bad oil pressure gauge?

bad oil pressure gauge?
stevr59

stevr59

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milton fl
Vehicle(s)
1985 cj7
258 6
t 176 4 speed
Dana 300
4" suspension lift
"upgrade".team rush ignition
Weber 32/36 carb
Holley fuel regulator
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nutter bypass
hey guy's i got a 85 c-j7 with the old AMC 258 i6 / 4.2l and my oil pressure gauge is not working how do i go about checking it to see if its bad and all so how do i remove it?
 
its cheap enough i would just go buy a sending unit and replace it. that is probally the problem.
 
well i changed out the sending this morn and that's not the problem... the gauge is still dead so i quess the gauge is bad so now my next question is.... how does it come out of the dash? do i have to pull the dash borad out or can i remove it with out taking the dash out.... and what size is it, was thinking of getting a white face gauge but not sure if the one i saw will work in the same hole. i dont want to make the hole bigger
 
you can pull it without removing the dash if you have a radio in the dash, pull the radio then reach up from underneath take the two nut off of the bracket that holds the gauge against the dash, pull the light plug and you should be able to disconnect the wire for the gauge itself
 
stevr59 said:
well i changed out the sending this morn and that's not the problem... the gauge is still dead so i quess the gauge is bad so now my next question is.... how does it come out of the dash? do i have to pull the dash borad out or can i remove it with out taking the dash out.... and what size is it, was thinking of getting a white face gauge but not sure if the one i saw will work in the same hole. i dont want to make the hole bigger
Click to expand...

Before you do that, how about a picture of the front of the gauge. There were two different oil pressure sending units used in a CJ and they are not even close to being compatible. The problem is the resistance range in the sending unit. The difference in the gauges is determined by the depth of the gauge. Usually you can determine wich you have by the design on the front.

This chart will help you get the right sending unit for the right gauge.
CJ Gauge Specification Chart
One of the sending units is like $60.00 so it might be cheaper to go with a new gauge by that time.
 
just a couple of words.
"Go mechanical":cool:
 
i like my electric sunpros i have.
 
John Strenk said:
Before you do that, how about a picture of the front of the gauge. There were two different oil pressure sending units used in a CJ and they are not even close to being compatible. The problem is the resistance range in the sending unit. The difference in the gauges is determined by the depth of the gauge. Usually you can determine wich you have by the design on the front.

This chart will help you get the right sending unit for the right gauge.
CJ Gauge Specification Chart
One of the sending units is like $60.00 so it might be cheaper to go with a new gauge by that time.
Click to expand...
there ya go

IOPort51 whats the pros of a mechanical gauge and would i have to change out my new oil presser sending unit?
 
stevr59 said:
there ya go

IOPort51 whats the pros of a mechanical gauge and would i have to change out my new oil presser sending unit?
Click to expand...

Thats a replacement Crown Gauge. I'm not sure on what the resistance range is on that one. You could run some test to see what will work but know your investing a lot of time into something that could of been fixed in less time and money.

Maybe mechanical would be the cheapest solution right now.

You would not use your new sending unit with a mechanical gauge. Maybe you could reurn it but maybe not, or could always sell it on some jeep forum once you find out the resistance range.
 
stevr59 said:
whats the pros of a mechanical gauge and would i have to change out my new oil presser sending unit?
Click to expand...

No sending unit with a mechanical gauge. You'd unscrew the sending unit and screw a threaded brass fitting in there (it comes with the gauge). Then you'd run a slim plastic tube (comes with the gauge, too) from that fitting in through the firewall to the back of the gauge.

I like mechanical gauges because they're absolutely positive. There's never any guessing - no voltage regulator or sending unit in the mix. They last darn near forever, too. The only thing that bothers 'em is eventually that plastic tube will get hardened oil built up inside it and get slower & slower & slower to react. Finally it'll just stop at some pressure or another & stay there until you replace the plastic tube (costs a couple bucks at any auto parts place). You get plenty of notice, though, so you're likely to have a replacement tube onhand when it finally goes.
 
And do make VERY SURE the hole through the firewall has a good gromet in it so you do not rub a hole in the thin plastic tube. It will make one hell of a mess and if not discovered in time can be a bit hard on the engine.:cool:
 
thanks guy's i may just go with a mechanical gauge... now only question that didn't get answed was, what size gauge do i need to fit the opening... i keep seeing 2 1/16 will that work or do i need a 2 " gauge to fit the opening.. as of now i do not want to make the holes bigger...
 
Might be I just don't shop around much, but I don't think I've ever seen a 2-1/16" aftermarket gauge. I've been installing bog-standard 2" gauges & they fit just nice.
 
Auto Meter

this is what I am using, it's 2 1/16"
 
dalefan88 said:
i like my electric sunpros i have.
Click to expand...


I don’t see a thing wrong with either, I had never used a mechanical oil pressure gauge and I thought I would give it a try. I am of the opinion that almost anything would be an improvement over the stock gauge. I have always thought that the prime function of the stock oil pressure and voltage gauge was to fill up the hole in the dash. They told you that you more than likely had oil pressure and the alternator was making some amount of voltage. :cool:
 
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