Member - Ross replied:

Hi Ray

I'm not a mechanic by a country mile but oil pressure problems are usually low in nature due to the engine being shagged .... old life or whatever.

That being the case I can't see where you could blow the filter off, unless it was completely blocked and the oil pump was doing its job.

CheersFidei defensor

Rosco

V8troopie replied:

Hi Ray,
I did have a 2H motor in my troopie which developed a very erratic oil pressure after about 170k kilometers. I was advised by a very reputable 4WD specialist that it was caused by wear in the pressure reliev valve piston/barrel. What's a new one I asked and was quoted several thousand dollars as the whole front housing had to come off to be either replaced or a sleeve machined for the pressure piston.
I opted for re powering with a bigger motor since I needed the extra grunt for towing anyway.
Leaving it as is was no option since diesel motors do require reliable oil pressure to run well, my 2H was dropping pressure badly most of the time when it started playing up rather than over pressure.
Bad news, these things playing up, I'm afraid.
Klaus

Paul replied:

I bought a 81 petrol Cruiser that had a 83 2H put in it a couple of years ago. The engine control unit was disconnected because of the lack of wiring so I connected the oil sensor for the control unit to a red light on the dash.
I got worried that every time the engine had a good run the this light came on at idle so I pulled the sump of and measured the big ends and mains with Plastigage, they were well within the required tolerances and showed very little wear. I put new big and main bearings in cause I had the thing to pieces. The light still comes on but I don't worry about it anymore. From the dates on the bearings the engine must have got a complete overhaul in about 1994 as they were marked June 1993. I reckon as long as you change the oil regularly the old 2H will go for ever.
Paul

Dave from Fraser Coast 4WD Club replied:

I've never heard of them suffering from over pressure, I was having an underpressure problem at low revs, but that was simply a retun line (inside the block) that had come loose, and was a very easy fix.

Phil G replied:

Most of the "low oil pressure problems" on 2H and 12H-T's were a problem with the sender unit going out of calibration with time. I replaced the sender once and the gauge read normally again, and later on when it began reading low again, didn't bother about it.

I'd love to have a dollar for every 2H motor that has had major mechanical work because the sender has gone out of calibration.

brownie replied:

Ray, I've had the over pressure problem with the 2h motor, and yes it DOES blow the filter off !!
The problem is the oil pressure relief valve at the front of the motor - it wears a little groove in the housing & then jams up. A new valve piston fixed the problem for me, but if this doesn't work then you can either buy a new housing (for mega$) or perhaps get a slightly longer valve piston machined up - this will stop the piston jamming on the groove in the housing.
Regards , Brownie

Nav 80 replied:

Gday Ray,,,The oil pressure relief valve as allready mentioned is very easy to remove. If you get under the front of the vehicle you will see just under the front crank pully a large nut, from memory I think it is about 24mm faceing out to the driver side of the engine. If you undo this nut you can pull out the spring and piston. There is a set length the spring should be but unfortunatly I cant remember what it is but it is listed in the Toyota workshop manual. Check to see that the piston slides freely in its place and replce the spring with a new one. If the piston is sticky,as mentioned it is not so simple and this indicates over pressure. If the pressure is low it indicates the spring is week and a new spring should do the trick. Another problem this valve causes if the spring is week is low brake vacum as the vanes in the vacum pump rely on oil pressure to push them out and seal.