oil leak from gearbox area

[Alan Reeves]

I have a small drip of oil every time I use the car.

 

New build Duratech 175. Leak drops from the lowest point, to the ground, of the box just set back from where it goes into the bell housing.

 

I have touched all around and cannot identify and being so small but seriously painful.

 

Any ideas before I go to CC

 

Alan

[Paul Deslandes]

 

 

Alan, did you build the car yourself and, if so, did you assemble the gearbox to the bellhousing using the paper gasket between the two? There should also be a smear of sealant on both faces of the gasket towards the top around the large round hole that the selector shaft runs through, otherwise it can leak and the g/b oil runs down as you describe. There are other possibilities but this is the most likely. Also check that the g/box lid bolts are done up tight enough. Not too tight as this can distort the lid which then leaks as the gasket can't seal.

 

Paul

[sevenmad]

Also check that the filler plug is done up! My first leak was as you describe and despite thinking I done the filler plug up tightly during the build, I found it was virtually out at 1000 miles.

[Alan Reeves]

Home build, had to take the eng/box out due the hydraulics in the bell housing failed, fortunately before the whole of the engine bay was completed ! Therefore the joint has been back together twice and could well be the issue and there was no mention of having to put a sealer in when assembling ( Im no mechanic for sure ).

 

Now you are going to tell me I have to take the eng/box out again at which point I jump.

 

alan

[Alan Reeves]

Oh let it be the filler plug.

[Paul Deslandes]

Let's hope it is the filler plug. I'm not sure where the sealant wisdom came from, I can't find it in my old build manual, but I've always done it and not had the problem.

[Paul Deslandes]

Just checked later build manual which advises application of sealant to gasket between gearbox and bellhousing. See section 8 page 2.

 

I knew I'd seen it somewhere.

[Michael H]

Hi all

I have exactly the same problem on my new-build Duratec 175. I've checked the drain plug is completely tight, and I did put sealant goo (not a paper gasket) between the box & bell-housing (although not between bell-housing and engine). I'm getting a couple of drips after a run - not sure if it engine or gearbox oil, not enough to worry about, but just an irritating...

 

 

Mike

[Paul Deslandes]

You shouldn't seal between the bellhousing and the engine or you'll never get it off again 😳

 

Maybe a paper gasket isn't included these days but sealant certainly should be applied around the selector rod hole as described previously.

 

Before you start ripping it all apart it would be worth cleaning down the areas where oil could potentially be getting out and then inspecting for a leak and the source after a short run. The usual suspects are the gearbox rear extension seal, where the pro shaft goes in, selector rod hole, drain plug, gearbox lid screws/gasket, speedo drive (although this is probably different on newer cars). Can you definitely see that the oil is coming from the gearbox/bellhousing interface?

 

The only other sources of gearbox leaks that I can think of are the crb extension tube on the front of the gearbox, which has a seal in it to seal the input shaft, and a gasket to the box casing, and the layshaft support spigot that is bolted into the front of the box and should be sealed and the three bolts loctited when it was assembled. None of these should be a problem on a new car as its all pre-built.

 

Is it definitely gearbox oil and not engine oil, or even hydraulic fluid if you have dry sump and hydraulic clutch release? You can usually tell by the smell.

 

Paul

[Alan Reeves]

Paul thanks for the very comprehensive list of things to check, dont suppose you live nearby...it would be quicker and for me and of course I wouldnt get dirty....( joking of course).

 

Will let you all know what the answer is and hopefully bget it fixed.

 

Michael do let me know of you find your leak,

 

alan

[jeffi]

Alan - this type of leak is very common and is usually (hopefully!) nothing to worry about. I've had one since last June when my SV150 went on the road. I get one or two drips on the garage floor after a blat. I initially lost a few night's sleep worrying about having to hoist the whole lot out again. There are quite a few other posts about this. In the end I thought I'd leave it and resolve in a few years when I do the clutch. I've checked the oil level since and it hasn't gone down noticeably, so it's not a significant loss of oil. I thought my leak was from one of the pre-fitted banking plates on the side of the box towards the top, but the gear shift interference coupling sounds a likely source now - I didn't seal that as it was a somewhat tight fit, but with hindsight I should have. This is an easier area to check without getting the engine/box out, just have to remove the tunnel cover. It's funny how its nice getting the engine in the first time but the idea of taking it all out again for a minor leak is not a nice thought!

