454 Engine remanufactured Jasper engine low oil pressure

Knowing the cause of low oil pressure before any long trips would be advised. The suggestion to plastiguage the bearings would be a start. Of course measuring the journals is best but I`ve used the plastiguage with no problems.
 
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.


Exactly ^^^^^

Jasper motors = good boat anchors...
 
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!

All "light duty" Big Blocks call for 5W30/10W30.....Even a fully loaded (GCRW) C3500. 550 miles wouldn't thin a 5W30 that much....Besides the low oil pressure continues with fresh oil.

If the engine can't achieve 10 PSI per 1000 RPM with fresh 5W30......Something is VERY wrong. In fact if I see under 20 PSI at hot idle on a fresh build, The Oil Pump is coming out to be inspected/replaced. If that doesn't correct the oil pressure....The engines coming out & will be gone over with a fine tooth comb.

GM is notorious for using slightly oversized main bearings (+.001"/+.002") to make up for inconsistencies in the machining process. If one simply polishes the Crank & slaps Standard Bearings in without checking clearances.....Low hot idle oil pressure will result.
 
All "light duty" Big Blocks call for 5W30/10W30.....Even a fully loaded (GCRW) C3500. 550 miles wouldn't thin a 5W30 that much....Besides the low oil pressure continues with fresh oil.

If the engine can't achieve 10 PSI per 1000 RPM with fresh 5W30......Something is VERY wrong. In fact if I see under 20 PSI at hot idle on a fresh build, The Oil Pump is coming out to be inspected/replaced. If that doesn't correct the oil pressure....The engines coming out & will be gone over with a fine tooth comb.

GM is notorious for using slightly oversized main bearings (+.001"/+.002") to make up for inconsistencies in the machining process. If one simply polishes the Crank & slaps Standard Bearings in without checking clearances.....Low hot idle oil pressure will result.

While I'm no engine builder, I couldn't agree more. From the very start, I was taught that 10 PSI per 1k revs hot was considered the minimum acceptable number as a rule of thumb.

For a freshly built engine to have that low of oil pressure... especially a GM big block... screams poor tolerances. As big a name as they may be I can almost guarantee that Jasper isn't line honing these cores, they aren't doing a true magnaflux, they give the cylinders a quick stone hone, no new cam bearings and on and on.

You're better off grabbing a JY motor and giving it a quick once over than trusting Jasper.
 
Jasper said it's within their tolerance. Not a good answer to me.
Is it within GM's tolerance? Forgot to ask, do you have a direct reading, accurate oil pressure gauge?

If you plan on keeping the engine, consider a quality high volume oil pump. And/or consider using Mobil 1, 10W-40HM oil.

Clearly, something is not right. If nothing is knocking, I'd first guess that the oil pump is insufficient.
 
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.

Does your 454 have an external engine oil cooler? If it does, I think there is a different filter bypass valve that is supposed to be used than if the engine did not have an oil cooler. I am not sure if this would cause low oil pressure or not, but it seems like something that could be easily overlooked with a replacement engine.
 
Still haven't heard from the O.P. if the pan can be dropped with the engine in the motorhome - or slightly lifted to gain clearance to drop the pan.

We can guess all day - gotta take a look if possible
 
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.
Hey Red Spider,
Off hand, would you know if an oil pressure relief valve could be the issue? Thanks, RAB TX
 
Does your 454 have an external engine oil cooler? If it does, I think there is a different filter bypass valve that is supposed to be used than if the engine did not have an oil cooler. I am not sure if this would cause low oil pressure or not, but it seems like something that could be easily overlooked with a replacement engine.
I'm also wondering along the same line. I do not know if it has an oil cooler. Need to find that out. I did see that there could be 2 oil pressure relieve valves. My one question about that as the being the problem is that it gets up to 60psi on a cold start, and doesn't drop too fast until it get to operating temp. If you have an idea or answer to that question, let me know.
Thanks for the help Rob_Roy,
RAB TX
 
Still haven't heard from the O.P. if the pan can be dropped with the engine in the motorhome - or slightly lifted to gain clearance to drop the pan.

We can guess all day - gotta take a look if possible
Agree if it comes to that. Looking at an oil pressure relief valve issue first as that's the easiest fix.
 
+1

Jasper has never been known for quality, but have been the go-to for many shops because of pricing. I remember a lot of issues in the Jeep community with their rebuilt 4.0 engines. They would come with all different sized bearings, clearly worn pistons, scored cam bearings, etc. It was like they took their cores and just spray painted them, put them on a different pallet, and shipped them out. Embarrassing.
I'm hoping none of that is the reason. I've also heard from others that Jasper isn't the top quality supplier of remanufactured engines
 
Just hope you don't have my sort of luck.... 3 Jasper engines in less than one year. They seem to have quality control issues.
Yes....Jasper ain't what they used to be. Back in my Midas days, (2014) we had a customer who we installed a 4.0 liter into his Jeep XJ. Twice. We took the 2nd one apart before Jasper picked it up and found 2 cylinders with original bores, and 3 undersized rod bearings, and 3 standard sized bearings. They're shoddy rebuilds at best. The customer had been coming to our Midas for years, and was very meticulous. He did everything correctly in regards to break-in. The Jasper engine was just trash. Cost cutting measures, I'm sure.
 
