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Galant Dented Oil Pan and Oil Leak After High RPM Driving

Pasta_Ricer

Probationary Member
27
2
Nov 2, 2021
Zanjan, Asia
Welp, my Galant has much bigger problems than the small IPS wiring error and dead IAC stepper motor.

Today while I was under the car looking for a cat, I noticed that my oil pan has a pretty big dent in it and it looks shiny and wet. Touched it and yup, it's definitely oil.
Everywhere is covered in oil; from the oil filter to the chassis.
I cleaned it with some degreaser spray and wiped it down and then turned on the car to let it fully warm and hopefully find the leak. It warmed up and I didn't see any new fluids dripping or soaking stuff, even after revving up to 3k. So, I decided to take it out for a spin and put it under heavy load after fully warming up. Took it to 6.5k maybe 5-6 times and maybe once to 7k, shifting hard from 1st to second. Then I immediately drove it back into the garage while doing a rip right before getting into our alley. I parked it and popped the hood after turning it off and I could hear a sort of bubbling/boiling sound coming from the top hose that's connected to the thermostat housing. Touched that and it was definitely boiling inside. Then I turned it back on to recirculate the water and let the fan take care of the heat. In the meanwhile, I peeked underneath the car and saw the oil dripping maybe a drop every 10 seconds from around the front right side of the oil pan.

Now I am truely stuck. I can't take the car to work, and I have spent most of my money on the actual car and some small maintenance like an oil and oil filter change, air filter cleaning (cause they are extremely rare here), new spark plugs and some other bits and pieces.
I can't do any sort of repair on the oil pan myself as I have not taking any oil pan off in my life and I don't have the equipment like a hydraulic jack and stuff.

Also, I think the damage had been done by the previous owner. The car is kinda lowered, especially with the thin tires. I always go over the bumps sideways to avoid scraping anything and I have only scraped my exhaust tip before.

What should I do? :(
This is my first car and TBH a rather hard one to maintain, but I absolutely love it, even with the flaws.

Thanks <3

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Pasta_Ricer

Probationary Member
27
2
Nov 2, 2021
Zanjan, Asia
Okay, folks. It's not my oil pan that's leaking; it's my oil pressure switch. When at anything above 1.5k RPM, it slowly leaks out of where the spade plug attaches to it, about a drop every 30 seconds. If you rev it and then shut it off or keep it at a constant high rev (high pressure oil) like when cruising at 2.5k RPM, it will leak a lot faster.

I tried tightening it a bit as it was super loose (could've rotated it by hand), but that didn't fix the leak fron the top of the switch.

I assume I can't fix the switch and I have to buy a new one?

Thanks in advance!
 

Pasta_Ricer

Probationary Member
27
2
Nov 2, 2021
Zanjan, Asia
Hey, Tony.

Doesn't removing it involve draining the oil? I don't know how I feel about doing that. I've never drained the oil out of any car before.

Also, I think the sensor is leaking from the middle of it (where the spade plug is) as it gets wet up there and then drips down on the lower part of it. So I don't believe teflon tape could fix it?

By the way, can someone please verify that this really is a Mitsubishi oil pressure sensor? As the original owner has added some sketchy parts from other cheap and crappy vehicles. Not even their original parts!

Picture attached below.

Thank you!

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AWD-Tony

Supporting Member
6,797
3,683
Sep 11, 2017
Cincinnati, Ohio
There will be a little oil that leaks out if you remove the sensor. Not too much to worry about. If the sensor is leaking from the center, you’ll have to replace the switch. They’re not that expensive and you can go aftermarket. It’s just for the light on the dash.
 

Pasta_Ricer

Probationary Member
27
2
Nov 2, 2021
Zanjan, Asia
Yeah, they are usually pretty cheap, but I'm afraid of the availability :)
I contact a seller which specializes in Galant parts (6th and 7th gen), hoping he can replies with good news.

Are the threads on these common to those cheap "Greddy" Aliexpress oil pressure sensors (gauges)? They look pretty handy and I'd absolutely LOVE to have the ability to see my oil temperature so I can know when I can floor it and have some fun :D
Although, they are sold 3 times the price of Aliexpress over here...
 