[Alan Reeves]

Thanks and will get at it ,

[wjblundell]

Hi Alan, they all seem to do this reading other posts. My 2010 new build drips a tiny amount after each blat from the gear box / shaft oil seal. 🙆🏻 I know it's really annoying after you take such care building it up, but personally I'm leaving it for the time being and may consider a fix during the winter. I just want to drive it now.

If you do go to CC, I'd be interested to hear their response.

Bill

[Alan Reeves]

I was under it today trying to isolate where it comes from, it is very small and not an issue with consumption/loss in total...but I really cant identify the area but I do have a feeling on that seal. definately not taking the lot out.

 

T a

[lavena]

Same issue, same engine - Duratech 175.

 

Seems to come from the RHS of the gearbox (looking towards the front). I only found this by cleaning it as best as possible then feeling after a couple of days.

 

Still trying to find where the source is.

 

Andy

[Alan Reeves]

its going to CC for first service tomorrow, will let you know what they find

[jonboylaw]

Clean the outside of the casing thoroughly and then use dry kitchen roll or toilet paper stuffed down the sides and back. After a day or so take it out carefully and where you see the oil on the paper, there is your leak source.

 

Edited by - jonboylaw on 14 Jun 2011 11:05:19

[paul jacobs]

Sounds as if it could be coming from the 5th gear stop plate on the side of the box. This is a little plate of about 2" x half and inch and will only let oil out after a bit of a run, but not whilst at rest. Almost impossible to fix whilst the g/b is in the car sadly.

 

Best of luck with it

[Paul Deslandes]

There's no excuse for a new box to leak from the 5th gear plate as it should have been sealed properly by the manufacturer. Its easy enough to do with the box out, pita though that will be. If you do decide to do it yourself, its position is critical to 5th gear selection so mark it carefully before undoing the bolts, applying sealant around the mating face and re-bolting on.

 

I would definitely talk to Caterham if this proves to be the cause to see if they'll fix it under warranty.

[Alan Reeves]

CC believe its between the box and the bellhousing ? and have resealed?

I have not yet got the paper out to do the test and am loosing the will to....

 

alan

 

oh that apart it is going well and I have plenty of grins

[Paul Deslandes]

As its only a weep, irritating though it is, drive it like you stole it for the summer and then get CC to fix it if its still a problem over the winter. At least you've registered the fault with them and it'll still be under warranty.

 

Max the enjoyment while you can.

 

Paul

[paul jacobs]

'its position is critical to 5th gear selection so mark it carefully before undoing the bolts' This is true, but it's not that difficult to sort it out [with the box out of the car] before you bolt it back in. A good bit of advice though, if this proves to be the fault.

[JimD]

Built my Duratec 175 with type 9 five speed box and had a small oil leak between box and bellhousing. Removed engine and found it to be from the gearchange rod which drags throught the oil into the blind hole in the bellhousing. This gets hydrauliced by the rod and squishes back into gearbox or if your unlucky, across the gasket face which is only about 2mm wide due to the deep chamfer. It then drips from the bottom of the gearbox. I cured it by having 2mm machined off the bell housing face to increase the width of the gasket face to about 4mm. Reassembled it with gasket sealant around this area and 2000 miles later all OK. What I also did was change the gearbox internals from the standard wide ratio box as supplied by CC to the BGH heavy duty long first. Not an easy DIY job but well worth while.

[Alan Reeves]

Well it still has the tiniest drip after CC put some sealant areoud the area and I have decided to ignore until the winter and a few miles have been put on it.

 

What is normally attached to this engine when fitted to a Ford car ? They would not accept any form of leak whilst we appear to.

 

What is a type 9 gearbox, is that what I have....

 

Thanks for the additional info,

 

alan

[Paul Deslandes]

The Ford 5-speed type 9 is what is fitted to all 7s since the early 90s, and probably before that, apart from Caterham's own 6 speed.

 

Increasing the area of the mating interface is an interesting and drastic way of solving the problem. I'm sure my old Vx bellhousing has more than a 2mm width land at the top. Perhaps the bellhousings produced to mate the newer engines need looking at by CC. Did you ask them the question JimD?