454 Engine remanufactured Jasper engine low oil pressure

Agree if it really has 20 @ 3000 it’s a warranty issue, make ‘EM fix it.

Jasper is very hit or miss, maybe more miss than hit from what I’ve heard lately. I have seen them with on hole 40 over and the rest std…

need to try to find workable GM crate motor… or build your core.
 
Agree if it really has 20 @ 3000 it’s a warranty issue, make ‘EM fix it.

Jasper is very hit or miss, maybe more miss than hit from what I’ve heard lately. I have seen them with on hole 40 over and the rest std…

need to try to find workable GM crate motor… or build your core.
Don't know how to force them to fix it. It's in a 2000 Motor Home; so, putting in a completely new/different engine isn't in the options list.
 
Switching to a higher viscosity oil to fix a low oil pressure problem is like super gluing your butt shut and declaring that you've cured your food poisoning.

The low oil pressure is telling us there is a problem, but the low pressure itself isnt THE problem.

This poor engine either has a bad oil pump or is hemorrhaging oil somewhere internally where it shouldnt be. Jasper definitely needs to be involved.
I fully agree with your answer, but how to convince Jasper is and continues to be the problem. If the crankshaft can be removed with the engine in place, I could go along with doing that, provided Jasper agrees.
 
Out of the question on a 2000 Motor Home. But that may be the only solution.
If you are not seeing 50psi at 4000 rpm with HOT oil - but are close, just go up to a 40 grade oil like a Mercruiser Quicksilver 25W40. If that gives you 50 revved hot, then you are good.

If not,

Can the pan be dropped with the engine in the vehicle?

A) Plastigage a couple main and rod bearings.

B) Check oil pickup for debris and clearance to pan floor
Check pump bypass or Maybe just install a new std volume pump with the pan dropped.

Hopefully the rebuilder installed the new cam bearings at a true 6 O'clock
 
Also bleed quart out that OP port and fitting to get machining debris out.
Use a mechanical gauge with a hose (plastic line) to insure a proper reading.

Does the engine clatter? Are lifters quiet?

what's the oil pressure on a dead cold start?
 
The 454 HO is not suitable for RV/HD use for many reasons, But the most glaring reason is the rectangular port heads will not match the oval port intake that's installed on L29 454's.

The HT502 is a more suitable replacement.....Though it would need larger injectors & some custom tuning.

The are some NOS L21/LP4 crate engines out there (P/N 19207551), But will require some parts from a/the L29 to make it work (Notably the Timing Cover, Crank Sensor & Reluctor Wheel)

Good point, Rectangular Port Heads are really only better from 5000 rpms and up.
 
Mechanic connected directly into the engine with a digital gauge
Well the only things than can effect oil pressure is bearing clearance,oil pump, extremely thin oil or a missing plug somewhere.

I personally would not use a 5w-30 in something that is worked that hard but that's just my uneducated opinion.

How did they get the engine in place? Did they take out the windshield?
 
In the 80's I worked as an engine builder in a marina with a big on premises machine shop. We built countless big and small block chevys.
The ones that didn't go on the dyno at least got ran on the test stand. We checked oil pressure, temp, timing... Always made sure they were good so we didn't have a surprise after it went in the boat.
It was normal for a fresh engine to have 20 psi at hot idle but they were always better than 10 psi per 1000 rpm.
 
Good luck with Jasper. One of my wholesale customers had 3 5.4 3V engines from them have low oil pressure and tons of valvetrain noise almost immediately. Even worse, they wouldn't pay his labor to change them out.
Also, after he put the one in that I sold him, the oil cooler failed. Ended up with oil in the coolant and coolant in the oil. That was a fun claim.
 
I still think the problem is the oil.
If you buy a GM crate big block; don’t they recommend 20W-50 if the engine is used in a race/hd application??
I’ve never seen a ‘relatively thin’ modern 5W-30 recommended for the 396/427/454 family of engines - they have always been a ‘runs best with thick oil’ design of engine.
Try a good-quality 15W-40 in it and don’t look back!
 
Your thread on 454 BB has me interested in what to do next. That engine was replaced in my 2000 Workhorse MH with a remanufactured Jasper engine. From the start, the hot engine oil pressure is 20# at every RPM between 2K and 3K, doesn’t matter. Idle RPM at 600 and pressure is 10 or less lbs. No break in oil came from Jasper and shop used 5W30 synthetic. Changed after 550 mi with the same type and weight of oil with no effect on oil pressure. Mechanic confirmed instrument panel reading is correct. What type of oil, weight and frequency should I use to improve oil pressure? Any other suggestions or ideas to get improved oil pressure. Original engine (45,961 at time of rod or main knock) operated at least at 40# oil pressure at 2K RPM.
I bought a couple 454 BBCs rebuilt from Promar, a few years ago for a boat. One was reverse rotation. Several hundred hours and several oil changes, with one Blackstone analysis, and all is well. Oil pressure at idle, both 60lbs. After a hard run the pressure at idle drops to 50. Temps run 180-190. Very pleased, the owner was gruff and in a hurry, but answered my questions and offered some break-in advice.
Highly recommended/
 
I still think the problem is the oil.
If you buy a GM crate big block; don’t they recommend 20W-50 if the engine is used in a race/hd application??
I’ve never seen a ‘relatively thin’ modern 5W-30 recommended for the 396/427/454 family of engines - they have always been a ‘runs best with thick oil’ design of engine.
Try a good-quality 15W-40 in it and don’t look back!
Iirc gm recommend 10w-30 for the 396 back in the 60's. Probably sae 30 too.
 
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