It may be a silicon sealant, I've attached a photo of the top of the case where I've just taken a bit off. It has a bit of stretch in it but less than a bathroom type of sealant. I'm thinking this baby needs to be taken apart, any thoughts on that and the bearing movement?
Do you have the time, tools, knowledge, commitment? Yes. Do it it’s always better to get things right. No. Pay someone else or Replace seal put it back and get a oil catcher tray!
I'd suggest someone has tried to rectify an oil leak by cleaning up the case and smeared sealer of some description along the join , rather than strip it down and doing a proper job ... Just my tuppenceworth.. Sent from my SM-G960F using Tapatalk
In answer to your questions......yes, probably, hopefully and absolutely.... with a little help from my virtual friends
1) The cap at the bottom of the engine is supposed to be there, but the sealant everywhere isn’t. The bolt above the cap looks to be too short. 2) 2mm main bearing clearance is about 10 times what it should be – rebuild time. 3)You’ve done the easy bit (it’s only 4 bolts), you get the certificate once you’ve rebuilt the engine and refitted it.
If you're going to dismantle it, the first job is to buy a load of zip lock plastic bags and a sharpie. Photograph, bag and tag EVERYTHING. You can thank me later when you're reassembling it
Thanks. Can I just check something. What would allow a bearing to have movement like mine which is side to side, i.e. like the hand of a clock. There is no movement front to back. I thought I might be a bit premature about the certificate.
Knackered bearing shells? Beaten case webs? @77 Westy will know. Might also be that half pound of bath sealant they've used on the case stopping the case halves closing up properly.
The sealant looks like a silicone type automotive sealer possibly 3 bond. It works well on modern engine sumps etc but no good for aircooled engine cases. As mentioned you want to be using Curil T when you reassemble.
The small dowel circled should stop it rotating... If the crank has taken a pounding the hole it sits in can get a bit oval and the pin wobbles.. letting the bearing move Sent from my SM-T580 using Tapatalk
@Chrisd - I’m looking again at the thin bead of sealant on the upper half of the case line above the end of the shaft. It looks like it’s been squished out when the halves were bolted together - it’s the wrong type of sealant - far too thick an gooey - Permatex for example that many folk use is more like a paint. May be worth splitting the case to reseal it and take a look at why the flywheel-end main bearing is able to rotate through a few degrees. It would be good to hear what the resident engine experts think....
That^. Take it apart, see why the bearings moving, sort that and anything else, put it back together. The dowel is just to locate the bearing, not to stop it turning. Crush is for that and as has been said, the bearings will not be held properly with that thick sealant holding the case halves apart.
At a guess.. dowel either missing and only case squeezing holding bearing to the limit you can move or before the last rebuild it seized on that bearing and pushed the dowel into the case making the hole oval.. If the oil holes dont line up that might add to your oil problem too ? .. and I love a rebuild thread so I'm saying what else you got planned this winter get it cracked open Sent from my SM-T580 using Tapatalk
So if the crush isn't enough to hold it might need a line bore to the next bearing size up I assume...? ..edit unless removing the thick layer of black etc sealant let's it close up and hold... I'd be JBwelding the dowel hole up a bit though.. but I'm a bit bodgy Sent from my SM-T580 using Tapatalk
If the dowel hole has been ovaled, what’s the remedy? Drill a fresh hole on the bearing and in the bearing seat?
I'll keep you all informed with my progress. I was hoping it was a simple oil seal as the engine runs well other than creating an Exxon Valdez wherever I park Zip lock bags at the ready and music playing, engine tear down begins.... As an aside, that cam plug looks odd to my untrained eyes, should it be flush with the edge of the case?
Okay, I misunderstood when you said side to side movement. If you can rotate the bearing in the case it’s obviously loose – and it shouldn’t be. When the two case halves are bolted together the bearing should be ‘crushed’ and it should be impossible to rotate. As zedders said the dowel is simply to locate the bearing in the correct position. Whoever built the engine has used far too much sealant and that has probably prevented the casing halves from coming together, resulting in the loose bearing. The oil leaks are a minor problem, the bigger problem now is that the casing will (probably) be oversize and will need to be machined. And the case has already been mistreated with some of it broken off. If it were mine, I’d buy another case and use the good bits – if there are any – from the damaged case to make a good one. You’re not going to fix any of the problems without dismantling the engine.
