I've got a leaking oil pressure switch/sending unit and will be replacing it tomorrow. The shop manual says to use a silicone sealant on the threads. Which kind is preferable? I've got RTV high-temp copper and water pump gasket kinds in the garage. Will one of these do?
oil pressure sending unit - what sealant to use?
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I'd use teflon tape.
permatex high temp teflon thread sealant (white in colour) to put some in the middle section of the tapered thread. Screw it in carefully and let it settle.
I've used Teflon tape many times on pressurized engine oil applications without issue.
The Permatex high temp thread sealant works very well also, but I have noticed that if I don't give it maybe 24 hours to cure before applying pressure it often will spring a leak. Note that it's an anaerobic sealant so excess outside the threads won't harden (but the parts on the threads not exposed to oxygen will harden).
The Permatex high temp thread sealant works very well also, but I have noticed that if I don't give it maybe 24 hours to cure before applying pressure it often will spring a leak. Note that it's an anaerobic sealant so excess outside the threads won't harden (but the parts on the threads not exposed to oxygen will harden).
its NPT thread so it will pretty much seal on its own. Teflon pipe tape should be fine also. I have been pulling mine oil pressure sender and screwing in a gauge back and forth over the past few weeks and no sealant and no leaks.
I used some teflon tape as I didn't want to worry about waiting for any sealant to dry. Worked fine, thanks.
Oil leak is fixed now, but my underbody has a new rust coating.
Also discovered that my clutch line has a tiny leak.
Oil leak is fixed now, but my underbody has a new rust coating.
Also discovered that my clutch line has a tiny leak.
Teflon tape will work well, but some part of the sender must contact the block to form an electrical ground.
Oh yah...good point! May want to check then that the oil light comes on with engine not running. Some vehicles the ground connection makes the light come on; others the loss of ground connection makes the light come on.
Yeah, I verified that the light was on before starting and it went off quickly, as it always does.
Any of the above,,,it's just not that critical.
Bob
Bob
While we are on this subject I want to run something by all
you knowledgeable guys. Someone made the statement it is a pipe thread and they pretty much seal themselves, which I agree with, providing they are tight enough . Thinking back to the days before teflon, pipe dopes as they were called
all contained oils, did they and does teflon seal a pipe thread or lubricate it enough to tighten it to the point where it won't leak?
you knowledgeable guys. Someone made the statement it is a pipe thread and they pretty much seal themselves, which I agree with, providing they are tight enough . Thinking back to the days before teflon, pipe dopes as they were called
all contained oils, did they and does teflon seal a pipe thread or lubricate it enough to tighten it to the point where it won't leak?
don't use silicone sealant, I'd wonder about that manual
Well the reason you need teflon tape or a sealant on NPT threads is that there is leak path between the crest and roots. The sealant needs to fill this gap to assure a leak free seal. NPTF (dryseal) is somewhat improved with a little different design that still works with NPT.
Clean the threads so that they are free of oil - both the sending unit and the hole in the head. Then you can use the RTV copper. I'd smear a little on the threads of the unit, and also in the head threads with a q-tip. It won't leak. Teflon tape is good, but temps can get very hot on a head, and it may be compromised.
you need something that won't insulate the sender from the block. if it doesn't ground to the block, the sender won't work (or end up working really weird)
SurfStar their should be an orange or wite band of sealant already on the threads of the new unit. If not any of the RTV you have will do. You do not cake it on either you simply put a very small amount on the tip of your finger and rub it into the threads then wipe the excess off.
Everyone is right about the electrical contact, but it never seems to be a problem, There is always some metal to metal contact.
Teflon tape or paste seems to work good.
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