Sudden (& apparently permanent) spike in oil pressure

As I was taking my '96 to the mechanic who put in a new cat/02 sensor/muffler/tailpipe today, a strange thing happened.

The car was not cold; temp here was in the high 70s & I'd driven a couple of miles already. As I went up the fairly steep ramp onto the hwy. in my normal firm-but-gentle accelleration mode, I thought I heard (or felt) a strange pulsing--oooOOOOM/ooOOOOm/ooOOOOM/ooOOOOM, as if someone were revving the engine up & down..

I looked at my gauges & saw that the oil pressure needle--which has always been exactly where it should be--had topped out as far to the right as it can go. It scarcely moved til I pulled in the mechanic's driveway. I told him what had just happened; he revved it a few times & though the needle twitched very slightly, it didn't move as it should. He said he'd look at it & I came home & started searching the forum for anything similar. I came up with clean plug & connectors first/check for clogged oil filter/replace sending unit.

He did the first two, found them apparently fine, called 2 places for prices on new senders; called me when the cheapest he found was not the "$6 & change"/"$15 at Autozone" I've seen posted here--& had mentioned to him, but $58!!! I got on the phone & found them from $25.95 (VIP) to $38.95 (CarQuest); dealer MOPAR is $33.75.

But it was too late in the day to do anything about it right now, & I'd like to pick up the car tonight because I have an unbreakable appt. at noon tomorrow. (He's going to change my oil out for synthetic next week & can install a new sending unit at the same time.)

My chief concern is that strange pulsing before the oil pressure gauge spike. Can anyone think of what that might have been, & any harm I might do to my car by driving it for a few days with the needle that high? (That pulsing, BTW, stopped as soon as the car shifted to HI at the top of the ramp.)

And I'm totally confused by the strange range of prices. In the first place I don't think for a minute that my mechanic or his parts supplier are gouging me with that $58 price; I know them both & they're honest & reasonable. Could they be thinking of another part entirely--a sensor instead of a sender, maybe?

And are the $6-$15 senders some of you guys mention a different type than my '96 has--for oil light instead of gauge, maybe? And is this sender one of those parts I'd do well to keep MOPAR? The dealership price was right in the middle.

The cheap sensors are likely either for an idiot light or the earlier version of the 4.0 which works the opposite of the later one, and is more conventional (disconnected, it drops to zero). I've bought a couple of the later ones and they were both in the mid-thirties. The dealer is probably as good a bet as any if it's convenient.

Matthew Currie said:

The cheap sensors are likely either for an idiot light or the earlier version of the 4.0 which works the opposite of the later one, and is more conventional (disconnected, it drops to zero). I've bought a couple of the later ones and they were both in the mid-thirties. The dealer is probably as good a bet as any if it's convenient.

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My oil pressure did the same thing a year ago.

It still reads a billion PSI and runs just fine, as it did before the "spike".

Thanks to both of you. Til I'm sure I can trust this mechanic I'm running everything he says & does by this forum. I want to have just one person working on my car from now on if possible.

He kindly brought my car home to me tonight (he wanted to test-drive it anyway), & said he's pretty sure it's the sender because the gauges so seldom wear out. The needle sits barely to the right of center, moves almost not at all no matter if you speed up or rev it, drops to zero when turned off. Does that still sound like a bad sender?

He said the rear diff. was leaking a bit of oil & he'd taken some out because it was overfilled (my recent tuneup, I guess), & that he'd pick up a new plug for it & put it in when he changes the oil next week. Does that sound right?

And speaking of oil: I stopped by Walmart for Castrol Syntec, & though they have most every other weight in the 5 qt. size, they only have the 5W50 in qts. & the price difference is awful: $9.97 for 5 qts., $4.97 for 1 qt. Eagle or anyone else who uses this weight, does Castrol sell it in the 5 qt. size? Where might I find it?

No more pulsing, I'm happy to say. Sounds GREAT w/new muffler/no rattling cat. I just filled it so I'll soon know if the new O2 sensor will bump my mpg.

