Flickering oil pressure light

[1969Mk3Spitfire]

In the recent warm weather and at idle after a run, my oil pressure light flickers. Idle speed is around 750-800 rpm.

Should I be concerned?

One option is to ignore it. Another is to increase idle to around 1,000 rpm. Another is to measure it and decided what, if any, steps to take from there.

Triumph engineers in their wisdom would have given us a pressure gauge if having such information was useful?

I’m not planning to install a gauge inside the car but I’m tempted to fit one temporarily inside the engine bay. Any recommendations for such a gauge?

[johny]

Oil condition makes a big difference and some makes stay thicker than others. Getting the car running cooler will obviously also help.

Flickering is not good but you could try a new switch.

You could also check oil pressure relief valve can close fully and meets the manual spec (a long shot).

However probably you have worn bearings and/or oil pump so should be listening for any bearing rumble/knock and prepare for a bearing/pump change before any major problem occurs.

I bought a small pressure gauge off eBay which I screw directly into the block in place of the pressure switch once a year to check my oil pressure...

[Chris A]

Is the oil pressure warning bulb filament or LED? I had a similar case and it turned out the LED was very susceptible, I put the filament one back in problem solved. Well, car hasn't blown up yet. That's jinxed it!

[JohnD]

An original oil pressure switch will light the bulb when the oil pressure is less than about ten psi.    That. Might be OK at idle, but means badly worn pump or bearings.

A gauge would tell you what it was at higher revs.   Less than 30 under load isn't good.

As for the factory giving you a gauge!    It wasn't an engineering decision not to fit one, it was a marketing one.  Triumph sold cars for the lowest price possible.   Even the heater was an optional extra!

John 

 

[dougbgt6]

1 hour ago, 1969Mk3Spitfire said:

I’m not planning to install a gauge inside the car but I’m tempted to fit one temporarily inside the engine bay.

and a system of mirrors to see what's going on at speed/load? 

As John says, Marketing vs engineering!

If you're gonna go to the trouble of putting one in the engine bay you might as well go the extra yard and put it in the cabin. 

I like gauges, and lots off 'em, but the essentials are fuel, temperature and oil.  

Doug

 

[Pete Lewis]

the switch swap is the simplest and cheapest test 

they dont last for ever 

Pete

 

[Iain T]

2 hours ago, johny said:

Oil condition makes a big difference and some makes stay thicker than others

Very true, my oil pressure increased by 5-10psi at cold and hot temperature when I used the club oil. I've bought some of Fuzz Townsend oil from Classic Oils for the next oil change. 

Iain 

[PeteH]

"Our" Engines where designed before the advent of multigrade oils. When it was recomended to change the oil grade from Summer to Winter and vice versa. Dependant on temperature. For example, the Herald (1200) Engine had a (recomended) viscocity range from 10W to 30W. An Oil suitable for for your "modern" may not have the correct specification for an Older design.

Pete

[Clive]

A better oil may help, it depends what is in there.

But if the light is accurate, it seems probable teh bearings are worn as others have mentioned. If so new set would see an increase in pressure and extend the time before more serious work is required. A set of main and big ends, and a gasket etc will set you back under £50, a bit over with new oil. Take half a day to do. (and you won't be able to change all the mains, but it all helps. And ypu need to see what size bearings are fitted first, before ordering bearings)

[Badwolf]

I had a similar problem some time ago. Cured it with a mix of.. new pressure sensor, fresh oil and replaced the pressure relief valve. No problems since.

[Chris A]

15 minutes ago, Badwolf said:

I had a similar problem some time ago. Cured it with a mix of.. new pressure sensor, fresh oil and replaced the pressure relief valve. No problems since.

Covered all the possible causes then, apart from doing a complete engine rebuild 😁 you'll never know what the real cause was. How do you sleep at night not knowing which of the changes weren't necessary . . 

I understand the logic though, none of the items being particularly expensive and easy to change plus an oil change is routine anyway.