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)
Hi clinebarger,
The workhorse chassis from National came with a 454 7.4 L engine. I don't know what a "454 HO" is. Jasper shipped a complete 454 engine, not a short block. The installation shop reused the injectors from the original engine. There is no crate engine involved; so, I don't think a L29, whatever that is, is going to be involved as well as the timing cover, crank sensor, or reluctor wheel since the engine runs and has about 1200 miles on the Jasper engine.
RAB TX
 
Yes....Jasper ain't what they used to be. Back in my Midas days, (2014) we had a customer who we installed a 4.0 liter into his Jeep XJ. Twice. We took the 2nd one apart before Jasper picked it up and found 2 cylinders with original bores, and 3 undersized rod bearings, and 3 standard sized bearings. They're shoddy rebuilds at best. The customer had been coming to our Midas for years, and was very meticulous. He did everything correctly in regards to break-in. The Jasper engine was just trash. Cost cutting measures, I'm sure.
Thanks for the additional info. I'm really hoping it may be an oil pressure relief valve issue. That' easily solved.
 
Thanks for the additional info. I'm really hoping it may be an oil pressure relief valve issue. That' easily solved.
I think the oil pressure relief valve is on the oil pump body. If the pressure relief valve is faulty for any reason, change the pump. I'd choose a high volume pump with at least 25% more flow.

It is nice to think these engines don't need high volume pumps. However, it's entirely possible that this is exactly what is needed. That's why they are so popular.

Keep in mind, the engine should have adequate oil pressure on normal conventional oil, but there are any number of non critical reasons why the pressure could be low on an overhauled engine. An oil pump that is low quality, or "overhauled" is suspect number 1. Even excess connecting rod side clearance can affect oil pressure, without affecting longevity one bit. Excess lifter side clearance, higher than normal flow in the lifters, etc. A couple of issues could really be terrible, like the wrong main bearings, or a missing or drilled oil gallery plug.
 
As big a name as they may be I can almost guarantee that Jasper isn't line honing these cores, they aren't doing a true magnaflux, they give the cylinders a quick stone hone, no new cam bearings and on and on.

You're better off grabbing a JY motor and giving it a quick once over than trusting Jasper.
I have a feeling Jasper and Cardone hire off the street for minimum wage and have little or no training. Not an engine builder - even I know critical clearances must be checked. But it takes time, tools(Plastigage, dial gauges) and training(how to read a dial indicator or Plastigage) to do that.

Those workers at Jasper and Cardone from what I’ve read here simply clean, assemble from “good” parts, paint, package and call it a day.
 
The shop tried for that, but said they are no longer available
We bought one of the last ones available for our old Kodiak box truck at the dealer I work at. The tech who did the swap ruined the wiring harness, and multiple other people who looked at it were not able to figure out the mess he created. Eventually we sold the truck at our auction for something like $800, the GM 454 had never been started. It was a huge fiasco and will be remembered by all involved.
 
Like Cujet, I believe that the majority of the problem has to do with the oil pump pressure relief. The other issue is relatively low hot oil pressure at idle. Without knowing any more about the installation, I would buy a new standard volume pump and set the oil pump gear end-play to the factory spec typically of 0.0018 to 0.0035". The average gear end play on a factory pump is one gear at 0.015 and the other at 0.035", which makes this an easy way to up the idling oil pressure. At above 1500 rpm the relief valve will start to open, limiting the oil pressure to 40, 50, 60 psig, depending on the relief spring. Verify measurement with a straight edge and a valve clearance feeler gage, and use a file to lightly chamfer the gear teeth after removing material with either a table top belt sander, or a plate of glass with 340 grit paper taped to it.

The oil pump is constant displacement meaning that turn it twice as fast you get almost (when you get out of engineering school you find out that nothing is perfect) twice as much oil flow. This feeds the engine which the bearing clearances add up to a fixed orifice of about 3/16" Centrifugal force at the connecting rod journals increases the oil pressure placed on these bearing causing the need for a little more oil flow as the rpm increases. FYI, earlier this year I tightened up a International gas engine oil pump, using a table top belt sander and increased the idle (450 rpm) oil pressure from 3 to 18 psig with no other changes.

