Low Oil Pressure; A tale of woe (1 Viewer)

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Brief history: 1986 FJ60 with 2F. I pulled the engine head off because 34K after a full rebuild it was still using oil. I thought it was valve guides. I made arrangement with Jim C. to exchange for an engine head that he built up with bigger valves, .050 decking, some polishing. When I got inside the engine, the #5 piston was scrubbing the cylinder wall orf #5 and #s 6 and 2 were starting. So, I pulled the rest of the engine and took it to a machine shop. They bored it out, installed a new cam, timing gear set, pistons, rings, crank bearings. They did not turn crank; said it looked OK. They did "polish" the crank. They assembled the engine and put the Jim C. head on for me. They bench tested the engine and it had oil pressure when cold (did not actually run it but had some kind of machine). I installed the engine with much travail.

Now installed, the engine runs great but when it gets up to temperature, the oil pressure drops dramatically at low rpms. I noticed this on my second trip to town (less that 100 miles on engine). My Toyota OEM gauge had never done this before. I tried to get a local mechanic to hook up his mechanical gauge but all that was accomplished was for him to reattach the oil pressure gauge wire to the ground tab and subsequently fry the dashboard unit.

So, I buy an el cheapo mechanical gauge at NAPA and install it for diagnostics. Same deal, good pressure cold or hot at high RPMs (50-60lbs) but low pressure at low RPMs (500-600) once it warms up. By low, I am talking 15-20 lbs if you believe the NAPA POS.

I am suspecting too much clearance in crank bearings but don't know much about this. WHat to do? Nothing? New Oil Pump? Tear down again? Increase Oil Weight? I do plan to get my OEM gauge fixed no matter what.
 

Cruiserdrew

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That's normal pressure and behavior. I say you're good to go.

You are way above the minimum spec for both. I think the opening pressure of the relief valve in the oil pump is 50-60 psi-. The minimum idle spec is something crazy low like 4psi, and the minimum pressure spec at 3000 rpm is 37 psi. What oil weight do you run?

What exactly has you concerned?

Just to make you feel better, the 2F in my FJ40 runs 10 psi at idle and 40 psi at 3000 rpm. I used to be concerned, but it has run like that for 10 years.
 
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My concern is that the oil pressure gauge did not drop nearly as much at idle before the recent tear down. If your quote on the specs for low pressure is right, I'm fine and you have made my day! Oh, I'm running 10W-30W.
 

Cruiserdrew

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Even if my memory is hazy on the exact spec, you are still ok by the 10psi per 1000 rpm rule.

I would run a heavier oil though, 15w-40 Heavy Duty would be my choice.


edit-I looked it up.

For the 2F at 600 rpm warm, the minimum oil pressure is 4.3 psi

For the 2F at 3000 rpm 37-75 psi.

Yours is entirely normal and within spec of a new motor.
 
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I'm in the same ball park and all is well...15-20psi@ idle, 50-60psi@ 3000rpm. I just un-hooked my mechanical in favor of the stock setup...no more leaks in the cab from the silly oil lines.
 
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# 1 never let them polish your crankit will never be a perfect surface. Always have it machined or replace. If you intend to rebuild a engine you must remember what a pain in the ### it is to take it out and the put it back in.New part s new surfaces every time and use a PLASTI GAUGE very important.Only do it once.You must pretend like you are a surgeon on your own vital organs when having someone build or building yourself. #2 never rebuild an engine without a new oil pump. Your oil pressure may be within spec but it is better to know that you have done every step right without thought to cost other then finding a good price (shopping around) so if ever you have a problem you will not have to second guess if it was done right. I have built many engines and all have been done by the manuals and using this type of thought process and i have only had 1 be a problem....it was the 1 that the crank was polished and the machinist told me it was good and he ordered the bearings.I installed it all and plastigage it and it all checked out. Ran great for about the first 20,000 miles and all the while i was seeing different pressures that were not like other 22rs that i had built. One day it let go and started knocking....cost me a crank and bearings and a in and out of that rats nest of tubes and wires for a second time and i learned a valuable lesson that day of which i just shared. Good luck with it.....P.S if you did not replace the oil pump when you built the engine that would be my next move. :beer:
 
