High Oil Pressure

rfj62

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I noticed that my FJ62 was reading lowish oil pressure, hovering around a 1/4 way up the gauge. I had another gauge so I thought I would do a quick swap just to see if it is the sending unit, also had a extra gauge to try (pressure gauge tester was on its way). Anyway, I noticed when I pulled the rubber boot off of the sending unit that the connector was off of the terminal, so I thought, hey that's my problem. Hooked everything back up and the oil pressure was through the roof, tried 2 sending units and dash gauges, all the same, high pressure. I got my mechanical tester and got these readings, 60 psi at idle and 70 at 4000rpms.
IMG_6144.jpeg
IMG_6145.jpeg


So, according to the FSM it is the oil pump relief valve,
IMG_6147.jpeg


So I got a new oil pump relief valve, spring and plug. (I found it interesting that it is made in the US)
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Is this the only possible scenario? I am going to drop the oil pan and change the valve but I'm a little concerned that this will not correct the problem. I don't want to have to drop the oil pan again for some other oil pump trouble. Any thoughts? I appreciate any input.

Jeff
 

OSS

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For all you know, the oil pressure could have been at that pressure for the last 25 years.
 
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With the wire off the sender it should have had zero oil pressure. Clogged oil filter will drive the pressure up if the sender is before the filter. I thought 60 psi was about right for a cold engine?
 

rfj62

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How many miles on the engine?

Do a top end compression test before you drain oil and drop the pan.
HTH

:cheers:
I will do that next, 295k
With the wire off the sender it should have had zero oil pressure. Clogged oil filter will drive the pressure up if the sender is before the filter. I thought 60 psi was about right for a cold engine?
That is also what I thought. But now when I hook it up and disconnect the sending unit, I do get a zero reading on the dash gauge, so I don't know. Thinking maybe it was kinda connected, barely touching, getting a little voltage or resistance.

For all you know, the oil pressure could have been at that pressure for the last 25 years.
Maybe, who knows. Just don't want to damage anything.
 

rfj62

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Did the compression, results are below. What do you guys think? Also, redid the oil pressure test, 60 psi, when warm and at idle. 70-75 PSI at around 2500 rpms. It pegs the dash gauge.

IMG_6159.jpeg


The first 3 spark plugs seemed pretty gunked up, does that indicate anything.
IMG_6161.jpeg


IMG_6158.jpeg
 
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Compression looks good. At the least I’d go and check the gaps on all 6 plugs. Either reset them to the proper gap or put a new set in if they look really worn.
 
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Your oil pressure is fine, the manual literally says 70 PSI is okay on the next page.

I bet you connected your oil pressure gauge wire to the wrong terminal on the sending unit. You do not connect it to the metal tab on the side - you push the side of the plug onto the little round peg sticking out of the center.
 

rfj62

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Your oil pressure is fine, the manual literally says 70 PSI is okay on the next page.

I bet you connected your oil pressure gauge wire to the wrong terminal on the sending unit. You do not connect it to the metal tab on the side - you push the side of the plug onto the little round peg sticking out of the center.
Ahh, that very well might be it! I did connect it to side terminal, since it was off when I pulled the rubber boot, I didn’t see what it was attached to. (how come that is there)? I did read that on the next page about the 70 psi but the psi’s kept climbing as I was getting up to 2500rpms, 75 psi’s and climbing.

I will move to the right terminal and should be good!

Thanks again!
 
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Ahh, that very well might be it! I did connect it to side terminal, since it was off when I pulled the rubber boot, I didn’t see what it was attached to. (how come that is there)? I did read that on the next page about the 70 psi but the psi’s kept climbing as I was getting up to 2500rpms, 75 psi’s and climbing.
That's normal.
I will move to the right terminal and should be good!
Maybe, but probably not. Usually when you do this, it over travels the gauge mechanism and damages it. What you'll find is that the needle will now sit way below the "L" mark, which it should rest exactly at "L" when off. I made the same mistake on my 62, and I turned the key off basically as soon as I noticed the needle firing upwards. It sounds like yours has been held pegged out for a while, so it's likely very bent up internally.

