Rebuilt 12HT not getting enough oil pressure?? (1 Viewer)

[Gengis]

I guess that the title says it all. I have rebuilt the engine and have set it up to bench run.
I get the correct idle pressure , but it never goes up to the 3+ bar when the revs are increased.Yes, I don't like to rev it too high without a load, but it's still not getting much above 1.5 bar.
I am using a mechanical guage which flicks up quite nicely even with my oilcan providing pressure.
Tested with the turbo and alternator and injection pump feeds blocked and still the same.
It has a new oil pressure regulator piston and spring fitted, and both pump rotors were replaced with new.
The filter is not Toyota, but the Fram equivalent and I have not changed this out yet.
When rebuilding the pump, I made sure that the two rotors were lined up (two marks on the rotors) , but do not recall that they had to be in any particular rotational position, did I get this wrong??
Any clues please folks???

G

 

[duncanrm]

Is it actually pumping oil? Perhaps its just not priming.. have you seen oil squirting out of the pressure sender port if its open?

 

[Gengis]

Ja, it’s definitely pumping, to all the ports mentioned, and enough to give that .3 bar pressure rising to just over 1 at revs where it should be 3 or over

 

[duncanrm]

Do you have the old pressure relief valve spring? Have you done a length comparison.. if there's not some major issue with tolerances after your rebuild then maybe the pressure relief valve is actuating too easily.

 

[Gengis]

I have both the old spring and valve piston, I'll compare them both thanks.

If tolerances are all good, which I believe they are, then what is left, becides the relief valve and or a faulty filter.??
It will be a day or two, I snuck down to the family cottage to avoide the Johannesburg lock down boredom.

G.

 

[dogfishlake]

Probably a long shot but Fram oil filter is a big red flag for me. I like @duncanrm 's idea on the old pressure relief spring too. Makes sense.

Good luck!

 

[Gengis]

Anyone ever seen an " Oil flow diagram" for the 12HT??? Please pass it on if you have one.

 

[himhj60]

The pressure was low and I couldn't get the oil pump gear, so I replaced the entire housing with a new one. The results have improved significantly.

 

[sodafeld1]

If it helps, on my 2h, I have experimented with different lengths of oil pressure relief valve springs with new ones, old ones and cutting both a little , adding shim washers to lengthen. Long aftermarket and short oem valves, the oem valve can get stuck on the 2h. Frigged around a bit.

With a mechanical marshal gauge calibrated with electrical autometer measuring the same, unlikely both would be wrong at the same time.

The spring length and tension gives a dramatic difference in oil pressure. Just one coil cut from a new spring would drop the pressure down by 20+ psi. I found it to be a fine balance,

Also, quality of gauges can make a difference.

Maybe a new spring if pressure is low? Or pack a washer behind the existing spring?

Understandably low pressure would be disheartening.

Wow, new pump! How much did that cost? Nothing like a fresh virgin tho...

 

[himhj60]

If it helps, on my 2h, I have experimented with different lengths of oil pressure relief valve springs with new ones, old ones and cutting both a little , adding shim washers to lengthen. Long aftermarket and short oem valves, the oem valve can get stuck on the 2h. Frigged around a bit.

With a mechanical marshal gauge calibrated with electrical autometer measuring the same, unlikely both would be wrong at the same time.

The spring length and tension gives a dramatic difference in oil pressure. Just one coil cut from a new spring would drop the pressure down by 20+ psi. I found it to be a fine balance,

Also, quality of gauges can make a difference.

Maybe a new spring if pressure is low? Or pack a washer behind the existing spring?

Understandably low pressure would be disheartening.

Wow, new pump! How much did that cost? Nothing like a fresh virgin tho...

I also purchased the longer valves. However, the housing of the oil pump of the engine, which ran 1 million kilometers, was worn out. It was around $500.

 

[sodafeld1]

million k's! that's ok then