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Oil Pressure Sending Unit

wishuwerehere82

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It's the black cylinder about 2" dia.-4" long on the top of the block next to and slightly behind the distributor on the drivers side. It has a 3-wire connector going into the end.
It screws into a 45 degree brass fitting that is in the block.
 

minifridge1138

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Ok, if that is the oil pressure sending unit, then where is the oil temperature sensor?

Basically, i'm leaking out from someplace around plug 8.
If I drive gently, i park and no leak.
If I go out and "play" a bit, then I park and within 2 minutes have a puddle under the car.

Any ideas?
 

bossvette

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try the valve cover gaskets, they are notorious leaker's and will run down the back of the block where you said its leaking from. Think about it spirited driving more oil to the valves and the acceleration pushing it to the back of the engine.
 

minifridge1138

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1982 Black Fastback
I really don't think it is valve covers. The top of the headers have no oil on them, but the underside of plug 8 has oil on it, as does just about everything that is lower than the oil pan gasket. Oddly, plug 6 is dry.

This is the post where i asked about oil pan gasket:
http://www.corvetteactioncenter.com/forums/showthread.php?p=802862#post802862

I was thinking that if the oil temp sensor was near plug 8, then that might be the problem. Anyone know if it is around there?

thanks everyone.
 

wishuwerehere82

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Sounds like a leak under the manifold gasket at the block between the heads.
Right where the ratchet is laying across the block.
The oil runs down the back of the head gasket where it mates to the block and around to the #8 cylinder plug. Seen it happen a few times on the GM V8's.
And it won't leak a drop unlesss you romp on it, because your PCV valve is pulling a vacuum on the crankcase normally. When you give it WOT, you lose the normal vacuum , and it slings a lot of oil into the valley area. Then the oil flows off the underside of the intake manifold and runs out the bad gasket.
 

wishuwerehere82

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Ok, if that is the oil pressure sending unit, then where is the oil temperature sensor?

Basically, i'm leaking out from someplace around plug 8.
If I drive gently, i park and no leak.
If I go out and "play" a bit, then I park and within 2 minutes have a puddle under the car.

Any ideas?
The temp sensor is on the drivers side of the block between #1 and #3 cylinders.
It has a green wire going to it from the fender under the alternator.
 

minifridge1138

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1982 Black Fastback
ok, well that's not the leak. Wrong side, and wrong plugs.

I'm not leaking coolant, so I don't think it is a head gasket.
I would bet good money that my oil pan is leaking, but i'm not sure how an oil pan leak would get up to #8 plug.

Thanks for the info.
 

wishuwerehere82

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Red '82 Coupe,Sebring Silver '98 Coupe
ok, well that's not the leak. Wrong side, and wrong plugs.

I'm not leaking coolant, so I don't think it is a head gasket.
I would bet good money that my oil pan is leaking, but i'm not sure how an oil pan leak would get up to #8 plug.

Thanks for the info.
Not a head gasket, but a manifold gasket rear seal.
Most gaskets have 2 separate rubber strips that connect the ridge between the heads. Over time, the rubber extrudes out from under the manifold and leaves a gap. Smart engine builders use a bead of silicone to replace the rubber seals and throw them away.

I drew some lines on the Photo to illustrate where it leaks and where it runs down.
 

minifridge1138

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1982 Black Fastback
I put the intake manifold on in September, so I hope it hasn't already slipped.

Honestly, i can't remember if i put silicone sealant on it or not.
The back of the motor near the manifold is dry. No oil there.

I was looking at it with the motor running, hoping to see oil spurt out. I couldn't find anything. I'd give it a shot of throttle and would see a puff of blue smoke. Is there anything around plug 8 that has oil in it and would get a boost in pressure under higher RPM's ?
 

wishuwerehere82

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I put the intake manifold on in September, so I hope it hasn't already slipped.

Honestly, i can't remember if i put silicone sealant on it or not.
The back of the motor near the manifold is dry. No oil there.

I was looking at it with the motor running, hoping to see oil spurt out. I couldn't find anything. I'd give it a shot of throttle and would see a puff of blue smoke. Is there anything around plug 8 that has oil in it and would get a boost in pressure under higher RPM's ?
Yeah, your oil return passages in the head gaskets. But if you're certain the head gasket isn't leaking, I would say valve cover gaskets are a good bet.
Try tightening the valve cover gasket bolts to see it they're a little loose.
Most do loosen a little after the gasket has taken a set.
 

jdp6000

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1982 CROSSFIRE
The oil pressure sender is on the driverside below the last cylinder plug (closest to the firewall). The oil pressure switch is the bell shaped one located to the driverside of the distributor. Most confuse the sender with the switch. Logic dictates that the oil pressure sender needs oil to work and therefore if it fail would leak.

Jim
 

wishuwerehere82

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Jim's right.
Pressure sender on side of block by the oil filter.
Pressure switch for fuel pump on top.

Neither on the side where the leak is.
 

minifridge1138

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1982 Black Fastback
I'm hoping that it is just some loose oil pan bolts. I'll tighten them.
I think i may also replace my Castrol Synthetic with a Castrol Organic for higher mileage engines.

Actually, i'm not positive that my head gasket isn't leaking. I'm not leaking coolant, just oil. I would think that if a head gasket was blown, i'd be leaking both.
 

jdp6000

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1982 CROSSFIRE
I'm hoping that it is just some loose oil pan bolts. I'll tighten them.
I think i may also replace my Castrol Synthetic with a Castrol Organic for higher mileage engines.

Actually, i'm not positive that my head gasket isn't leaking. I'm not leaking coolant, just oil. I would think that if a head gasket was blown, i'd be leaking both.


Isn't the knock sensor on the passengerside??
 

jdp6000

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646
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1982 CROSSFIRE
I'm hoping that it is just some loose oil pan bolts. I'll tighten them.
I think i may also replace my Castrol Synthetic with a Castrol Organic for higher mileage engines.

Actually, i'm not positive that my head gasket isn't leaking. I'm not leaking coolant, just oil. I would think that if a head gasket was blown, i'd be leaking both.


I had nothing but problems with the synthetic...seemed too thin. I'm running what GM recommends now. Two schools of thought on this though...
 

minifridge1138

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908
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1982 Black Fastback
Well judging from what I could see of the oil pan gasket, I bet it is shot. I'll have to replace it soon. I rubbed some RTV around the edge of the gasket on the passenger side, so hopefully that can buy me a week or two.

I also managed to tighten the valve covers a little bit, but i don't think they were leaking. I'll find out tomorrow.

I am also going to switch to Organic motor oil. Probably the Castrol GTX High Mileage. It can't hurt anything.

Oil Pan Gasket + DeWitt's direct fit radiator = FUN WEEKEND!!
 

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