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I'd be very wary of oil pumps that are not genuine Toyota. I ran one once and the pickup tube was longer than the stock one and because of that, being too close to the oil pan, it would starve the motor for oil as the RPM went up. Same thing happened to a friend of mine. The stock pump can be reused by taking it apart and flipping the gears so that they mesh on the other side. Sounds crazy, but that would be preferable to using the junk that the after market will sell you. Or just pop the cash for a new Toyota pump, but be prepared, they are not cheap. I think you can rebuild a small block Chevy for the cost of one 2F oil pump. Reason number 37 to make the switch, but I digress...
 

FJ40Jim

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What exactly has you concerned?
The reason for concern is that with the same grade of oil, same oil pump, same gage, the oil pressure is reading substantially lower. That means there is an increase in oil bleed-off in a main or cam bearing.

It is within the wear limits, so technically it is OK, but it would be comforting to see improved oil pressure after a rebuild.:meh:
 
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One more thing; I had to shim the blow off valve of my after market oil pump to achieve the same pressure as my 240K mile Toyota pump. That was after cutting and re-welding the pickup tube so it didn't kiss the bottom of the oil pan. Lame. I'd find out what pump is in your motor so you don't go through the same grief that I and my friend did.
 
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how expensive is the oil pump and how difficult to replace it? my new to me 84 seems to show lower oil pressure than my old 87 did. It will start out at 1/2 to 1/3 on stock gauge and get to just below 2/3 when running for a bit or on freeway. So a bit concerned though haven't hooked up better gauge to see what psi are.

sorry for partial hijack!

rob
 

FJ40Jim

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A new Aisin OP is $100.

Easy to replace: drop pan, remove one bolt, disconnect pipe. Reassemble w/ new pump & pan gasket.
 
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A new Aisin OP is $100.

Easy to replace: drop pan, remove one bolt, disconnect pipe. Reassemble w/ new pump & pan gasket.
Thanks Jim! i'll have to get a better gauge to see if i have an issue, but 100$ isn't too bad. Especially if it's that easy. I know the oil pan is likely the toughest part... Hopefully mine isn't stuck on like others... 35k on rebuild so crossing my fingers.

rob
 
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Thanks Jim! i'll have to get a better gauge to see if i have an issue, but 100$ isn't too bad. Especially if it's that easy. I know the oil pan is likely the toughest part... Hopefully mine isn't stuck on like others... 35k on rebuild so crossing my fingers.

rob
i havent looked at the book yet but if your engine has the sneeky pete style rear main seal than do it too. 22rs have a one piece and have to have the trans out to do those but just kep that in mind when you pull the pan ...its a couple of bucks and you are allready in there. (sneeky pete is a tool , small wire with a hook to place through the grove where the rear main seal goes through so you can hook the new seal and pull it back through)
 

Trollhole

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A new Aisin OP is $100.

Easy to replace: drop pan, remove one bolt, disconnect pipe. Reassemble w/ new pump & pan gasket.
At first I thought that was a little high as I bought mine last year in the low $80's. But I rechecked and they have gone up in price. Go figure. Still reasonably cheap assurance for a new rebuild.

I need to go through my links and see if I can find a cheaper source.

ALL-FOREIGN CAR PARTS - Import & Domestic Car Parts, Import & Domestic Truck Parts, Brakes, Rotors, Distrubutors
 
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thanks for the info guys. I'm keeping an eye on mine and will see if needed next time I meet w/ mechanic buddy. I figure we can check oil pressure w/ a reliable gauge and go from there. Might even be one i can do myself! :)

rob

EDIT - and sorry for the hijack!
 

Cruiserdrew

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I put an oil pump in mine and it made no difference in the pressure. It's easy to do, there is only 1 bolt holding it in.

I replaced the rod bearings at the same time. None of it made any difference in the pressure.

For Heartworm-just run it. Put in some heavier viscosity and forget it for the next 100k+ miles.
 

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