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TR2/3/3A Oil Pressure Problem/Puzzler....

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M_Pied_Lourd

M_Pied_Lourd

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Hi guys,

Ok, the first issue I have encountered is a bit of a puzzler...here is the background.

Last night, upon returning from my first little trip in the TR3A to the local gas station, I was alarmed to see my oil pressure at idle...almost NIL on the gauge (around 5/10 lbs). Although this was my first trip, I have run the car at idle up to temperature many times without this much of a noticeable drop...normally the hot idle was around 25 lbs. I have always used 20/50 in the engine. Cold idle on the engine was 50 lbs...would easily climb to 70 with some throttle. Now cold idle is about 30 for some reason.

Now, the engine wasn't rebuilt by me as I was assured by the PO that the engine was strong and my early test starts in the frame seemed to attest to this..

What is odd, is this problem appeared out of nowhere...engine still sounds great with no knocking etc..

So, here is what I have done so far today to try and trouble shoot.

1. Thought the gauge might be faulty so changed it out with the 1 from my 59. I installed the gauge at the Union in the engine bay to take the line running through the bulkhead out of the equation. Blew through the short flexible Union line to make sure it was clear. No change in pressure so the gauge is accurate.

2. Thought the filter might be an issue ( I think I read some filter are not compatible because of a valve issue)...it was a crossland filter...anyway, exchanged that for a new fram filter.

3. During the filter change, I noticed that my new oil was quite dark...I thought I might have some fuel in the oil from my webers although the dipstick level was fine and I couldn't smell gas...I decided to change the oil anyway with new 20/50.

4. While I was doing the filter, I decided to inspect the banjo fitting on the filter leading to the oil line...everything looked fine there and copper washers were in place.

5. Took the valve cover off to inspect the valve train...I was thinking there might be a screw missing in the rocker shaft (known TR6 issue). Everything fine there...

Anyway, after all that...cold oil pressure is only about 25/30 lbs (Again down from the previous readings of approx 50 lbs)


Not sure where to go next....I'm thinking of taking off the lower banjo line and blowing through it to see if there might be a blockage there. Good idea?

What else should I be looking at? Oil pump or pick up? At this point I'm not thinking bearings as this was such a quick occurrence....

You opinions and expertise are appreciated.

Cheers
Tush
 
Could be debris holding the oil pressure relief valve open or a broken oil pressure relief valve spring.

M.
 
Hi Merlin,

Thanks for the reply.

I haven't touched the relief valve at all. I suppose I could take it out and clean it? I'd have to read up on that in the manual...

Doesn't the relief valve only operate over 70 + lbs of oil pressure though?

Cheers
Tush
 
That is why I also mentioned a broken/weak oil pressure relief valve spring as a possible cause of your problem.

M.
 
Roger that thanks. I'll check it out.

Cheers
Tush
 
My first thought reading was along Merlin's thoughts. The pressure relief ball may have stuck open during one of the cold starts. All of my oil filter heads were pretty gummed up, so some sludge may have trapped the ball when you revved it cold one time.

Second thought would be the oil pick-up tube/screen could have come off. The originals were tack welded to hold it. If it falls off, the pump will suck air with the oil, and air doesn't pressurize that well.

Everything else I can think of would be so unlikely as to be near impossible...but I'll keep thinking.
 
Thanks John,

Tomorrows task will be to check and inspect the relief valve.

Do you think it would be a good idea to pull the whole filter housing off? Or, do you think I should just unscrew the set screw and take it out completely to inspect it before going all the way?

After that, I guess I'm dropping the pan :cool:

Cheers
Tush
 
As far as I know, there is no provision in the manual for setting the oil pressure relief valve, although I know lots of people do it. There is a possibility that the valve was disassembled by the re-builder and put back together without setting it. The only way to get around that, at least to my limited knowledge, is to crank the thing down and keep an eagle eye on the gauge when you fire it. Trial and error from there on, I guess. It would be best to swap with another filter and body, if you have or can get one, in my opinion. In my experience, that relief valve is quite trouble free unless someone mucks with it.
Tom
 
Thanks Tom,

When I take it apart, I'm going to count the threads showing above the lock nut so I can return it back to its location. As mentioned, I was happy with the oil pressure previously ...it's the sudden change that has me puzzled.

