"Proper" 3B oil pressure indicator function (1 Viewer)

[amaurer]

I know its not a true gauge of oil pressure, but I'd like to make sure my oil pressure indicator works "properly". I verified my pressure with a mechanical gauge several times, but the dash indicator has a life of its own.

The owners manual breaks down the "idle" region and the "cruise" region, but it doesn't say what, for example, a nice steady hot 90kph cruise level would be.

So where does your needle fall?

When very hot and idling, the needle is very low, maybe only 2mm above L. When hot and cruising, its a little over the 1/3 mark, usually just a hair above the white line at that point. (When cold it'll go all the way up to 3/4 of the gauge or more)

If that is anomalous, I'll replace the sender. So how do all of yours work?

 

[Joe Egolf]

Drew, That sounds just like my readings and I think we are wiithin engine manual specs

 

[AJAEbj42]

Yup, exactly like mine too. 3B with 345000 km's. I've always thought the low mark was the lower end of the operating range and not zero, so I haven't worried about it.

 

[Diesel42]

Mine too. High when cold, low when warm. Delo-15-40

 

[amaurer]

Mine too. High when cold, low when warm. Delo-15-40

I'm most interested in the hot cruise indication. Both because I'm simply fussy, and because I do rely on my stock indicator to tell me if something changes, so I wanna make sure its in good order:

When very hot and idling, the needle is very low, maybe only 2mm above L. When hot and cruising, its a little over the 1/3 mark, usually just a hair above the white line at that point.

 

[Big Blue 84BJ60]

hey all i just replaced my oil pump a month or two ago and before i changed it (old pump) i also have a mechanical oil pressure guage hooked up in the cab to give accurate readings (toyota's stock oil guage for my 3b sucks kohonas) heres what I see
out side temp depending -5deg to +15deg
cold first line/mark 40-50psi
cold 3/4 mark on guage 1200rpm 75+psi
hot runnin 2500rpm shy of the first mark/line 30psi
hot idle down into the L real good 5 psi
brand new oil pump gears (used cover & cressent)
cold idle 50-65psi half over first mark
cold anything over idle 80psi+ up there
hot 2500rpm 40psi+ first mark/over a bit
hot idle 15psi just under white line/on par

 

[Towpack]

Don't know if your sender is like those fitted to the IH series engines but they can be adjusted to give a better range.

https://forum.ih8mud.com/diesel-tech-24-volts-systems/230859-1hz-na-low-oil-pressure.html

 

[lostmarbles]

Don't know if your sender is like those fitted to the IH series engines but they can be adjusted to give a better range.

https://forum.ih8mud.com/diesel-tech-24-volts-systems/230859-1hz-na-low-oil-pressure.html

Now that's interesting tech Phil!

Without removing the sender unit on my B engine - it certainly looks the same as the IH series one. (I haven't gotten in behind it to see exactly how my shell is crimped onto my base.)

But then - I think my gauge tends to read a bit higher than what others here say theirs do. (So I have no need to adjust it.)

(I might take some photos of my gauge needle-positions today - but of course it is a B-engine rather than a 3B which could make doing so irrelevant to others here.)

 

[Eric Winkworth]

Honestly it's pretty much pointless to gauge your oil pressure using that thing.... Mine would change all the time, from working to not working, from high to low, both when hot and cold.... I changed to a mechnical sender... I get 80psi on a cold day off a cold start to about 22 psi on a hot day warmed right up...

Amsoil 15W-40

 

[Towpack]

Honestly it's pretty much pointless to gauge your oil pressure using that thing.... Mine would change all the time, from working to not working, from high to low, both when hot and cold.... I changed to a mechnical sender... I get 80psi on a cold day off a cold start to about 22 psi on a hot day warmed right up...

Amsoil 15W-40

I also had a mech gauge fitted temporarily to find out what the 'real' op was 'cos the OE gauge was so c**p.The mech gauge proved the op was OK (I get similar pressures to those above) so I re-adjusted the sender of the OE gauge to indicate over a wider range.After running both gauges simultaneousy for I while and comparing the readings I was able to 're-calibrate' the OE gauge and know pretty much what the actual op was in psi.The whole point of this was 'cos I don't have a permanent place to mount the mech gauge.

