• Welcome to the forum website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Online Forum Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this forum website.

    If you have previously registered to use this forum website, you should log in now. CLICK HERE.

    If you have never registered to use this forum website before, please CLICK HERE.

Migration of oil

Albervin

Well Known and Active Forum Website User
VOC Member
Oil seems to be migrating from gearbox to engine of my Rapide. After 14 years this is the first hiccough since a rebuild and constant use (albeit not a massive mileage). Also, the oil remaing in the gearbox is quite discoloured after a relatively low mileage. New seals are in the process of being fitted and except for PD26 they were in OK condition. PD21 had marks that indicated a less than perfect fit in G24 but nothing catastrophic. None of this seems to explain the badly discoloured gearbox oil. Suggestion please.
 

timetraveller

Well Known and Active Forum Website User
VOC Member
Why do you think that the oil is going from the gearbox to the engine? I would expect discoloured gearbox oil to be a sign of oil going the other way, i.e. engine to gearbox. Is the oil tank filling up and the oil level in the gearbox going down? A typical scenario is engine oil going into the primary chain case through the drive side main bearings and filling that up to the extent that either it blows out behind the dynamo drive or somehow gets past poor sealing into the gearbox. I would smell the oil in the gearbox and if it smells like used engine oil then that is probably what it is. No need at this stage for finding someone to do a chemical analysis. Your nose is relatively good at that. If it does not smell like used engine oil then it sounds like something in the gearbox is getting so hot that it is carbonising the oil and that is not good news. Did you try draining the gearbox oil and looking for particle in it? A magnet will quickly let you know whether they are steel or something else (ali or bronze). Good luck with it.
 
Last edited by a moderator:

nkt267

Well Known and Active Forum Website User
VOC Member
I know of a twin owner that had oil migrating into his gearbox from the crankcase joint..I think he ended up painting a sealant,possibly meant for Royal Enfields, inside the gearbox..John
 

Albervin

Well Known and Active Forum Website User
VOC Member
The oil level in the oil tank is going up and the gearbox level is going down. The old gearbox oil does not smell the same as the old engine oil. There was black residue on the gearbox drain plug but no
sign of bronze or steel in the oil. When seals are replaced I will change the engine oil and use some Penrite Enduro in the engine and Penrite Small Engine 20/50 in the gearbox.
 

timetraveller

Well Known and Active Forum Website User
VOC Member
O.K. Well here is one scenario but I hope that I am wrong (it would not be the first time). A leak has developed between the two crankcase halves or the castings have become porous. This would have to be at the front of the gearbox. If the leak, which must be very slow, is at a low level then oil is going from the gearbox into the catchment volume behind the flywheels where oil is flung by the flywheels before being sucked into the return side of the pump. This would then become part of the general engine oil circulation. The discolouration of the gearbox oil would then have to be caused by some of the engine oil which is left in that catchment leaking back when the engine is stationary. In principle the catchment should be empty but perhaps never completely. If the leak is above that level then it almost certainly has to be not much higher as not much further up there is the tunnel which is there to take a left hand kick starter. Oil at that level would probably find some other way out rather than go through two sealed faces and into the engine part of the crankcase. If the leak was above that tunnel then it could only mean that oil splash is getting at the leak, not the stationary oil when everything is just sitting there. A higher leak would also make it difficult for engine oil to get back into the gearbox to cause the discolouration. I can think of a test but it would be a pain to do. Remove the end plug from the oil pump and then rotate the engine so that the oil pump plunger is leaving the passage way from the catchment to the pump open. Then put lots of clean oil into the gearbox and wait to see if it starts to leak out of the rear of the oil pump. You might be able to speed up the test by applying a small amount of excess air pressure into the gearbox via the filler hole. If oil does start to show up then you know you have a leak and at what level. Unfortunately if it does not leak through that might just mean that the leak is only there when the engine is hot. Its a new one on me but there are people in the Club who have worked on far more engines than me so perhaps they can help out. If it turns out to be none of the above then we are all going to learn something new about Vins. Good luck.
 

Albervin

Well Known and Active Forum Website User
VOC Member
I fear you are correct with your diagnosis. The amount of oil "missing" from the gearbox was 150ml while the excess in the UFM was 140ml. Oh well, 14 years after the last rebuild and while everything else is working as it should, this is something that needs a proper fix. At least, if history repeats, this will take me close to my end of riding a Vincent twin. It will then be time to stick to Comets or, dare I say it, my RD350. Once again Magnetoman, a succinct and technical response that directly addressed the question asked.
 

Peter Holmes

Well Known and Active Forum Website User
VOC Member
I fear you are correct with your diagnosis. The amount of oil "missing" from the gearbox was 150ml while the excess in the UFM was 140ml. Oh well, 14 years after the last rebuild and while everything else is working as it should, this is something that needs a proper fix. At least, if history repeats, this will take me close to my end of riding a Vincent twin. It will then be time to stick to Comets or, dare I say it, my RD350. Once again Magnetoman, a succinct and technical response that directly addressed the question asked.
Magnetoman?
 

Bill Thomas

Well Known and Active Forum Website User
VOC Member
Hello Albervin, I know we don't agree on much, But here goes, You don't say how long it takes for this to happen, I have said befor with these old bikes we should check All the oils every trip or week or so, It does not take long ! You can suck a bit out the tank, You don't say what oil you use in the gearbox, My Twins like 90 oil, It may slow your trouble down a bit ?. Unless the problem is realy bad, I would not spend a lot of time and money. Good Luck, Bill.
 

timetraveller

Well Known and Active Forum Website User
VOC Member
I did have another thought that might help out in the short term. A few years ago Dick Sherwin had a twin engine/gearbox unit professionally rebuilt. After putting it back into the Knight frame and adding on a sidecar it was found that there was an oil leak from the joint at the base of the gearbox on the centre line. We successively tightened up the studs holding the two crankcase halves together around the rear over several days and several heating cooling cycles. It worked for quite a while before the unit had to come apart for other reasons. It might just keep you going until you are ready for a major job.
 

Albervin

Well Known and Active Forum Website User
VOC Member
Thanks and sorry TT. I just had a senior's moment :) Did the same a couple of months ago. Last month I took off the gearbox cover and went over all the nuts, bolts and screws. Only marginal as all except one nut, G72, were tight. Deep down I thought the problem was a separation of the halves but I was in denial. Bill, I appreciate your input. Whether we agree on other things or not shouldn't be an impediment to assist one another. I have been using the same oils for years and noticed a rise in UFM oil levels (with occasional messy outcomes) last year. After years of trouble free riding I was a bit blasé and put it down to a lapse in correct maintenance. I do a major oil change twice a year and it was at the last change I noticed the dirty gearbox oil and depleted volume. I will be more attentive in future.
 
Warning! This thread is more than 9yrs ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.
Top