ShopTalk Forums | Aircooled VW Tech & Restoration Help

Hi Guys, i have a 1911 type 4
New crank grind/ mains/ big ends etc
I have noticed the oil light flicker at HOT idle, a slightly higher idle speed makes it ok.
I could do with a way of increasing the idle oil pressure,
To be fair this engine with a c25 cam likes a slightly higher idle speed anyway.
What I'm going to do is change the oil pressure switch to eliminate that as a possible cause.
I do think the oil does drain back down from the oil pressure switch on switching off the engine as it takes a couple of seconds to turn the light off on re start. say half an hour.
I did check the oil pick up pipe when it down ,there was no air leaks.
The case does have the under number 1 relief valve fitted ,I haven't removed This to check anything. I believe there is a mod for this, some sort of rod spacer to close off the valve on a permanent basis.
Engine runs good , doesn't get hot...It's just this issue.
What to do
any thoughts

Standard case 0.5 mains. standard thrust cut
20/50 oil with zinc

Are you using one of those VDO pressure senders?
IIRC, they will turn the light on at around 10PSI vs. like 4PSI for the factory sender.

A mechanical gauge can tell you a lot.

EMW sells that 2nd relief valve replacement rod.

There's always thicker oil...

Well. Just removed the oil pressure switch. Its a standard style switch.
On the back of the switch it had no markings , no min psi etc. Changed it to another switch which does have psi ratings etc, The cold start up showed the light going out faster, Didn't have time to warm it up so will do that tomorrow.
I have known type 1 motors have an air lock beneath the oil switch in that part of the case ,and the removal and refit of the same switch on an engine I had stopped it happening all together .
I'm hoping for either an air lock or a copy oil switch were the light comes on at too high a pressure as you have said.
Fingers crossed.

I really don't worry about a flickering oil light at idle. There is no load at idle. And as long as the engine is in spec and in good running condition I ignore it.

what type of oil pump is fitted ?

Its a standard one. I'll do a run today, to test the new switch

well that rules out it bypassing back into the case . any idea on the condition of the pump ?

Pump is a good one , all stripped n checked . I drove it today and the light ,touch wood hasn't come on.
It's got good power for a 1911 with single weber, Runs really cool, in fact the fan housing is cool to touch after a run and gets hotter after the engine is off, so the long block heat then transfers to the fan housing , and the heat off the stainless exhaust.
Bit lumpy those C25 cams ,so gotta have the idle speed slightly higher and its better with a 12 static timing for pulling away from lights etc. I'm just gunna put some miles on it see how it goes.