Oil Pressure Sending Unit
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rlgrantjr
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Oil Pressure Sending Unit
My sending unit body was loose and leaking oil but it won't come off. I knocked the top of the unit off (gently) so I could see the nut and threaded portion. I put a box end wrench on it and put as much pressure on it as I dared but it won't budge. It's had penetrant on it all night, normally I'd put some heat on it but considering the oil in the area I'm reluctant to heat it up. Anyone have any other ideas for getting this thing off without having to take the oil filter adapter off of the block?
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fordman
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Re: Oil Pressure Sending Unit
use more leverage. do you know how to put two wrenches together to make them work as one? you take the open end and put it on the sender. then take the open end of another wrench and put it inside the box end of the first wrench so that it wedges making it a longer wrench. or a large pipe over the end wrench may also work. now this is the improper use of these tools. and damage to the tools or your person could happen. or a large pipe over the end wrench may also work. so if you use the about sugjections. it is all on you for doing it. i wont be held responsible. please be careful.
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70_F100
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Re: Oil Pressure Sending Unit
Niether heat nor penetrant will help on that sending unit.
The threads are NPT, or tapered pipe thread.
The tighter the unit it screwed into the threaded hole, the more it is "wedged" in there. This is how pipe threads achieve their sealing ability.
About the only choice you have is additional leverage, as fordman said.
Since you say you got a box end wrench on it, you should be able to get a socket on it with a long-handled ratchet or pull bar. To achieve additional leverage, put a pipe over the end of the ratchet/pull bar to make the handle longer.
A steady pull will be what it takes to get this loose. Jerking on it will not work, in most cases.
Once you get it loosened about a thread or two, it should become very easy to remove.
When you reinstall it, I recommend Loctite PST as a sealant. It's a teflon-based sealing paste that you apply to the outside of the male threads on the sender. Teflon tape will work, but many times that is the cause of exactly what you have now. The teflon acts like a lubricant as you are screwing in the fitting, and you inadvertently overtighten the fitting. Not only that, but oil attacks teflon tape and will cause it to degrade over time. The PST hardens after a short time, and will not leak. I personally won't use teflon tape unless it's the only thing I have available.
The threads are NPT, or tapered pipe thread.
The tighter the unit it screwed into the threaded hole, the more it is "wedged" in there. This is how pipe threads achieve their sealing ability.
About the only choice you have is additional leverage, as fordman said.
Since you say you got a box end wrench on it, you should be able to get a socket on it with a long-handled ratchet or pull bar. To achieve additional leverage, put a pipe over the end of the ratchet/pull bar to make the handle longer.
A steady pull will be what it takes to get this loose. Jerking on it will not work, in most cases.
Once you get it loosened about a thread or two, it should become very easy to remove.
When you reinstall it, I recommend Loctite PST as a sealant. It's a teflon-based sealing paste that you apply to the outside of the male threads on the sender. Teflon tape will work, but many times that is the cause of exactly what you have now. The teflon acts like a lubricant as you are screwing in the fitting, and you inadvertently overtighten the fitting. Not only that, but oil attacks teflon tape and will cause it to degrade over time. The PST hardens after a short time, and will not leak. I personally won't use teflon tape unless it's the only thing I have available.
Wise men talk because they have something to say; fools talk because they have to say something.--Plato
Why is it that there's seldom time to fix it right the first time, but there's always time to fix it right the second time???
That's not an oil leak
That's SWEAT from all that HORSEPOWER!! 
Why is it that there's seldom time to fix it right the first time, but there's always time to fix it right the second time???
That's not an oil leak
That's SWEAT from all that HORSEPOWER!! -
rlgrantjr
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- Joined: Thu May 14, 2009 2:56 pm
Re: Oil Pressure Sending Unit
Thanks guys, I used my 1/2 drive rachet for more leverage and a steady pull it it came off fine.
Incidentally, this was supposed to be exhaust manifold change weekend, but I bumped the low pressure line on the p.s. pump and it snapped off, dumping the fluid out. Turns out the line was practically carbonized and hard as a rock. So the exhaust will wait till next weekend. Bright side is I fixed a ps fluid leak and an oil leak.
Incidentally, this was supposed to be exhaust manifold change weekend, but I bumped the low pressure line on the p.s. pump and it snapped off, dumping the fluid out. Turns out the line was practically carbonized and hard as a rock. So the exhaust will wait till next weekend. Bright side is I fixed a ps fluid leak and an oil leak.