Need a little help
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Freshman User
Joined: Mar 2009
Posts: 36
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From: Cartersville,Ga
Need a little help
1989 4x4 xlt 2.9 auto.Today while stopped at stop sign in traffic the engine rpms dropped from around 800 to 500 or so and the oil pressure gauge dropped to nothing ,with a little gas the op returned to normal. At this same time the tach is jumping up and down. New iac,plugs,o2 sensor vacuum lines to map and airbox ,tps sensor(used)No new engine noises. I put a new oil sending switch on about 3 years ago (Advance auto )I guess it wore out. So any help would be most appreciated. Thanks
New User
Joined: Sep 2007
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It is not uncommon for the oil pressure to drop quite a bit during idle, I think this scared a lot of people when most gauges were actual mechanical pressure gauges, so the manufacturers replaced them with switches. I think the ranger went to a dummy gauge sometime in the late 80's, and if that is the case for the gauge to drop means you have dipped below the 7 PSI cutoff pressure. The oil pans on these vintage rangers (at least on the 2.3's) were originally made of cork which degraded and clogged up the inlet screen in the oil pan. This typically means you have to drop the pan to clean the screen, not difficult, but a bit time consuming.
Thread Starter
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Freshman User
Joined: Mar 2009
Posts: 36
Likes: 0
From: Cartersville,Ga
It is not uncommon for the oil pressure to drop quite a bit during idle, I think this scared a lot of people when most gauges were actual mechanical pressure gauges, so the manufacturers replaced them with switches. I think the ranger went to a dummy gauge sometime in the late 80's, and if that is the case for the gauge to drop means you have dipped below the 7 PSI cutoff pressure. The oil pans on these vintage rangers (at least on the 2.3's) were originally made of cork which degraded and clogged up the inlet screen in the oil pan. This typically means you have to drop the pan to clean the screen, not difficult, but a bit time consuming.
New User
Joined: Sep 2007
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This behavior was common with clogged oil screens. The oil pressure would be ok until the engine got real hot, and then the oil pressure plummets. Again my experience comes from the 2.3L, but I would guess that a clogged oil screen might manifest in a similar fashion. It could also be a loose oil pickup tube, or even bad pump, or even a pressure relief valve in the oil pump. Worst case scenario it could be a spun bearing and oil passages are wide open when the oil is thin and hence it cannot build pressure. Of course this would be a sudden event and probably accompanied by a change in engine behavior. The clogged oil screen is a slow change.
Before you dive into removing the oil pan, you should check the pressure with an actual mechanical oil pressure gauge, you should be able to pick one up for 20-40bucks. This way you will know for sure if it is instrumentation or real pressure issues.
Before you dive into removing the oil pan, you should check the pressure with an actual mechanical oil pressure gauge, you should be able to pick one up for 20-40bucks. This way you will know for sure if it is instrumentation or real pressure issues.
Thread Starter
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Freshman User
Joined: Mar 2009
Posts: 36
Likes: 0
From: Cartersville,Ga
This behavior was common with clogged oil screens. The oil pressure would be ok until the engine got real hot, and then the oil pressure plummets. Again my experience comes from the 2.3L, but I would guess that a clogged oil screen might manifest in a similar fashion. It could also be a loose oil pickup tube, or even bad pump, or even a pressure relief valve in the oil pump. Worst case scenario it could be a spun bearing and oil passages are wide open when the oil is thin and hence it cannot build pressure. Of course this would be a sudden event and probably accompanied by a change in engine behavior. The clogged oil screen is a slow change.
Before you dive into removing the oil pan, you should check the pressure with an actual mechanical oil pressure gauge, you should be able to pick one up for 20-40bucks. This way you will know for sure if it is instrumentation or real pressure issues.
Before you dive into removing the oil pan, you should check the pressure with an actual mechanical oil pressure gauge, you should be able to pick one up for 20-40bucks. This way you will know for sure if it is instrumentation or real pressure issues.
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Freshman User
Joined: Mar 2009
Posts: 36
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From: Cartersville,Ga
Well the news is in. At start up with a mechanical oil pressure gauge pegs 60psi. then when the engine warms it drops to nothing. So my mechanic is going to replace oil pump ,rods, mains. Hope this cures the problem. Will let yall know
New User
Joined: Sep 2007
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That should do the trick, but I would have him pay close attention to the oil pump screen prior to the rebuilding activities. If the screen is clogged, this is a quick and simple repair that only involves dropping he pan.
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Freshman User
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From: Cartersville,Ga
Thanks, I have already discussed this with the mechanic. Hope this is all I need.
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