Just replaced engine temp sensor a year ago because the original one was leaking. The new one is now leaking worse than the old one ever did. What gives? I apologize if this has been covered.. I did search the aRchives to no avail. Thanks.

clean threads and put a light coat of RTV on the threads.

2 things

1/ oil does not seep from your engine temp sensor, coolant may seep from it, but not oil.

 

2/ where is this temp sensor located? the oil pressure sending unit is located on the front of the engine under the alternator, it COULD leak oil. the power steering pump may leak oil on to the top of the engine making you think the temp sensor is leaking oil. and the temp sensor, both of them, are located on the crossover pipe under the intake manifold on the passenger side accessed from the rear.

 

but gary is right, if it is leaking, a little sealant on the threads should fix it. the power steering pump, if it is leaking, is a little bit more of a job.

For leaking sensors I often use "Rectorseal #5 softset". The crap won't wipe off at all.

 

Not effected by gas, oil, etc. Never gets hard. Tough to wipe off your hands and tools because of this.

 

On stubborn sensors with confirmed good threads (or to assist in getting CRAP to stop leaking) it's my last resort but almost always works.

 

Check your local plumbing/hardware/home center for it by name.

 

Professional plumbers have used it for years. A can will last until you loose it.

 

A few years ago I needed some at my weekend place and belive I bought it in a toothpaste tube at an ACE hardware.

When I install taper thread stuff like this, there are two important things to keep it from leaking. CLEAN THE THREADS!! Probably the most important thing. Taper threads rely on a good seal to keep from leaking. Wire brush the threads on the sensor, and get a wire brush thing for cleaning the threads in the engine.

 

Then I always use teflon tape on the threads, make sure you put it on the correct way so the tape doesn't peel off as you install it.

 

I have replaced many many many temp and oil senders on boats, and a few on my cars this way. None of them have ever leaked.

 

And, if the threads are clean you technically don't need any tape at all. The oil pressure switch and one of the temp senors on my car don't have tape because I didn't have any on hand. With nice clean threads on install, no leaks.

Edited February 10, 201214 yr by 987687

It Must the the oil pressure sensor!! Under the alternator. Def not power steering pump leak. Not leaking from the threads---leaking through sensor out the top of it. Dripping down front and rear of block.

Then I always use teflon tape on the threads, make sure you put it on the correct way so the tape doesn't peel off as you install it.

 

coming from a construction/ plumbing background i keep teflon tape in my toiletries kit. you just never know when you will come across a leaking shower head.

 

and i use it on anything having to do with liquids / air / steam / gases and pressure. but almost anything will do on low pressure automotive systems if it has lubricating and/or sealing properties. part of the old old old fashioned ''pipe dope'' (pipe joint compound) was oil to lube the threads. the other part was some kind of filler to fill in the gaps.

 

but i digress.....

Edited February 11, 201214 yr by johnceggleston

if the oil sensor is leaking oil down the back of the block you must be adding oil every week / day.

 

on the other hand, if you have evidence of oil leaking on the front and rear of the block, there are OTHER more common causes. in the front, the oil pump, cam and crank seals. on the rear, and this is a biggie, the oil separator plate on the rear of the block behind the flex plate or fly wheel, depending. or it could be the valve cover gaskets on either side of the engine. all of these are leak potential points.

 

we have come a pretty long way with out any car specific info, year, model, engine, trans, miles, would be helpful.

 

all subarus leak oil after a time. none of the leaks are deadly as long as you keep oil in the engine, and all are repairable given the right amount of time and a little bit of money. the most difficult one is the oil sep plate on the rear of the block. you have to pull the engine to address it. all the others can be done one day on a week end.

Edited February 11, 201214 yr by johnceggleston

Pipe dope makes a mess. I hate that stuff. But on BST sometimes it actually works better than teflon tape...

 

Anyway. it's not a big deal to change out the pressure switch. Pull the alternator off for more access (2 12mm bolts), then take the sensor out. I think it's about a 24mm, or just use vicegrips or a pipe wrench on it.

I wouldnt use pipe dope, but i would use ultra grey sealant. Teflon tape is non solvent.

It Must the the oil pressure sensor!! Under the alternator. Def not power steering pump leak. Not leaking from the threads---leaking through sensor out the top of it. Dripping down front and rear of block.

if it's leaking through the sensor then the sensor needs replaced.

 

since the title and first post is incorrect we need to clarify:

 

1. did you replace temp sensor and now oil sensor is leaking?

or

2. did you replace oil sensor and now it's leaking again?

 

if it's leaking again - did you replace with a used one or a new one?

subaru or aftermarket?

 

if the sensor is leaking is sounds fairly straight forward - replace the sensor.

Edited February 11, 201214 yr by grossgary

Replaced pressure sensor and forgot what it was called. Sorry for the confusion. There is no question it is leaking again after being replacing about a year ago. Did the separator plate etc. HG"S etc. 12000 miles ago and right valve cover still weeps a bit.

Is this an part that must be Subaru or else?

 

98 legacy outback 2.5

I use Fel-Pro for VC gasket set but some here seem to prefer especially the O rings for the spark plug holes to be OEM.

 

I have my own "must haves" to be OEM (2.5 HG's, WP gasket, crank/cam seals) but other things I use either Fel-Pro or OEM for depending on where I'm going next for parts and they include intake, exhaust, and VC gaskets.

Loctite 545. Hydraulic / Pnuematic thread sealant. Good to 10,000 psi. Never had a pipe thread leak after using it .

 

GD

The oil pressure switch/sender was leaking from the copper pin on the top. Not around the threads. Got one at NAPA that looks different than the Subaru one but threaded right in and seems to work. THanks, folks!!