Oil pressure issue

[subitoy]

I just purchased 97 4Runner Limited with 3.4l engine. Several times during my 800 miles trip low oil pressure light came on right after I stopped at idle. At about 700 rpm it was on and was off when rpm went above that. I checked oil level several times during the trip and it was full and engine does not appear to burn any oil. I was driving it before on short trips and had no light coming on. I just have a light for oil pressure monitoring and no gauge. I was wondering what is the best way to deal with it. Should I install new sensor and observe behavior or should I get a gauge and sending unit? Thank you for all your help.

[jetwhine]

subitoy,

That would be the first thing I would try is a new oil pressure sending unit.

[subitoy]

jetwhine,
Thank you for your reply. I was wondering if there is a difference between sending units. Napa has 2 in stock, is the one for $10 made by "Altrom" will be fine or should I get one for $25 made by "Echlin Ignition"?

[jetwhine]

subitoy,

Have you checked with Toyota yet? If it is not too much I would go with a stock one from Toyota. The others might be fine, but I always like the life and quality from Toyota parts. My preference would be a Toyota part, but the Napa parts are better than most others.

[subitoy]

On another 4runner forum I read about changing filter that may resolve the issue. Since I just bought the car I have no clue how old it was so I did oil change and so far I had no light coming on. I'll try to go on a road trip and see how it will do.

[jetwhine]

subitoy,

Changing the oil filter could be just a band-aid for the time being.

[profuse007]

Sounds like you need to drop the pan and see if your suction tube screen isn't blocked. Happens to me.

[subitoy]

Just remembered I have not updated my thread and in case someone else have the same problem they can see what works best. Before I'll start tearing the engine apart I have decided to install oil pressure gauge instead of changing sending unit. I followed instructions from here: http://www.4runners.org/writeups/gaugeoil/index.html
The only thing I would add that I have installed 4A fast acting fuse as recommended by Autometer. Now I have exact numbers to go by. At cold start I get 80 psi, at idle once it's warmed up it's 15 psi.
I also found interesting thread: http://www.yotatech.com/f2/oil-light-flicker-131175/
The official Toyota 1998 4runner Owners Manual, Chapter 1-5 p.69:

"(d) Low Oil Pressure Warning Light

This light warns that the engine oil pressure is too low. If it flickers or stays on while you are driving, pull off the road to a safe place and stop the engine immediately. Call a Toyota dealer or qualified repair shop for assistance.

The light may occasionally flicker when the engine is idling or it may come on briefly after a hard stop. There is no cause for concern if it then goes out when the engine is accelerated slightly.

The light may come on when the oil level is extremely low. It is not designed to indicate low oil level, and the oil level must be checked using the level dipstick."

[sam333]

!5 psi at idle when warm is good. Sounds like it was just your sender, unless the pressure is eratic( moves up and down at the same rpm).

What is your psi at 3000 rpm?

Pressure is usually checked at idle when warm and at around 3000 when warm.

Also what weight oil were you using? Outside air temp.?

[subitoy]

After the incident (light was on at idle) I changed oil to full synthetic 5w-30. Once warmed up the pressure at 3000 rpm is around 55 psi. At idle 12-15 psi. Temperature outside is around 55 F. The light never was on since the last oil change.

[sam333]

Your oil pressure is fine then. If your worried about it being a little low at idle in hot weather you can just use a heavier weight oil.

[subitoy]

Thanks to all for your input. I'm glad the issue is sorted out. I just hate that idiot light feature and would rather spend few $$ and some time to install real gauge.