Pennock's Fiero Forum
  Technical Discussion & Questions
  Low oil pressure light

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
Low oil pressure light by jimbolaya
Started on: 10-29-2014 07:34 PM
Replies: 14 (485 views)
Last post by: J Gunsett on 10-31-2014 06:02 PM
jimbolaya
Member
Posts: 10652
From: Virginia Beach, Virginia
Registered: Feb 2007


Feedback score: N/A
Leave feedback





Total ratings: 114
Rate this member

Report this Post10-29-2014 07:34 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
86 GT, but I have an 88 engine in it and it has the 88 oil sending unit. The 88 sending unit is supposed to be the better unit. However, it is giving me an intermittent low oil pressure light, for the third time. As in, I have replaced it twice, and this would be the third time changing it, if I do. The oil pressure has been checked with a manual gauge, and is fine. Why do I keep getting this reoccurring issue? Are the units just crap, or could there be an underlying issue, I am not aware of. I don't want to keep replacing the unit every 6 months or so, but if I ignore it I risk the chance that I might actually have an oil pressure problem, and then I mistakenly ignore it. Opinions? Thanks.

Jim
IP: Logged
PFF
System Bot
Old Lar
Member
Posts: 13756
From: Palm Bay, Florida
Registered: Nov 1999


Feedback score: N/A
Leave feedback





Total ratings: 214
Rate this member

Report this Post10-29-2014 07:40 PM Click Here to See the Profile for Old LarSend a Private Message to Old LarEdit/Delete MessageReply w/QuoteDirect Link to This Post
It may be the gauge itself and some wiring issue. When I have had sending units fail, I'd get a fluctuating reading (but no light).
IP: Logged
jimbolaya
Member
Posts: 10652
From: Virginia Beach, Virginia
Registered: Feb 2007


Feedback score: N/A
Leave feedback





Total ratings: 114
Rate this member

Report this Post10-29-2014 08:02 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Old Lar:

It may be the gauge itself and some wiring issue. When I have had sending units fail, I'd get a fluctuating reading (but no light).


How would I go about testing it? Electrical stuff is a weakness. Heck, they're all weaknesses, but electrical is the worst.

Jim

IP: Logged
J Gunsett
Member
Posts: 1281
From: KY
Registered: Apr 2003


Feedback score: (2)
Leave feedback

Rate this member

Report this Post10-30-2014 08:07 AM Click Here to See the Profile for J GunsettClick Here to visit J Gunsett's HomePageClick Here to Email J GunsettSend a Private Message to J GunsettEdit/Delete MessageReply w/QuoteDirect Link to This Post
What pressure were you reading from the manual gauge? And when you say it is intermittent does this happen when the engine is hot or first starting (cold) or both? Does your aux gauge go to zero? Did you know that there are 2 types of aux oil pressure gauges, 86 and 87 has a higher set point to turn the low pressure lamp on than the 88 aux gauge.

Jack
IP: Logged
jimbolaya
Member
Posts: 10652
From: Virginia Beach, Virginia
Registered: Feb 2007


Feedback score: N/A
Leave feedback





Total ratings: 114
Rate this member

Report this Post10-30-2014 12:57 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by J Gunsett:

What pressure were you reading from the manual gauge? And when you say it is intermittent does this happen when the engine is hot or first starting (cold) or both? Does your aux gauge go to zero? Did you know that there are 2 types of aux oil pressure gauges, 86 and 87 has a higher set point to turn the low pressure lamp on than the 88 aux gauge.

Jack


You may have touched on my problem. I did not know there are different set points. Is there a way to change that? When I say I have checked it with manual gauges, that means I took the sending unit off and connected a gauge there and got a reading while idling. I would have to go to a lot more work to get a reading while driving. I would have to run the gauge up to the front somehow, so I could see it. The light only come on after warmed up. I'll have to pay attention, but I would say the light comes on sometimes while idling, and also when moving. I can't say with 100% certainty at the moment, but I'll watch it.

Jim

IP: Logged
TONY_C
Member
Posts: 2747
From: North Bellmore, NY 11710
Registered: May 2001


Feedback score: (2)
Leave feedback

Rate this member

Report this Post10-30-2014 01:32 PM Click Here to See the Profile for TONY_CSend a Private Message to TONY_CEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jimbolaya:


You may have touched on my problem. I did not know there are different set points. Is there a way to change that? When I say I have checked it with manual gauges, that means I took the sending unit off and connected a gauge there and got a reading while idling. I would have to go to a lot more work to get a reading while driving. I would have to run the gauge up to the front somehow, so I could see it. The light only come on after warmed up. I'll have to pay attention, but I would say the light comes on sometimes while idling, and also when moving. I can't say with 100% certainty at the moment, but I'll watch it.

Jim

When you checked the pressure with the mechanical gauge, was the engine cold or warm? If the oil was warm and the mechanical gauge was reading OK it would seem to be an electrical gauge issue. If the mechanical gauge drops very low when the engine is warm, I think you have engine issues.

IP: Logged
jimbolaya
Member
Posts: 10652
From: Virginia Beach, Virginia
Registered: Feb 2007


Feedback score: N/A
Leave feedback





Total ratings: 114
Rate this member

Report this Post10-30-2014 02:02 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by TONY_C:

When you checked the pressure with the mechanical gauge, was the engine cold or warm? If the oil was warm and the mechanical gauge was reading OK it would seem to be an electrical gauge issue. If the mechanical gauge drops very low when the engine is warm, I think you have engine issues.


Engine was warm.

