Crankshaft play on 1978 Johnson 55 HP

Hello,<br /><br />I am rebuilding the powerhead of my '78 Johnson 55 HP, with a used crankshaft and new lower, middle and upper bearings.<br />A mechanic measured the crankshaft journals and they are within specifications.<br />After assembly of the powerhead I can feel some play on the crankshaft when I move the flywheel. The play is not up/down, but in the same direction as the pistons travel.<br />I don't know how I can measure the amount of play, so I can't really tell how much play it is.<br />The play is on the upper bearing, not within the flywheel/crankshaft (flywheel is properly mounted). <br />The Cylinder & crankcase are flat to each other and the the right amount of torque is applied.<br />So my only guess is that some play is normal, or the bearing isn't right.<br /><br />Can anybody tell something about this?<br /><br />Sorry for my bad english, I hope you all understand what I wrote.<br /><br />Cor

Re: Crankshaft play on 1978 Johnson 55 HP

The English seems pretty good to me.<br /><br />What brand bearings?

Re: Crankshaft play on 1978 Johnson 55 HP

I don't have the powerhead & parts within my reach right now. I have an idea it is Sierra or something, but not sure. I will look it up tomorrow.<br /><br />Thanks in advance.

Re: Crankshaft play on 1978 Johnson 55 HP

We havent heard of any Sierra bearing problems so, for the moment anyway, lets assume they are OK. <br /><br />Some years back we noticed the lateral movement you are talking about. The OMC engineers gave a very strange explanation but the bottom line was that it was OK. <br /><br />I think the main thing is to double check with the guy who measured the crank. Make sure he is confident that the used crank was within stock (as manufactured) specs.

Re: Crankshaft play on 1978 Johnson 55 HP

Thanks so far Dhadley for the explanation and many thanks for the quick response.<br /><br />I'll check on the bearings brand and double check with the mechanic. <br />I have an original OMC manual so I trust on the numbers about the crankshaft measurement.<br /><br />The problem with rebuilding is that you see a lot of "suspicious" things, that might have been there all the time, without causing any trouble.<br /><br />I'm already more relaxed about it, because it is a phenomenon already seen before and assumed to be OK.

Re: Crankshaft play on 1978 Johnson 55 HP

Let us know how it turns out.<br /><br />Good luck!!

Re: Crankshaft play on 1978 Johnson 55 HP

Ok, the definite situation is:<br /><br />Bearings are Sierra and they are new.<br /><br />I had the crankshaft measured again and the outcome is:<br /><br />Top journal measured: 1.497441" (should be 1.4979" - 1.4974")<br /><br />Center journal measured: 1.37441" (should be 1.3752" - 1.3748")<br /><br />Connecting rod crank pin top and bottom measured: 1.1823" (should be 1.1828" - 1.1823")<br /><br />(The numbers might seem a bit odd because of the decimal places, but I converted them from metric to inch)<br /><br />So the top journal is within specs, the connecting rod crank pin journals are just within specs and the center journal is 0.00039" smaller.<br /><br />The crankshaft is in great shape. So do you think I can use it and take a little feelable play for granted, or should I look for another crankshaft?<br /><br />Thanks for your help.

Re: Crankshaft play on 1978 Johnson 55 HP

Anybody a word of advice wether my crankshaft is still usable while the center journal is 0.00039" smaller/thinner then prescribed by OMC?<br /><br />Thanks in advance.

Re: Crankshaft play on 1978 Johnson 55 HP

Your within the .0005 the manual calls for. You said the crank looks good with no damage, so I would say your OK. In my experience, I have found that these crank's are held to close tolerance's, if they look good, they generally are. Keep in mind also that when you are measureing to 1/10 of a thousand that if you were to have two people doing the measureing, it is unlikely they would come up with the same figure to 1/10 with a hand held mic. If one man were to measure using the mic.'s ratchet, and the other going by feel, they will be different. Both method's are OK, it just depends on the skill of the operator.

Re: Crankshaft play on 1978 Johnson 55 HP

R. Johnson,<br /><br />Thanks a lot for your response. Apart from the fact that it is close within or just slightly above what the manual calls for, I was triggered by the fact that I could feel play when moving the flywheel.<br /><br />The mechanic (not specialised in outboards) who measured it, felt that it was OK to use it, your opinion is the same and Dhadley said earlier that some play is acceptable. That gives me enough comfort to just use it.<br /><br />Thanks!!!

Re: Crankshaft play on 1978 Johnson 55 HP

I've seen a couple running for years with feelable play in upper cranck bearing, not even getting worse