Oil Pressure ?

[turbocamino]

   I recall my old Kaw Z1/KZ engines had a about 5psi hot even with 20/50 oil... we were killing turbos weekly until we switched to Castrol Syntec. The Suzuki GS stuff was much better. Anyone know what type oil pressure our FJ's have hot/cold?

[chiz]

WAT 5psi Man T150 and rocket3 owners would loose their mess if they ever saw this on their OPG.

[Old Rider]

   I recall my old Kaw Z1/KZ engines had a about 5psi hot even with 20/50 oil... we were killing turbos weekly until we switched to Castrol Syntec. The Suzuki GS stuff was much better. Anyone know what type oil pressure our FJ's have hot/cold?

it should be about 50 to 65 psi on the oil-cooler circuit and 65 to 85psi on the main galley circuit not sure if it that numbers is on cold or hot engine but i guess operating temp

[turbocamino]

Wow,thanks..didn't expect anything close to that..are you sure?

[Old Rider]

I did check a workshop manual i have ,but the pages about oilpressure was missing (of Course)  =) i checked earlier when i rebuild the engine a couple of years ago. But  i have a haynes manual too and here is a picture from that manual specs they are alomst the same ,but i think it is something wrong in the haynes since it says relief valve opening pressure

[fj1289]

The by-pass valve opens to "by-pass" the oil filter if it is hopelessly clogged.  The idea is to wipe out the bearings with dirty oil vice wiping out the crank and rods with NO oil!

The relief valves are the small cylinder shaped items in the main oil galley in the engine case and the oil cooler galley in the oil pan.   You can disassemble these to add a washer on top of the spring to increase the pressure.   But then you need to consider restricting flow to the mains and rods to ensure the cams get the additional oiling. 

[fj1289]

I should also add - the relief valve pressure is the maximum you could see.  I don't think it is anywhere close to that - especially with hot oil - and especially at or near idle.    I remember talking with Randy a good while back about monitoring oil pressure.   His response was something to the effect that it would be lower than you think and would only worry you.   So I pretty much take the FJ oiling system on faith!

[aviationfred]

I actually have an Oil Pressure sensor on Casper. I installed the sensor in the Oil galley port on the left side of the engine, just below the ignition cover.
On a cool morning start up with full choke, it will read upwards of 80psi. Once warm and choke off, it will read about 55psi while riding at 70mph. At idle it will drop down to about 5psi.

1st photo shows the sensor location,
2nd photo shows PSI at a cold start idle
3rd photo  shows PSI warm at idle



Fred

[fj1289]

Thanks for the number Fred!

[RPM - Robert]

Yup. We had a lot of engines built and put into race cars, or people just buying a legends or roadster and they would call worrying about the psi being 5 or less lbs once warm.

[turbocamino]

70psi swing is considerable ..once the pump is spinning its certainly doing a job.  Thank for all the info.   I feel better about moving away from thick oils now.

[Motofun]

When starting up a cold engine, Do you blip the throttle up to about 4k rpm every couple of seconds?  I do this just to make sure higher pressure oil makes it to all the right spots.

[turbocamino]

 No..my theory on a cold start would be go easy until cold oil circulates some.  My choke dictates all that,,which is about 1500rpm.

[fj1289]

No..my theory on a cold start would be go easy until cold oil circulates some.  My choke dictates all that,,which is about 1500rpm.

Agreed!

[RPM - Robert]

I'll third that. There is a reason the oil pressure is so high on a cold start. It is because the oil is thick. I would venture to say that revving the motor when cold would not allow the thick oil to flow where it needs to as quickly; even with the higher oil pressures, thus starving the bearings and such for oil and causing early wear for no reason.

I am not this anal but we used to race with a guy that would start his Chevy duramax and let it idle for 30 minutes before he even put it in gear to move it. He had close to 750,000 miles on the original motor but I don't know that letting it idle for thirty minutes (certainly not an air cooled motor) is that beneficial. But then again that was before diesel was $7 a gallon here in the Kommiefornia.