oil leak, on a 100-4

My car is in the shop getting a going over. I've asked them to trace down an oil leak(oil on the pavement where it is usually parked). The mechanic suspected a leak at the termination of the tach cable and is checking it. However he also said that there are "tubes" on the intake manifold and also a "vent tube" on the crankcase. He tells me that both of these are desiggned to drip oil. This doesn't sound quite right to me, but not being a mechanic and knowing that British cars are a strange breed, I can't make a judgement.
I would appreciate some info from the experts.
Thanks

Thomas,

Those little tubes coming down from the intake manifolds are to drain gas in the event the carbs flood out. There's a little plastic ball in there that gets sucked up when the engine starts (producing vacuum) and closes them off. There shouldn't be any oil coming from there.

That vent tube is another story, it is a crankcase breather (a.k.a. road draft tube) and oil will come out of there in very limited quantities.

Walt

Thomas,

Oil leaks on 100-4's are pretty normal. I have heard it said that "they are just marking their territory"

Seriously, the fours have no real oil seals on the front or rear of the crankshaft or on the front of the transmission. There is even a drain hole in the bottom of the bellhousing to keep leaked oil from flooding the clutch.

There is an aftermarket seal available for the front of the crankshaft, & a seal assembly available for the rear of the crankshaft. Installation of the rear seal requires removal of the crankshaft & some precision machining on the block & on the shaft itself.

There is supposed to be a vent pipe in the valve cover which is connected to the front air cleaner. If this vent is plugged the excess pressure in the crankcase will push more than the normal amount of oil out of the so called "seals" on the crank. Ditto for the vent tube that you mentioned if it is blocked.

Not much you can do if the leaks are no more than 10 or 20 drops at a parking. Just don't park it where oil leaks will cause trouble & remember to check oil levels in engine & transmission frequently. BTW, the shocks are "designed" to leak a bit also.

D

Hello Walt:
I really appreciate your help. I'll pass this information on to my mechanic.
Thanks,
Thomas

Hello Dave:
From what you say, I believe my car is acting normally. The oil on the pavement isn't excessive.
Thanks for helping me.
Tom

Tom,
An old saying for British Car Owners; "If it's not leaking, then it's time to check your fluids, you probably don't have any."

The tach cable connection at the engine may be a source of oil drips. I believe there was some discussion on the email list about this.
My 100, with about 1500 miles on a rebuilt engine has extremely few drips. The front 'seal' on the timing cover where the crankshaft exits the engine is a felt ring--definitely doesn't last forever. On the Larry Varley web site, there is a photo of a ring soldered on his timing cover that will hold a rubber-type seal.
see https://www.acmefluid.com.au/larry/page12.html
Your road draft tube should have no drips if the engine is in good condition.

The rear seal problem is difficult to fix, regardless of what the vendors of the aftermarket kits say. There may be some luck involved here.

What it comes down to is: There were certain things acceptable when these engines were designed 50 years ago.

My engine is almost like it was when it left the factory---small fuel leak, small exhaust leak, small oil leak...!

66bj8 and LGalper:
Thanks for your advice guys. Since the oil drips are not excessive, I don't think I've got a problem. I'll just keep an eye on the fluid levels.

Sounds like the problem is licked! My 100M leaks a few drops after a drive -- then as oil cools and thickens, no drips! There's a negligible amount lost -- and after the entire summer, the dip stick still reads Maximum. Comments that if it doesn't leak, It's out of fluids -- or it's not a Healey -- are right on!