My oil pressure gauge peaked out on a long trip and it worried me silly. I stopped and checked everything I could, even changing the oil and filter. It drove and sounded fine, but it was still pegged to the max. I found out the wire was grounded to either the oil dip stick receptacle or the block near it. This caused the gauge to max out. I verified it first by moving the wire so it wasn't touching any metal part. Ended up replacing the sending unit anyway. Hopefully that's what is causing your problem because it's such an easy fix. Use a good electrical tape and insulate the wire where it runs against anything metal (usually around the oil dip stick area....well, at least on a '92), and perhaps wrap it in a small diameter loom too. Let us know what you find out.

Tom

Tom, are you saying you wrapped the wire of your new sender as prevention against the same thing happening to it? What is a loom?

Churchlady said:

Tom, are you saying you wrapped the wire of your new sender as prevention against the same thing happening to it? What is a loom?

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Step one: The mechanic should have done this right off the bat, unthread the electrical sender and stick a mechanical gauge on there, that will remove all doubts as to the problem. The lub system on the 4.0 has TWO bypasses, one in the engine itself and one in the oil filter. Some filters are better than others.
Once the pressure is verified as good or bad then go from there. If the new sender does not solve the problem I would unplug the dashboard, clean the connectors on the two banks of self docking connectors back in there and plug it back in. 98's and 99's had this problem where the dash would basically 'shut off' and the airbag light would come on, spedo, tach, gas, would just zero out and the odometer would stop working, hit a bump and it would come back on. Loose connectors, about a 20 min fix, maybe a bit longer the first time till you figure out how the dash comes apart but pretty easy. I converted my 98 from idiot lights to gagues back in jan or feb, so far so good.

The 'loom' he is talking about is a plastic hose that is split down the center, it is put over wires to protect them from abrasive wear on things they may be laying against. The stuff comes in basic black and a plethora of other colors that can be used to add some bling to the engine compartment and it also comes in various sizes. Handy stuff to have around, I usually keep a roll of 5/8" around with a bunch of end connectors.

Rich answered your question re the loom....thanks Rich. Let us know what fixes your problem.

Tom

OK; in my "Leave displayed on front seat to let mechanic know this is one old lady he'd better not mess with" kit I now have:

a roll of 5/8" loom
a can of Anti-seize
a factory service manual
a spare MOPAR thermostat w/bleeder hole.

Now when am I getting my bumper sticker?

and why would you go to walmart to buy anthing? and yes i do mean anything. I wouldnt be suprised if the box said castrol syntec and you found regular penzoil oil in the boxes.
they were selling 5qts for 10.00 and singles 1qt for 5.00??huh?? seems like they're just trying to rip everyone off, well thats wallmart for ya.
if you could try find someone who sells oil at wholesale, so you wont have to pay for the retail price which soemtimes is a good mark up in price . got my o2 sensor for 60 bucks wholesale as opposed to 83 bucks for retail

how do you people add the icons in here?

Sounds like someone has something against the Rollback Man.

I don't know any way to get things wholesale, but I've sure found it pays to phone around.

My Walker cat was $114, o2 sensor (also Walker I believe) was $59. My mechanic charged me $180, which incl a new muffler (think it was a Walker too--$36ish) & tailpipe he picked up for me after determining they were needed, & his labor to install all of it.

So my total parts/labor cost for new cat/sensor/muffler/tailpipe was $353. That seems pretty good to me, seeing as how my two bids from garages for just putting in a new Maremont cat were $363 & $250.

Re: oil. At the moment I'm thinking I'm going to end up w/Amsoil on a permanent basis, but could use a cheaper & more available brand for the first change to synthetic (for cleaning things out)--changing over to Amsoil oil & filter in 3000 miles. Is this sensible?

If so, I'll only be driving on this first oil change in the summer months so maybe I don't need the 5W50. What's a good summer weight oil for Maine?

(Come on, Z22; I love Walmart. It's the modern equiv. of the old smalltown "downtown".)

Churchlady said:

(Come on, Z22; I love Walmart. It's the modern equiv. of the old smalltown "downtown".)

