TR2/3/3A TR3 Oil pressure normal?

[NutmegCT]

Just finished a complete restoration on a 1959 TR3, with a rebuilt TR4 engine running new 2100 (I think) liners and pistons. Using valvoline VR1 10w50. Cold start idle at 1100 rpm shows about 40-50 on oil pressure guage. At 55 mph, guage shows 15-18, and this has me worried. At lights - warm idle - pressure drops to 10 or less. Car is running fine, oil is clear, and filled to just below full mark on the dipstick. Should I be concerned? If so, where should I start looking?

Good morning!

How 'bout an update ... have you tried another (or external) oil gauge yet? Any other diagnostics as suggested?

I'd hate to pull everything apart if the problem was just a bad gauge.

Thanks.
Tom

 

[rlandrum]

I will assume that you have checked the obvious:

oil level in sump
oil viscosity , 10W-30, 20W-50, etc.
bad oil pressure gauge or bad connection/line
worn oil pump

We have checked the level and it appears to be correct. It reads as 1/4 inch below the Max Fill line, and about 1 inch above the Min Fill line.

The viscosity is 20w-50, Valvoline VR1. No other oil was bought or used.

We suspect it may be the line. We assumed the puddle of fluid on the driver side floor mat was from the brakes overflowing. Now we suspect it may be a leaking guage connection.

I didn't check the pump. Everything else in the engine was in excellent condition when it was rebuilt and I assumed the same of the pump.

Since I don't know the level of your engine rebuild let me ask some otherwise elementary questions.

1. was the crank checked and reground and fitted with new main and rod bearings?
2. if yes to no. 1, after reassembly did you plastigauge the clearances? Did you record these numbers.

1. Yes. A regrind was not needed, however a mild polish was performed. New main bearings were used.

2. I plastigauged everything, and while I don't have the numbers on-hand, they were all within the clearances specified in the Bently, with one exception. The rear main was just slightly larger than the suggested new clearance, and I attributed this to the fact that it had been turned and polished to fit the 1 piece rear main seal. However, I do not believe this to be the cause of the low oil pressure.

Something that is often overlooked is the oil pressure relief valve which is located in the head of the oil filter assembly. Inside the head is a simple spring-ball valve arrangement. If there are problems with wear in this mechanism it is possible for the valve to open at too low a pressure. The valve is adjusted by loosening the locknut and rotating the screw clockwise to increase or counter clockwise to reduce pressure. If you can't get enough improvement by adjusting the valve you may have a corroided ball and/or weak spring. Both are available and easy to replace. You can test the valve with a known good oil pressure gauge. Start the engine and get it up to operating temp. Slowly increase engine revs to 2000 rpm and observe the gauge. Pressure should rise steadly to 75 psi and at 2000 rpm pressure should fall off to 70 psi.

Indeed we have overlooked this final step. We'll be working this weekend to determine the nature of the fault.

 

[angelfj1]

<span style="font-family: 'Arial'">Good luck Rob. Please keep us posted.</span>

 

[TR3driver]

I'd hate to pull everything apart if the problem was just a bad gauge.

I'll ditto that!

Many years ago, the wife called me while I was overseas and reported that the oil pressure gauge on her Chevy would rise just a bit after starting the car and then fall back to zero. She said there were no bad noises or smells, so I told her to drive it gently to a nearby garage that I <span style="font-style: italic">thought </span>was competant. They reported that the bearings were shot, and since the car was not worth the cost of rebuilding the engine, recommended that she start shopping for another car. Since they didn't try to sell her anything (didn't even charge for the inspection), I assumed they were honest.

So, the day after I got home, I dropped the pan. Bearings were fine as could be expected for an engine with that many miles; but the oil pump pickup fell off when I removed the pan. Aha, sez I, that was the problem.

So, I Loctited the pickup in place, replaced the main & rod bearings, buttoned it all back up. Started it up, exact same symptoms! It had been a faulty OP sender all along! :hammer:

 

[CraigLandrum]

Update after working on the car today (Apr 18th):

Bought a cheap oil pressure gauge and it gave the same readings as the original. Disconnected the original dash gauge and hooked it up to the shop airline with a regulator. 50 lbs on the regulator gave 50 lbs on the gauge so we think the original gauge is good. Next we disconnected the oil pressure line at the banjo fitting on the oil filter mounting and forced carb cleaner through the tubing from the top - no blockage and cleaner ran out freely at the bottom. OK, gauge and tubing are now known good. Checked the banjo fitting and believe we have the correct copper crush washer nearest the engine, then the banjo, a steel washer, then the capping piece. All looks OK. We then decided to play with the pressure relief adjustment screw and screwed it down 5 or 6 turns - no effect on the gauge at all that we could detect.

With the car on a lift, there appears to be oil leaking from *somewhere* - perhaps the rear engine seal (oh no!), but the volume was not great and the oil level appeared OK via the dipstick.

While the problem *may be* a flakey oil pump, we aren't sure. Am planning on ordering a new one to see if that helps.

There is a bolt hole (currently unoccupied) at the very bottom of the transmission, all the way forward, but it doesn't appear to be leaking and I can't see anything that bolts to this hole (its threaded with no bolt currently installed).

Any recommendations as to where we go from here?

 

[Merlin63Tr4]

Craig;
I suspect the cause is a worn oil pump. On my '63, when I bought it, the oil pressure would not rise above 50 psig. I dropped the pan and the bearings checked out, but the oil pump clearances were three times the max allowed. I replaced the gerotor assembly with one from TRF and the pressure went up to 70 psig. Life has been good ever since.

 

[CraigLandrum]

Just ordered a new oil pump that I hope to install next weekend. Will report back on the results.