Flickering oil light at low revs

[ral]

As heading, light flickering on below 1500 rpm on  GSX1100ET but only when warm, any ideas folks, just back from riding it and if the pump was faulty I would think it would have seized by now.

Are there alternatives to the std factory switch???? As I’m not convinced that

wire connection is great as it’s quite a loose fit.

Edited August 31, 2023 by ral

[DAZ]

If it's just a connection that you think is the issue then remake it so it's up to par ,then if that's not your issue the you need someone with an oil pressure gauge to get a definitive reading of what's happening at various rpm ,it may just be a faulty switch, it maybe the pump, those engines tended to rely on flow rather than pressure but until you get a idea of what the pump is doing then it just speculation

[DAZ]

As the oil pressure on these engines is usually very low and you may struggle to find a gauge that reads say 0-15psi I wonder if you could check the flow from say an oil gallery plug either on the head or crankcase,as with the roller cranks flow is the thing, I know that when they were available it used to be a thing fitting 750 pump gears to increase the pressure

[Rijko]

Sounds like the connection is easily tested with warm engine.
Does it flicker below 1500 rpm when cruising or at stand still ?
Or when pulling hard from low revs.

Made me think about this remark in Cycle World :

(source : https://magazine.cycleworld.com/article/1980/4/1/suzuki-gs1100e)

 

Quote

Unlike previous GS models, the GS 1100 has forward-facing spouts on the sump oil pickup to ensure that oil pressure is maintained under hard braking.

But because the pickups are pointed forward, the oil pressure warning light comes on under very hard acceleration in lower gears, which means that the force of acceleration pushes the oil to the rear of the sump, away from the pickup.

Suzuki engineers may have settled on the forward-facing pickups because a rider is more likely to use the brakes hard in normal riding than to accelerate at full throttle in the lower gears.

The important thing is that despite the oil pressure warning light flickering under extreme acceleration, the engine isn’t harmed.

Roller-bearing crankshaft engines use relatively low oil pressure, and losing that pressure momentarily doesn’t result in bearing damage as it can with a plain bearing crankshaft.

 

Edited August 31, 2023 by Rijko

[slayer61]

As the oil pressure switch references a "ground"... that is to say, a ground turns the oil pressure light on, a bad connection isn't your problem. A complete shite connection, like falling off of the terminal, is getting farther away from ground and becoming less likely to send a "ground" signal to the light. Should the wire come completely off the sender and land on the engine case, the light will indeed come on and stay on untill you move it. Does any of this make sense?  

 

Inside the sensor is a very small spring that must be overcome in order for the light to turn off. It is a "normally on" switch. That's why when you turn on the ignition, your oil light comes on and stays on until you have oil pressure. I "might" be the switch. It also "might" be a clogging pick up screen. If you can somehow prove you have good oil pressure, replace the switch. 

 

Good luck Sir!

Edited August 31, 2023 by slayer61
add

[rodneya]

Looks like a decent pressure gauge setup

https://www.Eblag.com/itm/293416783304?hash=item445100cdc8:g:ljAAAOSwkthZnGgw&amdata=enc%3AAQAIAAAA0Jt7hvQv5%2Bzq8eSO6cIomzvlNBr%2BFSm8WzegOoEOShT92b7QTdilouFLXiRtS8nvf225%2Fey6VbV86OIP1RB7B%2FNaGYcNjliCdATfjsmAiif2g81eIkZYs2thPRipCtM4w3Yv2%2BsKmsRer2B18ER521qG3UNxgK3wiGFlv69UdTIdNje8i4GUz39p94rcEW8aYYFiJ8lg0jgyuv%2Blaaw5u1m%2FILUYt19972cs%2Bk6xKKPEz5zUSbslc0X6N0yIICKRyBojj4Z7b4U4RCnxpq90KRU%3D|tkp%3ABk9SR9SL5sfJYg

[Dezza]

The switch could be all cacked up, faulty or you may have a clogged oil pump pick up screen as slayer says. This is accessable by removing the sump.

[ral]

Thanks for the reply’s folks, I’m aware that the switch requires an earth signal to illuminate, funny thing is the switch wasn’t initially making the earth thus no oil light, I put this down to it being covered in what looked like a varnish coating from old dried out engine oil, there was no continuity when checked with a meter, stripping the switch components and cleaning did the trick, maybe it’s too clean

Ive a couple of these anyway so will try changing to see if that makes any difference, it’s only flickering when stationary and ticking over, stops as soon a the throttle is blipped.

Next step is to confirm the wire connection push fit on top of the switch as it’s 40 years oldrest of wiring is all new.

 

[Dennisgs1085]

I had a similar issue, when I removed the switch the brass disc was broken. Fitted a different one and all good. I do have a low pressure guage that connects to the oil gallery on right bottom of cylinders.

[ral]

Changed the switch over and the flickering stopped.

Thanks again for you imput folks.

[bitzz]

On 8/31/2023 at 10:57 AM, DAZ said:

As the oil pressure on these engines is usually very low and ....

The 2 valve GS bikes usually have a roller bearing bottom end, and have next to no oil pressure, 17psi at full chat IIRC

The 4 valve GSx bikes usually have a shell bearing bottom end and DO require oil pressure.

You want 30psi at idle and to gain 10psi for every 1000rpm to a max of about 80psi on a GSx.

[Gixer1460]

1 hour ago, bitzz said:

The 4 valve GSx bikes usually have a shell bearing bottom end and DO require oil pressure.

You want 30psi at idle and to gain 10psi for every 1000rpm to a max of about 80psi on a GSx.

See that's where you are wrong! Only the GSX750s had shell bearings - all the bigger engines retained roller bearings with corresponding low pressures (you'll never see 80psi in any of these)

[ral]

Workshop manual states pressure of above 1.42 and below 7.11 psi, not a lot is it.

Measurement taken at 3000rpm

Edited September 3, 2023 by ral
Actual figs

[johnr]

what oil are you using? mine flickered when i used modern fully synth but when i went back to semi synth or just mineral oil it was fine.