Help with oil leaking from Sending Unit
Help with oil leaking from Sending Unit We installed a Autometer sending unit for an oil temp gauge near the oil filter in the aluminum adapter and now it is leaking. We drained the oil, put Permatex high temp sealant on the threads about 4 days ago. I drove the car today to work which is the first time since and I just checked under the car and it's still leaking oil. Does anyone know what else we can use to stop the leak?
Is it a mechanical(has small copper line going to gauge)or electrical sending unit? You can use some teflon tape around the threads of the sending unit if that is where the oil is leaking from.
It's an electrical one Josh. The teflon tape is the last thing we tried and are going to see if it held today when I take the car out. I'll let know and thanks for the reply 
TECH Resident
Joined: Jan 2003
Posts: 937
Likes: 0
From: South Alabama
When you tapped the fixture you did use a 1/8"-27 NPT (pipe tap) didn't you? At least this was the size of my auto meter oil temp sending unit. The tap drill size for this tap is the letter "R" drill (0.339" diameter). If you used a larger drill than this it will tend to cause sealing problems. The sending unit is tapered and if you accidently used a straight tap instead of the tapered pipe tap your going to have sealing problems. Also, if you did use the pipe tap and you tapped it deeper than 6-7 full threads from the top of the tap then the hole/threads are too wide (read too large diameter) to seal on the sending unit. Since a pipe tap is tapered, the deeper you go the wider the hole. This is the standard rule when tapping with a pipe tap, you always stop tapping 6-7 full threads from the top of the tap.
Last edited by Weezzer; Nov 3, 2007 at 09:10 AM.
We did everything you said with the exception that it may have been tapped further then 6-7 threads. Thanks for the reply. If its still leaking then we'll know this is the problem and I'll have to buy another piece and re-tap/drill.
TECH Resident
Joined: Jan 2003
Posts: 937
Likes: 0
From: South Alabama
As you look at the tap you will see about 3-4 threads at the very top of the tap (the top of the tap is the drive end, not the end you place in the hole to start the thread) that are thick and not at full depth or thickness-where the thread begins on the shank, count down from the first full depth thread 6 or 7 more threads. Some people put some tape around the tap to mark the point, and then tap till the tape touches the surface of the hole.
If you don't go deep enough the first time then you can pretty easily re-insert the tap, pick up the thread (don't cross-thread it though), and turn it another half turn or so and fit the sender in again.
Once you go too deep thats when the fun begins.
Last edited by Weezzer; Nov 3, 2007 at 02:40 PM.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
