Triumph Trident oil pressure...

[StormCrow]

1995 Triumph Trident 900... 14600 miles, oil changed recently for 10w40 semi synthetic.

Been having intermittent issues with the oil pressure light.

First time it came on when starting outside work - dimly lit but increasing with revs. Took bike to local mechanic (by trailer) who put a new crimp on the end of the wire and declared it fine.

About two weeks later, same problem. I replaced the oil pressure switch with a genuine new part.

Fast forward a month, and the light comes on AGAIN. Now it's on 'strong'...

Had a good poke around tonight. When the wire is disconnected, the light goes out, which I think proves that there is no short circuit in the wiring.

Running the bike at cold idle, the switch is outputting about 750ohms at ~2000rpm (obviously not going to rev higher!). Obviously this is enough to turn on the light - I'm not sure if the switch should 'snap' open and closed - anyone know?

This sounds like it's going to be expensive...

Anyone got any suggestions?

[Robby]

For a very basic bodge, try putting in some 20W50 oil and see if that gives you some more pressure.

But really you're clutching at straws - if the light is on, you don't have oil pressure. Hope it's just a blocked pickup.

[StormCrow]

Thanks for the reply

Yeah - I suspect it's going to be internal - either oil pump (plastic splines apparently - oh good) or pickup - the oil pump means splitting the cases which is beyond my level of effort!

Sounds like it's off to the mechanic then - I have a pressure testing kit here but it needs a special adaptor... which is £20... <sigh>

The bit that I don't understand is that the bike is fine - in that the light has been off for a month - ridden basically daily - no funny noises etc - but now it's on again - weird...

[uberkron]

Oil pressure senders fail ya know.
Sounds like yours may have failed, another sender would not cost much, and requires only simple tools to change, the ones fitted to smaller engines dont live as long i have noticed.
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i ride a zip 50 2smoke. It overtakes a hundred times a day.

[StormCrow]

[uberkron]

Ah, sorry. Bad news then,.
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i ride a zip 50 2smoke. It overtakes a hundred times a day.

[StormCrow]

Knowing my luck... probably!

Booked in for collection next Tuesday - got the sinking feeling it won't be good either way... the crank cases need splitting to get at the oil pump, so if pressure IS down, then it'll need stripping and rebuilding just to look at the problem...

[StormCrow]

Verdict is in - the bike is overpressuring.

Typically, the bike's oil light hasn't illuminated while at the mechanics - or at least not abnormally.

He pressure tested the system - it's producing 70psi @ 5000rpm - it should be 40psi @ 5000rpm.

He's suggested dropping the sump and looking at the pressure release valve and pickup strainer. I'm assuming the pressure valve is stuck... if the strainer was blocked then surely it'd have low pressure?

Anyone concur?

I didn't think high oil pressure would be too bad - certainly it's better than LOW pressure, but it ain't right so I'd best fix it!

[StormCrow]

Bit of an update (in case anyone cares!)

Picked up the bike from the mechanic and it's been fine. Haven't touched it - not dropped the sump.

Then... the light came on a-fuckin-gain. Put the bike back in the garage.

Next time I tried it, fine. Rode it to work and back. No problem.

Next time, rode to work (20 miles fast back roads), no problem.

Rode back - a mile from home (and possibly crucially, on a damp bit of road) the light came back on.

Rode it home (if it's fucked its fucked) and disconnected the light. Plugged in a test lead from the battery +ve to the switch - my test light was also on. (again, quite dim/intermittent). Wiring on the bike must be fine.

I've bought another oil pressure switch - but before I fitted it I've had another poke around tonight.

Warm the bike up - no oil light. Then once warm (not necessarily the same temperature - just warmish) the light comes back on. Suggesting no oil pressure when hot if it's not the switch.

I cracked off the top oil feed (to the head) banjo and started the bike - oil pisses out (well, would do if it was loose!) suggesting that there is at least SOME pressure at the head.

So - will get underneath ASAP (won't be ridden) and change the switch.

Reading the Triumph service manual, it says:

[lukamon]

if it is at 70psi then yes, the valve will be open.

think about it. the oil pump has to work at anywhere between 1000 and 15000 rpm on some machines. that's a ridiculously wide margin of operation. think of the pump, pumping oil into a pipe with a hole on one side. there is a flap of metal pressing down over the hole, the pressure inside bends the bit of metal a little bit , releasing oil, which falls into the sump. is there pressure in the pipe? of course, otherwise how could it push open the spring to get out?

tl;dr: the relief valve is open, yes. but that's normal. my money would be on an almost - blocked pickup strainer that maybe pick up and extra bit of crap that nearly seals it, then drops it again. drop the sump
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killa wrote: Im an ass man myself

[Robby]

The oil warning light is to tell you that the oil pressure is critically low, not that you don't have any. Also don't confuse oil quantity and oil pressure - when you crank open a high pressure line, it is no longer a high pressure line so lots of oil will come out.

Low oil pressure when warm points at a worn oil pump for me, and I've had the same problem in a car that had been neglected. Even with a multigrade oil, it gets thinner as it gets hotter. You get more pressure using thicker oil, because it takes more effort to pump it.

Clean the pickup just in case, but I would expect to find either a worn pump or worn bearings that receive a high pressure feed (crank bearings).

A bodge to make the light go out is to use thicker oil, but this is just a bodge and doesn't fix the underlying problem.