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Discussion Starter · #1 ·
While driving my 94 3.0 V6 AX4S I noticed when I come to rest at a stop light and keep the trans in D the oil light will flicker continuously and every few seconds a loud pumping noise will be heard. When this pumping noise happens the flickering stops. The pumping only happens for a few seconds then stops at which time the flickering resumes.

The oil light does not indicate any problems at other times like normal driving and I found that if I shift into neutral while stopped the light will not flicker and the loud pump will not run.

Any ideas on what this could be, if it's serious, and if I should keep driving with this going on? Thanks.
 

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You've checked the oil level, I guess. Was the oil pump driven off the distibutor gear on those?
 

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^^^^ Yup, WJC, oil pump is driven off the dist. I would first check the dist shaft for excessive play, both axial and radial. If bad, replace dist. If play is good, pull dist and inspect dist gear and cam gear for wear.
 

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Low oil pressure at idle with warm engine. When you put it in "N", rpm's increse a little and so does the presure too. The pressure switch has a 5psi limit (it shows "good" over 5psi, shows "zero" below 5psi).
Thumping noise might be the sound of oil-starved main berings. You can try to check the oil pump shaft - on Vulcan engines is driven by the Camshaft Syncronizer.

I would try using a 20W50 oil, but it might be too late.

Eventually the engine can seize and that will make removal of the engine more difficult - cannot be rotated anymore to unbolt the torque converter/transmission bolts.
 

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Discussion Starter · #5 ·
Could it just be the oil pressure sending unit? This engine only has 91,000 miles on it. I thought I have seen others mention that when coming off the freeway the oil pressure will drop and the light will come on. Could this be similar issue?
 

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I like the suggested suspect list.

Did this problem come about slowly over time, or suddenly, after some event???

I'm thinking like after an oil & filter change, maybe a different viscosity oil, or different brand oil filter???? I've seen a filter brand change cause a like problem on a Saturn!!!!

More thoughts for your suspect list, let us know what you find.
 

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Discussion Starter · #8 ·
I just bought the car. The seller claims it has always done this when coming down from high, sustained speeds.
 

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I just bought the car. The seller claims it has always done this when coming down from high, sustained speeds.
Well under those circumstances some thoughts come to mind, like oil not draining out of the top end of the engine because of restrictions in the oil return holes. Maybe sludge, maybe the wrong grade or viscosity oil was used to mask another problem & it's so vicious it doesn't drain back fast enough that the sump kevel gets low, maybe a cooling system problem causing the engine, or parts of it to run hotter than designed for & thinning the oil out such that the pump can't keep the pressure up, a weak/worn oil pump, wrong oil filter, wrong dipstick that causes the owner to put in too much oil & it gets whipped into a froth at high speeds so the pump has problems pumping areated oil & pressure drops, or to put in too little oil, so the crank case level is low & whats in the crank case is low & over heated & it's viscosity is too low for the pump to make good pressure after a high speed run, or as has been suggested, maybe it's a faulty idiot light pressure switch?????

Pull the oil fil cap & peek in to see how the top end looks for sludge.
Pull the dipstick & check it's part number. I've heard of oil change places & shops getting dipsticks swapped around & a couple of cases of the Engine Factory screwing up too!!!!!

Crawl under & have a look at the oil filter, to make sure it's the specified one for this engine. The Saturn had another brand/Orange Can filter on it & that caused the pressure light to flicker on when warm & coming to a stop!!!! Installed a Factory, or PueOne filter, problem solved!!!!!

Make sure the vehicle has the specified service grade & viscosity oil & the specified amount in the crank case.

If all that checks out, pull the oil pressure switch, install a mechanical shop gauge, to monitor the hot temp oil pressure, if it's ok, replace the pressure switch.

If pressure is low, the engine has a lot of mileage on it & your using 5W-20 which it's back specified for, maybe consider going/stepping back up to it's origionaly specified 5W-30, or maybe a 5W-40 synthetic if need be & see how it goes. Step back up in viscosity only to a level that stops the oil light from flickering on, or until you have the hot idle oil pressure specified for the engine.

A bunch more thoughts for consideration, let us know what you find.
 