We're on Boost

15+ Year Contributor
1,593
416
Aug 25, 2007
Seattle area, Washington
This is probably your part here:
https://www.rockauto.com/en/moreinfo.php?pk=944535&cc=1206177&pt=5700&jsn=10914

It is $2.51 from them (USD).
The thread they show in the pics (4 pictures) looks like 1/8" pipe thread. But they don't say.
This is on Rock Auto under 1991 Mitsubishi Galant, all models basically.
Rock auto shows OEM part numbers for it, one of which is MD001482. Pasting that part number into a search on MitsubishiPartsNow takes you to their page for the part, no picture, price $26.79 (USD), and it calls it an oil pressure sending unit with current part number 1258A002
"Replaces: MD001482, MD138993" and under "Vehicle Fitment" it drops down a list of hundreds of Mitsu cars that it fits, one of which is:
1991 Mitsubishi Galant Base, GS, GSR, GSX, LS, VR-4 2.0L L4 - Gas

Quite a mouthful, but that's how it goes sometimes looking for these parts!

Heck I might buy one for my car - it's on the list!

Don't try to put some other kind of sensor in there unless you are absolutely sure the thread is correct.
It's like this: Japanese pipe thread (JIS or PT) in these small sizes has more threads per inch than American pipe thread.
For example, 1/8" Japanese pipe thread is 28 threads per inch.
But 1/8" American pipe thread (NPT) is 27 threads per inch.

I'm sure the Rock Auto part (WVE 1S6556) will have the correct thread but check it anyway if you get your part from them.
 
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DSMPT

DSM Wiseman
2,170
1,754
Jun 12, 2014
Japan / Mexico, Arizona
I think the sensor is leaking from the middle of it
This happens sometimes. After market oil pressure switch would often leak between the metal and the plastic part where the green line is. Even it's new, it would happen. Many years ago I tried like 3~4 of them from different local parts stores and all leaked in the same way sooner or later. What I finally did was buy a new again and perfectly degreased it and applied RTV (Ultra Grey) between the metal tab and the plastic part, and made it completely dry to instal. At least it was working for some years until I removed the switch due to no use.
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Pasta_Ricer

Probationary Member
27
2
Nov 2, 2021
Zanjan, Asia
I’m not sure off hand but it the info should be on here. My guess is npt thread but do your research or make another post. An aftermarket oil pressure gauge is great idea to monitor the engine.
Yep, I think it's a great investment. Much much better than the "dummy light".

This is probably your part here:
https://www.rockauto.com/en/moreinfo.php?pk=944535&cc=1206177&pt=5700&jsn=10914

It is $2.51 from them (USD).
The thread they show in the pics (4 pictures) looks like 1/8" pipe thread. But they don't say.
This is on Rock Auto under 1991 Mitsubishi Galant, all models basically.
Rock auto shows OEM part numbers for it, one of which is MD001482. Pasting that part number into a search on MitsubishiPartsNow takes you to their page for the part, no picture, price $26.79 (USD), and it calls it an oil pressure sending unit with current part number 1258A002
"Replaces: MD001482, MD138993" and under "Vehicle Fitment" it drops down a list of hundreds of Mitsu cars that it fits, one of which is:
1991 Mitsubishi Galant Base, GS, GSR, GSX, LS, VR-4 2.0L L4 - Gas

Quite a mouthful, but that's how it goes sometimes looking for these parts!

Heck I might buy one for my car - it's on the list!

Don't try to put some other kind of sensor in there unless you are absolutely sure the thread is correct.
It's like this: Japanese pipe thread (JIS or PT) in these small sizes has more threads per inch than American pipe thread.
For example, 1/8" Japanese pipe thread is 28 threads per inch.
But 1/8" American pipe thread (NPT) is 27 threads per inch.

I'm sure the Rock Auto part (WVE 1S6556) will have the correct thread but check it anyway if you get your part from them.
Well, I found a new OEM part from a Mitsubishi distributor locally for about $6. Not that bad.

I'll install this and maybe install an aftermarket oil pressure and temp gauge later.
One thing I'm curious about is that yellow metallic cylinder thing that comes with these gauges. Do I need to pass the oil through that so the sensors inside it can take the measurements? If so, where would be a suitable place to tap into to get the oil pressure on a stock NT?