Jim

IP: Logged
Spoon
Member
Posts: 3446
From: Sadsburyville, PA. 19369 / USA
Registered: May 2004


Feedback score:    (16)
Leave feedback





Total ratings: 60
Rate this member

Report this Post10-30-2014 06:27 PM Click Here to See the Profile for SpoonSend a Private Message to SpoonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hook up your mechanical gauge but tee it into the same line as the oil pressure switch. You'll need a 1/4" brass tee, a short 1/4" nipple and the adapter that normally comes with the oil pressure gauge. Just run the tubing up thru the deck lid vent and duct tape the gauge to the rear window or if you have a sunroof and enough tubing ....you get the idea right?

Warm up the engine and compare the dash gauge with the mechanical one. All the fittings can be had at Home Depot or most hardware stores. When your done and have your readings you can put a 1/4" plug in the tee where the gauge adapter was.

Spoon


------------------
"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

IP: Logged
jimbolaya
Member
Posts: 10652
From: Virginia Beach, Virginia
Registered: Feb 2007


Feedback score: N/A
Leave feedback





Total ratings: 114
Rate this member

Report this Post10-30-2014 07:57 PM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Here's another question, coming from another direction. What if I remove the oil sending unit and permanently put in the manual gauge? What would that do to me? Are readings from the oil sending unit necessary for PCM calculations? The fuel pump is tied into the oil sending unit somehow, isn't it? Thanks.

Jim
IP: Logged
marc-alan
Member
Posts: 326
From: pottstown, pa usa
Registered: Mar 2010


Feedback score:    (8)
Leave feedback

Rate this member

Report this Post10-31-2014 08:37 AM Click Here to See the Profile for marc-alanSend a Private Message to marc-alanEdit/Delete MessageReply w/QuoteDirect Link to This Post
I ran into this myself after upgrading from the older style of oil pressure sending units (I have an '85). I had confirmed I had good oil pressure with a mechanical gauge and found that there was differences in the sending units. I finally just used one that did not turn on the oil pressure light when running. I found the '88 to be the best for my setup
IP: Logged
jimbolaya
Member
Posts: 10652
From: Virginia Beach, Virginia
Registered: Feb 2007


Feedback score: N/A
Leave feedback





Total ratings: 114
Rate this member

Report this Post10-31-2014 10:29 AM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post
Edit: Sorry, I was in the wrong thread. Forgot where I was.

Jim

[This message has been edited by jimbolaya (edited 10-31-2014).]

IP: Logged
PFF
System Bot
jimbolaya
Member
Posts: 10652
From: Virginia Beach, Virginia
Registered: Feb 2007


Feedback score: N/A
Leave feedback





Total ratings: 114
Rate this member

Report this Post10-31-2014 10:33 AM Click Here to See the Profile for jimbolayaClick Here to Email jimbolayaSend a Private Message to jimbolayaEdit/Delete MessageReply w/QuoteDirect Link to This Post

jimbolaya

10652 posts
Member since Feb 2007
 
quote
Originally posted by marc-alan:

I ran into this myself after upgrading from the older style of oil pressure sending units (I have an '85). I had confirmed I had good oil pressure with a mechanical gauge and found that there was differences in the sending units. I finally just used one that did not turn on the oil pressure light when running. I found the '88 to be the best for my setup


How did you manage to keep from turning the light on? This is an 88 sending unit I'm using.

Jim

IP: Logged
marc-alan
Member
Posts: 326
From: pottstown, pa usa
Registered: Mar 2010


Feedback score:    (8)
Leave feedback

Rate this member

Report this Post10-31-2014 11:07 AM Click Here to See the Profile for marc-alanSend a Private Message to marc-alanEdit/Delete MessageReply w/QuoteDirect Link to This Post
I had to go through a few different sending units. I found that different mfg and even different sending units would read differently (high and low). I had to replace it a few times until I got one that would read and not set off the light. I know I am OK, as I had checked my oil pressure with the mechanical gauge prior to going thru the steps of getting different sending units. It was a bit costly, as I had to buy 3 of them. Also, one had to be replaced as I had not sealed the new pig tail for the newer style sending unit. It got moisture in the contacts. Kept my fuel pump on, when the car was shut off. That was annoying.
IP: Logged
Spoon
Member
Posts: 3446
From: Sadsburyville, PA. 19369 / USA
Registered: May 2004


Feedback score:    (16)
Leave feedback





Total ratings: 60
Rate this member

Report this Post10-31-2014 05:38 PM Click Here to See the Profile for SpoonSend a Private Message to SpoonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by marc-alan:

I had to go through a few different sending units. I found that different mfg and even different sending units would read differently (high and low). I had to replace it a few times until I got one that would read and not set off the light. I know I am OK, as I had checked my oil pressure with the mechanical gauge prior to going thru the steps of getting different sending units. It was a bit costly, as I had to buy 3 of them. Also, one had to be replaced as I had not sealed the new pig tail for the newer style sending unit. It got moisture in the contacts. Kept my fuel pump on, when the car was shut off. That was annoying.


Perhaps removing the bulb could of saved you a few bucks. Or painting the bulb black. Just saying..

Spoon

------------------
"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

IP: Logged
J Gunsett
Member
Posts: 1281
From: KY
Registered: Apr 2003


Feedback score: (2)
Leave feedback

Rate this member

Report this Post10-31-2014 06:02 PM Click Here to See the Profile for J GunsettClick Here to visit J Gunsett's HomePageClick Here to Email J GunsettSend a Private Message to J GunsettEdit/Delete MessageReply w/QuoteDirect Link to This Post
Look for a 88 Aux gauge pod and switch it with the one you have in your 86.

Jack
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock