Replaced Alternator, but now my Oil Pressure guage says theres no pressure

syphon

Registered User
Does anyone have any idea what the problem is? I replaced my alternator, and once I started it back up, my oil pressure guage is pegged to the Low. I dont think I even touched an oil line, but I worry that maybe something got messed up when I pried the belt tensioner back up to put the belt back on.

Oil level is fine, dipstick shows plenty of oil.

No oil leaks, left it running for a good 10 minutes and no oil dripped onto the ground.

No noticable knocking or pinging, engine sounds as smooth as ever

No smell of burning oil

Has anyone experienced a similar problem? Is my oil pressure really low or is the guage messed up? Any ideas?
 
Small update, I took it for a drive and everything seems 100% fine with the exception of the Oil Pressure guage and the "Check Gage" light (is it just me or did they mis-spell guage?).

The guage stays buried in the L at all times, when at idle and when at WOT (wide open throttle). I know with some cars the oil pressure depends on the RPM's of the engine, it'll raise a wee bit when giving it gas, but mine doesnt budge at all. This is just another reason I believe the guage might be broken.

Before I changed my alt... my oil pressure would go straight to "norm" when I started the car, and it'd stay there at all times. I almost never saw it move.

Does anything to do with the guage run a line by the belt tensioner or behind it (at the base of the SC and lower). Like i said, I'm wondering if I messed something up when I pried the belt tensioner up.
 
The oil pressure sensor is indeed near enough to that area that you could've moved something. It's on the driver's side by the timing cover , and it's electrical not mechanical (no tube, just a wire).
Check the connector, clean it and make sure it's tight. The sensor is cheap (about $5 ) so replace it if necessary, and start from a clean slate if you have to.

resized%20dec%2001%20low%20pro%20side.jpg
 
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Does anyone have a picture of the Sensor or at least describe what it looks like? I havent a clue...
 
It's right beside the power steering pump. You should see a tube sticking out of the engine with a fitting on the end and a wire coming off of it. If the wire came off you will see what almost looks like a small stud on the end (It has ridges to keep the connector on that almost look like threads) The connector is just a contact with a red rubber cover on it.

Another thing to remember about the stock pressure guage is that it isn't really a guage, it's a fancy switch. All it has is a resistor that puts the guage at either normal or low.
 
mn12sc35th said:

Another thing to remember about the stock pressure guage is that it isn't really a guage, it's a fancy switch. All it has is a resistor that puts the guage at either normal or low.

You're kidding me right? So the pressure guage can only be where it is now... or in the "Norm" area? Wow.
 
Yep. I looked at the Electrial Manual when I was putting a 93 LX cluster in my 91 NA V6 (I Hate those 85 mph speedos) and looking at the wiring for the guage, all there is is a sensor and the resistor that decides norm or low.
 
It will read anywhere in the "normal" range if the sender gives it voltage indicating about 5-7 psi minimum.
 
I just did a motor swap and my check gauge light is on and no oil pressure aswell, but I thought the sensor was on -top of the valve cover...what is the sensor located on the tube that runs on-top of the passenger side valve cover?

Thanks,
Chris
 
The oil pressure sender is the round gray one to the right of the water pump and just above the oil pump. The wire coming off the harness just pushes onto the threaded stud on the end, so it probably just fell off.

shortblock.jpg


David
 
Thanks,
Now I need to find out what the sensor is above the passenger side valve cover !It's located in a tube that runs across the top of the valve cover.

Chris
 
???

C_More said:
Thanks,
Now I need to find out what the sensor is above the passenger side valve cover !It's located in a tube that runs across the top of the valve cover.

Chris
Chris, I think everyone is as confused as I am by your question. There are no "sensors" on or over the passenger side valve cover. The only thing I can think of that you may be talking about is a black plastic tube that goes from the driver side valve cover across the engine, under the SC, then over the pass valve cover and connects into the intake tube between the maf and throttle body. This is a vent that is part of the crankcase ventilation system. John
 
C_More said:
Thanks,
Now I need to find out what the sensor is above the passenger side valve cover !It's located in a tube that runs across the top of the valve cover.

Chris
ECT. Engine Coolant Temperature. It communicates to the EEC. There is a separate sender for the temp gauge. :)
 
David Neibert said:
I think he is talking about the Automatic Climate Control temp sensor located in the heater hose plumbing.

David
I guess that's why I was soooo confused. Mine doesn't have auto climate control, so wasn't aware of that sensor in that particular location. :)
 
Well I dont have autoclimate control either so this would explain why I don't have that wire on my 89 harness.The motor came out of a 91 sc with auto climate control,now it's in my 89.Its located on the heater hose that runs on-top of the vavle cover and into the firewall....I had know idea that was the heater hose and feel alot better knowing that its not an important sensor!



Thanks, for all your help I will rest easy now!!!

Chris
 
TbirdSCFan said:
ECT. Engine Coolant Temperature. It communicates to the EEC. There is a separate sender for the temp gauge. :)
Here's a pic with the ECT sensor highlighted. :cool:
 

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Here is a pic of that sensor in question and I think David hit the nail on the head with his answer!

<img src=http://cmore.realiteweb.com/cmores_pics/DSCF0411.jpg alt="">
 
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