Oil pressure saga

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Habitat.pat
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Oil pressure saga

Post by Habitat.pat »

On my newly rebuilt (200 miles) 1600 with Deans U20 oil pump, using a mechanical oil pressure gauge, I get about 35 PSI @ idle & about 75 PSI @ 3k, cold engine or hot. I just wanted an opinion ad to whether I needed to be concerned about this. I’m leaning towards “It’s fine”.

Also, I have newly rebuilt gauges from Jon & the pressure shows almost 90 PSI. I have an aftermarket sender & I’m not planning on trying to fix it, just another note of inaccurate gauges.

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fj20spl311
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Re: Oil pressure saga

Post by fj20spl311 »

general rule of thumb is 10 psi per 1000 rpm
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Re: Oil pressure saga

Post by fj20spl311 »

I would use a thinner oil for more volume, less pressure multi-grade like 10-40W or even 5-30
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Re: Oil pressure saga

Post by DAC21 »

Habitat.pat wrote: Wed May 03, 2023 10:27 am On my newly rebuilt (200 miles) 1600 with Deans U20 oil pump, using a mechanical oil pressure gauge, I get about 35 PSI @ idle & about 75 PSI @ 3k, cold engine or hot. I just wanted an opinion ad to whether I needed to be concerned about this. I’m leaning towards “It’s fine”.

Also, I have newly rebuilt gauges from Jon & the pressure shows almost 90 PSI. I have an aftermarket sender & I’m not planning on trying to fix it, just another note of inaccurate gauges.

Peace, Pat

IIRC Curtis mentioned some time ago that he had a stash of the oil pressure sending switches and not many of them were accurate. Could be a combination of issues.
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Re: Oil pressure saga

Post by SOUPY »

Pat, I also have a 1600 stroker with U20 oil pump and my pressures with a mechanical guage are about the same. I haven't hooked up stock guage yet, but 66 OP guage is adjustable from the back, not sure on half year. Good luck, Paul
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Re: Oil pressure saga

Post by Curtis »

I used a mechanical and then electric aftermarket to verify. My pressure was high at first, maybe 50psi at idle and 70psi at rpm and then switched to 10-40 or 10-30 I think. Pressure settled down to 25 and 50psi. What I read was something like 10psi per 1000rpm.

Both electric and mechanical read the same. I'm going to have my stock converted to mechanical and do like one of the guys here and put a protective sleeve over the tube.

I have 4 new oem type senders and only 1 worked and the two or 3 gauges I tried were all different.
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Re: Oil pressure saga

Post by redroadster »

I'd cut the filter up to see what's in it with the new ( how new) engine , is it oiling up top
good ? , change to 10-30w then , does it change, mech Guage it
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Re: Oil pressure saga

Post by unklpat »

Those are expected readings. I would not change a thing. Reducing viscosity will not increase pressure. Am I wrong? Pat
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Re: Oil pressure saga

Post by Curtis »

My saga involved changes of oil pumps as well. U20 and forklift pumps and learning about the pressure relief valve.

Frankly I don't know about the specs Datsun calls out. Have any of you seen 10 or so psi at idle with a mechanical gauge? My engine is a stroker which shouldn't matter. What is the U20 supposed to have at idle?
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Re: Oil pressure saga

Post by redroadster »

High pressure is sometimes a sign of a spun bearing that's why I'd cut the filter apart & look down the oil cap or pull the vc see if it's oiling good
Yeah it's too high at idle ,...unkipat. if it's 20w50. My bet it is ,he's keeping that secret , it seems . It cannot escape the bearing opening as quick or go thru the filter
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Re: Oil pressure saga

Post by Gregs672000 »

Curtis wrote: Thu May 04, 2023 11:46 pm I have 4 new oem type senders and only 1 worked and the two or 3 gauges I tried were all different.
Curtis, were those stock or the Standard parts aftermarket ones? I had one aftermarket that didn't work either. Did your's not give any signal at all or just inaccurate readings? I still need to replace mine and currently have no guage... trusting that, after 30 years of driving, the oil pump is pretty reliable!
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Re: Oil pressure saga

Post by unklpat »

The main point is OP is using a U20 pump in a R16, more volume without anywhere to go equals more pressure. Pat
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Re: Oil pressure saga

Post by unklpat »

Pat, is that a 1600 or are you using a U20/H20 crank? Pat
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Re: Oil pressure saga

Post by 23yrRebuild »

unklpat wrote: Sun May 07, 2023 1:12 pm The main point is OP is using a U20 pump in a R16, more volume without anywhere to go equals more pressure. Pat
Ahh...that's an interesting point...I've been following this thread from the beginning...My stroker 1600 also uses a new U20 oil pump. I've been scratching my head since last summer, while trying to correlate resistance readings on the sender at various rpms, and adjust and calibrate the gauge, etc...Now, at 180º operating temperature, my original oil pressure gauge and sender, shows 40 lbs at idle and 85 lbs driving, using VR-1 20w50....
I'm leaving it be....it's a lot of time and hassle to mess with it any further...I've got other roadster things to do... :? :roll:
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Re: Oil pressure saga

Post by Curtis »

I was told by our local guru that the high pressure can blow the oil filter apart or cause problems with it.
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