Oil light switch leaking again???

malpaslane · 04-09-2014, 06:55 AM

Hi guys,

i'm looking for some help on a leaking oil light switch on my 1975 2.7, engine was rebuilt for an unknown reason back in 1976-1977 and then covered 130,000 miles untill i rebuilt it about a year ago.

The problem started after i rebuilt the engine about a year ago , i had no problems with leaks before i rebuilt it, all was good for awhile , then i started to notice an oil leak , which got slowly worst and worst, i took the engine out again checked all gaskets and seals and the oil light switch seemed to be the problem, so i changed it and put the engine back , again all was ok for awhile and then the leak started again, i ve taken the engine back out and it looks like it's the switch again.....

One the questions i want to ask is , could this be anything to do with the oil bypass modification and the new style pressure pistons and springs i put in it at the rebulid,
the reason why i ask this is because when i was rebuilding the engine i asked the company that did the head studs for me and a porsche engine builder over here in the uk to see if the modification had been done and they both said yes , i asked that because when i had taken the engine apart the old style pressure pistons and springs were fitted in it and i wasn't sure weather it was done or not, i had no problems with oil presure before the rebuild with the old style pistons or with the oil presure after the rebuild with the new style pistons.

Now i'm confused.......has the mod been done , what pistons and springs should i be using in engine and is this anything to do with why my oil light switch seems to be the cause of my leaking problem all the time.

Before i took the engine out this time, if engine was running and hot you could see the oil running out of the engine and making a puddle of oil, it did this last time and on fitting a new switch the leak stops and then starts up again after afew runs .

Any help and advice would be great...

afterburn 549 · 04-09-2014, 02:41 PM

Get a new switch give it a shot of brake clean, mix up some epoxy and stuff it in the crimp area.
And no the oil by pass will have nothing to do with it.

malpaslane · 04-12-2014, 11:56 AM

Thanks for the info, but what about pressure relief pistons?, if I don't have the bypass modification done, is it alright to use the new style pistons in the engine?

Thanks again

afterburn 549 · 12:45 PM

That i do not know.......
If you have the oil mod done ( recommended ) the correct oil pistons in proper holes...I would say its a funk switch.
Is your oil pressure ok?

malpaslane · 04-13-2014, 01:13 AM

Oil pressure seems fine, but this is the second switch Since the rebuild and it hasn't done that much mileage, the switch that came out before the rebuild had never been a problem and I had owned the car for 8 years before I rebuilt the engine, the old style pistons have been in the engine for all that time to with no problems and from looking at the paperwork and history that came with the car, no engine work has been done since 1976, but since the rebuild and using the new style pistons I have oil leak problems.

afterburn 549 · 04-13-2014, 02:32 AM

Ok, i guess I will ask, what is your O.P.?? hot cold do you see a reaction on your guage as you come up through RPM?

malpaslane · 04-13-2014, 11:14 AM

Thanks for taking the time to answer these questions,the O P cold is about 50 - 60 on the gauge on start up, this settles down to just under 20 when warm at tick over, the gauge does react to Rpm, which is about 1bar per 1000 Rpm when warm

afterburn 549 · 04-13-2014, 11:21 AM

I certainly do not know everything...but my guess is if the O.P. was so high as to blow the switch, i think you would blow the cooler too.....The switch is a very small area...it takes more pressure per inch to do damage

Walt Fricke · 04-13-2014, 04:10 PM

Switches aren't all that expensive, are they? Just put in a new one (after doing the suggested epoxy reinforcement) and see if that does it.

Or put back in the old one which didn't leak, if you still have it. I'm not wont to opine that everything nowadays is worse than it was, but sometimes that seems to be the case with some parts - hydraulic brake light switches for certain models come to mind as a source of complaint on this score.

Walt Fricke · 04-13-2014, 04:15 PM

Oh, by the way - you don't need to remove the engine to replace this switch. You do need (most of us do, anyway) to do a partial drop (there is a Pelican tech article on that), but that's not a big deal. Nothing like pulling an engine. And to remove the rubber boot connecting the sides of the intake system.

You can also purchase switches from a different manufacturer which are made for cars not using the metric system (all older US cars, don't know how that is changing) - they use 1/8" tapered pipe thread, not M1.00. You can buy an adapter to go from one to the other. You can buy switches in a variety of pressure settings - I like one at maybe 20 psi, because 0.4 bar is OK for the light not to come on at idle, but not of much use if you lose oil pressure while driving.