I have a 2003 Montero Limited 3.8L.

I need to check and double check the oil pressures in any/all parts of motor that I can.

Anyone know of two ways or at least two different areas of the motor I can confirm what my idle and revved oil pressures are? Thanks!

PS...I do not have an oil pressure light on. I think I may have overall poor pressures under 2,900 RPMs or a section of the motor (passenger side rear, closest to the firewall.

I'm pretty sure that any situation which would cause low pressure, such as worn bearings, anywhere in the oil system, would register as low pressure all across the system. Conversely, if a blockage causes one section to be oil starved, it would create a high pressure situation in the whole system.

I'm pretty sure the above is accurate. The oiling system is just that,a system. What would have different pressures in it is something like an automatic transmission hydraulic system. But please, anyone feel free to jump in and correct me if'n I am wrong.

I saw your VLA post, and understand your question. Time to try and bring in some bigger brains.

I'm not sure that there's any good access point to the oil system other than at the oil pressure sending unit. While there are probably some oil galley plugs somewhere on the engine, finding one that you can actually get to is not going to be likely. Personally I don't think you've got an oil pressure problem - the 6G7x engines just don't have that problem unless they're really abused and neglected, and you sound like you've been the exact opposite of that with your maintenance.

Everyone was pretty much correct. Put a pressure gauge on the sender port. Check the oil pressure from there first. If you have a pressure problem, excluding really REALLY poor maintenance, its most likely bearings and/or pump, in that order. The likelihood there is a restriction is pretty small. Its not impossible - wouldn't be the first time a piece of gasket fell into somewhere it shouldn't.

And make sure its a good quality pressure gauge - some of them - including OEM gauges - aren't all that accurate. Electrical sender gauges can have a PSI variance caused by electrical issues. OEM electrical senders don't last forever, either. I've had to replace my GM senders several times over the years - they just start reading incorrectly - and the one on my '02 3.5L engine has started doing the same thing in the last month and a half or so. Sometimes it reads correctly and sometimes it reads 10 PSI or so low. Sigh.

I remember reading several years ago that there is a location somewhere towards the rear where a sender could be located. I don't know if there's somewhere already taped or what. I ran across this while doing research for something else.

Why do you think you have poor oil pressure? You won't have 'poor pressure under 2900' but fine above 3000. Either you will have poor pressure overall, none, or its fine.

According to the techs, 10ish at idle and 50-60 at 3K is reasonable. I see 8-10 and 50-60 on all my 3.0 and 3.5L engines. Depends on ambient temps and oil weight.

There is a big difference between oil PRESSURE and oil VOLUME. Oil pressure keeps the bearing journals from experiencing metal to metal contact and basically keeps the cam followers (lifters) operating properly. Volume lubricates and cools the engine.

If the engine doesn't actually need 60 PSI - and most don't - a high pressure pump is a waste of HP. In most cases I've ever heard, read or seen, 40-45 is sufficient, unless you're running a very high compression engine, forced induction and/or have serious issues with detonation.

Oil volume is important (IMHO, more important), but unfortunately can't be measured and there are no available specs that I've seen. If the pump doesn't move enough oil, areas like the rod and main bearing journals will get so hot that it will cause the oil to 'coke' - the effect you'd get if you just set the oil on fire - and you get gritty crud from the 'burned' oil that will trash the bearings, circulating through the system. Basically the same thing that can happen to oil and the bearings in turbochargers.

Not trying to be rude or trolling - but make sure you have the right amount of oil in the engine. Wouldn't be the first time someone's 'oil problem' was do to a incorrect dipstick replacement. I chased a problem like this for three months and went through three dipsticks on my 'Bird. Been there, got the tee-shirt.

Edward