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1919 K100rs 4valve

2K views 9 replies 3 participants last post by  H96669 
#1 ·
Hello,
I'm new to the group. And I do have a question. My oil pressure light came on. By reading other forums they suggested my oil/water pump seals maybe gone. (69,000 on bike) :confused: :confused: I bought a new sensor first. The light would not go out. Took out the pump and replaced all the seals. Got her back together and rode her the first time and the light was still on.
any suggestions about where to go next?
Thanks
Duke
 
#2 ·
I don't know at what pressure the light comes on, probably pretty low if it is anything like a car. In any case maybe you should put an oil pressure gauge on the bike and see what is happening. Those bikes run at pretty high oil pressure, probably up to 120 lbs cold if I recall well, and then at 90-100 lbs while warm, so you would need a gauge to up to 150 lbs.
Lots of oil would have had to go through the pump seals into the coolant (or vice-versa) if the pump was bad. Any signs of that? A plugged up oil filter going into it's bypass mode may cause the light to come on, could have happened from the coolant going into the oil, swelling and plugging the filter, it happened on my old Chevy more than once. :teeth
 
#4 ·
1. DON'T ride the bike or run the motor until you are sure of the oil pressure.

2. You need to get an oil pressure gauge on the bike with the same thread as the sensor, so you can see what is really happening.

3. Oil pressure switches usually go out at a very low oil pressures between 7-15 psi.

4. The oil light could be on (or even bulb blown, which it will eventually) and after a few hundred miles your engine could be wrecked beyond economic repair.



 
#5 ·
thanks

Voxmagna,
I have not ridden the bike. I have only turned the key on and started the engine. The light does not go out. Have not had time to look into it further but should be doing something this Labor day weekend.
Also, where can I get an oil pressure gauge that will fit the bike?

Thanks,

Duke
 
#6 · (Edited)
Finding an ohmeter/multimeter should be your first buy. When you have checked what the sensor is doing you may learn more.

I can't remember the thread size for the senders. They are definitely metric and I think could be M12 (12 mm). If you can get an old style non-electronic oil pressure gauge kit from a car accessory shop, they usually come with adapter threads. The newer electronic types with wires often have a large pressure sensor head and you may not be able to fit that in the tight space. Get the right thread that fits, damage the thread and you have big problems! If you are handy with things, at a push get the gauge that has the coiled copper tube, check the thread size is 12mm. Dill a tight fit hole down a hex head (Brass) bolt and solder in the copper capilliary tube. Wrap some ptfe tape around the thread. You probably only need to screw it in 6 turns.

I see most new mechanical gauges now have plastic pipes. I'm not saying this is plug and play, but check out if it comes with connecting hose and the metric adapter to suit your thread:

http://cgi.ebay.com/ebaymotors/Equu...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

A good bike/car repair shop should have an oil pressure test gauge and adapters, perhaps might loan out. The trade shops use special test gauges which come with most sizes and types of adapter thread. This might be best for you if you aren't able to make up a gauge. But I guess you don't want them to do the test then be in the position of having them do expensive work if the news is bad.



 
#7 ·
On my K100Rs I used a T Adapter from a Volkswagon air cooled engine to mount a mechanical oil pressure gauge and also retain the warning light. It worked so good that I kept it and reinstalled it on my R100Gs, now it is in my tool box waiting to be installed on my k1200RS.
I remember having a hard time finding that "Tee", but that was before internet searches and forums, and there is still plenty of Volkswagen stuff around. As long as you have the one adapter that fits the engine then you can always build up your own, they are always made of brass and very easy to solder together to make a suitable tee, but if I remember well there is not much room to screw them into the block so you have to be careful with clearances.
I've always had a gauge on all my bikes and cars, never trusted the light,(that's why they call them "Idiot Lights") by the time it comes on, there may not be any oil left in the engine, or you could have been running at low oil pressure for a long long time, turning what could have been a relatively cheap repair into a major engine rebuilt. Unless you have a catastrophic engine failure, an oil pressure gauge should give you some warning that something serious could be happening with your engine before it blows.... :wtf:
 
#8 ·
Thanks for your input

Voxmagna and all,
Thanks for your suggestions. I tried to follow the sensor wires in case of a short. noticed that 1) the wires led into the bike and 2) they were enclosed when the wires went to the dash. Decided to try the iol filter next. Drained the oil, took out the iol filter and on top of it was the prior oil filter rubber gasket. Cleaned the area up looking for other stuff. Put the oil filter back on, filled with oil and ta-da! Oil pressure light went out after start up. Well i just learned another lesson. When changing oil filters make sure everything comes out.
thanks for all your help and suggestions.

Duke :clap:
 
#9 ·
You could be right, but we are telling you not to trust conjecture!

You may feel good finding the doubled up sealing ring, but if that just got you sufficient oil pressure to put the light out, you won't be a happy bunny if the rattling and clanking starts or the 'rods fly out.

Yes, it really is an idiot light for those that want to believe it.



 
#10 ·
Oh la la.....and I was thinking about that filter seal when I first posted a reply.......!
The question now would be how long had that filter been in there robbing your engine of oil pressure.....?
I would get the oil pressure checked properly, it should read 90 PSI or thereabout with the engine hot, and should also be pretty steady. If the pressure is low or unsteady, problems somewhere.....!
 
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