About my 99 Chrysler

Tiny
ALWAYSME33
  • MEMBER
  • 1999 CHRYSLER 300
  • 131,000 MILES
I have a 99 chrysler m300 it has 130,000 miles on it. A while ago the oil light started flashing when id stop. Took it to a shop got the oil sending unit replaced light was worse than ever for a day then went away and by worse I mean it would come on as soon I slowed below 15 miles an hour. Took it to yet another shop and they said oh there is an oil cooling line leak. Replaced it. Got the car back now as soon as the car warms up when I stop the oil light is flashing and then if I sit too long it gets solid it goes away when I put the car in neutral or rev the engine even just a tap. Any suggestions? Last shop says my engine pressure was in specs etc. But I dont remember exactly what they were.
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Sunday, September 16th, 2012 AT 9:06 AM

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Tiny
CARADIODOC
  • EXPERT
First of all you should not be running to different shops. You don't run to a different doctor if you don't get the desired results on the first visit. Every new doctor and every new mechanic has to start over from the beginning and you're paying multiple times for the same diagnosis. Give the first shop a chance to correct any mistakes or to continue on with the diagnosis. With problems like yours it can be very time-consuming to eliminate the common causes and narrow it down to the less common ones. Rather than charge you for the many hours that can take, they often try the most likely suspect first and let YOU figure out if they need to go further. That is an attempt to save you money but it usually backfires because customers incorrectly think the mechanics don't know what they're doing. It's just like the doctor sending you home with a bottle of pills and instructions to "try these and see if they help".

The first shop may not be able to remove the new sending unit because electrical parts usually can't be returned, but they may have saved you an hour or two of labor already.

The next point of concern is if the second shop checked the oil pressure while the problem was acting up. If you had to leave the car there for hours until they could get to it, the engine and the oil would have cooled down and the oil would be thicker. That causes the pressure to go up for the first few minutes after starting the engine. If there's worn bearings in the engine the pressure will drop when the oil warms up and thins out.

There could also be an electrical problem such as the wire going to the sending unit is grounding out against the engine. You could prove that by disconnecting the plug from the sending unit. If the oil warning light still flickers, we know it's a wiring problem. That would not be common. From the way you described it, the sending unit would be a logical first suspect, and low oil pressure a close second.
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Sunday, September 16th, 2012 AT 10:26 AM
Tiny
CJ MEDEVAC
  • EXPERT
ADDING A LITTLE TO THAT

. DOC, YOU KNOW I'M HOLDING BACK ON GIVING A NOVEL-LIKE ANSWER LIKE YOURS!

EVEN BRAND NEW STUFF CAN BE BAD!---YES, DEFECTIVE ELECTRICAL PARTS CAN BE RETURNED TO A PARTS STORE. IF IT WAS A COMPETENT COMMERCIAL ACCOUNT THAT PURCHASED THEM. OR.A "COMPETENT SUPER REGULAR CUSTOMER" DID THE SAME (I SEE THIS 1ST HAND ALL OF THE TIME)

SO, IF THE SWITCH WAS DEFECTIVE AND A REPUTABLE SHOP, . NOT "JIM-BOB" OFF THE STREET WAS NOT WHO YOU TOOK IT TO. THE PART MAY BE UNDER WARRANTY STILL

WE'LL GO INTO "MECHANICAL GAUGES" IF NEED BE

CONCERNED AND HUMBLE. NOT IRATE, IS THE ATTITUDE TO APPROACH THEM WITH, AROUND HERE A FREEBIE MIGHT BE IN ORDER. SCREAMING, CUSSING, AND BAD BODY LANGUAGE GETS YOU NOWHERE. USUALLY 'CEPT OUT ON YOUR BUTT!

LIKE DOC SAID, THERE ARE OTHER VARIABLES THAT, "EVEN WILD AND UNCOMMON", COULD PLAY INTO THE SITUATION. THESE CRAPPY COMPUTER CARS OF TODAY ARE A REAL CHALLENGE, AS A COMPUTER OR BODY MODULE CAN COMPLICATE THE SYMPTOMS. A VEHICLE OF YESTERYEAR WAS MUCH SIMPLER TO FIGURE OUT AND WITH LESS DIAGNOSTIC EQUIPMENT. DON'T YOU WISH YOU HAD A CLASSIC?

