94-96 Van Dieman Bellhousing Rebuild

[rg2]

Gents, I'm in the process of rebuilding a 95 Van Dieman Bellhousing/Oil Tank casting and I cannot figure out (only speculate) what the purpose of the two 7/8 drilled holes in the casting and in line aft of the oil return swirl pot are for. They are directly above the aft oil tank compartment in the casing. I'm speculating they are a vent for that oil tank compartment since there is no vent hole at the top and in the interior of the oil tank compartment walls. Currently these holes were plugged with aluminum plugs. Your help and knowledge would be appreciated.

[CGOffroad]

The original design of the housing on the forward side of the internal wall is the oil tank. Aft of the wall was the overflow catch basin. If you have holes drilled through the interior wall, your car has been modified to increase the quantity of oil held in the oil tank. Then, an external catch can is needed. The holes on top and to the aft of the swirl pot were the overflows from swirl pot and into catch basin. It sounds to me like your bell housing has been modified.

[rg2]

The original design of the housing on the forward side of the internal wall is the oil tank. Aft of the wall was the overflow catch basin. If you have holes drilled through the interior wall, your car has been modified to increase the quantity of oil held in the oil tank. Then, an external catch can is needed. The holes on top and to the aft of the swirl pot were the overflows from swirl pot and into catch basin. It sounds to me like your bell housing has been modified.

I didn't realize that both compartments were not originally part of the oil tank since the forward compartment capacity is not that large and yes mine has been modified with three holes drilled between the compartments at the bottom of the wall that separates them. My question now is, shouldn't there be a small vent hole at the top of the internal wall that separates the compartments since there is oil now being drawn from the rear compartment and the 7/8 holes drilled above the rear compartment are now plugged?

[BeerBudgetRacing]

Mine has more that just the bottom holes...

Attachment 89531

I've also got some smaller 1/4in holes as near the bottom as someone could drill.

[rg2]

Mine has more that just the bottom holes...

That appears to makes sense to have at least one hole drilled at the top between the compartments otherwise wouldn't a vacuum be created in the rear compartment when oil was being drawn from the oil tank by the oil pump if there was no vent between them?

[BeerBudgetRacing]

That appears to makes sense to have at least one hole drilled at the top between the compartments otherwise wouldn't a vacuum be created in the rear compartment when oil was being drawn from the oil tank by the oil pump if there was no vent between them?

I think it just wouldn't fill up beyond the lower holes.

Smaller holes are probably enough.

[rg2]

I think it just wouldn't fill up beyond the lower holes.

Smaller holes are probably enough.

I agree. I've drilled two 5/16 holes near the top of the internal wall separating the oil tank compartments. That should take care of any oil filling/oil transfer and potential vacuum issues. My belief is that the aft oil tank compartment could NOT have functioned properly for the previous owner without an internal vent hole unless the factory drilled vent holes on the top of the casting were utilized. Hopefully this thread will bring this potential issue to the attention of other Van Dieman owners. Thanks to everyone who chimed in.

[Captain]

Not to hijack this thread, but since it is about bellhousings...

I have seen comments about a Mag LD200 bell housing/oil tank. What is the weight savings with this? Any idea if it sold anymore?

Thanks
Jim

[Rick Kirchner]

Never have seen one for a pre-97 car.