Turbo Return Line Bolts?

[Specter]

Can some one kindly tell me what is the length of the two 10mm bolts on the oil return line. I need to know of the turbo side, not the oil pan ones. I have couple of 10mm bolts but not sure what is the proper length.

Thanks!

 

[Muskrat]

going by memory probably 20 mm.

As long as you can get at least 3 threads fully engaged you'll be ok.

 

[Specter]

Thanks for the rough idea, and thanks for telling that around 3 threads is enough, i wanted to know what is the maximum length of the bolt too. I am trying to fit the return line, but its giving me a hard time. I just loosely turned the oil pan bolts with the return feed line so that it just hangs on, and then i was trying to fit it on the turbo side, but i could not get the bolts in the turbo holes. As soon as it felt that it has turned enough to grab, it became loose again, not because its slipping, but because i am unable to position them correctly. I easily got the longer bolts to turn around 3-4 threads but did not tighten them as they might be too big. The smaller ones i was using are 17mm in length while the longer ones are 28mm. I have some 22-24mm length bolts too.

 

[iceman69510]

CAPS says: 6 x 16 mm.

 

[Wizardawd]

A good rule of thumb is have at least as many threads holding that is equivalent to the diameter of the bolt. Don't worry about bolts being too long, there is plenty of room behind the return hole for longer bolts, though not needed.

I'll be honest, those nuts strip out so often it's not funny. If i have a pan off, I almost always change it to a stud mount instead, or weld an AN fitting on it.

Wiz

 

[Muskrat]

Quote:
CAPS says: 6 x 16 mm.


Damn, I was torn between saying 20mm or 15mm.

Quoting Specter:
Thanks for the rough idea, and thanks for telling that around 3 threads is enough, i wanted to know what is the maximum length of the bolt too. I am trying to fit the return line, but its giving me a hard time. I just loosely turned the oil pan bolts with the return feed line so that it just hangs on, and then i was trying to fit it on the turbo side, but i could not get the bolts in the turbo holes. As soon as it felt that it has turned enough to grab, it became loose again, not because its slipping, but because i am unable to position them correctly. I easily got the longer bolts to turn around 3-4 threads but did not tighten them as they might be too big. The smaller ones i was using are 17mm in length while the longer ones are 28mm. I have some 22-24mm length bolts too.



This is with a stock drain tube I'm guessing. I typically attach the turbo end first, as it's the hardest to get at and manipulate. This rule generally holds true for any fastener. Give yourself the most play/wiggle room with the hardest to reach fastener.

You can use any length bolt as long as it doesn't bottom out. Just turn it until it starts to get tight. If it's not tightening on the flange (aka you can still move the oil drain along the length of the bolt) then they are too long. 28mm might be to long. Try the 22-24 mm bolts.

BTW, the thread pitch for these bolts is M6x1.0

 

[Specter]

Thanks Guys! I want to use the longer bolts so that i can fit the line easily. Its easier to handle it that way for me at least. If i do the turbo side first i am unable to get the line to meet its bolt holes. I guess i can try one bolt on turbo side, then one on the pan, then the other on the turbo then the last one on the pan again. I wish we had AN fittings around here, people usually import them from your side of the world who need them very badly. Well thanks again for quick responses, i now have the idea of what bolts to use.

 

[Wizardawd]

Surely there is a hydraulic supply place somewhere there for tractors, earthmovers, etc. They aren't pretty and anodized, but they still do the job.

Wiz

 

[rgeier11]

The bolts you should be using that go into the oil pan should have washers on the bolts to prevent leaking. They are different than other bolts found on the car.

 

[mikus]

^ yes, crush washers (not actually "on" the bolt as in attached) I have some new in bag for sale in my "random crap for sale" post, as well as new gaskets for same application
/plug

 

[broxma]

A modification I make to the factory return line is to cut out the metal center flex section, flare both sides and replace it with fuel injection hose or steel braided rubber. I use fuel injection clamps on the hose to ensure the seal and use a proper flare tool to make the flares. This allows much more freedom of travel to get the two ends where they need to go and allows the ends to spin independent of each other. In the absence of making a fitting for -an line, I have found this to be the best solution to return line difficulties.

To answer any questions about leaks, never had any. The oil as it comes out of the turbo actually loses pressure as it goes through the turbo, so by the time it passes into the return line, it is not at a high enough pressure to be a leak concern. The common leak spot is at the pan, which this mod remedies completely.

/brox

 

[Specter]

I wanted to install a good quality rubber pipe, but how good do they actually hold? Can they hold the high temperature and not become brittle for a long time?

 

[broxma]

The SS rubber hose holds fairly well. We used them at the shop on some of the Miata turbo kits. Subaru's come with rubber return line, partially, from the factory and don't even use a decent clamp to hold them on, just a spring clamp.

I have personally seen a few daily driver Miatas which had the rubber return line hose that was upwards of 7-10 years old. Normally however, they are replaced every so often in the course of general maintenance so it isn't really an issue.

/brox

 

[Specter]

Subaru's come with partial rubber line from factory? Interesting i did not know that. I guess i will try it next time if the stock return line gives me hell.

 

[broxma]

Yes. The WRX return line has a flanged piece on the turbo which ends with a flanged pipe. You connect a rubber hose to that, held in by a single spring clip, which attached to the back of the block. There is not a lot of pressure there honestly. Just using quality hose and Fuel injector clamp eliminates many of the problems associated with the DSM return line and is cheaper than a SS line and the required flanges. I'd call it the middle ground between the stock setup and a fully SS setup. Plus, it's cheap.

/brox

 

[Specter]

^^ Thanks for the info! /ubbthreads/images/graemlins/grin.gif