Club Triumph

Hi Guys,

The oil pressure in my GT6 takes 3 or 4 seconds to indicate on the gauge and for the warning light to go out. I've heard this is not uncommon. Anyone know the cause? I'd like to sort it if it's not too much of a big deal.

Regards,

Hi, sorry to answer a query with more questions but: Is this everytime you start the engine hot or cold? And does the engine make any extra noises before the warning light goes out? How many miles has the engine done and has it had a bottom end rebuild in that time? Finally what pressure readings do you get when hot at tickover and 3000rpm?

One other question glang omitted - what brand/spec of oil do you use and when did you last change it?

Another question for you, sorry. Original oil filter or spin-on conversion?

oh dear I think we might have frightened Richard off with too many questions

The way it affects the pressure gauge as well I wonder if the relief valve isnt stuck open.....

Exactly, it would take longer to build up pressure but still give a normal reading once up to speed (presumibly thats the case as Richard didnt complain of low running oil pressure) however without answers to all our questions we'll never get to the bottom of the problem

Sorry guys, haven't been here for a while. I've been a little distracted of late with a new workshop build, sorting the garden and getting my '36 Morris 8 ready for the Shetland Classic in 2020.

But, I'm back!

I'm going to pen a proper response this weekend with answers to all your questions.

Please forgive my tardiness.

Regards,

Richard.

Hi all, and again, my apologies for not being around much recently.

Glang -

Hi, sorry to answer a query with more questions but: Is this everytime you start the engine hot or cold? Yes, unless it's within just a few minutes of switching off. And does the engine make any extra noises before the warning light goes out? If I rev it straight away it sort of rumbles a bit, so I don't do it! How many miles has the engine done and has it had a bottom end rebuild in that time? Engine was a recon short motor from RB about 11 years ago and has done 30,000 relatively trouble free miles. Finally what pressure readings do you get when hot at tickover and 3000rpm? Tickover 10 - 15, 3000 rpm 40psi.

Colin -

Spin-on conversion without oil cooler.

Iain -

Assuming you are talking about a “cold” engine & the oil-pressure switch is working correctly Seems to be both cold and warm (after say 5 or 10 minutes) and the light is backed up by the oil pressure gauge.
The pump is worn out? I hope not!
The bearing clearances are too large? I haven't checked.
Aftermarket external top end lubricator? I don't have one fitted.
Worn out mineral oil? Oils is changed every year regardless of mileage and has had a precautionary oil change JIC.
Magically thin oil? As above.
Oil dilution? As above.When the engine is running with the light off (Oil Pressure light) for a few seconds when you kill the engine and & stopped put ignition back on;
If it does not come on (Oil Pressure light)or goes off when 1 second, your flow is too much. If I've interpreted this correctly then when the engine is cold, the light stays off for a few seconds until the pressure drops off in lline with the gauge. When hot it does the same except much, much more quickly!

Some additional info - on cold start up I get 70ish psi at 1500 rpm which gradually drops to around 40 as the engine warms, finally hitting around 20 - 25 at 1500 once fully hot.

If you need any more info please let me know.

Many thanks,

Richard.

Welcome back Richard. I still think the first thing to check is your pressure relief valve on the side of the block as, although its unlikely to be the cause of the problem, its so easy and cheap to do.

You just undo it, inspect plunger and spring (manual says this has free length of 1.55" and then should compress to its working length of 1.25" when subjected to a load of 14.5lb) and check the former is seating correctly....

Thanks mate.

I'll try and check that tomorrow but it will likely be next weekend as I have relatives coming tomorrow for a few days.

Weekends have been mad the last few weeks but I should be getting back to normal by the BH weekend.

I'll let you know what I find.

Regards,

Cant you get the rellies out there helping you on the car🤣

I really don't think there's anything wrong with the relief valve, given the pressures quoted. And I'd say the bearings are probably in a reasonable state, too.

So back to the original question. If you were running the original oil filter, this 3-4 seconds delay would be considered perfectly normal and a consequence of the inherent design... oddity. I'm not going to use the term "flaw" that so many people throw around without understanding. It's not a fault, just a quirk. Don't thrash it in that first few seconds. But then, only an idiot thrashes an engine from cold or straight from a start, whatever the engine is.

Common "wisdom" is that a spin-on conversion ought to "fix" the slow oil pressure. They don't, at least not always (rarely, in my experience).

True we dont know how Richard has got his filter installed - could be pointing upwards in which case there wont be much improvement over the original set up so explaining the pressure delay....

Quoted from glang-

Cant you get the rellies out there helping you on the car🤣

Ha ha, I'd really rather not! :)

Quoted from glang-

True we dont know how Richard has got his filter installed - could be pointing upwards in which case there wont be much improvement over the original set up so explaining the pressure delay....

Hmm... I'll check.

Just checked the oil filter set up, see pic.

well thats spot on although I see it probably makes getting the PRV off more difficult. However even though, as Rob says, this is unlikely to be faulty, if it wasnt seating properly or the spring was damaged then at low revs it would dump too much pressure but as engine speed picks up and the valve opens normally the pressure becomes as expected. Other than this or possibly a faulty filter I cant think of any other explanations so maybe the best thing is to get along to a meet and compare your car with others there..... 

Quoted from glang-

...so maybe the best thing is to get along to a meet and compare your car with others there..... 

Oh, I see what you did there! 😄

You're quite right though, I should get along to a local meet or two. I have two within shouting distance, one in Bristol (actually right next to where I work!) and another north of Swindon.

I must try harder!

Thanks Glang.

Richard