'81 450L, oil lamp activates below 4K

[FoxyBLankworthy]

My brother's 450L is, for the most part, a sweet little ride. We're considering sprucing her up and taking her out to Brown County. It occurs to me that I'm running out of time to do any repairs. Luckily there's not a whole lot that troubles me aside from a little simple maintenance.

Except this:

The oil lamp comes on, and remains on while the bike is in low rpm. Anything <4k and that red lamp is on. Now, I had a similar problem with my 650G, and corrected it immediately with a drink of fresh Rotella. This problem is troubling as my brother assures me that the bike is fulla fresh oil.

Which leads me to believe the poor girl has a faulty oil pump. That's a rally disqualifier. I'm sincerely hoping that this is not the case. So I'm going to double check Shane's oil level.

The 450 is running Rotella 15W-40. This ~is~ a thicker weight oil then the bike was originally intended to run. I'm hoping maybe a switch to the synthetic 5W-40 and a good splash of SeaFoam might correct the pressure problem in the low side of the tach.

Have any of you GSers out there encountered this problem before? Does anyone have any advice or any clue if I'm on the right track with this problem?

Shane said he's been running her like this for a while. To which I say !
Which leads me to believe he's been lucky he hasn't seized her up. But it also leads me to wonder if his pressure sensor might be faulty. [Which seems unlikely, but it could be electrical, I suppose...especially supposing the problem corrects itself when the stator is charging] I'd not have risked it until I knew for sure. Perhaps I'll flip on the headlight next time and see if upping the stator output helps.

Any input you experienced fellows out there can provide would be just ducky.

[Mekanix]

Just below the timing cover there is a 14mm bolt (17mm socket head)

This is your oil test port. If you could get an oil pressure test kit you could see what is actually happening. Shoot for 40-75 psi above idle. The actual numbers are in the service manual.

If you wanted to make your own, Just get an oil pressure guage that is good to 100 psi for automotive applications. They usually come with a connection kit. You would need another bolt like that one, Its 14mm x1.25 thread pitch. Its an odd bolt to get so you might as well get one from the dealer. Now, just drill and tap that bolt for one of the adapters that come with the kit. Now you have a good working pressure gauge.

You could just change the sensor as well to see what that does.

A few things can cause this.

oil pump
pressure relief valve
right case installed with gasket goop instead of gasket and the port is plugged.
bad left case gasket or right case gasket or cylinder base gasket.
All those can create enough of a leak to drop the pressure.

The pump is an easy target but it has to be worn quite a bit.

INSTALLING THE OIL FILTER BACKWARDS (some members will remember this one :P) This will do it for sure
The hole goes towards the engine side and it can be installed backwards easily and fit without noticing.

[barnbiketom]

something ELSE that can cause low oil pressure is often overlooked......

If the cam bearing surfaces or plain bearing crank inserts or crank is WORN, then the pressure drops accordingly.

kinda like if you take off the spray head on a hose... the pressure will drop.

how many miles on this bike???

like Mekanix said above, the only way to logically diagnose this and avoid just throwing parts at it is to
TEST the oil pressure. hopefully its a bad sender... but.....?????

[FoxyBLankworthy]

Sorry for the quick reply. I've got to be at school for a final soon. You guys gave me some really excellent advice. The bike's got a little over 19k miles on it....not enough [I would hope] for her bearings or oil pump to be shot. But you never know. Let me check the pressure inside and let you know what I find.

Thanks guys!

[FoxyBLankworthy]

A follow-up with the solution.

After about a week and a half of noggin scratching and tinkering I've finally figured out the problem.

Initial examination rendered gasket goo on the cam chain tensioner. It was a sticky mess. Pulled that, replaced the gasket and re-set the tensioner. Also pulled out the oil pressure sensor and cleaned it off well with carb cleaner.

Oil light still came on at idle. Went off at 4k.

Ok. We figured there might be goo clogging up the crankcase. We went ahead and drained the oil and replaced the filter. The plan was the filter the oil, which had less than 100 miles on it with some pantyhose and put it back into the bike. Granted, the oil was a little sludgy [seems the Seafoam had done it's job] so we put in fresh. However, there wasn't anything in there that seemed solid enough to clog up any of the ports. - FYI, Advance, OReilly's and Autozone no longer rent out oil pressure tester kits. They want you to buy them now.

Frustrated, I reanalyzed one of my first theories. Electrical. The oil light would only be on if it were grounding out somewhere. At 4k that there could be enough electrical keneticism from the stator to correct a faulty ground?

Sure enough, I followed the sensor wire back into the harness, wiggled that old bullet connector and that oil light went right off. Wiggled it again, and it turned right back on. I'll be pulling those corroded bullet connectors and replacing them with fresh spades. So, if anyone has an oil light that likes to shut OFF when the bike is charging, check your oil level, and take a look at your harness.

[eil]

At 4k that there could be enough electrical keneticism from the stator to correct a faulty ground?

That's the most beautiful euphemism for voltage that I've heard in awhile.

Great that you found the solution and that it was an easy fix. The engines of these bikes are so well engineered that they almost never wear out, even against substantial abuse. Most of the gremlins tend to lie elsewhere but especially in the electrical system. I would have blamed the oil pressure sensor, but this just goes to show how important it is to always check all electrical connectors first. (And to clean them preemptively to prevent random problems like this!)