318 LA oil pressure sending switch source of oil leak

77 LeBaron

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Hi I think I have found the major oil leak on my 1977 LeBaron it appears to be the oil pressure switch which appears to be unthreading from the block . How difficult is this to replace . I use about 16 ounces of oil every 250 miles and this appears to be the major leak. Any advice and guidance would be greatly appreciated.
 
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Aspen500

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It just screws out. They do use a special socket for oil pressure sending units but you can do it with a regular deep socket that fits semi-close. I assume you have the small switch (oil light) and not the large sender for a gauge, in which case it's a 9/16" (or is it 1/2"?) wrench? Either way, easy to change.

They can be a huge oil leak.

Socket looks like this:
oil socket.jpg
 

77 LeBaron

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It looks difficult to get at . are their any videos or is it in the shop manual . I think this is my main oil leak , there is minimal seepage from the valve covers. I am not to mechanically inclined and have grip strength problems due to age.
 

BudW

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They make two different versions:
PS11T OPS photo.jpg

Oil pressure switch (for idiot light) (by far the most common).

PS59 OPS photo.jpg

And Oil pressure sender (for oil gauge).

The switch (smaller part) does require a special socket to remove – but in some cases, you can use a normal deep socket (depending on how your socket wrenches are made).

The sender (larger all metal part) uses an end wrench to remove/install. I “think” it is 7/16” size. Generally the only cars I see with the oil pressure gauge are special order, police and taxis.
A huge majority of M-bodies came with idiot light (smaller switch).

To replace:
First, I would highly recommend taking car to a car wash and washing that area well before performing repairs – for that area might be pretty oily.

Disconnecting the air cleaner and moving it to the driver’s side helps to gain access.

Then just push the wires aside, disconnect the electrical connector, put the sorta special socket over it )(straight down) and unscrew like a (weird) bolt.

Reverse to install – but I would recommend threading the first few threads by hand.
It doesn’t need to be too terribly tight – just tight enough not to leak past the pipe threads. Too tight and it can break off.

If paying a shop to replace it, the tech would get paid about 0.7 (seven tenths) of an hour to replace the sending unit. I don’t think is a very difficult job. Many auto part stores might even have a socket to loan out.


The oil pressure switch does have a tendency to seep, to leak oil and even has been known to come apart – which means you have full engine oil pressure creating a geyser effect in rear of engine (which can drain the engine out of oil in no time).

Also, in that same area, the rear intake manifold gasket also has a tendency to leak oil – and that job is not fun. Not difficult per se, but lifting that 50 pound intake off and back on – does a number on your back.
BudW
 

77 LeBaron

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Thankyou I have the top one (idiot light) ordered and in transit . Will a spark plug wrench work on that part ? I am hoping and praying it is just that oil pressure switch . I will post the results once job is done.
 

Aspen500

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No, spark plug socket won't work. I'd be willing to wager it is most likely the switch. Intake ends can (and do) leak but even if the gasket was completely missing, it wouldn't leak as much oil as yours is.
 

volare 77

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Some sending units come with sealer on the threads some don`t. A socket can be purchased at advance auto or autozone. If I remember correctly I used a long extension to get it out. They can leak horribly when they go bad.
 

77 LeBaron

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Thanks All parts on site and I will change it out this week. Do I really need pipe thread and if so will any type do ?
 

BudW

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Most new oil senders, come with some sealant on the threads – so in that case, nothing else is needed. Look at post #4, the top picture has nothing on threads and the bottom picture has some white sealant (or Teflon tape) already applied to it.
The lower part is ready to install.

If you reinstall a sender (or have a new sender without sealant), use a wire brush (or something) to scrape away the remaining dirt and/or sealant. Go to any hardware store and get a roll of Teflon tape – if you don’t already have some somewhere. It doesn’t take but 2-3 wraps around the threads to do its job. Wrap the tape in the same direction item is getting screwed in (so tape doesn’t un-roll when screwing it in).

The fitting is 1/8” NPTF.
Tightening spec is 60 inch-pounds (or 5 foot-pounds, or 7 newton meters) – which is not very tight.

DO NOT over-tighten, for you can and will break the fitting off in the block – which requires drilling and using hard-outs to extract.
Note: I disagree with the term “easy-out” – for it is not.

You do not have to use Teflon tape – but you will have an oil leak in that area, if you do not.
Not a gusher, but it will leak oil there.
BudW
 

77 LeBaron

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Thanks Bud my sender is not coated , so any old Teflon tape will suffice correct . I took a good well lit look in that area and it is caked with oil grime all in that area so I will probably be giving the engine a good cleaning before I attempt the install. On another matter Bud I have been averaging 13.95 MPG without A/C, and 12.54 MPG with A/C on with a high of 14.12 MPG and a low of 10.43 MPG . I have not tuned up the vehicle yet is this a normal MPG range for a 318 2BBL ?
 

BudW

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I have been averaging 13.95 MPG without A/C, and 12.54 MPG with A/C on with a high of 14.12 MPG and a low of 10.43 MPG . I have not tuned up the vehicle yet is this a normal MPG range for a 318 2BBL ?
Yes and no.
My ’86 8th Ave gets about the same range, for in town driving. I blame the catalytic converters which I have confirmed are mostly stopped up. I also blame the 2.2 ratio differential gears for part of it, as well. What it does is car is always under a load, so carburetor is always in “power” mode (thinking you are driving uphill all of the time).
I do have plans on installing an 8¼” differential with 2.94 gears in it soon, which will help with acceleration and should also help with fuel mileage a bunch.

My ’77 wagon has 3.21 (or 3.23) gears in it and it gets about 18 MPG in town (and I do have a heavy foot). It will also do circles around my 5th Ave on takeoffs (same engine and everything else).

I have a couple of questions for you:
Do you primary drive car in town or highway?
Do you know what your current (and exact) differential gear ratio is?
BudW
 

77 LeBaron

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My estimates were based on approximately 65 city /35 HWY . The city average is mostly around 25 to 30 MPH, I assume the gear ratio is the original stock one for the 1977 LeBaron.
 
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