Oil pressure guage problem

[69XSN]

Good day to all, I'm having a problem with my pressure guage. Whenever I start the car the guage needle shoots to the top, a little above 8 kgcm and stays there, even after driving for an extended period. On turning the engine off the needle goes back to zero. Car is 91, MT, 135,000 km. I've tried two brand new oil pressure sending units and the problem remains. I know the guage is not reading right and I wonder why? Any advice will be greatly appreciated. Thanks.

 

[Daedalus]

Are you sure you replaced the correct oil pressure sender? There's more than 1.

 

[69XSN]

I was not aware there is more than one. I went to Honda asked for the oil pressure sending unit, they sold me a round thingie with a black rubber boot cover. Bought the other thru SOS (Thanks SOS guys, they are great).
The part sits somewhat under the coolant tank with one blue and white wire coming out the top. If that was not the right one, where might the other be?

 

[CL65 Captain]

That's the right one. The other sits where the oil cooler / filter is and only turns on the Oil light when it detects extreme low pressure.

 

[69XSN]

Since that was the right sensor, I'm wondering what other part (other than the guage) might be the problem? Thanks for the input guys.

 

[Daedalus]

I see 2 possibilities:

1. The pressure really is that high. Unlikely, but you can rule it out by testing the pressure with a calibrated tester.

2. The gauge itself is bad. Not sure how to test it (if you could plot the pressure/resistance curve of the sender that would be a start). To replace it buy part # 78150-SL0-003.

 

[69XSN]

I see 2 possibilities:

1. The pressure really is that high. Unlikely, but you can rule it out by testing the pressure with a calibrated tester.

2. The gauge itself is bad. Not sure how to test it (if you could plot the pressure/resistance curve of the sender that would be a start). To replace it buy part # 78150-SL0-003.

Sorry the pressure reading was a little above 8kgcm not 4kgcm as posted earlier (edited). I know the pressure isn't that high not even on a freshly rebuilt engine. Again i'm just wondering if there is anything else that can create the sympthom (other than a bad guage). Thanks.

 

[Briank]

Assuming you don't have an oil pressure issue I would say the wire to the sensor is pinched and shorted to ground.

 

[Daedalus]

Sorry the pressure reading was a little above 8kgcm not 4kgcm as posted earlier (edited).

Then BrianK is probably right, as always. Sounds like your gauge is pegged. Test the resistance between the harness at the sender and vehicle ground to confirm.

 

[NSXclear]

If those don' work, you can also try replacing your temperature and oil pressure guage.

78150-SL0-003 $89. 12 List price.

Have you taken apart your cluster recently? If so, maybe you didn't tighten one of the bolt enough or one of your bolts are overtightened. If overtightened, it could damage one of the holes.

 

[69XSN]

First and foremost, thank you to the prime members for their assistance in resolving this issue. Thanks also to Acura of Agusta. Turns out it was the guage afterall. Thanks.

 

[NSXclear]

Becare when taking out the oil pressure guages. The little thin coiled copper wire can become unattached from their post.

If anyone else is having the same problems, look at post in the back and make sure all the wires are attached. Remove the tin sliver cover by just pulling it off. Note: one of the post does not have a copper wire attached. That is normal. Resolder it by unwinding the stranded copper wire to give you more sodering area.

 

[ATERPAK]

Gee a lot of great advice but has anyone really tried to find out what the true pressure is at the point of where the sending unit is reading the pressure. You should try putting a real (analog) oil pressure gauge at that point and see what it really is reading in lbs. or bar. I mean that's what a good technician would do first. From there you can work your way back to the gauge cluster to see what might be the problem. If there have been no other changes to the car, I wouldn't suspect any of the wires suddenly getting pinched to ground unless you made a change in that area. It's still a possible area but more rare in this case. The other possibility would be the gauge itself.
Al T.

 

[thouchin]

Read the Service Manual. It says to test the gauge, disconnect the sender unit and short the wire to ground. When the ignition is turned on the gauge should go to 8. It also says to turn off the ignition quickly or the gauge can be damaged (not sure I believe this part, that would be terrible design).