I've also seen these oil filter spacer things that are supposed to give you a couple of holes for sensors. Not sure if these gauges I've found interest in have them or not. Heck, I don't even know if I can find any here xD

This happens sometimes. After market oil pressure switch would often leak between the metal and the plastic part where the green line is. Even it's new, it would happen. Many years ago I tried like 3~4 of them from different local parts stores and all leaked in the same way sooner or later. What I finally did was buy a new again and perfectly degreased it and applied RTV (Ultra Grey) between the metal tab and the plastic part, and made it completely dry to instal. At least it was working for some years until I removed the switch due to no use.
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What a great idea. Even though I'm getting a new OEM part, I'll still do this small mod as I really, REALLY don't want to suddenly lose oil pressure while at 7k RPM :)
 

1990TSIAWDTALON

Moderator
9,673
5,508
Nov 14, 2013
Independence, Kansas
I have never seen a sensor on a 4g motor that is NPT. The threads on the oil filter housing are BSPT, as Steve mentioned earlier. DON'T try a NPT thread sensor, it will feel good to start but will cross thread it. Use teflon tape on the threads to keep it from seeping and DON'T over tighten it or you risk cracking the oil filter housing that you are screwing it into.
Just some tips.
 

1990TSIAWDTALON

Moderator
9,673
5,508
Nov 14, 2013
Independence, Kansas

We're on Boost

15+ Year Contributor
1,593
416
Aug 25, 2007
Seattle area, Washington
Well, I found a new OEM part from a Mitsubishi distributor locally for about $6. Not that bad.

Awesome!
The yellow thing you asked about, I don't know. But usually the thread adapter fittings are brass (yellow). AEM knurled machine screw nuts are usually brass (yellow). And often the sensor itself is brass (yellow).
Look at these pics. One is a picture of all the parts that come with an AEM X-series oil pressure gauge and sensor. In the instruction manual for this thing it says "The AEM pressure sensor has 1/8” NPT external threads. Install the sensor into a bung with mating threads." That bung is what people are talking about in here, to adapt the threads. Because our pipe threads are not going to be NPT.

The other pic is what is on my car, which has actually 2 oil pressure senders right next to each other side by side in the front - front is the left side of the picture. On the right side of the pic is that upside down hat looking thing which is the OEM pressure sender to the pressure gauge on the dash.

Back to the 2 senders on the the left of the pic, the farther away one is the "switch" thing that we are all talking about in this thread, which goes to the idiot light on the dash. That one has, looks like 1/8" size pipe threads on it (Japanese or British, the same). Those 1/8" pipe threads measure about 3/8" across the OD. That's not a typo.

The sender that is closer is a 0-150 psi AEM sender that goes to my AEM gauge. That one you can see is screwed into a brass (yellow) adapter or "bung" as AEM calls it. That's because the AEM sensor has 1/8" NPT threads and the hole in the filter housing has 3/8" pipe threads. So it needs that adapter. This adapter is short, which is good. All these things are an overhung load attached to something that vibrates a lot. If the overhang is way long and if there is a lot of weight on it, something in there could crack from fatigue after a few years.

You don't have to worry about whether the pipe threads are British or Japanese, because they are the same. It's the American pipe threads (NPT) that are different and not compatible.

If you still have your new sensor out where you can measure it up, you should, then you'll know what threads are there for sure, in case you want to do a fancier sensor there later. So posted below is the table I use to determine pipe thread sizes on my car. In this table, Thread Pitch is shown in threads per inch. Nominal size is shown in fractions of an inch. American pipe threads have different thread pitch, and have slightly different OD.

I'm going to be in Denver for about the next week so I'll be relatively not in here until after!


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Well I couldn't add my photo in Edit mode so I'll post it here.
Left in the picture is forward in the car:

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And while I'm at it, here's the shot of all the parts that come with an AEM X-series oil pressure gauge kit. They show 2 little knurled nuts which are brass (yellow) for mounting the gauge in a pod. And the sensor is yellow.

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1990TSIAWDTALON

Moderator
9,673
5,508
Nov 14, 2013
Independence, Kansas
Let me tell anyone that comes across this thread to not "Hang" any sensors off of a DSM OFH. The harmonics of the motor will create a crack and cause a failure of the brass.
All of the pictures I have seen are ok but dont add an extension on and then a sensor. We did it and we broke the extension. Instead, run a a dedicated oil pressure log with multiple outlets and done remotely with an AN line. The AN line will absorb any vibrations and you will never have one break off.
 

Pasta_Ricer

Probationary Member
27
2
Nov 2, 2021
Zanjan, Asia
I think most aftermarket gauge sensors are NPT so you’ll probably need an adapter to go from BSPT to NPT.
Ah, well that sucks. Things aren't standardized and marked very well here as it is in most countries, so I doubt I can find a suitable adapter. I guess I have to buy one indirectly from Amazon or something which would be a real pain in the butt.

