1HZ NA - Low oil pressure ?

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HZ Cruiser

HZ Cruiser

10 Year 15 Year
Joined
Jun 28, 2008
Threads
29
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235
Location
Coquitlam BC
I have a 92 HZ J73. My oil pressure never seems to register any higher than than the first bar on the guage. Is this normal ? Are there going to be major problems caused by low oil pressure?

(For those of you who have read the thread about the oil catch can, my oil pressure wasn't affected when I removed it.)

Here are some pics.

First one at a cold start
Second is climbing a hill
Third is driving on flat ground

When the motor heats up, at idle ,the oil pressure guage reads half of what you see here.

What do you think?
:cheers:
oil pressure cold start(Medium).webp
oil pressure hill climb(Medium).webp
oil pressure flat(Medium).webp
 
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Your readings are slightly lower than mine.
I once replaced ($$$!!!) the sensor and that 'improved' the indication by a needle-width.
So if you want to realy know the oilpressure, connect a mechanical guage parallel to the sensor and compare the 'toyota'-indication against the mechanical. I'm pretty sure there is nothing wrong.
BTW the sender is at the lefthand side of the engine (looking forward), a bit to the rear, just above the oilpan. It's cilindrical and about 5 cm high. It's screwed into the enginebody, the connection is on top (1 wire).
 
All the toyota oil pressure guages do is tell you that you have some oil pressure. - but not an actual psi pressure so don't worry about it.

Mine was actually lower than that and when I replaced it with an autometer I found that I was getting 80 or more pounds at start up, 40-60 at highway speed and about 27-30 at idle.

Your oil pressure is fine, if still concerned add a guage like an autometer - don't forget - the engine shuts down when extrememly low pressure happens.

Louis
 
that button is for unlocking the tranny without having the key turned on.

for factory readings the oil pressure you have shown is excellent... some will read barely above the dead line and still have tons of pressure.

TOYOTA GAUGES SUCK (but then so do some aftermarket)
 
HZ Cruiser said:
I have a 92 HZ J73. My oil pressure never seems to register any higher than than the first bar on the guage. Is this normal ? Are there going to be major problems caused by low oil pressure?

(For those of you who have read the thread about the oil catch can, my oil pressure wasn't affected when I removed it.)

Here are some pics.

First one at a cold start
Second is climbing a hill
Third is driving on flat ground

When the motor heats up, at idle ,the oil pressure guage reads half of what you see here.

What do you think?
:cheers:
Click to expand...

Looks pretty normal to me. My 75 with 220000 klms is about the same and so are all the 1HZ gauges I have inspected.
The petrol engine I had was a little more up and down ,but basically the same

If you can get the engine nice a warmand hold the rpms at about 2500 for 2 mins without the level dropping ,its perfect.
As the other guys said,the factory gauge is just a rough indication.


The danger signs are when it goes skyhigh when cold and falls away to nothing when warm 10 mins later.
This usually indicates worn main bearings.

Usually an oil change will push the pressure up a little on an older engine
My freshly rebuilt 1HZ in the 73 series can push 80 psi(Im glad Ishobies does too as I was a little worried it was too high)

The oil pressure sensor is identical to the ones used on about 30 other toyotas of a similar vintage.(camry corrola,crown,hilux
There are good aftermarket ones available in the $30-$40 range. Dont pay $150 at the dealer;)
 
Ron R said:
Your readings are slightly lower than mine.
I once replaced ($$$!!!) the sensor and that 'improved' the indication by a needle-width.
Click to expand...

The Taiwanese $30 jobs work fine;)
 
roscoFJ73 said:
The Taiwanese $30 jobs work fine;)
Click to expand...

And toyota's ain't worth more.:D
Once I had the new one I opened the old one. Very disappointing what you find inside. 50 cents stuff.
It's just a bi-metal switch, heated by the current coming from the gauge. This switch opens en closes sooner or later, depending on the pressure and amount of current. There is a little adjusment notch in there that you could fiddle with. But once you've opened the housing it's almost impossible to get it together again.
 
Ron R said:
And toyota's ain't worth more.:D
Once I had the new one I opened the old one. Very disappointing what you find inside. 50 cents stuff.
It's just a bi-metal switch, heated by the current coming from the gauge. This switch opens en closes sooner or later, depending on the pressure and amount of current. There is a little adjusment notch in there that you could fiddle with. But once you've opened the housing it's almost impossible to get it together again.
Click to expand...

I doubt Toyota pay their contractors comparatively high Japanese wages to assemble these when thay can go to Taiwan and use a highly skilled workforce at half the rate to do it;)

An aftemarket parts dealer I use says these are made in 8 factories in SE Asia that he knew of and the only bad ones was a batch from Thailand selling for $8 retail:D
 
Get a aftermarket one .. at least one for a test and see how much real oil press you have ..

BTW AT oil Temp come on at more than 300ºF on the tranny ( toasted tranny ! ) and go off around 248ºF ... they usually run around 140 - 160ºF depends on your out temp ..

ATP light indicate that you are in N in your t-case and you can't trust in your parking pawl.
 
