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TR2/3/3A TR3 Low oil pressure [again!]


Jedi Hopeful
A few weeks ago my son and I replaced the oil pump in our TR3 to correct a low oil pressure problem. We replaced the oil (VR1 20-50) along with the oil filter at the same time. When we fired it up, it got 20-25 at idle and 60 at about 2000 RPM, which I considered to be OK, since the guage was previously reading 10-12 for all revs.

After driving it for about 100 miles, the oil pressure is back to being consistently low, and I'm soliciting opinions as to what might be happening. After reviewing some of the latest posts (the one about Tony's bad filter causing zero oil pressure), I am starting to suspect the spin-on filter or the spin-on adapter that we installed when we rebuilt the engine.

I do not suspect the gauge - we actually tested it with a regulated air supply when we were troubleshooting the problem some time ago and it was reasonably accurate - 30 lbs of air gave 30 lbs on the gauge.

The car actually runs fine and oil does seem to be getting up top to the rocker area, but that low oil pressure really scares me.

We do not believe that non-offset ring gaps are an issue - Bob was careful to offset them when he installed the new pistons.

The car does not appear to be dumping oil onto the garage floor, although there's always a couple of drops in that area whenever I check, but I suspect that's fairly normal, and I wouldn't think a leak slow enough to produce a few drops after a drive would be large enough to lower the oil pressure.

The spin-on oil filter that is on there now is the same as we put on originally - its marked as the "high performance" one on the Moss site where we got it.

The oil level on the dipstick seems fine.

So why am I (back to) getting 10-12 lbs of pressure - even at highway speeds?

This is a real pain....


Hi Craig,

I had a similar situation once. Here`s what was happening with mine.

Oil Pressure drop when under load (Dramatically). What I never noticed was the "TEMP" reading which was abnormally high but not overheating to the point of steam, pinging etc.

When the engine was cold or cool; No problems with the Oil Pressure (Normal Readings).

So; I had the Radiator boiled out, New Hoses, Thermostat etc. & The Low Oil Pressure stayed at its normal reading.

This "May or May Not" be happening to yourself but just a passing thought.

Best Wishes,



Jedi Hopeful
Russ- we are running with a brand new radiator, new hoses and thermostat. The car will creep up to 190 degrees or so if run long enough at idle sitting still, but runs right at 185 (needle straight down on original temp gauge) when on the road. I'm not sure if we are running a sleeved or non-sleeved thermostat and I've seen an ad recently for some sleeved TR3 types, so I might pick up one and try it. However, temperature does not seem to be the main factor in all this. Yes, the oil pressure gauge will read a bit higher when the oil is cool, but rapidly settles in at 10-12 lbs.

This almost *has* to be related to something we replaced - oil pump, oil, or filter, since immediately after we installed the replacements, the pressure was great, but declined over a period of 100 miles. That sort of points to the oil pump going bad quickly (probably not), or something wonky with the interaction between the oil, oil filter, and possibly the spin-on adapter.

If I don't get any additional suggestions, I'm going to order a new oil filter of a different brand (like Tony) and see if simply replacing the filter (and nothing else) fixes the problem.

Hey, I know! It's all the ZDDP in the oil clogging up the new filter - LOL. Although to be perfectly sober, that's *exactly* what the effect looks like...


Great Pumpkin - R.I.P
CraigLandrum said:
That sort of points to the oil pump going bad quickly (probably not),
OTOH, several other people have reported aftermarket pumps that fail just like that ... in addition to rotors coming loose on the shaft, I've also heard of outer rotors cracking to both form a big oil leak and put a lot of heat into the oil just as it goes through the pump.


Country flag
The latest VTR magazine has a good article on these pumps, talking about the weakness on the rotor and poor aftermarket products. An attempt to redesign a more robust pump is underway - a little pricey but interesting - I can dig out the contact information if needed.



Jedi Hopeful
Country flag
You might try a A/C Delco PF2123 filter.
I also use the VR1 50 weight racing oil. It seems to work better, with ambient temps running 75 to 95 degrees in Ms.


Darth Vader
Craig, do you still have the old canister housing?

To eliminate the filter as the culprit, you could run the engine briefly with no filter in the canister and see if the pressure is normal.