Awesome!
The yellow thing you asked about, I don't know. But usually the thread adapter fittings are brass (yellow). AEM knurled machine screw nuts are usually brass (yellow). And often the sensor itself is brass (yellow).
Look at these pics. One is a picture of all the parts that come with an AEM X-series oil pressure gauge and sensor. In the instruction manual for this thing it says "The AEM pressure sensor has 1/8” NPT external threads. Install the sensor into a bung with mating threads." That bung is what people are talking about in here, to adapt the threads. Because our pipe threads are not going to be NPT.

The other pic is what is on my car, which has actually 2 oil pressure senders right next to each other side by side in the front - front is the left side of the picture. On the right side of the pic is that upside down hat looking thing which is the OEM pressure sender to the pressure gauge on the dash.

Back to the 2 senders on the the left of the pic, the farther away one is the "switch" thing that we are all talking about in this thread, which goes to the idiot light on the dash. That one has, looks like 1/8" size pipe threads on it (Japanese or British, the same). Those 1/8" pipe threads measure about 3/8" across the OD. That's not a typo.

The sender that is closer is a 0-150 psi AEM sender that goes to my AEM gauge. That one you can see is screwed into a brass (yellow) adapter or "bung" as AEM calls it. That's because the AEM sensor has 1/8" NPT threads and the hole in the filter housing has 3/8" pipe threads. So it needs that adapter. This adapter is short, which is good. All these things are an overhung load attached to something that vibrates a lot. If the overhang is way long and if there is a lot of weight on it, something in there could crack from fatigue after a few years.

You don't have to worry about whether the pipe threads are British or Japanese, because they are the same. It's the American pipe threads (NPT) that are different and not compatible.

If you still have your new sensor out where you can measure it up, you should, then you'll know what threads are there for sure, in case you want to do a fancier sensor there later. So posted below is the table I use to determine pipe thread sizes on my car. In this table, Thread Pitch is shown in threads per inch. Nominal size is shown in fractions of an inch. American pipe threads have different thread pitch, and have slightly different OD.

I'm going to be in Denver for about the next week so I'll be relatively not in here until after!


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Hey, thanks for all the great info.

Yeah, I'm talking about those fat and round brass sensors. They look like old school fuel pumps.
I think I'll have quite the challenge mating a sensor to the hole :/

Those AEM gauges seem nice and are available here too at about 5 times the cost of the cheapo one I was talking about LOL. But they don't have the extra goodies of the Chinese one :D

It will have to wait though. I ordered the OEM sender unit and should be here by Wednesday, hopefully. I plan on installing it myself, but I don't know how much oil to expect from the hole after unplugging the old one when the car has been sitting without a start for about 4-5 days.
Also, do you think I should add teflon tape to the OEM one too? Do I need to worry about small particles of the tape getting into the oil? I have only used those taped like once or twice so I don't have much experience with them.

Thanks!
 

We're on Boost

15+ Year Contributor
1,593
416
Aug 25, 2007
Seattle area, Washington
Let me tell anyone that comes across this thread to not "Hang" any sensors off of a DSM OFH. The harmonics of the motor will create a crack and cause a failure of the brass.
All of the pictures I have seen are ok but dont add an extension on and then a sensor. We did it and we broke the extension. Instead, run a a dedicated oil pressure log with multiple outlets and done remotely with an AN line. The AN line will absorb any vibrations and you will never have one break off.

Yeah I agree.
On mine the threaded part going into the housing is so much bigger diameter than the smaller thread for the sensor, that the smaller thread can fit inside of the bigger thread. It's a pipe bushing actually. So it's very short, and it is very stout where it goes into the housing.

If you tried to do this into the 1/8" port, your adapter would be 1/8" to 1/8", about the same diameter, they have no choice but to be stacked up lengthwise, so it would be longer, and a lot weaker where it enters the housing. I wouldn't do it that way.
 

