Low oil pressure or faulty switch?

[jacksdad63]

Following on from my earlier posts, I took my bike  on a holiday.

The uprated injector kit finally turned up....on the morning we were setting off! So I did a very quick fairing removal and swapped old for new and the bike fired up settled into a smooth idle. 

Off I went, just 130 miles to our destination, in glorious sunshine. Then the oil pressure light came on. I've had enough of this bike so I just ignored it 

Oil temperature stayed at 5 bars, all seemed prefectly well so I hit the motorway and did most of the ride at 80mph ish.

We then did another 500 miles of touring at max 50mph,  then rode home again at 80. I'm sure its just a faulty sender....or is it? 

I'm going to swap the sender, and the relief valve spring, is there anything else I should do? I can't easily check the oil pressure,  but as stated the bike is running well!

1998 R1100RT 68,000 mles   

 

[dirtrider]

32 minutes ago, jacksdad63 said:

Following on from my earlier posts, I took my bike  on a holiday.

The uprated injector kit finally turned up....on the morning we were setting off! So I did a very quick fairing removal and swapped old for new and the bike fired up settled into a smooth idle. 

Off I went, just 130 miles to our destination, in glorious sunshine. Then the oil pressure light came on. I've had enough of this bike so I just ignored it 

Oil temperature stayed at 5 bars, all seemed prefectly well so I hit the motorway and did most of the ride at 80mph ish.

We then did another 500 miles of touring at max 50mph,  then rode home again at 80. I'm sure its just a faulty sender....or is it? 

I'm going to swap the sender, and the relief valve spring, is there anything else I should do? I can't easily check the oil pressure,  but as stated the bike is running well!

1998 R1100RT 68,000 mles   

 

Afternoon jacksdad63

 

Your 1100RT has an oil light not a gauge so it has an oil pressure switch not a sender. 

 

If you rode it that far then I  doubt that you have real low oil pressure. With a good Oil Pressure Switch the oil light should come on a someplace at or under 3 psi to 7 psi but most I have seen are closer to 5-7 psi range.

 

Make sure that the oil pressure switch pigtail wire didn't come loose then go to ground someplace. 

 

Otherwise try a new (or good used) OPS (Oil Pressure Switch). 

 

I wouldn't mess with the relief valve spring until you verify the switch is working OK. 

[jacksdad63]

Thanks DR, I did mean switch not a 'sender' as you say. I checked the wire, its working properly. 

I think my bike has a lower switching pressure than earlier engines, is that correct?  I'll fit a new switch first, then see what happens...then maybe swap the spring?

[dirtrider]

36 minutes ago, jacksdad63 said:

Thanks DR, I did mean switch not a 'sender' as you say. I checked the wire, its working properly. 

I think my bike has a lower switching pressure than earlier engines, is that correct?  I'll fit a new switch first, then see what happens...then maybe swap the spring?

Evening jacksdad63

 

Sometimes it is difficult to tell what is what when it comes to oil pressure switch trigger pressures as the old service manuals don't always line up with the current replacement switches. Probably between 3 to 7 psi will be in the ballpark. 

[jacksdad63]

Thanks again DR,  I'll order the 1998 on switch, its lower switching pressure  then I'll see what is fitted now when I do the swap. Getting pretty good at removing the bodywork now, most jobs start with removing everything! 

[jacksdad63]

Just checked: part # 114 113 42 807 is listed as 12/1997  on, 0.15 bar or 2.17psi.

Then in the fitting list it says it fits lots of earlier bikes. I think the earlier switch was set too high, so were coming on well before the oil pressure dropped too low.

I'll order this one and just hope mine is either faulty or is the early 'high pressure' one 

[dirtrider]

1 hour ago, jacksdad63 said:

Just checked: part # 114 113 42 807 is listed as 12/1997  on, 0.15 bar or 2.17psi.

Then in the fitting list it says it fits lots of earlier bikes. I think the earlier switch was set too high, so were coming on well before the oil pressure dropped too low.

I'll order this one and just hope mine is either faulty or is the early 'high pressure' one 

Afternoon  jacksdad63

 

A couple of PSI difference in Oil Pressure Switches should not make any difference in the oil light coming on.  

 

Your engine needs around 10+ psi per 1000 RPM's so at a proper idle RPM it should have AT LEAST 10 psi oil pressure & most good engines will have a lot more than that at idle. Running down the road  (depending on engine RPM) it should have 50-87 psi. 

 

Where you can see a difference in the oil pressure switch turn-on pressure is it at a very hot engine & at slow launch speed that almost gives you an engine stall. (where you kind of have to double clutch it to get a launch without stalling)

 

A worn engine with a thinner oil & very hot engine with a low idle RPM will sometimes give you an oil light flicker at the low curb idle speed.

[jacksdad63]

Ok thanks: I've just invested in an oil pressure gauge/test kit, so hoping I can check whats really going on.

The kit has an M12 adaptor, but its 1.5 pitch....thats seems way to coarse ...any idea what it is? 

[dirtrider]

15 minutes ago, jacksdad63 said:

Ok thanks: I've just invested in an oil pressure gauge/test kit, so hoping I can check whats really going on.

The kit has an M12 adaptor, but its 1.5 pitch....thats seems way to coarse ...any idea what it is? 

Afternoon  jacksdad63

 

It's 12mm x1.5mm straight thread (not a tapered pipe thread).

[jacksdad63]

Thanks again my friend: My new  gauge kit has the correct adaptor

Not too bad for 68k miles

 

 

[dirtrider]

20 minutes ago, jacksdad63 said:

Thanks again my friend: My new  gauge kit has the correct adaptor

Not too bad for 68k miles

 

 

 

Afternoon  jacksdad63

 

You need a hot engine with hot engine oil to get an accurate reading but you look pretty good even if it was cool oil/cool engine  at testing as the by-pass valve will limit the max.  

