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1/2" turbo drain back port for a T3/T4 (flow question)


tpoof100
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I am finishing up a T3/T4 setup and I have a log type exhaust manifold that makes the turbo sit lower than stock. The turbo drain fitting is about 1.5" lower than the drain return thats on the passanger side of the motor just above the water pump. Is that difference something I should worry about? Is there any pressure to push the oil back into the block? Does that drain fitting serve a purpose, like oiling the timeing chain or oil pump? If it doesn't have a purpose than I could cap the fitting in the block and add a new drain line into the oil pan making it all gravity?

 

Which will be a better route?

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i had the same problem with my T3, oil does not drain well "up hill". the best way to go is to tap the pan. have a small metal plate welded to the location on the pan where you want the drain, drill and tap thru the the plate and pan. reason for the plate is to give your fitting someting to hold on to. the walls of the oil pan are not very thick and without the extra thickness you will probably get a leak.
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Ok, I will be putting a new fitting in the oil pan for the drain back. Guess my only other question is: Does the return fitting in the block oil anything? Can I safely cap that and forget about it?

 

Thanks for the help.

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You may safely cap that. And how come I didn't know there was another member here from the cities!

 

If you want some help with that thing, let me know, I'm up in golden valley, but will travel the metro to help out a fellow starquester!

Edited by Technology
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  • 4 weeks later...

The block oil return for the turbo just goes to the oil pan; I'm pretty sure it doesn't feed anything else. So capping this when you re-route the turbo oil drain hose is the right thing to do. Remember, the later 2.6 non-turbo motors have the same block - Mitsu just didn't drill all the turbo specific holes/ports like the oil squirters and this oil return line. If this oil passage actually was needed on non-turbo blocks it would have its own oil supply source since there isn't a turbo drain to supply it.

 

Anybody have a good reason why one couldn't "T" into the return hose from the oil separator? It's just a non-pressurized drainback to the oil pan too... no need to add another pipe to the pan this way. Just put the "T" close to the oil pan and use heavy rubber hose from the "T" to the turbo and from the "T" to the pan - the turbo drain oil will be rather hot compared to the much cooler oil drops/mist coming from the oil separator. The factory hose from the oil separator tank might not last very long with over-hot oil... after all, look at the factory turbo to block hose: a fat hose with extra braiding.

 

mike c.

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You can't share that return with anything else, too much volume and it's slightly under pressure, I thought about using the air box return too, but it may travel to the air box with enough volume.

 

Any bakc pressure in the return path puts stress on the rear oil seal in the turbo, which causes it to leak and prematurely fail.

 

That timing cover port just dumps the hot turbo on on the top of the oil pump, there is nothing wrong with routing that oil to the pan directly.

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I have a T3/T4 with a cast manifold, its shape is very similiar to log style which I also had. I am routing the oil drain right into the return from the OE seperator. The stock air cleaner was removed so I just had that line plugged anyway.

 

The log manifold, I had, set the turbo just high enough to continue using the stock drain location however when I switched to the cast manifold it set the turbo much lower and I was forced to seek other means.

 

In a quick "what the heck I'll try It" mind set I used the return line for OS it works just fine for me. I capped off the stock drain with a pipe plug.

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on my t3t4 60-1 i used a short peice of threaded pipe to get it below the compressor housing and then put a 90 on it. then ran the line right over to the drain hole. jus some food for thought. easier than drillin and stuff. ill try to post a pic later if ya want to see it.
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on my t3t4 60-1 i used a short peice of threaded pipe to get it below the compressor housing and then put a 90 on it. then ran the line right over to the drain hole. jus some food for thought. easier than drillin and stuff. ill try to post a pic later if ya want to see it.

 

 

Please do I really want to see and hear about this I am about to take the car to the shop tomorrow but I rather not spend any doe..

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So it's been done and seems to be working perfectly. :thumbsup:

 

 

Definitely more convenient than having a custom mani made but then again one of those fine pieces of art would have it's advantages..

Oh and original oil return on the block was cap'd with a rubber and a fastener easy as pie..

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Keep in mind that a turbo can generate pressure due to blow-by at both the turbine seal and compressor seal. It needs a nice open return path to the block for this.

 

 

I read on an AU forum they cut the stock pipe off at the flange end and shorten the section there. The idea with the short section with the 90 degree bend should work if the pipe opens up

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