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That's funny, since Wal-Mart helped kill many hundreds of smalltown "downtowns" across the country.

Yucca-Man said:

That's funny, since Wal-Mart helped kill many hundreds of smalltown "downtowns" across the country.

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Still saves me money.
I live in a small downtown town and the markup is so high, even the small business owners in town don't shop here, they go to Wal Mart.

Modern equivilent bs?? No they were the ones responsible for the smalltown downtowns disappearing.
Back then the people who worked in downtown were paid enough and could afford what was being sold.
I dont care about those commercials they make, they can say whatever they want to(lie or the truth, but the later in this circumstance).
Not one good has ever come out of walmart.
I further could say that if anypiece of forest or anywhere we go wheeling/camping/hikining etc were up for sale walmart would take it. All we'd have left then, is a flat parking lot and jobs that pay minimum wage.
Even the people who go there aren't any good, or should i say walmart made people that way. Last winter during the xmas season they had a sale for 40$ dvd players. There was a mad rush to get them, and someone ended up being pushed down, and knocked unconscious, but people kept going in for that dvd player.
They treat thier employees like crap. In my college newspaper there was quite a lot about that. Something interesting I heard in the news a while back was this. Illegal immigrants were hired by walmart. The gov't got wind but decieded to arrest the illegal workers after their shifts were over. Makes no since does it. I'm sure since they were illegal workers walmart has no obligation to pay them. Since the workers were illegaly working they cant force walmart to pay them. Its most likely not posible to hire a lawyer, and if they could with what money?
All the smalltown "downtowns" i've been to, all there stuff is made well, with real caftmanship. You take something home from wallmart its been made in some 3rd or 4th world country and falls apart, or still has the materials that were used to make it inside it (sewing needles, razors, etc)
How do they make so much money(1.2 billion twice as much as the 2nd place company target) but yet aren't a good corporation?? Both to their employees and to the customers.
How are they going to get away selling one quart or oil for 5 bucks then selling the same exact stuff, but 4 quarts more for just 5 bucks above the 1 qt price? This may sound like a good deal(if it were to different companies), but when it comes to corporations buying something the prices are all basiclly the same for one product, especially if its the same company. If they make so much money why cant they pay their employees better? I havent seen or even heard of them giving any money back to the community. Target gives what 10% back to schools i believe? Its not much but its something.
I think we should boycott walmart until we get the old way, the real American way of life back.
Who's with me!

Grab a sign while I continue my real American way of life, choice.

I appreciate the fact that I don't have to pay an overpriced mom and pop if I don't want to.

How about the fact that I can get groceries at Wal Mart for a 2/3 the price of the grocery store in my town. Gas there is .20 cheaper than it is around the corner.

Sorry, deaf ears here.

Something i didnt put in. Why is the markup so high? Well there are probably a few reasons.
One, those small town places have to make money, if no ones buying as much they are forced to raise prices, so they can still make enough money to buy food. No competing shops in the area means everyone is forced to shop wallmart.
Wallmart deliberately marks their prices low so competing companies will go under. (People naturally always want to save a buck.) This has happend to much, walmart must be stopped.
Then those people who lost thier buisness because of wallmart need a job right? Only place for them to go is wallmart. Now they arent losing money but are making even less, now there is less money for food and other needed essentials, car payments mortgage etc.

I wouldnt suggest buying gas there. Its not good for your car, its cheap gas and i imagine doesnt come with the right additives and such that your engine needs to run well.
If we dont stop wallmart now, what will happen when all the competing companies go under, becuase they cant make money anymore? You think wallmart will keep their prices low?

Then what happens to your choice?? Its gone.
I suggested this so maybe one day wallmart wont be the only choice.
Yes there is choice now, but for how long after wallmart takes over

Z22_Z33 you need to take this elsewhere. You've hijacked a thread on oil pressure to get a small minded point across. Go play on Walmarthaters.com or something.

alright i'll do that. not sure how its a small minded point, but then again you guys are from a different part of the country then me.