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#2260052 - 01/24/08 11:37 PM Chrysler....low oil pressure when brake is applied??
RacerXI Offline
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Registered: 07/04/00
Posts: 8871
Loc: Dothan, AL
The woman owns a PT cruiser. Recently her oil pressure light started coming on just as she hit her brakes. It has all of 55K miles. After some searching, this seems to be a common issue with PT's. It seems there are 3 scenarios at hand here.
1. The pressure sending unit is bad or going
2. The oil pump itself is bad or going
3. There is a "sludge" issue

Has anyone had experience with this? I did some searching here and there and seems the 1st plan is to remove the sending unit and attach a gauge to read the pressure at idle and 3K rpm. That'll help to determine 1 or 2. Any ideas or thoughts?

See link below for references.
http://www.ptcruiserproblems.com/chrysler/pt_cruiser/pt_cruiser_owner_complaints.htm
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#2260068 - 01/24/08 11:43 PM Re: Chrysler....low oil pressure when brake is applied?? [Re: RacerXI]
ReplicaR Offline
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Registered: 05/26/06
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Loc: E.E.B.
Possibly poor baffle design in the oil pan, but highly unlikely.
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#2260399 - 01/25/08 02:04 AM Re: Chrysler....low oil pressure when brake is applied?? [Re: RacerXI]
ewww,ruiner Offline
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Registered: 03/30/02
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If it is sludge related, I recommend a full cleaning cycle with http://www.auto-rx.com. That stuff worked wonders on my Dakota.
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#2260420 - 01/25/08 02:12 AM Re: Chrysler....low oil pressure when brake is applied?? [Re: ewww,ruiner]
Relix Offline
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Registered: 07/10/03
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Is the oil filled to the correct level?
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#2260653 - 01/25/08 07:33 AM Re: Chrysler....low oil pressure when brake is applied?? [Re: Relix]
RacerXI Offline
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Registered: 07/04/00
Posts: 8871
Loc: Dothan, AL
 Originally Posted By: 92_Civic_VX_B18c
Is the oil filled to the correct level?

Yes. It was checked and then completely changed. The issue has only happened once since the oil change. She had 2500 on the prev. oil change and it was still full at that point so I ruled out oil being burned.
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#2282949 - 01/31/08 10:00 PM Re: Chrysler....low oil pressure when brake is applied?? [Re: RacerXI]
Noob4Life Offline
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Registered: 05/30/02
Posts: 26648
Loc: IL, USA
I just had this happen on the way home tonight. It only happened once, but it freaked me out. I was in second, at like 1200rpm or so. I tapped the brakes, and the oil light went on for a split second. I think maybe the RPM's dropped a little too low and the engine was about to stall out.
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#2283076 - 01/31/08 10:35 PM Re: Chrysler....low oil pressure when brake is applied?? [Re: Noob4Life]
RacerXI Offline
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Registered: 07/04/00
Posts: 8871
Loc: Dothan, AL
She's got an autotragic. I did some more reading and found out the sensor triggers when the psi reads between 2 and 4. Normal seems to be 7psi at idle. I need to pull the sensor and manually test the pressure at idle and with the tranny in drive with the brake applied. That condition is the only time her oil light comes on. It would seem that would be a high load moment, but I'm going to have her do the same with it in reverse. I'm holding out on blame until I can test the pressure.
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#2283766 - 02/01/08 07:47 AM Re: Chrysler....low oil pressure when brake is applied?? [Re: RacerXI]
Chris92Sc2 Online   shocked
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Registered: 12/21/00
Posts: 12994
Loc: MI USA
Makes sense that its the sensor if the MAster cylinder is pulling pressure away from it when she hits the brakes. Maybe a vac leak somewhere too.
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#2283860 - 02/01/08 08:48 AM Re: Chrysler....low oil pressure when brake is applied?? [Re: Chris92Sc2]
UglyValiant Offline
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Registered: 10/09/02
Posts: 6360
Loc: Milwaukee, WI
An odd guess would be the throttle posistion sensor...it may be that when she puts on the brake, she's just lifting her foot off the gas. Car tries to return to an idle setting with regards to the throttle...with a bad tps, it'll tend to stall out, but only occassionally/randomly. If the rpm's are dropping much lower than the factory idle speed (~600rpm), it'll trip the oil pressure sensor.

Have you run an obd scan? I'd start there...
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#2285389 - 02/01/08 03:49 PM Re: Chrysler....low oil pressure when brake is applied?? [Re: Chris92Sc2]
SyFastfedful Offline
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Registered: 07/06/01
Posts: 5567
Loc: Portland, OR, USA
 Originally Posted By: Chris92Sc2
Makes sense that its the sensor if the MAster cylinder is pulling pressure away from it when she hits the brakes. Maybe a vac leak somewhere too.


How would something powered by intake vacuum affect something pressurized by a mechanical oil pump?
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#2285498 - 02/01/08 04:25 PM Re: Chrysler....low oil pressure when brake is applied?? [Re: SyFastfedful]
Chris92Sc2 Online   shocked
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Registered: 12/21/00
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Loc: MI USA
 Originally Posted By: SyHopeful
 Originally Posted By: Chris92Sc2
Makes sense that its the sensor if the MAster cylinder is pulling pressure away from it when she hits the brakes. Maybe a vac leak somewhere too.


How would something powered by intake vacuum affect something pressurized by a mechanical oil pump?


Sometimes the sender for the dash CEL gets its signal from a vacuum source. At least I thought it did. Guess not.


Edited by Chris92Sc2 (02/01/08 04:25 PM)
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#2285892 - 02/01/08 06:11 PM Re: Chrysler....low oil pressure when brake is applied?? [Re: Chris92Sc2]
RacerXI Offline
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Registered: 07/04/00
Posts: 8871
Loc: Dothan, AL
It did throw a cam position sensor code and a local shop replaced it last week. The only other code I'm aware it has thrown was a random missfire. It still trips the oil light when braking.
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04 S2000

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#2287669 - 02/02/08 05:15 PM Re: Chrysler....low oil pressure when brake is applied?? [Re: RacerXI]
UglyValiant Offline
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Registered: 10/09/02
Posts: 6360
Loc: Milwaukee, WI
No problems with acceleration or hard turning?

If not...I'd go ahead and check the pressure manually and drive around...see if it changes at all.

I mean are you actually "braking" braking? or just tapping it without slowing down? How hard do you have to brake to get it to trip the lights?

Could be some bizzarre short/crossed wire type thing...otherwise, there really isn't any reason why it'd just do it braking.

It wouldn't be too hard to pull the pan and inspect the pick-up too if you're getting really perplexed.

call click n' clack (the tappet brothers) if all else fails...


Edited by UglyValiant (02/02/08 05:16 PM)
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#2289807 - 02/03/08 07:20 PM Re: Chrysler....low oil pressure when brake is applied?? [Re: UglyValiant]
RacerXI Offline
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Registered: 07/04/00
Posts: 8871
Loc: Dothan, AL
There are no problems accelerating. It pretty much only happens when she brakes to a stop. Once it gets still, ding light goes on. I could see how it would only happen while it's in gear and stopped. That's a high amount of load. I wonder if it happens in reverse also. I'm going to throw a manual gauge on it next.
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04 S2000

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