My oil light is on and I don't know why!

[johnstewart]

1979 XS11, 12k miles on it, I've had it for almost a year now.

This past weekend, I finally got around to changing the gear oil. Also, I tried to change the air filter, but the dang thing got twisted up in the cotter pin which holds the wing bolt to the air box. Took me an hour to get it off (which included a LOT of swearing and banging). Also topped off the engine oil; it was a bit low.

Anyway, all seemed to go well, finally. The gear oil is a little bit high in both, but not much, and the old air filter is back on.

However, when I started it up a few mornings later, the oil light stayed on. It ran fine, but I shut it off after a minute or two in fear of no lubrication.

I can't imagine what I would have done to cause the oil pressure to go south. I thought the cause was most likely electrical as I was banging around the air box a lot in my efforts to get it off; perhaps I knocked out a wire? However, I looked tonight and didn't see any obviously loose wires. Also, I replaced the brake light bulb in case that had gone bad (even though all lights were working normally).

I'm not sure where the pressure gauge is wired from and to - can anyone clue me there? Any ways to eliminate this as a problem?

When I ran it tonight, the engine did sound a bit rough, and one of the cylinders was coming in and out. However, I never let it get warmed up, so it's hard to say if it really is sounding abnormal. I am extremely worried.

The light stays on constantly, even whilst jiggling various wires, and I've never had it come on before now, so I don't suspect a bad tail light ground or anything like that.

I saw in this thread that someone bought a relatively cheap oil pressure gauge. I'm wondering where this goes. Where does it install??

http://www.xs11.com/forum/showthread...ressure+switch

Any suggestions for how to proceed? I'm thinking either change the oil/filter (maybe gunk in the filter - but I did change it less than a year ago; it's probably due but it certainly shouldn't cause any problem like this, methinks).

Maybe if an oil pressure gauge is cheap and easily installed, that's worth a go.

help please

[TopCatGr58]

Hey there John,
The pressure sending unit is just below the carbs, just behind the jugs, just in front of the starter. The light is activated when the wire is grounded. The pressure from the oil separates the contacts in the sending unit, and only if the pressure isn't high enough does it let the wire make contact and ground, causing the light to come on, that's why the light is on until you start the engine, then it should go out. Having said that, the wire can get a worn spot on it, and it can ground to the engine case, causing the light to come on. Find the wire, I believe it screws onto the sending unit, you'll need to pull the rubber cap back to see it, take it off of the unit and inspect it for rubbed insulator. Then with it OFF the sending unit, turn the key on but don't start the bike, the light should NOT be on with the wire pulled off the sending unit, if it is on, then that wire is grounding somewhere else from the instrument cluster on down!?!?

If the light is NOT on, then touch the wire to the case and the light should come on, if it does, the light circuit is working, however, you could still have a defective sending unit!?!? The unit screws into the engine, and that is where some folks have placed those cheap gauges instead of using the sending unit. Others, have put a "T" or "Y" adapter there, and so they have both the sending unit and the gauge. There is a long tube that runs to the left side of the engine from the area of the sending unit, with a bolt in the end of it, I believe a few have screwed a gauge into that end of that channel. There are some pictures on the Yahoo Pictures site in the Mods section, I don't have the exact link right now to include in this message.

But, most likely, the wire either got pulled off, or accidentally grounded and the sending unit is probably okay, but you'll want to investigate this further to prevent burning up your engine.
Good luck.

T.C.

[xssiveone]

You did not have this problem before you started changing the air filter? If not, then I would double check all your wiring near the air filter. Also, check the wire going to the oil pressure switch. It's located approximately under number 3 carb on the top of the engine. Maybe in your wresting match with the air filter you moved it and caused it to short agains the engine. Disconnect the wire lead from the switch and see if the light goes out. If it still stays on, then its a short somewhere else in the wiring. If it goes out, then it is definetely the switch that is causing it. It might not be bad tho.

If the wiring checks out OK, then it is a simple matter to unscrew the oil pressure switch. Check the part that screws into the engine, there will be a small hole in the bottom of it. Flush this out with WD40 or carb cleaner, or something similar. Occasionally a piece of crud will lodge in it and block the flow of oil to the switch. This can happen quite easily if someone doesn't perform regular oil and filter changes.

If it's not plugged, then I would say the switch has gone bad.

[beechfront]

i would say it about has to be an electrical issue. i sure as hell was worried when mine started acting up - but determined it to be either a short in the line somewhere or a bad sending unit. i didn't read all the responses to your post as i'm getting ready to crash for the night - but to test mine i just went to the local auto parts store and bought a $12 oil pressure guage. at operating temp the pressure would barely register (around 1 psi?). This seemed a little low to me but a friend of mine assured me that it's not uncommon for some cars run just 1 or 2 psi at idle. besides the times when my light was coming on were very random and seldom at idle. i'm for sure running good pressure at anything above idle so i figure i'm good. put 2000 miles on since and still going strong.

hope this helps.

[johnstewart]

Thanks so much, guys! I'll take a look and hopefully find the errant wire...

<prints out thread to take to garage>

[Jerry]

I had a similar problem on my Yamaha XS400. turned out there was enough crud built up on the top of the sensor that it was shorting it out. Cleaned the top and light operation returned to normal.

[johnstewart]

Ugh... not good, not good at all.

First off, thanks for the detailed info guys; it was a great help!

Disconnecting the wire shuts off the light, so it's not an electrical problem. The sensor is detecting low oil pressure, whether it's correct or not I'm not yet sure.

I went ahead and took out the sensor and sprayed it out (had to disconnect the nearby oil hose leading to the top of the engine - even still not easy to get a tool in there!) with some WD40 (though it didn't look like there was any crud).