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Noise

Well under those circumstances some thoughts come to mind, like oil not draining out of the top end of the engine because of restrictions in the oil return holes. Maybe sludge, maybe the wrong grade or viscosity oil was used to mask another problem & it's so vicious it doesn't drain back fast enough that the sump kevel gets low, maybe a cooling system problem causing the engine, or parts of it to run hotter than designed for & thinning the oil out such that the pump can't keep the pressure up, a weak/worn oil pump, wrong oil filter, wrong dipstick that causes the owner to put in too much oil & it gets whipped into a froth at high speeds so the pump has problems pumping areated oil & pressure drops, or to put in too little oil, so the crank case level is low & whats in the crank case is low & over heated & it's viscosity is too low for the pump to make good pressure after a high speed run, or as has been suggested, maybe it's a faulty idiot light pressure switch?????

Pull the oil fil cap & peek in to see how the top end looks for sludge.
Pull the dipstick & check it's part number. I've heard of oil change places & shops getting dipsticks swapped around & a couple of cases of the Engine Factory screwing up too!!!!!

Crawl under & have a look at the oil filter, to make sure it's the specified one for this engine. The Saturn had another brand/Orange Can filter on it & that caused the pressure light to flicker on when warm & coming to a stop!!!! Installed a Factory, or PueOne filter, problem solved!!!!!

Make sure the vehicle has the specified service grade & viscosity oil & the specified amount in the crank case.

If all that checks out, pull the oil pressure switch, install a mechanical shop gauge, to monitor the hot temp oil pressure, if it's ok, replace the pressure switch.

If pressure is low, the engine has a lot of mileage on it & your using 5W-20 which it's back specified for, maybe consider going/stepping back up to it's origionaly specified 5W-30, or maybe a 5W-40 synthetic if need be & see how it goes. Step back up in viscosity only to a level that stops the oil light from flickering on, or until you have the hot idle oil pressure specified for the engine.

A bunch more thoughts for consideration, let us know what you find.
The noise at the time the light went off, indicates a likely gear problem. First to pull the cam pos and check gear and the rod connecting to the pump. If it was only pressure, you can run an engine a long time with low pressure at idle, as long it is not zero. The noise is the bad indicator.

Just my take.

-chart-
 

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After reading chartmakers post & then rereading the op's first post, I realised I forgot he posted about hearing a "pumping noise" & when the pumping noise begins, the flickering op light stops, so this makes me wonder if the problem is an acting out IAC????
If the pumping noise is the A/C compressor cycling on, which it does for about the time frame he noted, the computer would call for the IAC to idle the engine up to compensate for the A/C compressor load, so the increased engine idle speed would increase oil pressure & turn the flickering op light off!!!!

SO, maybe try pulling & cleaning the IAC to see if that fixes the problem.

If it does, cleaning it may not last, it didn't for me on my Ranger & is probably why Ford recommends replacement, but it was a good easy to do trouble shooting step in my Rangers hanging up idle problem, so when it acted out again, I knew for sure what to replace.

Yet more thoughts for consideration. Let us know what you find.
 

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Discussion Starter · #12 ·
I replaced the oil pressure sensor. We'll see if that was faulty. I also see the previous owner has a nuclear orange oil can on there. I'll switch that out with a real oil filter and see if that helps. The car runs great otherwise, except on the 45 degree inclines of Seattle. The trans gets bogged down and confused.
 

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Yup I'd opt for the specified FL-400S Motorcraft filter in place of whats on there now, you might be pleasantly surprised.

Know what you mean about the hilly streats of Seattle, been there & driven them, so try shifting that puppy out of OD when you driving all those hills & the engine/tranny will likely appreciate it.
 

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Discussion Starter · #15 ·
I almost always drive in D only. I use OD on the freeway over 60 mph. I actually need to shift into 1 on those hills and keep it under 15 mph.

By the way, changing out the oil pressure sensor fixed the issue as of now. I took it for a long test drive with lots of high speed, sustained driving followed by long stops while leaving the trans in D and have yet to see or hear the issue.
 

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OK, good feedback on the op switch seeming to have fixed the flashing op light.
 
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