PZJ77 Low Oil Pressure Reading

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Oct 28, 2013
Thanks up front for any assistance. I have a 1991 PZJ77. Just thinking that I really need to supply a bit more info than I have handy but I'll grab it and update. The PZj77 is a 5 cylinder diesel. It runs amazing!! Starts cold with not even a full crank and doesn't smoke at all. My problem is that the Factory oil pressure gauge reads VERY low and there is an after market that reads only slightly higher. At Idle the aftermarket is around 15 psi and the factory gauge is pretty much at the bottom line. When idling at 2,000 RPM the aftermarket gauge moves to 46 psi and the factory gauge moves to slightly under 1/4 of the way up. I'm just wondering if I should be worried. Last week I changed the oil only (didn't have my filters in yet) just to see if maybe the viscosity of the oil had possibly broke down, but that didn't change anything. I am running a diesel grade 15w40. ANY help would be greatly appreciated.

Here is a youtube vid I uploaded: All

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Here you go.

Your oil pressure is fine. The factory gauge is notorious for reading low.


Thanks a ton for the help! I need to locate some manuals for that guy. Thanks again. Your help is appreciated.

BTW, sweet ride you have. I would love to get one of those imported.

I've owned a BJ71, BJ74, LJ78 and now a 77 Series and the oil pressure has read relatively low on all of them.
This photo is idling, hot.
When I replaced my oil sender, my gauge readings increased.
I am still going to add a mechanical gauge.
Thats where mine sits too. I think it's normal for these. Did my BEB for the heck of it and they were immaculate after 200,000km, so must be good enough.
My 2L-TE actually had the lowest readings (the needle just barely moved at idle and never got above 1/4 scale at road speed)
I installed a manual gauge and the oil pressure turned out to be excellent.
Ill have to take a pic of mine, im a little below and a little above when pushing 3k. I dont get as low as the pics charles posted.
Ill have to take a pic of mine, im a little below and a little above when pushing 3k. I dont get as low as the pics charles posted.
I make up for the low readings by added a little oat mill to the oil system. :)
i realize how immaculate your cluster glass is..... i havent cleaned mine since moab... she needs a good cleaning
2000 rpm
close to 3k.... doesnt really go up much more than this

Your first picture at idle is with a cold engine? With thicker cold oil your pressure will sit around where the picture shows, but with a hot engine at idle usually it will sit lower. Your other two pictures seem to match the average 70 series readings.

Out of curiosity, your trip meter reads 762km or so. Was that on one tank of fuel? If so, nice. I only see that under the most ideal highway conditions in my LJ78.
idle when cold yes. 15-40 oil. Re trip, no, its on the aux tank, i normally switch at 475 per tank, dont like going completely empty. Hits E at about 500 kms, so have 1000kms of fuel. Sucks when you are waiting to pee "when you stop for gas"

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