Same deal; the light stays on (and I'm getting more worried that it doesn't sound right when I start it up - I don't want to do any more damage than I have to, of course).

So it's looking more likely that there actually is an oil pressure problem.

The only thing I did that had anything to do with the oil was top it off this past weekend. But I had been running pretty low - perhaps a half-quart or so - for a while. Maybe this screwed up something? My oil pump?

I do have a donor bike I can pull a pressure sensor off of, so that's something I can do relatively easily. Of course, I am hesitant to start this thing back up again to test it out if the oil pressure really is low.

But perhaps the sensor is the most likely problem?

Assuming it is still screwed up after replacing the sensor, what next? An oil change? I've read in another thread to perhaps pull off the oil pan and see if the screen is clogged?

thanks!

[xssiveone]

Swap out the sensor if you have a spare. Odds are in your favour that both of them won't be bad. As for the noise... without hearing it I can't say, but I know from my own past experience when something goes wrong, ie oil pressure light comes on, right away I start hearing all sorts of noises that have probably been there all along. The screen on the bottom of the pump could certainly be dirty, but I find it hard to believe that it could be totally blocked.

[johnstewart]

Okay someone on the triples list admonished me to not run the thing if there is any question of low pressure, which I can understand. I don't want to make a worse problem for myself.

I went to 2 auto parts stores on my way home from work tonight looking for an oil pressure gauge, and all I got were some puzzled looks.

I found gauges, meant to mount someplace to receive the electrical signal from the sensor. And I found pressure sensors, which send those signals.

But nowhere did I find anything like something that would plug in where the XS11 pressure sensor is, and give me a direct readout. And certainly nothing under $20.

Can anyone tell me exactly what it is I'm looking for??

thanks!

[NOMAD]

You can pick up a mechanical oil guage and a flexible hose to make a test guage at any auto parts store. These wouldn't cost much and you would know exactly what pressure you have. Plus it's a good tool to have around. Good Luck!!!

NOMAD

[johnstewart]

Originally posted by NOMAD
You can pick up a mechanical oil guage and a flexible hose to make a test guage at any auto parts store. These wouldn't cost much and you would know exactly what pressure you have. Plus it's a good tool to have around. Good Luck!!!

NOMAD

Hrm... well, shoot... a "mechanical oil gauge"... I asked at Checkers Auto Parts and a NAPA, no one seemed to have a clue...

[NOMAD]

John,

I don't know your location or what type of auto parts stores you have around you, but I just called an O'Reilly's store just a block away and they have a whole kit for $7.89. You might have to just shop around. Good Luck Again!!!!!

NOMAD

[TopCatGr58]

Hey there John,

I know it will be a bit of a pain or a mess, but a test you could do would be to unbolt the valve cover, have the tank off, unplug all the spark plug wires and remove the plugs to make the engine turn over easier, then you can run the starter for a few(15+) seconds and view the top end to see if you can see the oil being squirted up to that location into the cams and such. Or, you could unbolt the top oil supply line that goes to the top end, have it over a can or bucket, or a larger hose/rag over the end of it to keep the oil from spraying everywhere, and again crank the engine with the starter for 10-15 seconds to see if you get oil coming out that top supply tube. If so, then you probably do have enough oil pressure to send it where it's needed!!!!

You mentioned a spare partzer, if your oil pump "IS" bad, you can borrow the one from the partzer, you can pull the oil pan without pulling the engine, just have to drain the oil first. It's doubtful that running it a little low or a little over full would have caused any damage to your pump. These pumps are pretty sturdy. And unless you have just neglected to change your oil for several years, I would doubt the strainer is clogged to that degree either!
There's a rubber o-ring that will need to be replaced if you do have to replace the oil pump, you can get one at almost any decent hardware store, that's where I got mine!!

Good Luck. T.C.

[Chuck Olds]

Ya' gotta' love that little red light that says "Oil/Brake", eh? Next time you have the engine running for a second, try pulling the front brake lever and see if the light goes out, will you? Mine does. It's done that for a year now because I keep forgetting to trace some wires and look for shorts. (If the engine starts rattling, shut it off!) The light isn't on all the time, but goes out when I just touch the front brake lever, so I know it's in the brake circuit and not an oil pressure problem. I changed the front brake switch ($23 new from the dealer) and the brake light, but that didn't fix it. My SF has a little over 22K miles.

The O'Reilly's near me has the mechanical oil pressure guage kit too, for the same price NOMAD mentioned.

One more thing, my oil light stayed on at the first startup after winter storage a couple of years ago, but the engine was quiet, so I gave it a short rev to about 3500 rpm and the light went out and never did it again. Must have been something stuck in the sensor. (BTW, I installed the sensor new in '95 or '96. The story behind that is embarrassing.) The light now goes on and off randomly and even has a fade in and out feature. Very pretty. (I check it with the brake lever pretty often to verify it's not low oil pressure.) If I really had low oil pressure, I'm sure I'd have had engine trouble by now. If your light does go out when you pull the front brake lever, please let me know how you fix it!

[johnstewart]

Okay, I just spent a little time with it. I didn't get a pressure gauge, but what I did do was just leave the pressure sensor out and turned the bike over.

Oil didn't shoot out, but after a couple of seconds it did bubble out of the hole, so it seems like there is *some* pressure. So I went ahead and replaced the sensor with the one from my donor bike, started it up, and still the same symptom - the light is not going off. Now of course, I'm even more worried that I've f***ed the engine by running it.

I guess I'm gonna try to head over to Farm and Fleet today and try and find one of these oil pressure testers. If not, I'll have to order one online.

I'm getting more worried that it is the oil pump or something. Looking in Clymer, my heart just about stopped - you gotta take the engine OUT. I'm certainly not qualified to do that, I don't think. Perhaps it's getting time to have it towed to an expert (and pay out the nose). =(