6 Speed question
Discussion
I think this is different to the problem Daniel had, but a very slow leak coming from where the gearbox joins the engine is very common I have head. I see one or two small drops every few weeks appear under my car. Apparently this is the case with almost all cars with the 6 speed. I'm not sure if this is specific to the duratec engine.
Oil seals should last for many years and many thousands of miles. If they fail frequently, there's probably an underlying reason for it. Oil leaks in gearboxes and diffs tend be due to rapid wear of the seal as a result of contamination in the oil, or excessive wear in bearings and bushes. It is the sort of thing that would suggest an overhaul might be required.
Edited by DCL on Tuesday 6th October 09:28
DCL said:
Oil seals should last for many years and many thousands of miles. If they fail frequently, there's probably an underlying reason for it. Oil leaks in gearboxes and diffs tend be due to rapid wear of the seal as a result of contamination in the oil, or excessive wear in bearings and bushes. It is the sort of thing that would suggest an overhaul might be required.
So I should be concerned about any amount of oil appearing where the bell-housing joins the engine?Edited by DCL on Tuesday 6th October 09:28
Maybe it's time I cleaned it up and watched it more carefully.
There'll always be some - the six can run very hot and a drip on the floor is to be expected after a good run. But a puddle, or leaking when not used would be a worry.
It's also worth saying that the vent can leak some oil (particuarly if it has been over filled) and that can be confused with oil coming from the tail seal, as it will ends up in the same place. If you clean it all with brake cleaner, it's easier to spot where it is coming from.
It's also worth saying that the vent can leak some oil (particuarly if it has been over filled) and that can be confused with oil coming from the tail seal, as it will ends up in the same place. If you clean it all with brake cleaner, it's easier to spot where it is coming from.
The selector shaft passes through the casing and is sealed to the bellhousing with an 'o' ring at the front of the gearbox. I've seen leaks from there if it's fitted without a little extra RTV. On the more powerful cars, IMHO the bell housing (or bolts) can flex a bit. The primary shaft is usually OK, as is the crank.
Edited by DCL on Tuesday 6th October 13:38
DCL said:
The selector shaft passes through the casing and is sealed to the bellhousing with an 'o' ring at the front of the gearbox. I've seen leaks from there if it's fitted without a little extra RTV. On the more powerful cars, IMHO the bell housing (or bolts) can flex a bit. The primary shaft is usually OK, as is the crank.
Do these photos illustrate what you are referring to?Edited by DCL on Tuesday 6th October 13:38
https://picasaweb.google.com/118358463285944574343...
This might very well explain what I am seeing. On second inspection (just now) it looks like there may be a very small amount of oil building up where the gearbox meets the bell-housing (not where the engine meet the bell-housing as I previously said).
From the smell of it, I assume it is gearbox oil.
I remember giving the gearbox an extra squirt of oil with the oil pump 'for good measure', before quickly replacing the fill plug. So, my gearbox might be a little more full than some
I might now take the fill plug out and drain it to the exact level and see if this has an effect. In the end it is only a few drops over the last year, and nothing seemed to change over winter, so I don't think it is something serious.
Edit - that design seems like an engineering fail.
Edited by rotorwings on Tuesday 6th October 14:12
DCL said:
Oil seals should last for many years and many thousands of miles. If they fail frequently, there's probably an underlying reason for it. Oil leaks in gearboxes and diffs tend be due to rapid wear of the seal as a result of contamination in the oil, or excessive wear in bearings and bushes. It is the sort of thing that would suggest an overhaul might be required.
Reading the blog again I wonder if the problem Daniel has can be traced back to the build? He fitted the propshaft before the engine/box and had some trouble getting the box fitting to the prop. Perhaps that did for the original seal and subsequent ones are harder to fit than when building the box new?Edited by anonymous-user on Tuesday 6th October 09:28
Shropcat said:
My 6 speed leaks from the unused speedo drive which is very common according to the archives
Don't get me started! The bungs Caterham used where too deep and bottomed out on the gearing on the output shaft. That wears them through and fills your gearbox with crap for good measure. I would not run a new box now without checking the bung first, my first gearbox was sent back for this reason. Edited by DCL on Tuesday 6th October 19:26
REALIST123 said:
Reading the blog again I wonder if the problem Daniel has can be traced back to the build? He fitted the propshaft before the engine/box and had some trouble getting the box fitting to the prop. Perhaps that did for the original seal and subsequent ones are harder to fit than when building the box new?
You might be right, but if it was difficult to fit in the first place, there may be an alignment problem with the bearings in the box. That would explain the reoccurring seal failure. Reading through the blog you can forensically piece together a possible cause. Firstly he mentions fitting the gearbox speedo drive blanking bung, then we see a picture of it pressed fully home. It's possible (if it was like mine) that this is touching the output shaft teeth and grinding up a nice cocktail of steel particles that are destroying the seals and probably more. 
DCL said:
Reading through the blog you can forensically piece together a possible cause. Firstly he mentions fitting the gearbox speedo drive blanking bung, then we see a picture of it pressed fully home. It's possible (if it was like mine) that this is touching the output shaft teeth and grinding up a nice cocktail of steel particles that are destroying the seals and probably more.
I bow to your vastly greater experience! This is what caught my eye:
"As I had already installed the diff and prop shaft this made fitting the gearbox to the prop shaft a nightmare, that and the fact the R500 has a prop shaft guard, which completely restricted the movement of the prop shaft spline. We must've spent an hour with jacks, lifting, trying to move the engine that little bit further forward, back, left, right - it really didn't want to go in"
Whatever, I'll be having a look at that bung on my gearbox!
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