Thread sealant for engine parts, oil sensor gauge ?

Question

I had a small leak on my Volvo motor in my boat last summer. Had a mechanic replace an elbow fitting that connects to the oil sensor where it was leaking. Now along with the small leak still, the oil sensor gauge on the dash intermittently works.

I figured I would just purchase a new oil sensor, nipple (screws into engine block) and elbow fitting (screws into nipple and to sensor).

When I questioned him about the "fix" he failed at, he said he used the best marine grade sealant on the threads of the parts and thought maybe some debris had got into the oil sensor and that was what was causing the gauge to not stay stable.

The gauge works most of the time, but every once in a while when I go full throttle it drops to 0 until I back off then it reads fine.

I was wondering what I should use for the threads on the nipple, elbow fitting and sensor to get a good seal?

And what could be causing the sensor gauge to drop?

Hopefully putting all new parts in corrects the problem, but the gauge all of a sudden not working worries me.

Answer 1

I use teflon tape.

Answer 2

Teflon tape is NOT an approved sealant for automotive use. The teflon can break off and clog oil galleries. The fittings are tapered just like plumbing fittings. Use a dab of pipe dope and apply it a few threads back from the starting threads.

Answer 3

Kenny, thumbs!

the correct app is teflon tape. commonly know as simple "thread tape". good for marine apps (it's teflon, so....)

fix leaks go from there.

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IMHO,

i see no indications of a bad crank or bearings. at WOT-wide open throttle, she'll have pressure even if the bearings are toast. and if they were toast, you have some serious crank noise to indicate such. bearings so degraded that no pressure can be built, not happening w/o a host of other symptoms. prolly lock up/freeze the crank in that instance. it wouldn't live at rpm w/o oil pressure of some kind.

and you've given us no indications at cold start up either. such as a knock.

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respect,

thread tape, if used properly won't hurt a thing. like to see some documentation on the comment of *NOT approved for automotive use*.

Answer 4

Replace the electrical oil pressure sending unit!

Answer 5

Silicone RTV. Let dry for 3 days.

Answer 6

Oddly enough this kinda sounds like bad crankshaft bearings to me.