Morning everyone, I am stripping down my Darmah engine and have reached a problem. Having got the Primary Gear off I thought it would be simple enough to split the cases but it looks like I have a Bush stuck on the Crankshaft (26 and 27 below). I have been using a rubber mallet on the end of the crank as per the Manual to no avail - the Bush will not move. I have tried heating with a blow torch (hence bluing) and freezing. I have removed all the engine bolts/gear indicator cam and rotated the kickstart - there is daylight between the cases all round and I can see the bearings pulling out in the opposite case. There are no visible signs of the Bush having had a seizure or any scoring. I'm kind of hoping I've missed something obvious - and suggestions out there? Thanks in advance.
Use a dremel type grinder and grind the bush longitudinally until you are nearly through to the crankshaft. You should be able to split it and it should pull off. Be very careful not to go right through, the bush will change colour as it gets thinner where you are grinding.
Thanks for the advice. On the plus side - with a combination of careful grinding, heating and levering, I have finally removed the bearing! On the down side - the crank is still solid inside Main Bearing. I have clumped the end of crank as hard as I dare. I'm going to try heating the bearing inner only unless someone has a better idea?
Is this stopping you seperating the cases? If so i dont understand why that would be. Its been a long time since i've done this kind of thing and i may well have missed a crucial detail. If you have seperated the cases then the state of the main bearing should be obvious. This is why i think perhaps you cannot for some forgotten reason. In either scenario the bearing is going to get replaced anyway isn't it so a little more violence is appropriate. Good luck and lets see and hear the next chapter.
Hi there, thanks for your reply. the issue I now have is the Crankshaft is seized inside the Main Bearing and preventing the cases from parting. The Workshop manual indicates I should be able to separate the cases by 'lightly tapping' on the end of the crank. This doesn't work - and I've been as forceful as I dare. As far as I can see my only option is the try and heat the left case to release the main bearing and crank as one - then worry about getting the bearing off once separated. So far there has been no sign of movement from the Main Bearing in this LH Casing.
I would use an electric hot air gun on the area around the bearing location on one crankcase, then like you say remove the bearing and crank together. After that you can get all medieval on the bearing with the trusty dremel. I wouldnt use a naked flame for heating as it can be a bit savage.
Good idea - I hadn't thought of a heat gun. It might keep the shed warm as well. I'll let you know what happens. Thanks
Depending on your domestic situation you could put the cases(if they fit) in the oven. I have done this with an old triumph engine which i think is probably a little smaller than the bevel. It worked perfectly by the way. You can control the temperature for a slow but low heat and dont leave it too long. The ali expands more than the steel, especially if you time it correctly and i would be amazed if the bearing doesn't fall out with a decent tap. The grief you get for doing this might mean that buying a 1098s is a better solution long term !
Success! - with careful use of a blowtorch and a drift I managed to separate the cases with the bearing still on the crank. Now the fun begins..
