TR4/4A Oil drain hole from rear crank seal/rear main cap

[TuffTR250]

The oil drain hole in the main bearing cap in the TR4 engine in my TR3 is very small and it seems to me that this hole is not large enough to adequately drain the oil from the rear crank seal assembly tossed there by the crankshaft thrower grooves. I have attached a picture showing the very small hole in the tube which acts as the drain. In the picture it is just above the large pipe. Should I drill out this small hole in the rear main bearing cap so the oil would drain out better? Thanks!

Regards,
Bob

 

[TR4nut]

Bob-

I wouldn't touch the smaller drain hole. The large tube is actually the main drain there while the engine is running - my guess is the little tube is for draining any small amount of oil out when the car is shut down. A common practice to help drain is to add some larger drain holes - Mark Macy has a good writeup:
https://www.macysgarage.com/myweb6/Rear_seals.htm

I did this on two engines I rebuilt, no problems but not sure it helped much either.

I've also gone to the new design seal by Christian Marx, sold in the use by Joe Alexander, Roadster Factory, etc. Chris has a good writeup of the install of his seal:
https://www.tr4-racing.de/download/splitseal.pdf

I think when Chris first came up with the design, he also showed drilling extra drain holes in the rear cap - but has since eliminated that step. My next rebuild, I'm staying with the new seal design and leaving the cap alone.

 

[TomMull]

TR4nut is completely correct. If you look on the other side of that small hole, you will find very little room for enlarging. Tom

 

[TuffTR250]

Thanks for the information!
Regards,
Bob