Sensors - which are these?

[PHOENIX]

Two questions:
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1. What is the sensor right above the oil filter?
This is were my biggest oil leak is coming from, at least it looks that way.
I need to know what it is so I can decide if I replace it or remove it all together.
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2. What is the sensor on the middle of the passenger side block just above the oil pan?
Knock sensor for use with ESC?
I need to know what it is so I can decide if I replace it or remove it all together.
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Thanks

[Jonboy]

On my 87, the sensor right above the oil filter is the oil pressure sending unit. I have a gauge, and that thing is huge. Looks kinda like a bell. The second sensor is the knock sensor. If you pull it out, get ready for an antifreeze bath.

[KShortell]

Eddie,

Your signature says you've got a 350. I'm going to venture to say that you don't have an original ignition setup from a 305 on it, right?

The sensor above your oil filter is indeed an oil pressure switch or sender. On my truck, they're up behind the distributor instead. However, I still have the hole, it's just got a threaded plug from the factory instead.

With regards to your oil leak-- do you have the factory towing package or even an aftermarket oil cooler adapter where the filter spins on? I just finally solved a big oil leak on my truck. The 18-year old gasket on the adapter finally had been leaking. $4.10 for a new gasket at the local Chevy dealer solved my problem. I only confirmed it by sitting underneath the engine with the truck running and seeing the oil seep out around the top of the adapter housing. The oil will creep up the block and bellhousing in the air currents, making tracking down the leak with pinpoint accuracy a bit tricky. It took me a few months and even looking at it from below while running a few times over that period. It's not always obvious or easy.

As far as the block sensor goes, I don't have any sensors/senders on the passenger side of my 350. Factory 350s didn't use ESC. If on the driver's side, then it would be the engine coolant temperature sensor and have a single green wire leading up to it.

Good luck!

[PHOENIX]

Thanks for the help guys, you pretty much confirmed what I thought.

1.
The reason I ask about the sensor above the oil filter is because my oil pressure (bell shaped stock/electric) was next to the distributor on the back of the block. I removed that and installed the fitting and hose for my mechanical oil pressure switch. Why would my truck have (2) oil pressure switched unless someone added one up top and left the old one by the filter?
I guess Ill remove and plug it, then see what happens.

2.
Thanks for the coolant warning on that knock sensor, I didnt know that.

I removed the esc system and now currently running an msd hei distributor.

No tow package or oil cooler.

X.
I just replaced the valve cover gaskets (were leaking) and oil pan gasket (may have been leaking) and cleaned the crap out of the block and were I could reach. I have been playing with the distr. curve and decided to check for leaks. I noticed a few new spots under the truck. The sensor above the oil filter is were it came from, it ran towards the back, down the front and side of the bell housing then dripped onto the ground. Its not easy to see clean oil running down the black paint I used on the bell housing guard. If I remove that sensor I think I may have a little drop coming from somewhere else, but maybe not. I cant wait to not have an more leaks

[Slonaker]

On my '86 305, I believe the sensor on the passenger side above the pan is a knock sensor for the ESC.

Slonaker

[swervin ervin]

Eddie, these trucks came with two sensors, one is the oil pressure sending unit (big bell shaped), and the other is the oil pressure switch, for the electric choke. I don't know when they changed or why, but both of mine were up top. I've seen older trucks and newer trucks have one at the oil filter and one up top. Do you still have the switch hooked up to your choke?

The knock sensor goes into the front block drain hole. There are four drain holes so you can drain all the coolant from the engine, two on each side. As stated, when you remove the knock sensor, you will get drowned with coolant. Just as well go ahead and take the other three plugs out and install new coolant while you are at it. A lot of folks don't know that draining the radiator doesn't remove all the coolant. I always drain the block when changine antifreeze. I also do this when removing the heads so coolant don't go into the lifter valley and cylinders.

[piecesparts]

The sensor above the oil filter is the pressure switch that controls things like your electric choke. Once there is oil pressure, the circuit closes and energizes the choke to heat and thus open the chole plate.

[PHOENIX]

OK thanks for the clarification guys. I guess Ill pull the switch out and check it out. Maybe replace it if I feel it needs it. If not Ill through some tape on the threads and put 'er back in. Hope that stops the leak.

I guess I still need it because I have electric choke and I cant tell where the wires from this oil pressure switch go.

Thanks again!

[SanitysBane]

i don't have a choke, period. never conectedit so we just removed the butterflies, i've started the truck up when it was 40 degrees out side like that jsut fine, helps to have an eltric fuel pump

[KShortell]

The big bell-shaped one is the oil pressure gauge sender. The narrower one is the choke oil pressure switch. Both are teed into the same fitting up by my distributor, just as in the original setup you described.

I only know this because I replaced the oil pressure switch for the choke a couple months ago...