 

[lostmarbles]

Well my "OE oil gauge" has always been consistant in its readings and I have an aversion to fitting aftermarket gauges.

Just took a squizz behind my sender with a mirror and I note that the shell is crimped on without any tabs. -So I think she'd be difficult to open up without damaging the shell (that is, - if I wanted to open her up - which I don't):



I use 15W-40 Valvoline oil and here is my oil pressure at "cold idle":

 

[lostmarbles]

And here are my oil pressure readings under other conditions:



Changed down to third gear from top:

 

[amaurer]

For comparison, here are mine. The scale is very different. Shown below is a HOT cruise and HOT idle.

It is not lost on me that the position of the marks *Does* correlate pretty well with my readings - hot cruise hangs right by the 2nd line, while cold cruise (not shown) hangs right by the 3rd line (I assume the relief valve is opening in that case).

 

[lostmarbles]

......I assume the relief valve is opening in that case........

Here's an image of my oil circuit:



With low oil pressure my "relief valve" would be passing most of my oil to my bearings via my oil cooler.

And with high oil pressure my "relief valve" would tend to be bypassing my oil cooler.

So it doesn't really affect my oil pressure in the traditional way.

And I think this is why Toyota referred to it in some places in the FSM as an "oil cooler bypass valve" rather than an "oil pressure relief valve":



(I know of no REAL "oil pressure relief valve" on my engine - Do you have one on your 3B?)

PS.I note that a lot of information in our manuals (both Toyota FSM and Max Ellery's) refers to our engines as having an "oil pressure relief valve". Yet this oil circuit drawing from my Toyota FSM shows that the valve simply "proportions" oil flow between "going through the oil cooler" and "bypassing the oil cooler". So on that basis it can't impose any "upper limit" on our oil pressure when our engines are cold (when the coolant and oil are at the same temperature).

 

[RedHeadedStepChild]

Waking up a long dead thread with a question

I just replaced the oil cooler cover plate on my 2B.
While doing so, I learned that some of these (mine) never oil coolers, just a coolant filled chamber behind the plate.
I replaced my plate with one that has an oil cooler, but while I was cleaning up the filter bracket prior to install, I noticed it had no valve. I suppose that makes sense since there was no cooler to bypass. Now I'm trying to think through whether or not this will be a problem. If it's not truly used in regulating pressure, it doesn't seem like it will matter, but I wouldn't mind hearing opinions from you all prior to running.

 

[amaurer]

I just replaced the oil cooler cover plate on my 2B.
While doing so, I learned that some of these (mine) never oil coolers, just a coolant filled chamber behind the plate.
I replaced my plate with one that has an oil cooler, but while I was cleaning up the filter bracket prior to install, I noticed it had no valve. I suppose that makes sense since there was no cooler to bypass. Now I'm trying to think through whether or not this will be a problem. If it's not truly used in regulating pressure, it doesn't seem like it will matter, but I wouldn't mind hearing opinions from you all prior to running.

Interesting.

What is your market and VIN/configuration number? Does the EPC properly capture the fact that you have no oil cooler?

 

[RedHeadedStepChild]

It's a '81 BJ44 (-001666) so it has a 2B post August of '80.
I recently put a new head on and this came up a bit during that thread. Which can be read here:
https://forum.ih8mud.com/diesel-tech-24-volts-systems/774486-searching-2b-head-gasket-4.html

Tom (lostmarbles) looked into it a bit, and it does appear that post-Aug '80 B and 2B were sold WITHOUT oil coolers. Not sure why really, but since there is no oil cooler, I suppose it makes sense that Toyota would not bother with the bypass valve. The oil filter mount is machined for it, it just lacks the spring and valve...uh... plug I guess I'll call it.

Anyway, as I'm thinking through this, it seems that it shouldn't be a problem. The pressure in the system should be the same whether oil is flowing through that circuit or not, it may just affect warm-up, though I can't see it having a huge affect.

...unless the concern is that as it sits, the cooler empties and will be pumped full again at start up, which without some back pressure from the valve could starve other circuits until some sort of steady-state is reached.