oil pressure problem, pissing me off

[bigbadwolf078]

i have 1 91 4.0 4x4 with roughly 135,000 Ive had it for about a year now and never had any problems. just recently had a routine oil change and now when my truck warms up the oil pressure drops off, I know its an idiot gauge, it doesn't knock or make any noises and only does it at idle. I also would like to note that none of the gauges work on my dash other then the voltage gauge and I thought the oil pressure gauge, im contemplating trying to change out the switch for the gauge and seeing if that makes a difference but just wanted to see if anyone else has had similar problems. im wondering if maybe they put a ****ty filter on it and if that would make a difference or what? im at a loss now and just wondering where to start. I would like to note it still runs perfectly fine and doesn't make a sound suck as knocks or ticks.

 

[natenkiki2004]

It could just be that your sender is faulty or gummed up. I think they're cheap enough, replace it and see what happens. As you said, they're an idiot gauge. I believe someone on here stated that they only look for 5 PSI and if it has more than 5, it shows in the middle of NORMAL but below 5, nothing. On/off kinda gauge.

 

[Roadrunner777]

If you noticed this a day or two after the oil change, then clearly it is the wrong oil or a bad filter. I would go back and make my case to them right away. I suspect one of two things:

1. They put in the wrong oil. Newer cars are using thinner oils and I could see a load of 0W-20 doing this. (That's what Toyota requires in their new cars, BTW).

2. Quick change shops try to use a small variety of filters for a large variety of vehicles. I got an oil change once and I was appalled later when I changed my own oil to see the tiny little thing they put on there. Not exactly a mistake, the oil change company give them the filters and tell them what to put them on.

If this happened to me, I would call the shop and see what they have to say. I might propose that I bring in my own filter (a nice WIX/NAPA one), and have them re-change the oil with that filter. I think it will take care of your problem. If it does, and you can prove it to them, then they owe you something, though it would probably be a discount on your next service, and I'm not sure I would go there again.

Ok, all that said... if you cannot really connect the two... you noticed a few weeks or a month later, then that's a different thing. I would screw a gauge where the switch is and get some real information. I'd get your gauges fixed... an engine running on the hot side will do this too. If you are working on the gauge cluster and the oil switch, you might just as well do the oil gauge fix to make it actually read pressure. There's a few thread on it.

I would not put this off. Just because it is not making bad noises now does not mean everything is ok. The noises usually happen AFTER the damage is done.

Best of Luck!

 

[bigbadwolf078]

they put some filter on made by prime, ive never heard of them. I guess the first thing im going to try is a new filter and hope that solves the problem, probably a wix 51515 or a fram hm8a and probably some new oil.

 

[bigbadwolf078]

with it being as old as it is should I still use the stand oil?

 

[Maniak]

they put some filter on made by prime, ive never heard of them. I guess the first thing im going to try is a new filter and hope that solves the problem, probably a wix 51515 or a fram hm8a and probably some new oil.

Prime (Prime Guard) is just a filter that many shops use.. It isn't anything special but if your changing you oil every 3k miles it'll be fine...

Personally, I use Wix Filters.. That would be a 51515 model for your truck...

Since you aren't getting noises plus you have dash issues, I'm betting your oil pressure is fine. The Oil pressure switch (driver side of motor, near power steering pump) go bad over time... I've also seen the wire for it fall into the exhaust before which can give you odd readings..

As it was posted above.. anything over 5psi should show normal pressure.. anything below shows low.

If you really want to know, pick up a cheap mechanical oil pressure gauge with the long tube (I paid $15 for mine). Pull the oil pressure switch out, screw in the new gauge end and run the line out the fender and zip tie it to your wiper. You will know within a day if your having real oil pressure problems..

While you are at it... might as well do the oil pressure gauge mod listed in the useful thread forum, in the interior section...

~Mark

 

[Bobmbx]

I think the most impressive part of this thread is that the OP has a 91 with 135k on it.

I put ~100k on my 06 in two years.

What kind of shape is your truck in?

You may find that the oil pressure controller has failed, and is just dumping the output of the pump back into the pan. Its just a spring, and its a part of the oil pump.

First, do what Maniak suggests: Verify your oil pressure.

 

[bigbadwolf078]

I got it from a bunch of old folks that never drove it and bought it new...other then the clear coat is gone it was perfect when I got it, now ive put a few dents in it here and there from wheeling myself but was fine when I got it. no rust or anything

 

[bigbadwolf078]

so to either mech gauge deal all I have to do is unscrew what's there now and replace with what comes with the mech gauge and hook up a hose?

 

[Maniak]

Yup... I have a mech. oil pressure gauge just for testing purposes...

I grabbed it from the local parts store... It came with like 10 feet of plastic hose, and the fitting that matches the oil pressure switch on the explorer.

I've used it multiple times on multiple vehicles. This way I could know 100% if I was having oil pressure issues or some kind of wiring/dash issue.

~Mark

Edit: A gauge like this... http://www.oreillyauto.com/site/c/detail/EQU0/7234/N0528.oap and then you'll need the hose/fittings (this one doesn't look like it comes with it).. Total cost will be $20ish and you now have a new "tool". If they have any mechanical gauges with the hose, that might be cheaper....

 

[bigbadwolf078]

that's the exact one I was looking at...you know the size fitting I would need or what else to ask for when I pick it up? going to try and do this tomorrow if I have time when I get out of work

 

[Maniak]

1/4 npt...

 

[bigbadwolf078]

thanks...fingers crossed lol