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post #1 of 5 (permalink) Old 03-22-2005, 12:11 AM Thread Starter
 
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some problems after replacing head gasket

After doing a head gasket replacement on my '93 3.8, I was left with a couple of problems. My oil pressure gauge no longer works, I have what sounds like an exhaust leak coming from the rear center area of the engine compartment around the EGR, and my AC compressor won't cycle on.

I noticed that there is a single wire small red plug coming out from a harness which comes out from under the front of the plenum and I can't find anywhere to plug it into. Its the same harness with that roundish plug that doesn't go to anything. Hopefuly it doesn't go to anything underneath the plenum. It's a small gauge wire, white with red stripe, and shows 5.5 volts with the key on and engine off and about 6.5 volts with the engine running. Where's the oil pressure sending unit on this car. I did change the oil filter obviously, is the sender down there somewhere and maybe I knocked off the wire? What's the red plugged wire for?

I measured the voltage to the AC switch on the clutch and it reads less than 1 volt, what should it read?

I also changed the plugs and fuel filter. When I went to relieve the pressure from the fuel system, I noticed that when I disconnected the inertia switch for the fuel pump, the car wouldn't start at all. When I plugged it back in, then started the car, and then unplugged it to let the car use up the gas and relieve the pressure, it stalled right away. Do I not have any fuel pressure in my lines?

The car runs ok, although it feels a bit sluggish. I don't know how many miles are on the car, I've owned it since new, but the odometer stopped working around 92,000. I'd guess it has about 120 -140K on it.

Any help would be greatly appreciated.
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post #2 of 5 (permalink) Old 03-22-2005, 12:44 AM
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I know my engine bay looks a little different than yours, but this should help you out. I circled the oil pressure sending unit in red. Thats where that lost red plug you have goes to, which will make your oil pressure gauge work again. So that fixes two of your problems.



For the A/C. Did you disconnect any of the A/C lines while disassembling the engine? If so, this released the refrigerant and you wont have enough pressure to cycle the A/C. If you didnt, you must have unplugged something, there's no reason the A/C compressor should stop working spontaneously after a HG swap. Have you checked the line pressure in the A/C lines?

-Thomas

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post #3 of 5 (permalink) Old 03-22-2005, 01:11 AM Thread Starter
 
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Thanks !! You're right, your engine looks different than mine but it got me searching in the right place for the screw for the red wire...found it right away. That solves 2 problems like you said

I didn't disconnect any A/C lines or discharge the system at all. The compressor only has one electrical connection that I could see, and I think it's the plug from the pressure switch on the dryer. I checked both connections and cleaned them and they seem ok. I haven't checked the pressure, don't have a set of gauges. I could borrow some, but the compressor won't run...can I still check the pressure without the compressor running?

Thanks for the pic and the help, I appreciate it a lot!
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post #4 of 5 (permalink) Old 03-22-2005, 01:16 AM
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i believe you can check the pressure without it running. When you fill the system with refrigerant it pressurizes, so I'd think you could just get an A/C pressure gauge and read the pressure. Are you still running on r-12 or have you converted to r134a? If youre still on r-12, go to an auto parts store and pick up a r134a conversion kit, it's around 35-45 dollars and includes the r134a refrigerant. 1lb of r-12 is about 80 dollars and requries a special license.
-Thomas

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post #5 of 5 (permalink) Old 03-22-2005, 01:32 AM Thread Starter
 
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I had the A/C converted over to r134a when my compressor gave out a couple of years ago. I didn't do the work though, a shop did it. Come to think of it, they charged me $100 for the conversion and that didn't include the freon. I guess I could borrow some gauges from the auto parts store to check the pressure. The car sat for 2 months in my garage without starting it, I wonder if the seals dried out during that time. I took the heads off, then got injured and couldn't put it back together for 2 months.
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