Oil leak from crankcase bolt

[AustinW]

I fitted a Cymarc Crudcatcher the other week, when I removed the bolt just below the oil level sight glass there was a weep of oil from the bolt hole. Which seemed very odd, and as this was the first bolt i undid I fitted the Crudcatcher by only removing one bolt at a time and tightened them to 10Nm torque. No weeps of oil from any of the other bolts. Since then I have a small oil leak from the bolt - it is running down the thread, along the spacer to the Crudcatcher and then dropping on the floor. Not much of a leak, but they never get better by themselves do they.

There is no leak from the Cover/engine face, only along the bolt. This is very puzzling as it sort of implies the crank case is cracked or something to allow oil into the threads. Any other ideas coz I really really really don't want it to be that.

I took the crudcatcher off tonight and refitted the original bolts which do seem to have very close fitting washers, but that would be a really unusual way of keeping an engine oil tight. I will keep an eye on it.

One other thing, the dealer I got it from (Blackpool Honda) serviced it before I bought it 6 weeks ago, and seems to have overfilled the oil slightly - the sight-glass is completely full, after following the right procedure to check, although on start up the level immediately drops so I am assuming only a little overfull. There is quite often a strong smell of burnt oil which I am guessing is the crankcase breather dealing with the excess oil.

Thanks in advance for your thoughts

 

[Bendy toy]

Don't worry about the oil level. A tad high won't do any harm. Check the oil thread for insults on that subject.
The oil smell is likely to be the leak dripping on the exhaust.
Try an oil tolerant thread lock on the offending bolt.
The only sure fix is a new gasket, but it gives an excuse to have the cover powder coated. After 5 years it's likely to have corrosion seeping under stone chips. I'm guessing the crud catcher is new to the bike.


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[AustinW]

Thanks for the reply and Reassurance on the oil level. In my experience I have never heard of a bike or any engine come to that being damaged unless stupidly overfilled.

I have removed the crud catcher and refitted the original bolts. When the bike has cooled down I am going to check again. I think I will try nipping up the bolts a tad tighter than standard spec together with a bit of thread tape or something to try and seal it. Standard torque is 9nm. I will try about 12 on this bolt and about 10 on the ones either side and see what happens. If it still leaks I will try another couple of Nm's.

Cheers


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[hutchy]

This has reminded me of this Austin

When I picked up my 04 GSA I noticed a few days later that a small weep of oil around a crankcase bolt too

Anyway I got to the bottom of it, turned out pervious owner had replaced all bolts with stainless, this bolt was just a thread or two too short, replaced it with a longer bolt, torqued, and now no weep

May help, may not, just a thought

H

Edit: just be carful though that you don't go out and get a larger bolt and totally feck it

 

[AustinW]

This has reminded me of this Austin

When I picked up my 04 GSA I noticed a few days later that a small weep of oil around a crankcase bolt too

Anyway I got to the bottom of it, turned out pervious owner had replaced all bolts with stainless, this bolt was just a thread or two too short, replaced it with a longer bolt, torqued, and now no weep

May help, may not, just a thought

H

Edit: just be carful though that you don't go out and get a larger bolt and totally feck it

Thanks once I had the crud catcher on I did check and all four original bolts are identical and the same length. The thing is that there should be no oil from the engine getting into bolt hole unless it leaking through a crack or more likely the gasket is not sealing properly.

Tonight I have removed the bolt, cleaned and dried the threads in the bolt hole and on the bolt and retorqued it to 10nm. Will give it a few days and check again. If all ok I will then refit the crud catcher and check again. If just a little bit of oil a small soft washer and something on the threads should do it.


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[AustinW]

A little update. The bike went to Blackpool Honda and as predicted it was a case of "they all do that sir". They did fit a new battery and admit it looked like the crankcase cover had been removed at some point in the bikes life so could explain the leak into the threads past a damaged gasket. But as it wasn't actually leaking at the time they weren't ready to do anything. They removed some engine oil and its no longer has that whiff of oil about it - which is good.

On the suspension and damping that's where they said its fine, and after a 200 mile blast round the northern Pennines today I am inclined to agree. I let the tyres down to the proper pressure for solo use and I think I just need to get used to the size and weight of the bike and the foibles of the shaft drive. After all it couldnt be much more different to my XT660R. It definitely responds to a robust riding style and big handfuls of throttle to get it round corners. I really liked the way it went on the open roads round Teesdale and the eastern lakes. The bike was in its element. But the traction control light came on unexpectedly a couple of times on rough (not loose) surfaces under decent acceleration.

I am going to take to the nearest BMW dealer (southpprt super bikes - who supplied it and serviced it to date) for a chat and their view but overall feeling a lot happier now I have the chance for a proper ride .


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[Bendy toy]

An oiled thread torqued to the book risks being stripped. Turn it by hand until you feel the spring. It's not a cylinder head bolt so no need for absolute precision.
The thread is almost certainly leaking because the gasket is damaged inside. But no point in removing the cover just fit a copper washer with anaerobic gasket seal on either side. What can't get past the bolt head can't drop on the floor.

 

[AustinW]

An oiled thread torqued to the book risks being stripped. Turn it by hand until you feel the spring. It's not a cylinder head bolt so no need for absolute precision.
The thread is almost certainly leaking because the gasket is damaged inside. But no point in removing the cover just fit a copper washer with anaerobic gasket seal on either side. What can't get past the bolt head can't drop on the floor.

Thanks. I will do something like that. Anaerobic gasket seal - I will need to get googles help with that.


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[Bendy toy]

It's same technology as thread lock but different formulation. It won't set until air (oxygen) is excluded. Loctite 510 is very good
Ordinary thread lock either side of the washer might be enough b seal it.


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