Oil pressure sending unit light

[07bigdog]

Could one of you expert members tell me at what oil pressure trips the oil light to come on? I'm still dealing with low oil pressure at idle. I checked the sending unit. It reads 1 ohm when the wire is unhooked and open circuit when you start the bike. Hook the wire back up and turn the key on. The light comes on. This is telling me that the sending unit is okay. Is it possible that the sending unit is over sensitive or subject to vibration and it is tripping too early? I had 2800 miles before the light started acting up. When the light was coming on tonight, it looked like the oil pressure gauge was reading about 5 psi. The outside temperature was 63 degrees.

 

[Vegas]

Something to consider is liquid filled gauges become innacurate with heat. So I wouldn't put much emphasis on your gauge if it's liquid filled.

 

[07bigdog]

No my gauge isn't liquid filled. It is an autometer gauge. Any suggestions as to why the light keeps trippin?

 

[V]

Make sure you don't have the idle speed set to low. Should be around 1000 rpm hot

 

[07bigdog]

Idle speed is set good. I cranked it up to around 1400 rpm and it didn't make any difference. Set back to about 1100 rpm. Dumped the oil and changed filter. (20w50 with evo HD filter) Tried synethic and conventional oil. Changed oil relief valve spring. Once it gets to running temperature, the light starts coming on at idle. That's why i was wondering if the oil pressure sending unit might be weak even if it tests good.

 

[Loafington]

Have you cleaned and reinstalled your tappet screen?

Unless you have a new oil pressure sending unit to compare your resistance reading through the old sending unit, it would be tough to tell whether or not the sending unit is good.

Sending units such as the ones installed on our engines are pretty inexpensive and if you doubt its accuracy, change it and then you would know.

If you have a mechanical gauge, try it and see what it reads. Doing so will basically eliminate whether or not the problem is in your engine, or in the oil pressure indication circuitry.

 

[Vegas]

Call S&S and ask what the oil pressure requirements are at hot idle and certain rpm's. An engine problem will show up at all rpm's hot. Also, ask at what pressure the light is supposed to come on. Another member had the same problem and they found rust in his oil pump from the oil tank. Hope that's not your problem.

 

[Raywood]

Could one of you expert members tell me at what oil pressure trips the oil light to come on? I'm still dealing with low oil pressure at idle. I checked the sending unit. It reads 1 ohm when the wire is unhooked and open circuit when you start the bike. Hook the wire back up and turn the key on. The light comes on. This is telling me that the sending unit is okay. Is it possible that the sending unit is over sensitive or subject to vibration and it is tripping too early? I had 2800 miles before the light started acting up. When the light was coming on tonight, it looked like the oil pressure gauge was reading about 5 psi. The outside temperature was 63 degrees.

Can't figure if you question is about oil pressure or oil pressure lite issues!
My oil pressure light started flashing on and off so went with the gauge to ensure I had oil pressure.
Problem was a grounded wire (orange) under the tank. Re-wrapped wire and all was good.
Mine idles at about 5# at idle and runs about 30 # at speed.

 

[07bigdog]

The tappet screen is clean. The gauge is showing about 4- 5 psi. when the light comes on. I also have 30 psi. at speed, but once it warms up it drops about 10 psi. I don't want to pull the tank off until i get my wider speedo bracket in 2 weeks. Then i will check for the orange wire. I'm going to change the sending unit, but i don't think it will change any thing.

 

[Loafington]

When the engine is warmed up, you have 10 lbs. of oil pressure at speed?

 

[07bigdog]

No, when warmed up i have between 16-20 psi. It drops down approximately 10 psi. when at running temperature. I installed the new sending unit and the light is still coming on. No change. About 5 psi. at idle when hot. Stumped.

 

[Vegas]

You have engine problems...specifically oil pump, bearing clearance, or a crimped oil line. It's under warranty...make them fix it.

 

[Gas Man]

Did we already cover that you changed the oil?

Did you check the tappet?
What oil filter?

 

[07bigdog]

I changed out the oil and filter. The rep at S&S says that the piston oilers may be stuck open at idle. They are supposed to close below 10 psi. To check that out, basically the cyclinders have to come off. The guy that assembled my bike has warranty with S&S, so we are just trying to decide how we are going to approach the problem.

 

[jhall]

I have a 2003 BD, 107" engine I recently installed in a Harley FXR. Having ridden the bike over 40,000 miles before this engine swap I am pretty familiar with the oil light. Before, once good and hot, i.e. interstate riding in 90+ degree weather, the oil light would come on at idle around 900 and go off 1000 rpm. Now, under the same conditions it comes on around 1100 and goes off around 1200.

Soo it is definitely idling at lower oil pressure, but not sure about when at speed. Also, not sure why, unless maybe it is operating at a higher temp. I may put an oil cooler on it, and maybe thicker oil, but for now just gonna ride it.

Joe H

 

[07bigdog]

The light did start coming on when we had hotter temperatures. I'm in Canada, so we don't get a lot of real hot days. On the cooler days the light would flicker on and then go out when you give it some throttle. I did change the oil sending unit and it seems to read about 2 psi. higher on the gauge, but then again the temperatures aren't as hot. I was reading about Baisley Performance making a stiffer spring to bring up the oil pressure 15%. I know they say the evo motors don't really work off of pressure, but more on volume. With the new sending unit and i added a .056 shim in the oil pressure relief valve, the light did not come on today. Oil pressure gauge was reading about 7-8 psi. at idle when at running temperature. Hope i am not just bandaiding a problem.

 

[jhall]

Today I had accumulated 700 miles since installing the new 107" engine, so I drained the 20W50 Castrol and replaced it with Mobil 1 and a quart of Lucas oil treatment. Now, at hot idle the oil light only comes on if the RPMs drop below 900, anything above 1000 and it goes off and stays off. This is even better than with the previous, smaller engine. Soo it seems the synthetic oil, fortified with Lucas operated at a greater pressure. Plus, I am thinking the Castrol was beginning to break down.

Joe H

 

[slowrower]

Today I had accumulated 700 miles since installing the new 107" engine, so I drained the 20W50 Castrol and replaced it with Mobil 1 and a quart of Lucas oil treatment. Now, at hot idle the oil light only comes on if the RPMs drop below 900, anything above 1000 and it goes off and stays off. This is even better than with the previous, smaller engine. Soo it seems the synthetic oil, fortified with Lucas operated at a greater pressure. Plus, I am thinking the Castrol was beginning to break down.

Joe H

Joe, you may want to head to this link if your adding so called additives to you oil (generally a no no).

What about Additives?

 

[07bigdog]

We had a real hot day yesterday. Even at 10 P.M. it was still 85 degrees out. Rode for about half hour and the oil light started coming on again at idle. The gauge was showing 5 psi. I turned up the idle a bit before i parked the bike last night. This morning i removed the .056 shim in the relief valve. Nothing i've tried helps. I guess will have to do some more investigating with S&S.

 

[Gas Man]

There is still something wrong... we rode today and even in some traffic... 85 degrees with Mobil 1 20W-50 (from this spring). Always had over 10# at idle...