M1165 Oil Pressure

[Fallujahveteran]

New to me M1165.

No blow by, no leaks, runs great. Cold start oil pressure is 30-ish PSI, once warm at idle it goes down to about 10 PSI, give it gas jumps right up to 30 PSI and holds while driving until you stop and go back to idle. Is this normal or should it be cause for concern? I've downloaded the TMs from the TM section of Steel Soldiers and am slowly trying to teach myself how to read/use them and understand the info contained in them. Would the hive recommend a new gauge and/or oil pressure sending unit? I have plans to keep this truck as original in appearance to the USMC truck it is, so if I get new gauge(s) they will most likely just be new old stock surplus equipment.


Thanks for any input.

 

[TOBASH]

My vehicles live there.

Hummer H1 has 300,000 miles and has lived there.

 

[MarkM]

These gauges are notoriously inaccurate. I'm changing mine out for the same reason.

Mark

 

[Coug]

Use a mechanical gauge to verify, but those numbers sound decent enough. I wouldn't worry.
These use mechanical oil pump, so either it's working and you have pressure, or you don't. If you didn't the engine would have let you know by now. Not much middle ground.

Every gauge and sender will end up giving you different readings. First set that came in my truck showed 0psi at hot idle, and current ones show about 30-40psi hot idle, and 60-70psi under load.

 

[Mogman]

As Coug said verify with a mechanical 1/4 NPT IIRC gauge and then just treat the dash gauge as a reference.
It is very common for these to have "low" oil pressure, the 6.5L has piston coolers and that bleeds off allot of the pressure squirting oil into the bottom of the piston dome to cool the pistons.

Also there is little to nothing you can do about it anyway, just use the correct oil (most are using 15W40) and a good (not Fram) oil filter.

And here is one for you OCD guys, if you drive a "this century" FOMOCO vehicle with an oil pressure gauge, it is not a gauge at all, it simply uses an idiot light oil pressure switch and as long as the engine is making around 7psi or more the gauge stays exactly in the same spot, hot, cold, idle, WOT, rolling down a hill on fire all the same.