Jedi Knight
You are getting pressure that low on straight 50 weight??? I would have a look at a rod bearing or two, and perhaps a main bearing as well. Except for a pump failure, the leading cause of low pressure is excess clearance at the bearings. Also, when you rebuilt the engine were the cam bearings changed? They can bleed off pressure as well. I also concur with checking the pressure relief setting at the filter head area. Good luck


Jedi Warrior
Country flag
I would suspect the bearings too. The pressure should be:


50 PSI at idle
70 PSI at speed


25-30 PSI at idle
70 PSI at speed



Great Pumpkin - R.I.P
Mkutz said:
Whats the consensus on the best spin-on oil filters to use to alleviate oil pressure problems?
Can't be an issue on a TR3! The TR3 gauge picks up oil pressure <span style="font-weight: bold">before </span>the filter ... even if the filter is totally blocked and the bypass valve does not open, the gauge will show pressure.

This appears to have been a hold-over from the engines before TS12650E, where the galleries were fed directly from the pump and the output of the filter was returned to the crankcase (meaning no pressure at all).

That said, I've always used Fram filters and never had a problem. (The exact part number has changed several times, think it was PF3600 last time and maybe PF2780 before that.)


Country flag
Fram PF3600 is what came with my Moss spin-on kit and the one I'm currently using.

One question to Craig (original poster)...Was this new pump a replacement for an original pump that showed low pressure, or was this a replacement for a NEW pump that you installed during the rebuild??


Jedi Trainee
Since I have gone back to the Fram PH 3600 all has been well (oil pressure)
I do plan on changing the filter again in a few weeks just as a pre - cautionary measure

I think !!! that my problem was that the new pump cleared out all of the gunk (40+) years developed by just setting about
As I just rolled 38K (original)

Best of luck to you Craig as I know it is a head scratcher


Jedi Hopeful
Pressure is the resistance to oil flow. If the bearing clearances are in tolerance the flow of oil is reduced and oil pressure is increased. As the enigne gets warm then hot,
clearances open up and the pressure will decrease slightly.

If all of the other member posts are checked then bearings are suspect. My TR3A had a very similar issue then finally spun a bearing while driving on the interstate. It had been totally rebuilt as well but it was over 100 deg that day and probably contributed to its failure.



Jedi Knight
All the above is good info. Did you measure the clearances in the new pump before you installed it? If you did and it was ok, i would do the following:

1. pull the pan and check the bearings-rods and center main-check for metal in the pan. you could also get an oil analysis done with the oil you drain- go to the "bob's the oil guy" site.
2. pull the pump and inspect and measure-check for scoring. check the pin. I would replace the pin with a threaded set screw with red loctite on it as per gregg solow stated in Kas kastners books.
3. change the oil filter
4. check the oil pressure releif valve and spring-check the spring rate and the seat the check sits on and the ball.
5. if you have one of those increased oil flow hoses to the head kits, i would go back to stock and check the rockers for excessive wear between the shaft and rocker.

good luck.


Country flag
Sorry to be obvious, but you did try a different Gauge?. I once had a gauge with a loose needle that would give weired readings that would change as the vehicle warmed up.


Jedi Hopeful
The gauge is working fine - no loose needle.
The oil pump that we replaced is of unknown age and condition.
My son replaced all cylinder inserts, pistons, rings, and bearings. Crank was ground and mod made for new-style rear oil seal. When we replaced the pump there was no metal chips or filings in the pan. Will see what effect a new filter has.

Not sure it makes any difference, but we think this is a tr4 engine block.


Jedi Trainee
It is a TR4 engine block.

I checked all the clearances while assembling the engine, and all, except 1, were at or slight under the recommended "New" clearance values. The only exception (the rear main, as I recall), was just slightly over the "New" clearance value, but still well under the "Worn" value.

We had to remove the pan to replace the pump. At the time, I was careful to check for little metal bits and "shiny stuff". I found nothing to indicate a failure or potential failure.

I hand drilled the holes in the rear main as per the instructions sent with out 1-piece rear main seal conversion kit. This is the only area where we intentionally opened up oil passages to reduce pressure.


Jedi Knight
Did you measure the internals of the oil pump? measure all the clearances in the oil pump. Check the end float clearance and all the inter-rotor clearances. did you check this. It's not just a matter of "it looks ok". Does the end plate have ANY wear? does the inside of the pump body have any scoring?
Please confirm
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