Help with Leaky Van Diemen Oil Tank

[David Ferguson]

So my new Van Diemen Sports 2000 started leaking as soon as I put oil in the tank. The rear of this car uses the same tank/bellhousing found on the 94-96 F2000 cars (perhaps later years, but at least these).

The oil is escaping from the tank through the tube that the transmission input shaft runs through. The result is dumping oil on the clutch and causing it to slip!

It doesn't seem to be dropping much oil while running, only when parked, or transported in the trailer. It might be worse as the car is jacked up at one end.

I've removed the tank, and unbolted the LD200 transmission. There is an aluminum plate that forms the back of the tank and is held in place by the transmission. This plate is relieved for some o-rings -- one is installed around the perimeter, and one around the input shaft tube. The front of the transmission also has an o-ring around the input shaft tube.

All of these O-rings have also been sealed with clear silicon. I image that this is the root of the problem -- it seems like with the proper O-ring, silicon wouldn't be needed -- or without O-rings you could just use silicon -- I suspect that doing both prevents either from doing their job effectively.

It also possible that I've got a leaky casting -- I was going to try a leakdown test to determine if this was happening.

What's the best solution to prevent oil tank leaks on these cars? The O-rings supplied (.100" rubber diameter), seem small for the grooves (.085d x .145w). Do folks use a different size O-ring? A different silicon? Or alternate sealing methods?

[R. Pare]

The groove is the correct dimensions for that x-section seal. That will give about 15% squeeze, and 80% fill. Using both silicone and the o-ring is usually not a problem - I've done that for years on various things.

The best silicone can be had at various places dirt cheap. It's GE silicone made by DAP, and comes in chaulking gun tubes for less than $5. Use the Aluminium colored stuff - don't know why, but it is the strongest by far.

I've only seen that VD setup once, so my memory may not be spot-on in the following:

Check the tube for cracks or porosity. That's a long run for the metal to flow when casting that thing, and I'd expect that porosity or "cold pour" spots would be easy to get. You can check this by pluging one end of the tube, setting the bellhousing with the still-open end of the tube upright, and filling the tube with water.

Check that the end plates are staying sealed when the trans is bolted up. Easiest way to do that is to seal it all up dismounted from the car, and pour oil in it. If it doesn't leak then, but does after bolting up the trans, look to see that the tube is centered correctly and isn't being shifted when the tranny is being fit in place.

Good luck!

[David Ferguson]

You nailed it Richard -- it was a casting flaw in the tube. After everything was cleaned up, and I looked real closely, I saw a section that looked like folded up yarn. It had small cracks running through it. I confirmed this by sealing the tank up and connecting the shop vac to create a vacuum in the tank. I then turned the casting so the flaw was on the bottom of the tube, and sprayed brake cleaner on it.

It was sucked into the crack immediately!

After doing that a few times (to remove residual oil), and allowing to dry, I have applied epoxy to the affected area -- and I sucked that into the flaw using the vac as well.

Tomorrow, I'll epoxy the inside of the tank in the area of the flaw.

Thanks for confirming the o-ring/groove size is correct. I guess I'll use silicon when I do the final assembly, I'm afraid if I don't, I'll be taking it all apart next weekend!

[R. Pare]

If I remember correctly, that tank only held something like 3 quarts of oil - a bitt too little for my taste and peace of mind. You might want to talk with someone like Sandy at QC or JJ to see what, if anything, was done to give a bit more capacity.

I hope that you were able to thoroughly clean the bad spot with brake cleaner or acetone before applying the epoxy, 'cause if not, there WILL be a path left for the oil to pass thru. I'd probably let the first stuff set up, then thoroughly sand & rough up the surface and apply another top coat. Most likely you'll have to repair this at least once a year.

Anothe possible way to repair it permanently would be to get a decent machine shop to bore out the tube ID a bit and insert a new tube with seals between the two.

Quite frankly, VD should replace the tank free of charge.

[David Ferguson]

That tank originally had two separate compartments, with one to be used as an overflow/catch tank. What Van Diemen is doing these days is drilling holes betwen the two sides, effective adding about 1.5 qts to the capacity. My car took 5-6 qts of oil, so I think I'm OK there.

My use of the vacuum did pull epoxy through the void, I could see a couple of small pin-head sized spots where it came through to the inside.

[Rick Kirchner]

David - I had a lot of trouble geting the plate to sandwitch evenly side-to-side when installing the bell to the tranny. Primus told me to ditch the long perimeter seal and just goop it up. It's worked flawlessly ever since.

Same goes for the cleanout plate on the bottom.

[Tim Reed]

I agree with Rick in the post above. I just redid mine a short time ago and when I remove the cleanout plate, there was an o-ring, in addition to "goop". I decided that both were there for a good reason, so I put the plate back using both and haven't had any leaks.

TDR

[David Ferguson]

Thanks for the replies. This is just the kind of experience sharing I was hoping for!