Oil Leak Into Cab

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DANNILAFAELE32

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Hello everyone, I’ve got an 1986 GMC K1500 with an oil leak going into my cab under the dash right in the center. Yes! It is oil not coolant or tranny fluid. Does anyone or has anyone ever come across this issue? I have no idea how this happened and I have never heard of this before. Thank you for your time
 
75gmck25

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‘86 has an electric sending unit, so no oil leak into the cab is possible. Up until about ‘76 they used a mechanical oil pressure gauge with an oil line into the cab. Did someone swap your gauge cluster?
 
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Could have been changed to or added a mechanical gauge. Is it dirty or clear-ish? PAG type oil from an a/c system? More info is needed.
 
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Snoots said:
Leak in the line to or at, the Oil Pressure gauge.

You're the first person to have this problem.
Click to expand...
That makes sense. It’s coming right under the dash through the firewall and I have no idea how. Might have to remove the ac vents so I can get a better look at it
 
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DANNILAFAELE32 said:
That makes sense. It’s coming right under the dash through the firewall and I have no idea how. Might have to remove the ac vents so I can get a better look at it
Click to expand...

Is there an aftermarket oil pressure gauge installed?
 
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All of my heater controls are vacuum operated. I’d it possible that I am sucking oil through a vacuum line off the manifold?
 
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It is possible and not unheard of to push oil through the wire going to the electric gauge there's enough space between the wire strands that oil under pressure can be pushed up the wire,the jacket contains it until it gets to the other end. I do not know where the speedometer drive is on an 86k but gear oil can be pushed up speedometer cables also. Pull the wire at the oil pressure switch's see if oil drips out of the boots.
 
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bucket

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Ricko1966 said:
It is possible and not unheard of to push oil through the wire going to the electric gauge there's enough space between the wire strands that oil under pressure can be pushed up the wire the jacket contains it until it gets to the other end. I do not know where the speedometer drive is on an 86k but gear oil can be pushed up speedometer cables also. Pull the wire at the oil pressure switch's see of oil drips out of the boots.
Click to expand...

You just reminded me of something that I always wondered about... and you answered my question too! So maybe 20 years ago, Chrysler put out an updated oil pressure sender pigtail for a lot of their mid and late 90's cars. They had problematic and leaky oil senders. But anyway, the updated pigtail had a tiny little hose coming out of the connector. I always wondered "how the hell is that supposed to improve anything"? I thought it was really dumb.

But now I know why! That hose vented the leaking oil and kept it from pushing up the strands of the wire and ruining it. Of course, I guess it still didn't matter much because those cars were terrible with underhood wiring anyway, lol.
 
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75gmck25 said:
‘86 has an electric sending unit, so no oil leak into the cab is possible. Up until about ‘76 they used a mechanical oil pressure gauge with an oil line into the cab. Did someone swap your gauge cluster?
Click to expand...
My 1977 K10 Suburban had a mechanical oil pressure gauge from the factory.
 
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ballencd

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I had a VW that had an oil leak once!
 
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