More oil leaks. Oil pressure sending unit?

Dave Bassett

True Classic
When I got my 850 Spider, it leaked lots of oil. LOTS! So far I have replaced the valve cover gasket, fuel pump gasket, oil pan gasket, and front main seal. The engine is now mostly dry but wet around the oil pressure sending unit and on the heat shield over the muffler. Is the sending unit a likely culprit? Do I need to replace the unit or is there a gasket involved. It seems to read just fine. Thanks.
 

Loren Field

True Classic
I just remember the copper washers to seal, no gasket. I have had several of the dash light senders (not the gauge sender) leak over the years; those are fairly inexpensive to replace whereas the gauge senders can be pricey. If you clean it up and start the car, you might be able to see where it is coming from.
 

kmead

Old enough to know better
When I got my 850 Spider, it leaked lots of oil. LOTS! So far I have replaced the valve cover gasket, fuel pump gasket, oil pan gasket, and front main seal. The engine is now mostly dry but wet around the oil pressure sending unit and on the heat shield over the muffler. Is the sending unit a likely culprit? Do I need to replace the unit or is there a gasket involved. It seems to read just fine. Thanks.
The oil pressure sending unit itself is a known leak point. These don’t seem to last very long. The connection is another point as you have one component (the idiot light) clamping multiple washers and a cast aluminum component, all with different levels of expansion and contraction. Add to that the group of these parts are in the warm nestle of the header and muffler.
 

Dave Bassett

True Classic
Thank you guys. I think that I will attempt tightening first, just because. If components have to be repalced, it looks like it maybe worth it, in terms of access, to remove the left tin and exhaust. Does that seem correct?
 

Jeff Stich

True Classic
Thank you guys. I think that I will attempt tightening first, just because. If components have to be repalced, it looks like it maybe worth it, in terms of access, to remove the left tin and exhaust. Does that seem correct?
Replace the two copper washers first, one goes between the oil light sensor and the oil pressure gauge sensor, and the other one goes between the oil pressure gauge sensor and the engine block.

Clean all oil/residue off of the 2 sensors & the top of the muffler heat shield, then run the engine for a few minutes to check for leaks. If it's still leaking, it's most likely the large oil pressure gauge sensor. They tend to leak either on top where the wiring connectors are, or along the crimped edge where the large metal cap meets the aluminum base section.

Or you might get lucky & it'll be the smaller oil light sensor mentioned by Loren Field.
 

Dave Bassett

True Classic
Thank you Karl and Jeff,
Are these specific copper washers?I have a supply of "crush washers" for the oil plug. Or, are they different.I didn't see them on the Bayless site.
 

kmead

Old enough to know better
They need to be annealed washers. You can anneal old washers again, you likely need to ensure they are still flat by filing off any ridges etc but the two surfaces need to be parallel.
Thank you Karl and Jeff,
Are these specific copper washers?I have a supply of "crush washers" for the oil plug. Or, are they different.I didn't see them on the Bayless site.
 
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