Triumph 1500 Motor Oil pressure question

[77_MG_Midget]

First, for those that read both the Triumph and Spriget posts like me, sorry for the cross post. But, my question may be best answered here, as this is the Triumph 1500 Motor.

Took my 1500 midget for a drive last night. After about 5 miles, I noticed the oil pressure wasn't quite what I thought it should be. Currently running 20W-50 oil.

Cold, it's 70 psi at 3000 rpm, 20 psi at idle. But after the engine warms up good, it drops to 45 psi at 3000 rpm and 12-15 psi at idle.

Engine temp is good at 160-165. The engine is fresh, only 25 miles on it so far after the rebuild. During the rebuild, I put in a new oil pump and pressure relief spring. Crank was cut .010 and the new rod/main bearings seemed to be within spec.

The workshop manual says the oil pressure should be 40-70 at "running speed" (which it doesn't define running speed, so is it 40, 50, 60 mph???) and 20 at idle. So, this made me a bit concerned as mine is lower at idle when hot.

Is this normal? I was reading a thread about making an adjustable oil pressure relief valve. Would this be worthwhile?

Advice is much appreciated!!!!

 

[Guest]

Whew, that is low. Did you stagger your rings?


Bill

 

[77_MG_Midget]

Yes Bill, I was very careful to stagger the rings.

 

[shorn]

You can shim the oil pressure relief spring with a metal washer or two between the spring and the inside of the cap nut. Not sure it will help much at idle speed though as the relief valve should be fully seated at low pressure anyway. It would only help if for some reason the relief valve is not seating properly. Basically the shims just add some extra pressure to the spring and valve.
You might also check to see if you are gushing oil out of the rocker arm assembly. It should only drip out.

 

[aeronca65t]

Stagger rings?!?

I'm going to guess that you are reading the original question as compression psi.....it's actually *oil pressure*.

For the record, my 1500 racer runs at around 55-60 psi "at speed" (it rarely gets under 5000 rpm).
When in the pits, I am running around 20 psi with an 800-ish idle speed. A lower idle speed my register a bit lower (mine can't hold much lower than about 800).
I'm using 20W-50 Castrol (changed with filter about every two hours of use).
My car runs about 160-180 coolant temp (with a blanking plate).
The 12 psi number you mentioned may be on the lower end of acceptable, assuming you have an idle speed down in the 500-600 rpm range.
But overall, I'd say your oil pressure is OK and "within acceptable tolerances".

 

[77_MG_Midget]

Shorn... No, oil is not "gushing" out of the rocker arms. As a matter of fact, it seemed a bit odd to me not to have it shoot all over you like a chevy motor... lol

Aero... I'm getting about 12-15 psi hot at 800 rpm idle.

 

[aeronca65t]

...As a matter of fact, it seemed a bit odd to me not to have it shoot all over you like a chevy motor... lol..

As you probably know, Chevies have hydraulic lifters, so they really need the upper oiling. The 1500 has solid lifters and does not really need that much oil. "Oozing" is fine.
If it were me, I'd tweak the idle speed up just a bit to keep it at 15 psi minimum when hot (but try to keep it below 1000). As long as you're getting over 40 psi at speed, I think you're OK.
And as always, your gauge could be off. Some folks will buy a new gauge (from a place like Northern Equipment) and screw it directly in the block to see what the pressure really is. An appropriate gauge can be bought for around $20.

 

[Guest]

[ QUOTE ]
Stagger rings?!?

I'm going to guess that you are reading the original question as compression psi.....it's actually *oil pressure*.



[/ QUOTE ]

I dunno. On my original engine rebuild, I was plagued by chronic lower than acceptable oil pressure. Finally, we pulled the head and found that all the rings were lined up in a straight line, no 120degree staggering. We honed the bores and installed a set of Deves stainless steel rings, after they seated (about 500 miles) the compression went up and the oil pressure went up dramatically. No other changes to the engine. Go figure.


Bill

 

[Simon TR4a]

My wifes Spit 1500 is at 65 on the highway at 60 mph for several miles, it has an aftermarket oil pressure gauge, idles at about 20 when it gets off the highway, but 30 psi normally at 1000rpm idle speed.
My rev counter may not be accurate at low revs, though it sounds about right by ear, but the engine doesn't like to idle below that .
Simon.