The good news is that provided the coil hasn't been completely smoked yet, you can take the cluster apart and carefully bend the mechanism back so the needle reads on "L" with the key off.
 

fjc-man

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Why don’t you check the pressure after driving it for a half hour? Engine oil takes longer to come up to operating temperature than coolant ( at approximately 300 degrees ) and the pressure will decrease as its viscosity thins with the temperature increase.
 

rfj62

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That's normal.

Maybe, but probably not. Usually when you do this, it over travels the gauge mechanism and damages it. What you'll find is that the needle will now sit way below the "L" mark, which it should rest exactly at "L" when off. I made the same mistake on my 62, and I turned the key off basically as soon as I noticed the needle firing upwards. It sounds like yours has been held pegged out for a while, so it's likely very bent up internally.

The good news is that provided the coil hasn't been completely smoked yet, you can take the cluster apart and carefully bend the mechanism back so the needle reads on "L" with the key off.
Actually, it was always reading low. So when I started investigating this and connected this to wrong terminal, the Cruiser ran no more then about 10-20 seconds being pegged. So fingers crossed.
 

rfj62

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Why don’t you check the pressure after driving it for a half hour? Engine oil takes longer to come up to operating temperature than coolant ( at approximately 300 degrees ) and the pressure will decrease as its viscosity thins with the temperature increase.
Will do!
 

rfj62

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That's normal.

Maybe, but probably not. Usually when you do this, it over travels the gauge mechanism and damages it. What you'll find is that the needle will now sit way below the "L" mark, which it should rest exactly at "L" when off. I made the same mistake on my 62, and I turned the key off basically as soon as I noticed the needle firing upwards. It sounds like yours has been held pegged out for a while, so it's likely very bent up internally.

The good news is that provided the coil hasn't been completely smoked yet, you can take the cluster apart and carefully bend the mechanism back so the needle reads on "L" with the key off.
Yep, you were right, the gauge is toast. I tried bending it back but can't get it to zero. Luckily, I had an extra gauge. It was definitely the old sending unit giving me low pressure, fixed with a new one.
IMG_6166.jpeg


I drove it around an hour and checked the pressure with a mechanical test again, I got 52psi at idle and 65-70 psi at 2500 rpms. I'm still not use to seeing the oil pressure this high at idle, all my other 62s read around 1/3 on the gauge when idling, then went to around 2/3 when driving under load, instead of being at 2/3 all the time. I guess it's better than having low pressure. Thanks again. Next stop temp gauge barely moving.
 
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Your oil pressure is fine, the manual literally says 70 PSI is okay on the next page.

I bet you connected your oil pressure gauge wire to the wrong terminal on the sending unit. You do not connect it to the metal tab on the side - you push the side of the plug onto the little round peg sticking out of the center.

Ahh, that very well might be it! I did connect it to side terminal, since it was off when I pulled the rubber boot, I didn’t see what it was attached to. (how come that is there)? I did read that on the next page about the 70 psi but the psi’s kept climbing as I was getting up to 2500rpms, 75 psi’s and climbing.

I will move to the right terminal and should be good!

Thanks again!
Anybody by chance have a photo of the sender's two connection points? My shop had to replace the sender because the wire failed on the original. Once installing the new one, the pressure gauge pegged. The presumption is that the new sender is faulty. After reading here, I'm not so sure.

@rfj62...I just did a test of the pressure with an external test gauge and found pressure at about 60psi at idle and up to almost 70psi at 2500 RPM. This is confirmed on the additional under-dash aftermarket oil pressure gauge I've added. So, I'm not sure either of us has a problem, per se.
 
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Thank you. Now how tough would it be for Toyota to provide proper directions?

I just went over and took a look. It is connected to the side connector. I started up and watched the dash pressure gauge. It started coming up, but not like a rocket...and I shut it down before it could peg. I have a feeling it's not fried. It will be disconnected until we figure this out.

By what means does one connect to that center post? What connector or interface? There is no plug, but a bare wire onto which we need to put some kind of plug. Perhaps this is also a question for @Lead Head
 
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