Clucking Dry Sump System

[Peter Carmichael]

Tor,

 

All dry sump tanks vent to atmosphere, via a catch tank. Whether the pressure pump is internal or external should make no difference.

 

Unfortunately, there is no pressure gradient from the head to the crankcase, so there is no benefit for drainage. (Interestingly, Minister have been known to run the R500 engines on the dyno with a breathing oil filler cap.)

 

Oily,

 

I have been investigating doing away with the spring loaded tensioner, which is easy enough. This would pave the way to going to a larger belt as I would only need to get two pulleys made up rather than worry about a tensioner as well.

 

The mode of failure that I previously experienced was almost certainly down to the tensioner arrangement. I don't know whether belt growth will be a factor with a move to static tensioning, but the alternator belt seems to stay put. I reckon a combination of a slightly better belt arrangement and an early warning system is good enough.

 

Rob,

 

God knows what the original belt was, but it was as supplied by Caterham. It has now disappeared forever. A trip to Caterham parts counter has got me a correct 3-vee belt; it really is too small.

 

The 4-vee belt also came from Caterham, so I don't know quite what they think they're up to.

 

Paul,

 

A toothed belt is a strange solution to this problem. It is probably safe because it is wide. I did the maths on my degree course which showed that a poly-vee belt is vastly superior for power transmission and can cope better with shock loads - it is the correct answer to a power transmission problem. However, I'm not going to argue with an installation that evidently works.

 

I think the problem is with the size of belt, not the type of belt.

[Mike Bees]

FWIW my earlyish K dry sump system doesn't have a spring-loaded tensioner on the belt, it has the same tensioning pulley as yours (I guess) but it's manually locked in a position of your choosing to give whatever you deem to be an appropriate belt tension.

 

Mike

[Rob Walker]

Peter the Rover power steering belt is slightly bigger at 785mm thats 18mm longer than the Caterham one " If size matters ".

 

On the reliablity issue I have been advised that its not unknown for the scavenge pump pulley to work loose as its only held on by a 5mm cap allen screw, I have been advised to put a little locktite on this screw.

[Peter Carmichael]

I had a good look at the scavenge pump pulley over the weekend; I gave my gold pump a full strip down and clean.

 

I loctited the bolt and then had second thoughts. There is, as you say, no positive locking of the pulley to the shaft. In the end I went for a clean thread and a drop of oil on the thread so that any slippage stands a chance of tightening the bolt (not the other way round IYSWIM).

[Peter Carmichael]

It was more width (number of vees) rather than length that I was thinking about.

 

Mike, I am designing a tensionerless setup for the belt - no tensioner pulley at all.