Oil return line leaking

RoadRunner2g · Jun 4, 2026

I know there are a million threads on this topic, and I’m sorry if it’s already been discussed, but I couldn’t find anything. I’m having an oil leak on my turbo oil return line, but it’s not in the oil pan side, it’s on the turbo side. It was leaking slightly before, so I replaced the gasket with an oem gasket, and now it’s leaking worse. The bolts are torqued to spec too. It looks like it’s leaking from around the front bolt head. It isn’t leaking from around the back bolt (closer to the engine block), and the gasket doesn’t look like it’s leaking either. My initial thought is to put some sealant on the threads of the bolds to stop it from leaking, but I have no idea what sealant would hold up to that high of temps. My second thought was maybe put some crush washers on the heads of the bolts? Would that be a good or a bad idea? Any other advice would also be great.

Bud92gsx · Jun 4, 2026

Dude. Honestly. Replace the gaskets on the turbo and oil pan. Its not hard with a socket extension. If your gonna take the bolts off anyway why not???

if i had 100 bux for everytime I skimped out on a 3$ part for my dsm, and then had to completely do it all over again the right way. Well I'd probably still daily a dsm, just saying

RoadRunner2g · Jun 4, 2026

Bud92gsx said:
Dude. Honestly. Replace the gaskets on the turbo and oil pan. Its not hard with a socket extension. If your gonna take the bolts off anyway why not???

if i had 100 bux for everytime I skimped out on a 3$ part for my dsm, and then had to completely do it all over again the right way. Well I'd probably still daily a dsm, just saying

I already replaced the gaskets… both of them with oem gaskets. Installed properly, and torqued to spec. The gaskets were in perfect shape, and there were no scratches our gouges on the flange surfaces. I was already planning on getting a new gasket to replace it when I have to take the bolts off. I was asking for a solution to the bolt heads leaking so I could ensure it won’t just leak out from them again.

Drewpy Dawg · Jun 4, 2026

Somebody correct me if I'm wrong, but as far as I know the bolts don't go into the turbo's oil passage. So if oil is leaking around the bolts then the flange/gasket must not be sealing properly, allowing oil to seep outward to the bolts and then leak out around the bolt heads. I would check that the flange on your oil tube where it seats against the turbo is perfectly flat. Take the tube off the car. Get a sheet of sand paper somewhere between 200-400 grit. Put the sandpaper on a surface that is especially flat. A thick plate of glass is good, or a granite countertop. Hold the flange of the tube flat against the sandpaper and move it in a figure 8 a few passes. If you see that the edges of the flange have been sanded but not the middle then you know the flange is not perfectly flat. You can continue the same sanding technique until the flange is flat. Alternatively, you could put sealing/crush washers on the bolts and see if the leak stops. I would consider that a bit of a band-aid, but it should confirm that the oil is leaking from around the bolts and not just accumulating around the bolt heads.

RoadRunner2g · Jun 4, 2026

Drewpy Dawg said:
Somebody correct me if I'm wrong, but as far as I know the bolts don't go into the turbo's oil passage. So if oil is leaking around the bolts then the flange/gasket must not be sealing properly, allowing oil to seep outward to the bolts and then leak out around the bolt heads. I would check that the flange on your oil tube where it seats against the turbo is perfectly flat. Take the tube off the car. Get a sheet of sand paper somewhere between 200-400 grit. Put the sandpaper on a surface that is especially flat. A thick plate of glass is good, or a granite countertop. Hold the flange of the tube flat against the sandpaper and move it in a figure 8 a few passes. If you see that the edges of the flange have been sanded but not the middle then you know the flange is not perfectly flat. You can continue the same sanding technique until the flange is flat. Alternatively, you could put sealing/crush washers on the bolts and see if the leak stops. I would consider that a bit of a band-aid, but it should confirm that the oil is leaking from around the bolts and not just accumulating around the bolt heads.

Ok, thank you. This entire time I thought the bolts went into the oil passage LOL

. Do you know if it’s a common issue for the turbo side gasket to leak? Or is that only for the oil pan side? I never really saw any posts about it and it got me curious.

dwb · Jun 5, 2026

RoadRunner2g said:
Ok, thank you. This entire time I thought the bolts went into the oil passage . Do you know if it’s a common issue for the turbo side gasket to leak? Or is that only for the oil pan side? I never really saw any posts about it and it got me curious.

It could depend on your turbo. I know a Mitsu CHRA does not.
The oil pan side will definitely leak via the bolts. These washers plus a new gasket fixed it for me. Maybe this would work for you turbo-side if your gasket surfaces check out flat.

OEM Turbo Oil Return Line Washer for Oil Pan (2x): Mitsubishi

If you're having problems with your oil return line bolts leaking, this is the solution. This washer has a built in center seal to prevent oil from leaking. Includes 2 washers.

www.extremepsi.com

I would try to stay away from a sealant if possible.

RoadRunner2g · Jun 5, 2026

dwb said:
It could depend on your turbo. I know a Mitsu CHRA does not.
The oil pan side will definitely leak via the bolts. These washers plus a new gasket fixed it for me. Maybe this would work for you turbo-side if your gasket surfaces check out flat.

OEM Turbo Oil Return Line Washer for Oil Pan (2x): Mitsubishi
If you're having problems with your oil return line bolts leaking, this is the solution. This washer has a built in center seal to prevent oil from leaking. Includes 2 washers.
www.extremepsi.com
I would try to stay away from a sealant if possible.

Ok, I definitely want to stay away from a sealant too. And I have an scm6152 on the car right now. The journal bearing version unfortunately

… I pulled the bolts out today while at work and the bolts definitely go through the oil passage. The bolts are bigger than the ones on the oil pan, and those gaskets won’t fit around them. Could I get another slightly larger aluminum rubber gasket to put around them? Would the rubber hold up to the hot temps of the turbo? Does anyone know how hot the flange right there actually gets?

Drewpy Dawg · Jun 5, 2026

There's your problem!

Use properly sized copper crush washers.

RoadRunner2g · Saturday at 1:42 AM

Drewpy Dawg said:
There's your problem!

Use properly sized copper crush washers.

Thank you, I tried putting some washers on while at work but I think they are a bit too small, they barely sealed all the way around the hole in the flange and they still ended up leaking. I definitely need to find some that are the right size

chrysler kid · Monday at 8:16 AM

The other variable is that one of the bolts may be too long to seat the contact on the turbo. The aftermarket hose style returns that I run always have a thick drain plate to the turbo where as the oem ones aren’t as thick. If I recall correctly the t25 bolts are slightly longer than the 1g style return needs, but I have switched to the aftermarket drain hose style and never had issues with them leaking since then

The Central Hub for DSM Community and Information

Oil return line leaking

RoadRunner2g

Bud92gsx

RoadRunner2g

Drewpy Dawg

RoadRunner2g

dwb

OEM Turbo Oil Return Line Washer for Oil Pan (2x): Mitsubishi

RoadRunner2g

OEM Turbo Oil Return Line Washer for Oil Pan (2x): Mitsubishi

Drewpy Dawg

RoadRunner2g

chrysler kid

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