Saturday, December 26, 2015

Rough Journal Entry!

Well folks, it's been a while, but finally after a month or so of waiting, the parts I sent off for balancing were ready for collection. Fantastic I thought, I now can crack on at long last with rebuilding the engine once again. Of course though, being a 'have a go hooligan', nothing ever seems to go smoothly...

Regular readers, will know that for the last year or so I've been slowly building my very first engine. After it was finally complete and installed, I felt flush with pride which lasted until I turned the key and realised that I had created a rattily, horrible rumble monster.

This was due mostly to the fact that nearly all the parts were either new or from different engines and were not balanced together. So, out came the engine again and it was stripped down so the crank, flywheel and pistons could be sent off to be professionally balanced.


Pistons
Now the parts are back, the first and easiest thing to check is that the pistons and conrods are all the same weight as each other.



Thankfully they were all weighing in at 970 grams instead of the randomness they were in this post here. Hurray, that's a big tick and one step closer to getting the engine built.


Flywheel
Measuring the pistons was easy, but the only way I know how to test the crank is to spin it up and the only way to do that is to build the engine. I'm pretty sure it will be fine though as I can see new bits of metal cut out of the flywheel where it was balanced.



When I picked everything up, the flywheel was attached to the crank as you can see in the first picture. I was concerned that if I separated the two parts without any thought, I might loose their relative positions to each other and run the risk of reassembling them at a different angle.

I have seen on TV programs that there is usually a blob of paint on the parts that lines everything up and when you separate the flywheel and crank, as long as you line up the blobs, everything is back where it is meant to be.

As I couldn't find any such marking on my flywheel or the crank, I decided not to separate them until I had some way of making sure I know how to reassemble them again and then it dawned on me when I removed the large retaining bolt.



As you can see from the picture above there is an offset cutout that is just left of centre and locates the flywheel to the crank. Because of this offset, there is only ever one way that the flywheel will ever fit on the crank. Phew, that's that sorted! I can now go ahead and separate the two parts and to do that, out came my handy 'home made' clutch puller which didn't let me down.



Rebuilding
Once the crank was free, I could set about cleaning the journals. I used carb cleaner as it does a very good job of blasting all the contamination off the surface and also through the oil holes. I also use a new nitrile glove to 'polish' the surface of the journals. The reason I use a glove is that it leaves behind no traces of lint or specks of dust that you would get if you used a cloth.



Once both the crank and the block was spotless, I popped out a new set of bearings and pushed them into the block and lubed them up.



In goes the crank...



... with lubed up bearings in the caps.



Once all the caps were finger tight, I nipped them all up and checked the crank rotation which did not feel good at all. In fact, moving it back and forth by hand, it felt decidedly ropey. So off came the caps and out came the crank to reveal that the nice new bearings I had just fitter were being scratched to ribbons!!!!!!!!



AAAGGGGHHH!!! I thought, that's not the best start! After a few breaths, I cleaned the lube off the corresponding crank journal and found the reason for the problem. On the journal there were a few scratches, but the real problem was a rough band circling the journal. This band lined up with the main damage on the bearing.



When I examined the crank further, there was another such band further along.


My suspicion is that these were caused by rollers that were in contact with the crank during the balancing process. Although I don't know this for certain, I do know that they weren't like that when I sent it. Here is a before photo. Thank goodness for photos!!



If only I had checked the journals before I started, I wouldn't have knackered the bearing!! Oh, you live and learn I guess.

So now I have the job of taking everything back to the machine shop and explaining the problem and hoping that they are willing to rectify it. I would love them to say that they will re-polish the crank journals for me and would be ecstatic if they offered new bearings, but that may be pushing it a bit, time will tell.

As it's the bit between Christmas and New Year at the moment, almost everything is closed and machine shops are no exception, so I'll have to wait until January 4th 2016 before I can do anything, so let's wait until then and see what happens.



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