[jacksdad63]

Thanks again DR,  you beat me to it!

HOT..I almost forgot about it! 6 bars on temp gauge, it runs at 5 bars all the time:

Idle                35psi

2000rpm       45

3000              65

4000              80

 

Happy bunny  

[RPG]

J,

I would be interested to know if the switch is shorted internally. I believe it's more common for the switch to fail in an open state (oil light doesn't come on with key on, engine not running) than the light staying on with the engine running.

[dirtrider]

16 hours ago, RPG said:

J,

I would be interested to know if the switch is shorted internally. I believe it's more common for the switch to fail in an open state (oil light doesn't come on with key on, engine not running) than the light staying on with the engine running.

Morning Rick

 

I have seen way more oil pressure switches that stay N/C than fail open. Note I said "have seen" as most drivers or riders never notice that the oil light doesn't come on, but they quickly notice that it doesn't go off.

 

The usual source of oil light switch failure that I have seen over the years is leaking oil, I have seen a few that failed with the oil light illuminated  due to the oil passage in the switch being plugged with crud or ???  

 

I haven't actually cut many OPS  apart but years ago I did cut a few apart as we had a run of switches that had internal leakage that allowed the oil to enter both sides of the switching diaphragm so the switch could not properly react to oil pressure on switch. 

[jacksdad63]

Hi all: further to our discussions I went to order the oil pressure switch....it is almost £24 with postage!

So, being 'careful' with cash as we say here, I did a bit of searching. I soon found that BMW E range 3 series cars, most petrol engines and years, use the same M12x1.5 thread.

I went for a 1992 E30 2.5 engine, and found a Febi Bilstein (aka genuine part) switch,  switch point from/to 0.2-0.5 Bar or about 3-7 Psi  

Even got a standard male spade connector fitting so the original wire will fit straight on,    £4.40 delivered!  

 

[jacksdad63]

I've fitted the switch, all is well again!

The switch I used is a Febi 04428. This fits hundreds of cars and vans! Most BMW, Mercedes cars,  VW cars and vans, petrol and diesel use this so its readily available...and very cheap. I've seen other brands for £2.30...but I went for Febi as its OE and top quality.

To fit to my 1100RT I removed the 2 screws holding the belly pan to the fairing, from which I removed the 4 screws above & below the exhaust header. This gave me just enough room to wedge open with a torch, which lit up the work area. I removed the original switch with a 1/2" ratchet and extension bar. 15/16" to remove, and 22mm for the new one. The latter has a male spade connector which uses the original wire connector, wire is just a little short, but does reach! 

Ideally you use a 22mm deep socket, due to the spade connector but I managed to use a standard one, placed the extension bar just inside the socket, and used a small magnet to hold it in place. 

Very easy, took me 10 minutes, don't forget the sealing washer! The oil light switched off as soon as the engine fires, then goes out a couple seconds after stopping the engine. 

The pressure rating is almost the same as the genuine part, and I feel its correct for the Boxer engine, is easy to find stock, and a fraction of the price!   

[dirtrider]

2 minutes ago, jacksdad63 said:

I've fitted the switch, all is well again!

The switch I used is a Febi 04428. This fits hundreds of cars and vans! Most BMW, Mercedes cars,  VW cars and vans, petrol and diesel use this so its readily available...and very cheap. I've seen other brands for £2.30...but I went for Febi as its OE and top quality.

To fit to my 1100RT I removed the 2 screws holding the belly pan to the fairing, from which I removed the 4 screws above & below the exhaust header. This gave me just enough room to wedge open with a torch, which lit up the work area. I removed the original switch with a 1/2" ratchet and extension bar. 15/16" to remove, and 22mm for the new one. The latter has a male spade connector which uses the original wire connector, wire is just a little short, but does reach! 

Ideally you use a 22mm deep socket, due to the spade connector but I managed to use a standard one, placed the extension bar just inside the socket, and used a small magnet to hold it in place. 

Very easy, took me 10 minutes, don't forget the sealing washer! The oil light switched off as soon as the engine fires, then goes out a couple seconds after stopping the engine. 

The pressure rating is almost the same as the genuine part, and I feel its correct for the Boxer engine, is easy to find stock, and a fraction of the price!   

Morning jacksdad63

 

That's good information for non USA areas. Here in the U.S. just about every auto parts store carries a few different  M12x1.5 straight thread oil pressure switch's that have a close enough trigger point to use in the BMW boxer. In fact a number of auto parts stores carry a M12x1.5 OPS that has the correct button head terminal. 

[jacksdad63]

There's loads over here as well: just had to find it all out myself, no posts on here about any alternative. 

Problem is that all the parts places are full of people who need a registration or chassis number to use their computer, they cannot do anything without such info...they are just button pushers, most have no idea how vehicles work at all! 

I went to a big parts stockist and asked the youth if they had a 0.5 bar M12x1.5 oil pressure switch, he just stood there totally blank, just didn't have the slightest idea what I was saying 

[Skywagon]

1 hour ago, jacksdad63 said:

they are just button pushers

So true. You want to have some fun, take in a part and say I need a new one. If you don’t tell them what the part is they can’t help you. Same at my BMW cycle dealer. Glad you got it sorted. 

[jacksdad63]

It's true, just another job dumbed down by computers so that anyone can press buttons and get results...or not.

I actually started work 43 years ago in a Datsun parts dept. I already had a good understanding of mechanics, having wned ane built motorbikes from aged 13.

You needed to know how cars worked to have any  chance of finding a part number, now its an unskilled button pusher job!