[Iain T]

It could be a worn oil pump. I assume it's easy to take the sump off then remove and check clearances. If it has too much end float it kills pressure. Don't rely on a new pump being OK measure it before fitting. 

Iain 

[DerekS]

There is a website that covers raising the oil pressure with a quick tweek,

tr6.danielsonfamily.org 

It simply involves putting a thin washer/spacer behind the spring on the pressure relief valve...

 

[JohnD]

As I said, the OE oil pressure sensor only lights the dash lamp at a ridiculously low pressure.    Sensors that give warning at a higher pressure are available, or else adjustable sensors, for instance: https://www.merlinmotorsport.co.uk/p/adjustable-low-oil-pressure-warning-switch-35psi-set-m-ops-35

[NonMember]

16 minutes ago, DerekS said:

There is a website that covers raising the oil pressure with a quick tweek

At the risk of being called argumentative...

That's not good advice. All it does is increase the blow-off pressure of the relief valve. You don't need that. If the bulb is flickering then you're nowhere near the blow-off pressure and the valve is already solidly closed with the standard (or even badly worn) spring. Adding a washer won't help, it'll just line up potential problems for when you do get round to actually fixing the problem.

[Iain T]

Personally I would buy some hose with 1/8npt fittings and a guage. Loads about eg car builder solutions and they are not expensive. You could buy a new sensor and the light stays on, it doesn't identify the possible problem. If the engine has a rumble or clstters about then that's another issue and a rebuild. 

[johny]

41 minutes ago, NonMember said:

That's not good advice. All it does is increase the blow-off pressure of the relief valve. You don't need that. If the bulb is flickering then you're nowhere near the blow-off pressure and the valve is already solidly closed with the standard (or even badly worn) spring. Adding a washer won't help, it'll just line up potential problems for when you do get round to actually fixing the problem.

Yes thats right and the only possible problem with the PRV is that it doesnt close completely so that at low pressures this small amount of oil pressure dumped causes a problem. If only it were the problem🤞

[Pete Lewis]

before you dive into major thoughts of engine wear  do change the LP switch thats the first job 

forget all other clues till you have proven the thing that lights the lamp its s simple spring and diaphragm 

they fail with regular occurance and  a fiver puts the mind at peace 

 

[Chris A]

1 hour ago, JohnD said:

As I said, the OE oil pressure sensor only lights the dash lamp at a ridiculously low pressure.    Sensors that give warning at a higher pressure are available,

I've fitted one that has a higher pressure, 0.8bar, I know it isn't all that high but it makes me feel I'll get a bit more warning of impending doom.

It was the highest pressure I could track down here that was a straight swap. Buying from the UK would have cost way too much, for reasons I won't mention.

[Pete Lewis]

most drivers dont see any warning light till they hear the noise see the steam  small the leak   ....and then have a look 

buzzers bells  horns are a  much more effective warning 

Pete

[Chris A]

21 minutes ago, Pete Lewis said:

buzzers bells  horns are a  much more effective warning 

That's a good point. I know that when driving the Herald, a convertible, there are times when the sunlight makes it look as if the charge and /or oil warning lights are on.

OK then who has done the mod . . .🤪

[Pete Lewis]

there are loads on flea bay 

[Chris A]

Buy 2 get a third free. Great, 1 for the oil pressure, 1 for the charging & 1 for the indicators.

Heart attack guaranteed at every junction and roundabout.

[Badwolf]

Found my spare buzzer last week when I was looking for something else (and need a chuck out!!). Put it in the box for when the original one packed up. That was over 30 years ago. Tandy's best.

[Badwolf]

1 minute ago, Chris A said:

Buy 2 get a third free. Great, 1 for the oil pressure, 1 for the charging & 1 for the indicators.

Heart attack guaranteed at every junction and roundabout.

You would need a bell for one, a buzzer for another. Klaxon for a third and for something really disasterous, you would need one of these..

 

I know that PeteL had something similar somewhere.