DSMPT

DSM Wiseman
2,170
1,754
Jun 12, 2014
Japan / Mexico, Arizona
I think most aftermarket gauge sensors are NPT so you’ll probably need an adapter to go from BSPT to NPT.
Ah, well that sucks. Things aren't standardized and marked very well here as it is in most countries, so I doubt I can find a suitable adapter. I guess I have to buy one indirectly from Amazon or something which would be a real pain in the butt.
Japanese aftermarket sensors are PT (Not NPT) unless it's knock offs. So keep in mind, in case if you would buy Japanese brand's products in the future such as GReddy, Defi, HKS etc, oil filter sandwich, oil cooler, temp sensor adapters etc etc, usually they come with PT.
 

We're on Boost

15+ Year Contributor
1,593
416
Aug 25, 2007
Seattle area, Washington
Just want to put this chart in here for taper thread tightening torque. This is from page 28 of the 1991 factory service manual for the Laser and Talon, should also apply to your car.

Like people have said already, don't overtighten. This chart shows ft-lbs numbers in ( ).

For PT 1/8 the range they show is 5.8 to 8.7 ft-lbs when you are tightening into "Light alloy" which is what this is. You might not be able to get a torque wrench on this, but this torque is about the same as you would put on a 6mm bolt. Given that PT 1/8 has almost a 10mm OD, probably some people would think they should tighten it like a 10mm bolt. But no, that would be way too much.

For thread sealant, personally I would use Loctite 567. This is a goop that cures anaerobically. It will seal even lightly tightened threads, and yet is still easy to take apart again years later.
Teflon tape tends to creep and loosen up during the first day or 2. People tend to over tighten to compensate. You don't want to do that here. And you get those little shreds from it. Yuk!
Gotta go. Good luck with it!

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Pasta_Ricer

Probationary Member
27
2
Nov 2, 2021
Zanjan, Asia
Hello folks.

I got the switch about 4 days ago and installed it. I also added a quart of oil as I had lost quite a bit before (about 1.2 maybe?).
When changing out the sensor, it was kinda leaking oil constantly and maybe lost about half a glass of oil. The oil was extremely dark and reeked of gasoline. It was still oily and viscous, but still. This is only 700 km after an oil and oil filter change.

Unfortunately, today when I started it, the engine made some very loud noises for about 3 mins or so after which it ended. The sound was maybe like hammering? But it wasn't like a repeated thing (striking a hammer). It was like a continuous loud engine sound, as if you had put your ear on the block. I popped the hood and took a look around, trying to see if I can pin-point the source and it sounded like the whole emgine was making the noise.

Some history on the engine:

The timing belt had broken while in the hands of the previous owner so he had to change out the whole head, change two pistons, and the bearings.

The engine had been running rich for a while and I fixed it the second week it was in my hands.

The spark plugs look pretty good with only minimal amount of signs of being rich.

The intake manifold is just absolutely chock-full oily crap which unfortunately is too hard for me to get off and clean and don't have much time as I'm going to uni soon.

Thanks everyone.
Tell me if I should make a new thread for this or not.
 

AWD-Tony

Supporting Member
6,797
3,683
Sep 11, 2017
Cincinnati, Ohio
It's possible that valves are bent from when the timing belt broke or combustion is getting past worn/damaged piston rings causing fuel to mix with oil. Do a leak down test.

Noise could be air in the lifters since you drained the oil from the oil filter housing. Was it a constant tapping noise and did it go away? You should be fine if it went away.

When you do an oil change, there's about half a quart left in the engine. Some in the head, pan, oil filter housing and rest of the oil system so it's impossible to get everything completely out. Once you do an oil change, the oil gets dirty fairly quick since it mixes with what's left inside.
 

Pasta_Ricer

Probationary Member
27
2
Nov 2, 2021
Zanjan, Asia
It's possible that valves are bent from when the timing belt broke or combustion is getting past worn/damaged piston rings causing fuel to mix with oil. Do a leak down test.

Noise could be air in the lifters since you drained the oil from the oil filter housing. Was it a constant tapping noise and did it go away? You should be fine if it went away.

When you do an oil change, there's about half a quart left in the engine. Some in the head, pan, oil filter housing and rest of the oil system so it's impossible to get everything completely out. Once you do an oil change, the oil gets dirty fairly quick since it mixes with what's left inside.

No, the guy changed the whole head which had valves in it.

Yeah, it went away once it warmed up a tiny bit.

When I changing the oil, the tech after draining the oil, took compressed air to the oil feet port and a whole bunch of oil splattered on the ground. But yeah, it could have just been crappy oil contaminating it.

But, is it really possible that air could get into the tappets after just a day of sitting?

Thank you!
 
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