The Stupid Engine Questions Thread

[PlayingWithTBI]

Can anyone explain what the MEMCAL and CALPAK do?

The memory and calibration unit is a removable part of the ECM. MEMCAL is GM-talk for PROM and it contains a 27C256 ROM, PROM, or EPROM. It also houses back-up fuel control system which consists of an IC and some analog circuitry.

Calpak is the base "limp mode" calibration chip. In the GN's, it's the smaller chip under the ECM cover, as opposed to the PROM "Chip". It's basically a series of precision resistors in a matrix, which bypass and "hardwire" the engine's sensors and base functions.

 

[C2164]

The oil pressure has always seemed high in my 2000 K2500 454. When cold it is 65-70 psi at idle on up. When warm it drops to about 45 psi at idle and 60 psi at higher rpm.

Running 5W-30 Mobil 1.

Only ask because I just saw in the service manual it shows oil pressure 10 psi at 600 rpm and 25 psi at 2000 rpm. I would assume that means "minimum" specification, but is obviously way lower than I ever see.

Just curious to know what others see. Could a pressure relief on the pump be stuck? If so it has been stuck for at least 17 years.

 

[Intragration]

How many miles on your truck, C2164? 10 PSI at idle would be minimum, with a loose or worn out engine. I can't remember where mine is, but I want to say around 30-40 at warm idle, and so a bit higher on cold start or higher RPMs. This is with 10w30 at 240k miles. If yours has always been the way it is, I don't think you have anything to worry about.

 

[df2x4]

The oil pressure has always seemed high in my 2000 K2500 454. When cold it is 65-70 psi at idle on up. When warm it drops to about 45 psi at idle and 60 psi at higher rpm.

Running 5W-30 Mobil 1.

Only ask because I just saw in the service manual it shows oil pressure 10 psi at 600 rpm and 25 psi at 2000 rpm. I would assume that means "minimum" specification, but is obviously way lower than I ever see.

Just curious to know what others see. Could a pressure relief on the pump be stuck? If so it has been stuck for at least 17 years.

My red truck ('97 C1500 4.3L) will sometimes peg the gauge at 80psi on cold starts but always settles to around 40. It's done this since it was new. I wouldn't worry about it.

 

[VIKING_MECHANIC]

Oil pressure on my 97 C1500(5.7L) is nearly always 80PSI. It will drop down to 40-60 when I come to a stop (or towing a trailer, which still doesn't drop below 60) and go back up to 80 when I accelarate. It's been like that ever since I had the engine rebuilt 10+ years ago.

I was taught that high oil pressure, is an indication of healthy bearings.

 

[Erik the Awful]

WCJr is always close to pegg!ng out the gauge. Probably a thousand miles since the engine rebuild.

 

[Supercharged111]

Oil pressure on my 97 C1500(5.7L) is nearly always 80PSI. It will drop down to 40-60 when I come to a stop (or towing a trailer, which still doesn't drop below 60) and go back up to 80 when I accelarate. It's been like that ever since I had the engine rebuilt 10+ years ago.

I was taught that high oil pressure, is an indication of healthy bearings.

Yes and no. More simply put it's an indication of restriction to oil flow. Too tight of clearances = high pressure = insufficient flow = bad. A HV oil pump with stock clearances can also drive pressures to the moon if the bypass gets overwhelmed, also not a good scenario. Not saying that's the case here, but simply stating high oil pressure = healthy motor doesn't tell the whole story.

 

[Keeper]

The oil pressure has always seemed high in my 2000 K2500 454. When cold it is 65-70 psi at idle on up. When warm it drops to about 45 psi at idle and 60 psi at higher rpm.

Running 5W-30 Mobil 1.

Only ask because I just saw in the service manual it shows oil pressure 10 psi at 600 rpm and 25 psi at 2000 rpm. I would assume that means "minimum" specification, but is obviously way lower than I ever see.

Just curious to know what others see. Could a pressure relief on the pump be stuck? If so it has been stuck for at least 17 years.

Same 454 engine, same Mobil 1 oil since I bought it new in 1999, 325k miles, heads never off, all compression still 150+.... and your oil pressure numbers are the same as mine, or at least we match gauges at a minimum. Run it.

 

[Horntoad]

what type of drive/bit is this screw? it's square-shaped. Robertson? Do they only go up to #4, much smaller than this? The hole is too big for 1/4" and too small for 3/8" ratchet drive tangs and measures about 7/16" (but could be metric). The screw drive type is found on the plugs in the two ports of my 1995 5.7L 4WD w/KC4 engine-oil cooler, right-angle oil filter adapter (GM 12553036). What can I use to fit/drive this screw and back it out of from the port?

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[Supercharged111]

what type of drive/bit is this screw? it's square-shaped. Robertson? Do they only go up to #4, much smaller than this? The hole is too big for 1/4" and too small for 3/8" ratchet drive tangs and measures about 7/16" (but could be metric). The screw drive type is found on the plugs in the two ports of my 1995 5.7L 4WD w/KC4 engine-oil cooler, right-angle oil filter adapter (GM 12553036). What can I use to fit/drive this screw and back it out of from the port?

You must be registered for see images attach

8mm square drive, you can get that socket in a plug remover set. You working on a Vortec 454?