Should i worry?

Nick · Post by **Nick** » Tue Jul 20, 2010 7:42 pm

As some of you know, ive just put new liners etc in my major. Replaced the conrod bearings with new ones (+0.010), these are what came out so i replaced with the same. Before i tore the engine down, it would turn over if i pulled the water pump/dynamo belt, fairly easily. Now it has new parts etc fitted, it feels a bit tighter, although if i put a small pair of pipe grips on the end of the crank pulley, it turns over ok. I briefly tried the starter motor and that does it fine.

However, should i worry about this? Is this fairly common on an engine thats been re-built?

Gavin · Post by **Gavin** » Tue Jul 20, 2010 8:07 pm

I would expect a newly built engine to be tighter than prior to rebuilding. The clearances on bearings and pistons / bores are all going to be less than previously.

Nick · Post by **Nick** » Tue Jul 20, 2010 8:14 pm

thats what i thought, its not like seized or anything, just really dont want it to seize up when it gets warm (if this will happen). feels smooth when i turn it over, maybe im just worrying too much.

Post by **Brian** » Tue Jul 20, 2010 8:43 pm

Did ypu oil/grease all the bearings and the seal on the rear of the crank?

I used to use oil but I now use moly grease.

I did all the work on Henrietta about three years ago and she has ploughed and worked the rotovator yet she is still tight to turn over on the crank.

Nick · Post by **Nick** » Tue Jul 20, 2010 8:59 pm

yes i did replace the crank seal, and i also put lots of engine oil in the bearings. like i said though, its just a bit tighter, and is nice and smooth, so i wonder if its just me worrying too much. when it runs first time, should i let it idle for a while and get up to temperature?

Steven B · Post by **Steven B** » Wed Jul 21, 2010 3:05 am

The short answer is NO.

The reason your engine is tight is because you have new liners and rings.

The liners have been honed and have a cross hatch file like finish. This finish is important, it "files" the rings so that they bed into the bore. While running in the rings also smooth out the hatch so that after time the bores become smooth and the rings are bedded in for a perfect fit.

During the run in in period your engine may also use a small amount of oil. This is caused by oil sitting inside the cross hatch on the liners. Only once run in can the rings fully control the amount of oil that passes them.

Another factor that causes drag on a new engine is the rope oil seal. It is crushed against the crank and also needs to bed in.

I usually do a pre-assembly test before final assembly.

I check main and big end clearances with plastiguage.

I then install the crank less oil seal and pistons less rings. I check to see how freely it turns then take it apart and start final assembly. Always oil the bearings before spinning anything.

If you use molly/graphite assembly lube (Like a black graphite grease) then you must change the oil and filter after 20 mins of running otherwise the slippery molly lube will not allow the rings to be filed by the hone and they won't bed in.

Hope this puts your mind at ease.

Steve

Nick · Post by **Nick** » Wed Jul 21, 2010 8:12 am

aha, i see, i did wonder why the liners had that cross hatch on them.
Thankyou everyone for your comments, i will keep up to date when she fires up!

Dandy Dave · Post by **Dandy Dave** » Fri Jul 23, 2010 1:55 pm

Like Alfred E. Newman's motto from Mad Magazine. What? Me worry?

Yes, I agree that you worry a little too much.

Get it running and put it under a steady medium load like disking. A friend of mine had a stone boat that he would load and pull to help break in a tractor with a fresh engine. Dandy Dave!