Cheers
Tush
 
There is an adjustment procedure for the pressure relief valve in the Workshop Manual, ref page 1.134.

But before you get too carried away, you might want to start the engine cold and rev it up to over 3K rpm to see what the max cold oil pressure is and possibly dislodge the suspected debris (if any) keeping the ball from closing.

M.
 
This may not be applicable to a TR3 at all but way back in the day I had a 1951 MG TD - the first of 3 - with low pressure. There was a ball and spring mechanism to regulate the pressure and it turned out I had a "scored ball" which allowed oil to bypass, thus reducing the pressure. I replaced the ball and spring and the pressure did increase but not nearly as high as I wanted. My two later TDs - a '53 Mk II and much later, a '52, did not have that problem. I would replace the corresponding mechanism in your car just to see if that will make any difference. Just a thought.
 
OK Dave, after sleeping on it, I did come up with a couple other areas you can check before pulling the pan ( I hate bottom end work!). If the distributor housing is not seated, it could leave a path for the oil to leak internally. Also, may be worth pulling the distributor just to check the bushings. If the bushings slipped oil pressure would also leak internally.

After that, everything I can think of is internal.

I would think you can easily check the pressure relief valve with the head on the car. The threads for the adjuster are sealed with lead. You can duplicate that with a wind of soft solder. Getting the ball out to check it may take a magnet or blowing air to force it out. The balls do tend to get pretty corroded.

I'll keep thinking!
 
Sounds great John.

I'm taking a break from working on the car today though. I'm in grass cutting/garage cleaning mode today.

I did take a video of my oil pressure at cold start up today while moving the car out of the garage. I'll post that later on just for interest sake.

Cheers
Tush
 
Merlin63Tr4 said:
There is an adjustment procedure for the pressure relief valve in the Workshop Manual, ref page 1.134.

M.
Click to expand...

What manual do you refer to? My Factory Service Manual manual seems to be organized differently. Tom
 
Ok Guys, Good Morning!

Early start to the day today.

Ok, I am relieved to report that I have oil pressure again!

Here is what I did this morning (video to follow).

- removed the pressure relief valve to inspect the valve/spring/ball. Everything looked fine there....there was a little shiny spot on the spring so maybe it was rubbing/hanging...just speculation. I bumped the starter to push some oil up through opening to make sure there was nothing stuck in there.

- removed/inspected/reinstalled the distributor.

So, I'm back to approx 50 lbs oil pressure at cold idle. I'm going to run it up to temperature and check my hot oil pressure.

Now I need to bleed my clutch slave and take it for a spin!

I did find one other issue...I have a silicone gasket for my aftermarket valve cover. It seems to have grown about an inch and doesn't fit well anymore...

Thanks for all the help and support. I really appreciate it. There is always something to learn that is for sure!

Cheers
Tush
 
Glad to hear it's back!

I have one of those silicone gaskets on the shelf. I figured it would be the last one I ever buy...but it sounds like maybe not!?!
 
I have had a Justin Wagner silicone gasket on my TR6 for about 8 years and have had no issues with it...I bought the TR3 one from him as well (gasket innovations). So, not sure what the issue is with this one...i think that ARE does them now...



Cheers
Tush
 
Great news with oil pressure. I assume it idles at 50 and then goes to about 70 as you rev it up. It shouldn't go much higher than that if the relief valve is working properly (mine would go as high as 90 on a cold winter day). Tom
 
Hi Tom,

Thanks. Yes, it goes to about 65 when I rev it to about 3000 RPM.

Cheers
Tush
 
Tom,
The TR4 Workshop Manual section on engine reconditioning page 1-134 has the procedure.
If you have the pdf version look at page 83.

M.
 
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