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Here is my Stock untouched 1985 video of the oil pressure I'm getting and the oil is a month old and needs to be changed. I get almost 70 psi cold and at about 200 degrees water temp at about 650 rpm I'm around 45 psi.
I checked out the oil cooler and clean it out looking for debris... it was clean as a whistle.
Engine's running great. I'm trending oil pressure for the next few rides. Glad I have some of my history too before the swap.
I'm not sure how some guys get such high pressure, maybe something is not stock, maybe HV oil pump or an oil relief valve 's been adjusted.
Here's an interesting tidbit, my oil pressure, (as measured on my dash by my replaced oil sender unit by the dizzy) maxes out at 38-39. I mean at cold idle it's 39, revving it up cold (1800 rpm) it stays at 39. It's was like this before the swap and as far as I can remember. Seems like stock oil pressure relief maxes this out.
Once it warm up, oil around 180 F, then at idle the engine humms at 600 rpm with OP around 18 psi. From there I can rev it up and get 10 psi per 1k rpm. But still maxes out to 39. I'll see how it behaves when I get it on the road.
I plan to measure the oil pressure at the oil temp sender by the oil filter next time I get it up on ramps or 500 miles when I switch to Mobil 1 10W-30.
That's not good. IMO. I think u need, min. 10 psi per 1000 rpm to be safe from Internal Engine Damage. All the bearings ride on a cushing of oil.
YOUR MOTOR MIGHT BE O.K. WITH 39 PSI MAX. IF U DON'T GO OVER 3500 RPM WITH IT
Truly fantastic news about the oil cooler...I had been fearing the worst.
That oil pressure does sound low though, there must be some reason...the plot thickens!
Used to have a 350 fresh with a melling pump that got the same pressure cold, warmwas 15-18 ran itup past 6k alot no issues
That's reassuring, I hear so much conflicting data, the 1989 owner's manual state: "Out of normal range" will occur for oil pressure below 4 psi under 800 rpm, below 28 psi over 6000 rpm.
I am curious as to why I max out around 40 at cold start even when I rev the engine as I mentioned. This must be by OP relief valves - where are they for an '89 coup? I know there's one in the melling oil pump, the oil filter has a relief/bypass valve. Is there another one somewhere?
Also, when I measure oil pressure at the oil temp sensor plug, won't I be measuring higher pressure because it's at the start of things? Would it be best to set it up at the OP sender even though that'll be tough to get to. Either way, can I run the car when I make the measurements (OP sender or temp disconnected)?
My fresh 383 has lower oil pressure (12-15 hot idle) with a high volume pump but no noise and plenty of oil up top. Have you looked in the oil fill on the valve cover while it's running? I'm gonna drop some 15w-50 in next, only because I can only get 10w-40 high mileage readily available locally
I wouldn't be concerned with the idle oil pressure (I have an engine in a drag deal that has those numbers down low and has been in service for 7 years) but if you aren't seeing more pressure than 39 up top I would be taking a look at the oiling system. If it were me, I would be looking for around 10 psi per 1000 rpm minimum. Just my .02
And all this Discussion is Crap for this motor until a mechanical gauge is put on it. The darn dash gauge resistance can be off or just not reading right. It could be 66 instead of 36 and the gauge needs to be installed right where the sending unit goes.
1. check pressure with a mechanical gauge.
2. If it it really low, drop the oil pan and plastigage some bearings.
3. If the bearings look good get a different oil pump.
Its easy to drop the pan. No reason to risk hurting the motor when you can spend an afternoon fixing it.
And the std/std new pump from melling still should produce 60 psi or better if the bottom end is right but when cold it should still be close to 60 psi
my 87 L98 with 101k miles idles at 80 psi cold, and 40 psi hot, it idles at 500rpm using 10w-30 synthetic, got a LT1 Camaro with 205k miles, and it idles 30psi hot at 800rpm
And all this Discussion is Crap for this motor until a mechanical gauge is put on it. The darn dash gauge resistance can be off or just not reading right. It could be 66 instead of 36 and the gauge needs to be installed right where the sending unit goes.
Well said, I'm trying to fix the last of my little problems first (found defective MAF sensor on a bad cold hesitation problem) before I pull the dizzy out again. Looks like I'll have to pull the dizzy, disconnect the oil pressure sender, hook up oil pressure gauge, put dizzy back on and measure pressure.
I like the idea that it could be dash gauge resistance since the oil pressure sender I just replaced had around the same dash reading (within 5 psi). If the mechanical gauge reads much higher, I'll probably be happy but not bother troubleshooting dash resistance, I'd just make a note of my new cals - but I'll cross that bridge when I get to it. I'll report back on this one. I hate seeing old thread problems that get resolved but the thread originator doesn't write up the conclusion.
Its easy to drop the pan. No reason to risk hurting the motor when you can spend an afternoon fixing it.
Not for me, takes me a lot of effort. Maybe if I had a lift, but it takes me about 5 days to pull the pan and check bearings with plastigage. I am quite certain the new ZZ4 engine short block is good - it was really shiny
Seriously, the debris in the oil pump screen didn't get through to affect the old engines main bearings - at least the rear main I checked was within spec and that bearing looked good. (That's when I found my bent piston). I just got the old engine up on a stand - if those main and rod bearings are all OK, its gotta be the sender or dash resistance. But I'm proceeding with the mech oil gauge first.
Kool man. Ilike the Idea that you won't leave all of us hanging on the outcome. You most likely are good with that new motor and the old dash might be the problem.
Post a small phone video of your motors pressure once you get that mechanical gauge mounted
Took the car out to drop off 13 gallons of oil, trans, power steering, and brake fluid - to the waste disposal plant now that it's running well. Some freeway driving and local about 20 miles. It is running perfect except for the dashboard gage oil pressure - still reading 39 cold and goes down to 14 psi hot idle (203 F oil temp).
The oil in valve covers is flowing nicely at idle - I took the pic (and a video) at hot idle at 14psi. - very nice little river flowing. Actually the flow looks very similar at cold 39psi but with the oil thicker.
I'm planning to check oil pressure first at the oil temp port above the oil filter. That'll be easier and it'll be good to have this reading anyway. If the pressure is normal there (a lot higher) I'll go ahead and take the dizzy out to put the mech oil gage on the oil sender port. I guess there will be just a little residual oil when I unscrew the oil temp gage.
I have a nice MP4 video I just took from my android phone but I can't seem to attach it - maybe MP4 isn't compatible with this site.
It's been really hot and humid so I've been slow, but I'll post the reading from the oil temp port within a couple days. I'm so far thrilled that there's a nice river flowing under there at idle 14psi 600 rpm.
Here is my Stock untouched 1985 video of the oil pressure I'm getting and the oil is a month old and needs to be changed. I get almost 70 psi cold and at about 200 degrees water temp at about 650 rpm I'm around 45 psi.
btw : cudamax, thanks for posting your 10 minute video of your oil pressure reading from cold to hot. It's very helpful to have this over the entire time to trend against.
When I watch the entire video, your readings are very similar to mine except mine is 30 psi lower throughout the cycle. Almost like a bias. I'm hoping of course that it'll be a dash problem. I can't believe that if you look under your oil cap (at 40 psi) that you'd see more oil than I see at my 14psi reading - mine sure seems like a little stream.
It seems to flowing nicely. Got to be that old dash and its most likely 69 psi cold and 44 psi hot but just make sure. For piece of mind. Good luck Dude.
08-28-2014, 10:40 AM
