The D238 service manual states that the max running clearing is .0045", and it lists the journal diameter as follows:

Engines with Tin-Babbitt cam bearings  2.2823 - 2.2835

Engines with lead-bronze cam bearings  2.2813 - 2.2825

Why would the finished bearing size be 2.292?  The only thing I can think is that finished bearing was intended for engines that originally had Tin-Babbitt bearings because in those engines the cam had larger diameter journals?

My cam appears to be in spec at 2.2825 so the running clearance with this new bearing would be 2.292 - 2.2825 = .0095?  This is way out of spec according to the service manual (max running clearance of .0045).  I assume at this point that I will need to return these finished cam bearings and order unfinished cam bearings and have them line bored.   When they are line bored how much clearance should the machine shop allow between cam journal and bearing?

 

The IT Shop Service Manual states:  Camshaft Bushings are furnished semi-finished for service and must be line bored after installation to an inside diameter of 2.2844 - 2.2856.  Normal operating clearance of camshaft journals in bearings is .0009 - .0033 with a maximum allowable clearance of .0045.   

 

According to the above, if machined to 2.2844 (smallest size mentioned) the running clearance would be 2.2844 - 2.2825 = .0019.  This seems reasonable and is within the spec.

 

Thanks for your replies.

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I'm assuming your measureing those bearings uninstalled. Measure od of bearing and id of block bore. Will give an idea of shrink upon installation.

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Yes I am measuring the bearings uninstalled.  I have not removed the old cam bearings because I don't have the tool to do that.  My plan is to have the machine shop do that, but I didn't want to take the engine to the machine shop until I had the cam bearings.

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U either need to find a shop to line hone them, not cheap. Or order bearings that are finished size

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2 hours ago, andrewn269 said:

U either need to find a shop to line hone them, not cheap. Or order bearings that are finished size

Which I think he has. The bearings will shrink by what ever press fit he has when installed.

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Any idea what type of shrink can be expected?    Currently if I use the finished bearings that I have, I would have a running clearance of .0095 less shrinkage from installation.   The bearing ID would need to shrink by .006 during installation for me to be within tolerance.  Is .006 a reasonable expectation for shrink rate during installation?

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Thats what you need bearing od and bore id for. .oo6 would be tight but doable with proper chamfer and lube. Are the bushings seamless or do they have a joint?

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Last one I had line honed was ridiculously expensive 800-1200dont remember probably got hosed but only place around to do it. Last one I overhauled had lots of wear from the cam local machine shop put sized ones in for me seemed to fit right and has good oil pressure so not to worried about. Every other engine has seized bearings that u shove in

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toss the i t   get a neuss or sealed power specs

would have shop source and do bearings if they are not press fit.then they can eat the screw up

did 100s of pre fit 30 years ago...if any where ever tight suppose we polished them....? do have some 3' hones...?

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