Possibly modding the OEM dash oil gauge?

Ron R said:
And toyota's ain't worth more.:D
Once I had the new one I opened the old one. Very disappointing what you find inside. 50 cents stuff.
It's just a bi-metal switch, heated by the current coming from the gauge. This switch opens en closes sooner or later, depending on the pressure and amount of current. There is a little adjusment notch in there that you could fiddle with. But once you've opened the housing it's almost impossible to get it together again.
Click to expand...
You are talking about the dash gauge, aren't you? They are very simple indeed and not very accurate, but very sturdy. Neat thing, discovering that you can actually adjust the bimetal's response. Is there a variable resistor inline with the bimetal heating coil?

It would be very interesting to start a 'mod your low reading OEM oil gauge', as no one seems to have done anything like what was done to improve the OEM temp guage...
 
83bj60 said:
You are talking about the dash gauge, aren't you? They are very simple indeed and not very accurate, but very sturdy. Neat thing, discovering that you can actually adjust the bimetal's response. Is there a variable resistor inline with the bimetal heating coil?

It would be very interesting to start a 'mod your low reading OEM oil gauge', as no one seems to have done anything like what was done to improve the OEM temp guage...
Click to expand...

Yes I'm talking about the in-dash guage.
The setting is done by a notch, not a resistor.
The bi-metal switch 'switches' as it get heated by the current, running through the metal of the bi-metal. (Or a small heating-coil around it, ...cannot remember).
The amount of heating needed to get the bi-metal make the 'switch' is depending on the pressure with which this bi-metal's contact is pressing on the opposite contact.
This pressure is depending on two values.
The first one is the pressure that the oil excerts on a (metal)membrane.
The second one is the notch.
This notch can be adjusted with a small screwdriver. Cannot remember or it was an excentric part or a matter of 'tightning' a nut. To my opinion that's the way to go.
Problem is getting to the notch -adjuster. After opening the sensor it will be hard to get it properly closed (sealing) again because you have to bend away parts of the cap in the process of opening it up.
Maybe drilling a hole in the top of the cap, near the connection point can shed some light on it as where the adjuster is located. Probably a second hole is neccessary then because this adjuster is fairly small.

Some time ago (2-3 years?) I've read about people 'adjusting' the indication by adding a resistor parallel to the sensor.
All this does is providing some current flowing past the sensor. This will give some 'pressure' indicated on the guage, even when the engine is 'off' but the indication with engine on is higher.
This resistor can be placed either near the guage or the sensor. Near the guage, use the post connected to the wire that leads to the sensor. The other end of the resistor to be connected to ground.
Near the sensor, connect the resistor to the post the wire is connected to and the other end of the resistor to the sensor-body which is grounded.
Having the resistor near the guage has the advantage of it being in a more or less guarded area, but involves a bit of work.
Near the sensor is an easy fit, but it then is prone to damage and wear.
Dunno about the value for that resistor. Would start by trial and error with several hundreds (thousands to be completely safe) of Ohm's. Think you'll need 1/2 or 1 Watt.(can start with 1/4 or 1/8 Watt to establish the needed value and later on buy the same value in the havier range if it heats up too much)
Just connect it to the sensor wire at the sensor end, the other end of the resistor to ground (Contact on!) and see what happens. If the indication rises too much take a higher value for the resistor. If too low, a lower value. Make sure the resitor doesn't get hot. If so, take one that can carry a higher load.
 
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WOW! That's what I call 'In- Depth'! I happen to have a spare pressure swicth, I will check it out and see what can be done... But only in a couple of days when I'm finally off on vacation and can't worry about answering calls and such :)

Thanks for the post!!! :beer:
 
83bj60 said:
WOW! That's what I call 'In- Depth'! I happen to have a spare pressure swicth, I will check it out and see what can be done... But only in a couple of days when I'm finally off on vacation and can't worry about answering calls and such :)

Thanks for the post!!! :beer:
Click to expand...

Welcome!
If you go in there, make pictures!!
Looking forward to what you find.
 
Ron R said:
Welcome!
If you go in there, make pictures!!
Looking forward to what you find.
Click to expand...
It may not be easy to modify the sender with an external access port drilled in the can (which would be ideal as it wouldn't require destroying the outside can, which is press-fitted to the internal element), but I'll check it out anyway.

It would be ideal if I had a couple of spare senders to play with, though... Any volunteers? I have a couple of weeks vacation starting in a couple of days :)
 
Just had a play with an old OP sender (OE) as fitted to the 1HD-T(FT) engines and you can,as stated, adjust it to get the gauge to read pretty much what you want.The cover is held on primeraly by 4 tabs which bend back easily but the remaining rim of the cover is swaged over the base unit slightly but a few minutes careful use of some small flat blade pliers will get the cover to pop off relatively undamaged so you can re-fit it and swage over the rim again on completion.There's a rubber seal under the rim which prevents the ingress of water.The 'adjuster' is a small toothed wheel,the surface of which is shaped like a cam and acts on the 2 contacts.Quite easy really.
 
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