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Triumph TR6 - Oil Pressure

I've noticed that my oil pressure tends to drop when cruising. When the motor fires up the pressure is present right away and is around 35 at idle. As I motor around town, up and down the gears the pressure hits 75ish at 3.5 to 4 grand. However when I'm on the highway for a while, running at 60-70 mph (3-3.5k rpm), the pressure drops back to 35-40. Is this common or is it cause for concern?
Thanks. Steve
Steve Crosby

Hi Steve,

Quite normal shows a little on the worn side. As the engine and lubricant warm up even though its multi viscosity the oil pressure will go down.

What oil viscosity range are you using?

Bill Brayford


I had the same problem. Suspect a little wear to be the cause. It helped quite a bit when I did a fresh oil change with Castrol 20/50 as well as replaced the pressure relief valve and spring. 30+ years of heating and cooling did a number on the relief valve spring. Both fixes are easy and cheap to try. The clear givaway on the spring was the fact that three shims behind it substantially improved pressure readings indicating a new one was in order.

Worth a try. I wouldn't worry too much as long as you're not blowing smoke and don't have any rattles at start-up.

Don from Jersey
D Hasara

I'm currently running GTX 10/30. It might be time to switch to a heavier viscosity, and I'll look into the relief valve spring - to bring that up to date. My '74 tends to blow a little smoke when restarted hot. Otherwise no heavy oil use and no smoke in normal running. Thanks for the reassurance guys.
Steve Crosby

Steve - Not just the spring, but plan on replacing the RV plunger/piston too. The one in my engine was quite worn which will keep it from seating well.

Also, 10W-30 is on the thin side....

Brent B


Ditto Brent on the valve/plunger. Replace at the same time as the spring. Total time to replace both - 60 seconds.

Don from Jersey
D Hasara

Maybe Bill can comment on this, but I recall reading some publications out of the U.K. when I bought my TR in '77 that suggested that changing out the main and big end bearings was essentially a service item to be done every 50K miles. The mechanic at the dealersip agreed. I did that at the time, at 55K miles, and again last winter at 96K miles, since the engine was apart anyway. The bearings looked fine in both cases, but I got a bump in oil pressure each time. The original manuals also recommended 20/50 for summer use (is there any other kind?)

A. J. Koschinsky

10W-30!! What was I thinking?? Force of habit I guess. I'll be recycling that today (and locating a new piston and spring). Thanks again for the wake-up. SC
Steve Crosby

This thread was discussed between 25/04/2004 and 26/04/2004

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