Hi guys! Hope everyone's getting on well!

My 1990 Magna TP is still going along, mostly thanks to this forum!

Unfortunately, I've hit a problem with the oil pressure switch. Started leaking yesterday, dumped most of the oil overnight, and is still leaking today.

I've looked online for a replacement but had no luck. Does anyone know of a source? I'm going to check the wreckers in the next few days, but I've not seen many other magnas around town (Kalgoorlie, WA).

Also, my plan is to replace this myself. Is there anything that could have caused this to leak? Oil pressure too high? Blocked PCV? Recently there was positive pressure in the rocker cover - ie with the engine running and oil cap off, air and oil was blown out - is that normal?

As always, thanks in advance for the help :happy:

Hi guys! Hope everyone's getting on well!

My 1990 Magna TP is still going along, mostly thanks to this forum!

Unfortunately, I've hit a problem with the oil pressure switch. Started leaking yesterday, dumped most of the oil overnight, and is still leaking today.

I've looked online for a replacement but had no luck. Does anyone know of a source? I'm going to check the wreckers in the next few days, but I've not seen many other magnas around town (Kalgoorlie, WA).

I bought mine from this eBay seller a couple of weeks ago: http://www.ebay.com.au/itm/260740569294?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

They were very efficient and it arrived in a couple of days.


Also, my plan is to replace this myself. Is there anything that could have caused this to leak? Oil pressure too high? Blocked PCV? Recently there was positive pressure in the rocker cover - ie with the engine running and oil cap off, air and oil was blown out - is that normal?

That's not normal but I don't think any amount of pressure could actually break the oil pressure switch. If there was a crack in the plastic part of the switch or a failure where the plastic joins the metal part, a pressure build-up might cause a sudden increase in the amount of leakage from it. The one that I replaced was leaking from the upper (plastic) part of the switch, not from the threads.

As far as the pressure build-up is concerned, a blocked PCV valve would be the first suspect.

You might find it worthwhile to read my post about replacing the oil pressure switch. I had trouble undoing it because of its odd shape and the lack of spanner space. See here: http://www.aussiemagna.com/forums/showthread.php?t=102225

Is there anything that could have caused this to leak?
Quite common on these as the plastic gets brittle over time they are close to the exhaust which does not help at all.
Often have to replace it every few years on mine. There is a shield on the front mount to help keep some heat off.


Recently there was positive pressure in the rocker cover - ie with the engine running and oil cap off, air and oil was blown out
Can be quite normal on high mileage engines as they suffer from blowby and you get a bit of pressure build up. Even good engine will spew oil out the cap if you remove it while the engine is running.
Check the PCV valve is functioning and the other hose to the airfilter is also not blocked. Vee


I'm going to check the wreckers in the next few days
Donot use a secondhand one they will most often if not already leaking not last very long.
Super cheap auto will have them in stock also and autobarn if you have them there.

Cheers guys!

It was the plastic that snapped, it was pretty brittle. Noone on site had ever heard of these, I was getting all sort of horror diagnoses of warped heads(!) etc despite the oil clearly pumping out by the wire.

I'm reassured that it's just the plastic that's become brittle. I was just being a little bit paranoid, this time it happened around 10km from home and I lost most of the oil, lucky I wasn't out bush somewhere! :happy:

I did phone Mitsubishi to try and find out if there was a generic part, I was told my car was too old and wasn't in the system, and the part wouldn't be in stock anyway.


There is a shield on the front mount to help keep some heat off.

I wondered what that was for!


Can be quite normal on high mileage engines as they suffer from blowby and you get a bit of pressure build up.

I bought the car at 160k, it's just under 190 now. Figured it was normal, but I'm sure it wasn't doing it before. I replaced the other air hose but the PCV is on my to do list.


Donot use a secondhand one they will most often if not already leaking not last very long.


Good advice! no point replacing it twice if I can get a new one.


I bought mine from this eBay seller a couple of weeks ago: http://www.ebay.com.au/itm/260740569...84.m1497.l2649


Cheers for the link, Ebay was my first stop but that didn't show up in my search. Just ordered one. :happy:

I've just printed out your how-to post to get the stuff ready for when the part arrives! Hopefully it will go smoothly.

Thanks again guys!