KEEP US POSTED ON YOUR FINDINGS

THE MEDIC
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Sunday, September 16th, 2012 AT 2:38 PM
Tiny
CARADIODOC
  • EXPERT
I DO have classics; two '72 Challengers in the restoration shop, two more at home, and two '80 Volares. Plus my uncommonly reliable '88 Grand Caravan daily driver up here in the heart of road salt country. I know what you're saying about the inappropriate overuse of unnecessary technology. I'm on my way out of town shortly to help a very knowledgeable friend figure out a simple brake light problem on an over-technologized computer-controlled vehicle.

What I'm referring to about returning electrical parts is when that new sending unit didn't solve the problem. They don't want people buying parts to try, then returning them if it didn't solve it. Nobody else wants to buy a part that someone else had first. At that point it isn't "new" anymore. The parts stores aren't in the "here, take it and try it, then bring it back" business.

The proper thing for the shop to do is continue with the diagnosis, fix the problem, THEN remove any parts that weren't needed, however, some parts are hard or not practical to remove, or are so low-cost that the labor time to remove them would cost more than the cost of those parts. In the case of the sending unit, the shop would typically put it back in their inventory and hope to sell it to someone else in the future. Problem is they can't do that real often or all their profits would be tied up in unsold parts. Oil pressure sending units do have a well-known failure rate on all vehicles so the argument can be made that it's better in the long run to just leave the new one in.

My cousin learned early on at his tv repair shop that you can't just buy lots of parts to "try" on each tv. We had to become very good at diagnosing exactly which five and ten-dollar parts were needed rather than just buying a dozen suspect parts and only using two or three of them. The boss was so pathetically honest that he would never leave in a part that wasn't needed, but that meant for every tv or vcr repaired at a 20 dollar profit, there would have been thirty dollars worth of leftover parts on the shelf representing breakfast not on his table the next day. Most of those parts were specific to one brand and model that the chances of them ever being needed again was remote. No one buys three house insurance policies in case you need one. No one buys three different computers, all involved with turning on the head lights, in hopes one will solve the problem. Few people, (other than me) buy more tomatoes than you can eat before they spoil. The point is a business can't afford to stock a lot of unneeded parts. Their parts room would start to look like a Walmart store with no customers.

Of course it's a different story when a new part is defective, but the clue here is the symptoms are exactly the same with either the old or new sending unit. Even a defective new one would act a little differently in some respect. Since the symptoms are the same either way, we can deduce the real cause of the problem is something that wasn't changed which is everything in the circuit other than the sending unit. That leaves the actual oil pressure when the engine is warm, the wiring, or as you reminded me, a computer. Transistor driver circuits are notoriously unreliable and one is used in computerized cars to operate the warning light, unlike in the days of our old reliable cars where the sending unit ran the light directly. A little corrosion between two terminals in a connector can trick the computer into thinking it should be turning on the warning light. The sending unit was still the logical first suspect, but there's a whole bunch of other variables and complexity to consider on newer cars. The first shop should be given the chance to continue on with the diagnosis rather than having new shops start over at "step one". Running to new shops is like a record, (remember those?) With a skip backward on the first song so it never gets to the final song. The mechanic needs a chance to get to the final song, the solution.
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Sunday, September 16th, 2012 AT 8:15 PM
Tiny
ALWAYSME33
  • MEMBER
Hey guys thank you so much car is going back to the first shop today. Just so you know though I didnt just jump ship on the first mechanic. I have a warranty through a 3rd party on my car tht doesnt cover my mechanic. Stupid me got divorced and of all places got a car at carhop when the oil light wasnt fixed with the sending unit I got mad because we werw so sure thats what it was and my car had been in the shop for other things recently and I was frustrated so I was advised by them to please take it to one of their mechanics, no I believe in keeping one mechanic all the time trust me. Ill keep you posted on the car as it moves along ty for all your help tips and ideas at least I know where to start lol
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Monday, September 17th, 2012 AT 1:42 PM

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