1995 Montero SR, 3.0 Auto, 4X4

What are the normal idle rpm and oil pressure gauge reading supposed to be?

I,m new to these engines and my oil pressure looks a little on the low side at idle, seems fine when driving and at cold starts (higher rpms)

Also, occasionally the idle drops a little under the normal rpm reading and this causes a rougher idle with some valve noise...thought this might be a sensor somewhere...dirty or in need of service???

Any insight would be appreciated...........Ed

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Hello,

I have a 95 Montero LS so my engine is a bit different than yours (mine is anemic but extremely reliable). Mine has 147k on it and I have owned it since it had 20k and I have done all my own service (almost) which has been almost nothing. On my car the idle oil pressure is a bit lower than when it was new. During idle gauge only move up a bit from zero. (I dont recall the exact number) When the engine is at speed the gauge reads about in the middle. I figure that is just a sign of age for the engine. My car burns a bit of oil now too, but it runs and idles great.

As far as your rough idle there is a bit of maintanance you should do on the air intake system. There is something called an "idle air control motor." This thing maintains your idle speed. The area around it tends to get dirty and should be cleaned periodically with carb cleaner. It is best to remove the motor and flush it out with carb cleaner. Also, if it stays dirty the little motor will work too hard and wear out. (yes, mine wore out). If your idle is not smooth, this is the first place I would look.

One other thing. I believe your engine has dual overhead cams (I have only one cam for each cyl bank). Your engines timing belt is very long and prone to break. If it breaks while running it will almost always destroy then engine. Do not exceed the 50k interval between changes.

 

I have always been perplexed by my 92 Montero's oil pressure. The idle pressure does look low but it's never been a problem. The pressure changes depending on rpm(as you know), oil temp, and oil grade and age. My cold high idle oil pressure just after oil change can go to 60psi. Cold weather the same. My factory manual does not contain any specs on proper oil pressure. My owners manual only gives a range for idle and 3k rpm. The idle pressure runs somewhere between 27psi and just off "0" mark on gauge. The 3k range runs between 59psi and 32psi. You could temporarily install an oil pressure gauge where the oil pressure switch is to read the pressure and compare that to your gauge. The dealer may be able to give you a factory spec. Oil pressure is just an indication of the resistance to flow the oil is experiencing, on lubrication systems flow is more important as long as there is enough pressure produced to squeeze into the bearing surfaces. One thing that has always bothered me on this vehicle is how the pressure drops just after hard hill climbing. The oil temp rises and thins out the oil and it really affects the pressure reading. My Montero has a factory oil cooler that I would have expected to keep the oil temp constant but I guess this is just not the case. The engine has 115k and I have never had any lub. related problems. I had thought to add a oil temp gauge and mount it in the spot where the non-working (useless) inclinometer is but have always said, what would I do different if I knew what the oil temp was. Right now I use 5W-30 full synthetic oil and don't worry about the heat or pressure. I found too thick an oil produces temporary valve tap on this engine when cold.