oil switch question

[crvc]

The old switch worked. At idle the green light was on but went out once I was moving. But it quit working so I ordered a new switch. This one the green light stays on unless I'm revving the engine. Once the bug is moving the light goes out as I'm shifting into 2nd gear, roughly 10mph. I don't have an rpm meter. The oil is recent and goes to the top line on the oil stick. I've used a pump and Fram filter for about a year without problems.

Something wrong with the switch or not?

TIA,

kevin

[Marc]

Sounds a bit frightening, considering that it only takes a couple of PSI to make the switch contacts open - I wouldn't want to drive this without connecting a mechanical gauge and observing the actual oil pressure.
Normally the only time you should see the warning light on a running engine is at an extremely low idle, or perhaps briefly on a hot day when you come to a stop after a hard highway pull. The "rule of thumb" for acceptable pressure is about 10 PSI for every 1000 RPM; ambient temperature and oil viscosity are both factors, but the biggie is the internal clearances of the engine and the pump itself...and of course the oil temperature, but you said that you'd licked your overheating problem.

Last I recall, about 5 weeks ago you said you had a filter-pump installed - those add significant restriction to the oil flow because of the tortuous internal passages, but they're typically made with outsized gears which compensates some. Many of them have a bypass valve to prevent having too much pressure and blowing out the filter seal when you rev a cold motor; if yours has that, it's possible that it's sticking partway open and causing you to lose pressure...I'd check that, and maybe try a new filter.

[Piledriver]

...not an Orange Fram...

[Marc]

...not an Orange Fram...

Yeah well, while Frams may be far from the best filters out there, that's not the cause of this problem. If the present filter's plugged to the point that the warning light's staying on until its bypass opens, even a Fram would be an improvement

[Piledriver]

...not an Orange Fram...

Yeah well, while Frams may be far from the best filters out there, that's not the cause of this problem. If the present filter's plugged to the point that the warning light's staying on until its bypass opens, even a Fram would be an improvement

Not if it blows out and fills the oil passages with filter media.

[Marc]

OK, I'll grant you that...never seen it personally, but theoretically of course that scenario is possible.

[Piledriver]

I have personally seen it on at least two occasions, and IIRC so has Wally.
Fortunately I was just doing a freindly post mortem on the motors, Wally had it kill one of his own.

It isn't myth or an internet story. It likely happens on a regular basis to many folks, most probably never understood what happened.

The "better" FRAM filters are probably OK, the air filters etc are perfectly fine, but the orange cheapo ones are the kiss of death. (also once and possibly still banned by many racing organisations due to blowing off mid race on a regular basis)

[Ol'fogasaurus]

The only times I have seen the orange Fram filters blow was on the race track back in the 50s and 60s. That was when they thought they had to run some pretty high oil pressures (at times the oil was actually were cutting the bearing material) and then the filters blew their bottom out not internally (very impressive to see happen; I think I saw it happen twice. A dark orange fire under the car as it passed the finish line). I've also seen the results of other oil filters that blew at a lot less pressure. In tests that have been done by reputable testing businesses, the Fram product maybe was not at the top as far as durability goes but it was also way above the bottom.

Spin on filters have a bad rep to start with because, as I understand it, they all have a/some plastic parts in them and, like certain brands of oil or other parts, a negative opinion starts by someone and stays with the product and continues to grow over the years. When I hear them (and this in not about the Fram filters) I usually ask for proof but so far no one has been able to come up with it. It usually ends up with: well a friend of mine had ... and told me about it.

I have used several different brands of filters over the years and IMO as long as you change them at the correct intervals they all were OK. A lot of people do cut theirs apart to check what is being captured in there and the internals/material of the filters aren't always the same.

Lee

[Marc]

I started running filters made for MK 1 Rabbit Diesels way back in the `70s - they fit the ubiquitous spin-on adapters and have no problem handling 150+ PSI (a Bunny pump puts out that much and more when the oil's cold and the pump relief can't handle the volume). Better filters and usually cheaper than the Fram HP-1. First choice, Mann - if that's not available, Mahle/Knecht or Bosch...but I've never had even a "Brand X" filter fail if it was one that was intended to replace the stock diesel unit.

[crvc]

http://www2.cip1.com/ProductDetails.asp ... C10%2D5384

It's this pump but the filter that came with it is black, not orange. I said Fram because that's the screw-on filter most people are familiar with. I remember I had smeared sealant on the threads before mounting the switch. Maybe some got inside and is screwing up the little piston inside. Regardless, I've ordered a new one.

[Marc]

I wouldn't expect sealant to impede the function of the switch (it's a diaphragm, not a piston, in there so the tolerances aren't all that tight)...maybe if you packed it into the hole, but if a trace amount were to transfer there from the threads during installation the switch should still function. You really need to confirm the actual oil pressure with a gauge before you drive this. The switchpoint should be stamped into the body of the sender (it may be in Bar). There do exist some switches intended for Rabbits which have higher setpoints, but the one you should be using (021 919 021B) switches in the range of .15 to .45 Bar (2.2 to 6.6 PSI)...if the pressure's that low the engine can be damaged in short order.

It peeves me when a parts-seller tries to pass off the same pump for pre`70 and `70-up 3-rivet, since the passages in the case were substantially enlarged for `70...the "wrong" one may work, but it's definitely not optimal to have mismatched passages. From the photo it looks as though the EMPI pump has a control valve out near the filter; located there it's most likely just meant to protect the filter from overpressure by bypassing it when the oil's cold (so the oil getting to the engine might not always be filtered, but the pressure won't suffer if it leaks)...the style that might cause pressure loss if it stuck open would be located at the pump end.

Check the pressure.

Have you been into the control valve(s) in the engine block? They rarely have issues (at least if all stock internals are used) but a problem there could cause your symptom.

What's the oil viscosity number? Might it be diluted by gasoline? (a leaking fuel pump diaphragm will do that - the sump level mysteriously rises and the oil smells gassy)

[Piledriver]

Most aftermarket pumps also are machined so they are easy to install, by intention or simple bad spec.
This causes both air suction leaks and direct pressure leaks internally.

Did the pump body easily slide in when you installed it, or did you have to loosen the bolts around it and ~beat it in with a rubber mallet? (no gears, they go in after to align the tang etc)

As Marc noted, get a mechanical pressure gauge on there temporarily to see what is really going on.

[crvc]

http://i1325.photobucket.com/albums/u63 ... 923063.jpg

I found what looks kinda like an oil pressure switch. Except it takes two wires. I tried it on the bench using a dry cell battery and it's functional. I want to take the new one back to the parts store but can't drive the car without it. If I could mount this old one my wife can take to new one back to Salt Lake City--three hour drive--since she's going down there anyway.

So what is it if it's not a switch? And if it is an oil pressure switch, why does it need two wires?

TIA,

kevin

[Piledriver]

Looks like a brake light switch.
You should be able to get a pressure gauge at Home Depot and a usable idiot light switch at any decent auto parts store.

[crvc]

I've got a pressure gauge. I was looking for it in my junk pile when I found that switch. What I don't have is a way to screw it into the block. Would the brake switch fit into the oil pressure switch hole? That way I can send the new switch back and get a replacement.

Yes, I am mightily embarrassed that I didn't recognize it as a brake light switch. I blame it on the heat; It's nearly 70 degrees today. Heat wave!

kevin