The 10 psig per 1000 rpm is just a rule of thumb. The actual required pressure is being able to over come the centrifugal force at the main journal so that oil can flow to the connecting rods plus overcoming the friction loses through the oil passages. For a 3" diameter main (yours is 2-3/4") this requires 50 psig at 6500 rpm and another 25 psig for the oil passages. The oil passages are typically only 5/16" diameter, drilled from both side and don't meet all that concentric at the center of the engine. Also Chevy factory engines come with upper bearing inserts with oil channels and solid bottom bearing with no oil channel. If you engine still has this configuration, then it works passively as a second oil pump so that 30 psig is just fine. There are aftermarket Chevy bearings with the oil channels both top and bottom, so don't rely on this.

The other issue is that the original engine was replaced for a rod knock. Years ago I had a job doing tech inspection on circle track cars. The only guys with bearing issues, were the one using 20W-50 oil. Keep in mind that the oil is gravity returned within the engine to the oil pump. The combination of thick cold oil and 4000 to 6000 rpm operation would take out the bearings in about 4 minutes of race time. I bring this up, as being a RV, when you camp at a gas station near the interstate highway, the next morning you're doing 3000 to 4500 rpm entering the highway. Thick oil is fine, as long as you warm the engine up. For road race drivers schools they tell you to warm up the tires and brakes for this reason.

Lastly high volume oil pumps cover up bad bearing clearances, aerate and heat the oil. With 10 psig at idle you will likely see 20 psig with a tightened up oil pump using a standard volume oil pump.

Good Luck
 
Like Cujet, I believe that the majority of the problem has to do with the oil pump pressure relief. The other issue is relatively low hot oil pressure at idle. Without knowing any more about the installation, I would buy a new standard volume pump and set the oil pump gear end-play to the factory spec typically of 0.0018 to 0.0035". The average gear end play on a factory pump is one gear at 0.015 and the other at 0.035", which makes this an easy way to up the idling oil pressure. At above 1500 rpm the relief valve will start to open, limiting the oil pressure to 40, 50, 60 psig, depending on the relief spring. Verify measurement with a straight edge and a valve clearance feeler gage, and use a file to lightly chamfer the gear teeth after removing material with either a table top belt sander, or a plate of glass with 340 grit paper taped to it.

The oil pump is constant displacement meaning that turn it twice as fast you get almost (when you get out of engineering school you find out that nothing is perfect) twice as much oil flow. This feeds the engine which the bearing clearances add up to a fixed orifice of about 3/16" Centrifugal force at the connecting rod journals increases the oil pressure placed on these bearing causing the need for a little more oil flow as the rpm increases. FYI, earlier this year I tightened up a International gas engine oil pump, using a table top belt sander and increased the idle (450 rpm) oil pressure from 3 to 18 psig with no other changes.

The 10 psig per 1000 rpm is just a rule of thumb. The actual required pressure is being able to over come the centrifugal force at the main journal so that oil can flow to the connecting rods plus overcoming the friction loses through the oil passages. For a 3" diameter main (yours is 2-3/4") this requires 50 psig at 6500 rpm and another 25 psig for the oil passages. The oil passages are typically only 5/16" diameter, drilled from both side and don't meet all that concentric at the center of the engine. Also Chevy factory engines come with upper bearing inserts with oil channels and solid bottom bearing with no oil channel. If you engine still has this configuration, then it works passively as a second oil pump so that 30 psig is just fine. There are aftermarket Chevy bearings with the oil channels both top and bottom, so don't rely on this.

The other issue is that the original engine was replaced for a rod knock. Years ago I had a job doing tech inspection on circle track cars. The only guys with bearing issues, were the one using 20W-50 oil. Keep in mind that the oil is gravity returned within the engine to the oil pump. The combination of thick cold oil and 4000 to 6000 rpm operation would take out the bearings in about 4 minutes of race time. I bring this up, as being a RV, when you camp at a gas station near the interstate highway, the next morning you're doing 3000 to 4500 rpm entering the highway. Thick oil is fine, as long as you warm the engine up. For road race drivers schools they tell you to warm up the tires and brakes for this reason.

Lastly high volume oil pumps cover up bad bearing clearances, aerate and heat the oil. With 10 psig at idle you will likely see 20 psig with a tightened up oil pump using a standard volume oil pump.

Good Luck
Thank you so much. You've really helped me understand. Have a previous shop owner coming over tomorrow and we can discuss your info. Thanks for taking the time to give me the information.
 
The bottom line is you bought a long block and they should either repair or replace it regardless if its oil pump or bad bearing clearances.
20 psi@3000 is not good by any ones standard. IMO it does no good guessing what the cause is, there could be so many from a weak pump/relief valve, a loose oil pump or gasket not seated properly, loose/leaking galley plugs, loose cam/crank/rod bearings to a engine that should have been line bored that instead had mismatched bearings installed to compensate for a tight crank (which doesnt work btw). Over the years I have seen all of these and more.
 
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