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420a Oil pressure switch BROKEN on block, HELP!

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96rsSTBRWD

10+ Year Contributor
140
2
Sep 5, 2008
Myrtle Beach, South_Carolina
So, I have an interesting dilemma. My oil pressure switch began leaking oil, as ive heard that they often do on the 420a. I went to autozone to get a new switch before i saw what mine even looked like.

Later, i got under the car and began replacing my switch and knock sensor. (Both on the firewall side of the block.)
The knock sensor came out, but the pressure switch is being a major pain in my ass. Not only that but i think autozone gave me the wrong part.

What mine kinda looked like:
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I'm not sure if this was exactly it, but it has small guides on the side that the one they gave me does not have.

What autozone gave me:
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But THAT'S THE LEAST OF MY PROBLEMS. :banghead:
While removing my old switch with vice grips the connector end got all mangled and snapped in half. And the plastic half that remains is now spinning freely but still connected to the metal part with the hex pattern that screws into the block.

:confused: I want to know what other members used to get the oil pressure switch out. :confused:

The hex portion seems to be too big for a 1" and too small for a 1, 1/16 socket. My wrench is too big to get around it and turn with the intake support in the way.

Any help or tips the get this sucker out is much appreciated! Thanks!
 
Last edited:
You need a tool specifically for removing the oil pressure sending unit; it's basically a 1-1/16" socket, but deep enough to accommodate the long plastic part. If you already broke the old OPSU, you could just snap the plastic part off completely and use a standard socket to remove it, but you'll need this tool to install the new one. I wouldn't use pliers or vice grips...

The tool costs $10-$20, and you can buy it from most auto parts stores.
 
VelocitàPaola;152629339 said:
You need a tool specifically for removing the oil pressure sending unit; it's basically a 1-1/16" socket, but deep enough to accommodate the long plastic part. If you already broke the old OPSU, you could just snap the plastic part off completely and use a standard socket to remove it, but you'll need this tool to install the new one. I wouldn't use pliers or vice grips...

The tool costs $10-$20, and you can buy it from most auto parts stores.

Man thanks for the info. I have been searching for a picture of this sensor/switch for hours on the site because I have the same problem ... a leaking switch. I just found it a few hours ago. Then to have instructions on what to watch for let alone what to look for when I go to the store is great.

Question 1: Is it possible to get the switch out without taking the exhaust and middle frame piece out?

Question 2: I don't have gauges, but I would like some. Is this the same sensor that I need to T off of if I get an oil pressure gauge today? :hellyeah:

Question 3: Anything else I should watch for before I start?

Thank You in advance for the help. DSM Tuners are GREAT!:thumb:
 
I don't know if they are the same but some sensors on the 95 are different from 96+ cars. Autozone may have given you a newer model sensor
 
Question 1: Is it possible to get the switch out without taking the exhaust and middle frame piece out?
Yep. I'd get to it from above, not below. Remove the battery and intake and you should have access.

Question 2: I don't have gauges, but I would like some. Is this the same sensor that I need to T off of if I get an oil pressure gauge today?
Yes.

Question 3: Anything else I should watch for before I start?
You might want to put a little anaerobic sealant on the threads of the new sender/T fitting. Wait a good 24 hours for it to dry. You could use yellow Teflon tape/joint compound too -- it can't be the regular white stuff, though, because oil degrades it.
 
VelocitàPaola;152629752 said:
Yep. I'd get to it from above, not below. Remove the battery and intake and you should have access.

You might want to put a little anaerobic sealant on the threads of the new sender/T fitting. Wait a good 24 hours for it to dry. You could use yellow Teflon tape/joint compound too -- it can't be the regular white stuff, though, because oil degrades it.

When you say intake do you mean the intake tube that connects to the throttle body only or do I need to take out the throttle body as well along with the battery?

Thanks. That helps a lot because I have loads of the white stuff and knowing me, I would have used it. I will locate and use the anaerobic sealant instead. :thumb:
 
Okay so AUTOZONE has the wrong part number for the 420A oil pressure switch.

They gave me PS277
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When our actual sensor is PS278
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They will argue with you over it. LOL. Must have been put in the computer wrong.

The wrong one doesnt even fit our wiring connector, and to top it off the false one (PS277) is $40+.
While the correct one (PS278) is about $10...
 
hey i have a gs 97 420a motor and one of my sensors wire is broken and doesnt mark it becuz its not connected and it doesnt give me check engine light but im tring to figure out which one is it ### the one that is messd up on mine is on the driver side and i think that has something to do with my slow acceleration.... knock sensor or oil pressure sensor??
 
I just replaced mine and I had no issues getting it out. I used an open box end wrench and deep socket to get it off instead of buying that tool. I didn't have to take anything off only had to Jack the car up. I had the same issue at checkers with getting the right part number sorted out.
 
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