TR2/3/3A TR3 Oil pressure normal?

[CraigLandrum]

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?

 

[NutmegCT]

Craig - greater minds than me will chime in, but my first thought would be the gauge itself has a "problem".

Beg, borrow or ... find an external oil pressure gauge. See what that shows at cold idle, 3000rpm, warm idle, etc.

Could also be air working its way through the line, as it's all new, right?

Tom

 

[Perrymip]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Should I be concerned?[/QUOTE]

Those meter readings don't sound even close to what I'm familiar with. I have a cold start normal reading of of 60-70; at warmed-up highway-speed driving the gauge stays steady at 55; after sustained highway-speed driving and dropping to idle, the gauge might drop to twenty, but would pick up again to 50-55 with any acceleration. And I have lots of miles on my engine.

I would be worrying about the oil pump (whether I replaced it or not), did I stagger the rings, does the main oil seal seal: those kind of awful, ugly things.

 

[NutmegCT]

Perry - those are pretty much the readings I get too.

Craig - try an external oil pressure gauge. Need to find out if the pressures are really that "off" - or if it's your gauge itself.

Tom

 

[PeterK]

Did you follow the workshop manual procedure for checking the oil pump clearance? Also take apart the oil filter housing completely and possibly not set-back the presssure relief valve to the original position?

 

[CraigLandrum]

FYI, we have the spin-on oil filter adaptor. Will borrow a pressure guage to verify that mine is working. I sorta suspect it since I recall seeing readings of 70 when we were first getting the engine timing and carbs set up. Are there any external failure indicators - such as leaks - I should look for?

 

[PeterK]

Craig, the spin on adapter attaches to the oil filter housing. There is an adjustment screw that is factory set on this housing. Perhaps, you disassembled this to clean it and didn't turn the screw back in the same number of turns.

But hopefully, it's just your gauge as you suspect.

 

[TR3driver]

FWIW, a cheap mechanical oil pressure gauge shouldn't cost much (I see JCW has a 270 sweep Sunpro for $21) and is a handy tool to have around.

I agree those numbers are way too low for a 'fresh' engine, and are something to be worried about. I've run a TR3 engine that carried that little pressure, but it was in an advanced state of wear. Rod & main bearings were worn into the copper!

 

[emmett1010]

Hi Craig fyi, my fresh engine runs 75 at start up, 55 on the highway, and 25 at idle hot. I'm using Mobil one 10w40. Ambient air is 75, engine temp 160/170.
I have around 100 miles on the car.
When you use the guage to verify your pressure, make sure that the banjo, bolt fitting is not leaking. That would give you low pressure readings.
Best of luck, Emmett

 

[rlandrum]

I would be worrying about the oil pump (whether I replaced it or not), did I stagger the rings, does the main oil seal seal: those kind of awful, ugly things.

Against my better judgement, I opted to re-use the existing pump. I did not check it's internals. :frown: If that's the problem, at least it's something (somewhat) easy to fix.

As for the rings, I was pretty careful, and took my time. I think they are gapped correctly and staggered properly.

The rear main seal was replaced with an aftermarket 1-piece. It looks like it's holding fine. There's very little oil under the car, and what little there is seems to have come from the dip stick.

 

[prb51]

RL,
Mine has the original pump (shows wear) but provides good oil pressure. They are pretty robust units.
I'd start with the pressure gauge test. Odds are everything is ok and you have a plugged/bad gauge.

 

[TR3driver]

Against my better judgement, I opted to re-use the existing pump. I did not check it's internals. :frown: If that's the problem, at least it's something (somewhat) easy to fix.

Seems unlikely to me. I've never had to replace one; all I do during a rebuild is check the clearances as mentioned in the book, and work the body down a bit if needed (again by the book). IMO the relief valve and/or gauge are much more likely suspects.

I've heard that the gauge connection to the filter head can sometimes get blocked, so if the culprit isn't immediately obvious, it might be worth checking pressure at an oil gallery plug or similar.

 

[PeterK]

I've heard that the gauge connection to the filter head can sometimes get blocked, so if the culprit isn't immediately obvious, it might be worth checking pressure at an oil gallery plug or similar.

Good point. It brings to mind the two copper washers that allow oil flow around the front lower oil housing stud where the oil gauge tube mounts.

i.e. there are two copper sealing washers, one inside and one ouside of the banjo fitting on the engine end of the oil line. Oil flows around the outside of the mounting stud and larger id of the copper washer where it is allowed to flow into the hole inside the banjo fitting and up to the gauge. The outer copper washer seals the the oil from leaking from leaking.

If you used two of the same sized washers, you might be blocking off flow resulting in an erroneous gauge reading.

Hadn't thought of that until you jogged my grey matter.

 

[SCguy]

Mine TR4 oil pressure drops quite low once the engine is fully warmed up. 15-20 lbs. It's a new oil pump on a rebuilt engine. Everyone on the forum seemed to think it was too low when I asked the same question, but a local mechanic who owns and has raced his TR4 seems to think it's nothing to worry about (I also talked to the mechanic who did the rebuild) so I'm just going to drive it, enjoy it and see.

 

[NutmegCT]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Mine TR4 oil pressure drops quite low once the engine is fully warmed up. 15-20 lbs[/QUOTE]

Larry - are you saying your pressure at idle drops *by* 15-20 lbs? Or that it drops *to* 15-20 lbs?

Thanks.
Tom

 

[tdskip]

Tom, I think Larry's oil pressure drops to 15-20 lbs once warm...

 

[Andrew Mace]

Mine TR4 oil pressure drops quite low once the engine is fully warmed up. 15-20 lbs....

At what engine speed: idle or 3000 rpm? If at idle, that's not necessarily horrible. If at 3000 rpm, I'd be double-checking gauges and other things to find out what's really happening.

Oh, and what oil weight are you using?

 

[angelfj1]

Don't tell me you didn't replace the oil pump!

Well, no biggie, if the clearances were within spec. After all, that's what its all about. I have seen brand new pumps that are inferior in operation to used ones. So, you might eventually have to measure the pump critical clearances - explained very well in Bentley's, etc.

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

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.

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.

One final suggestion. If you have regulated, shop air available, you can test the oil pressure gauge against the reading on your shop air gauge by connecting it to the air line. Be sure your regulator is set for a value well within the range of the oil pressure gauge. 30 psi is a good start. Then raise and lower the regulator setting and the oil presure gauge vaule should read about the same value as the shop air gauge. I've done this many times and the readings should be close. If you have a bad guage, I may have an extra for you.

good luck,

Frank

 

[TR3driver]

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?

If you're going to start asking questions like that, then I would also ask if the cam bearings were checked & replaced. They don't get as much respect as rod & main bearings, but can also be the cause of low oil pressure. As I recall, there is also a bushing on the oil pump shaft that is frequently overlooked.

 

[SCguy]

My pressure is at idle. It picks up nicely with the RPMs.