So I have a GT35-2 eBay turbo, and right now I have a AN4 copper restrictor fitting on it, but oil seems to start leaking through the threads almost where it threads into the turbo and comes out very slowly, only after about 2-3 minutes after car running, drain line should be plenty big enough and not sure why this is happening. I have tried loctite high temp on it, also teflon tape. Both still leak from same spot. Wondering if maybe I should try a -4AN fitting. Or maybe a brass fitting instead because it expands more under heat? My first ball bearing turbo so I’m a little confused on the difference between the restrictor sizes still. Wondering if maybe the threads into turbo are bad somehow because I did buy it used. Any answers appreciated, thanks.

 

you should be using the restrictor that is required with for that turbo. i cant say what you should be using but a AN4 doesnt sound right at all, the -4AN is more common on larger turbos. also, could you post a picture of your return line therefore we can ensure you have proper gravity return

 

Ok thanks will do in the AM 👍🏼

 

From what I know, the oil restrictor isn't usually the cause of oil leaks on turbos. Like justYncredible mentioned, double check your return line to the oil pan.

 

Pull the fitting out and use a flashlight to closely inspect the center housing for cracks around where the fitting threads in. It may be a bad casting. How much oil are we talking? Enough to see it form droplets that drip off?

 

So this is the restrictor fitting you can see on the right side the oil seeping out of it, this was after the car was running for about 5-10 minutes. I took feed line off to get better picture.

This is the restrictor fittings itself AN4 I believe it is 0.038”. There are no cracks in it and the threads look fine.

This is drain line. I’m aware that I am in much need up getting shorter line, but I didn’t think it was causing this leak at the top. Do you think it’s possible because it doesn’t have enough gravity to drain the turbo fast enough?? Only way it will be Able to have no turns in it is if I get on to go over the intercooler piping, and be about a 10” line. Also if anyone could let me know some quality drain lines or any advice you have to make ball bearing turbos last. All awnsers appreciated.

 

Your drain line could definitely be improved, but oil backing up would make its way out through the turbo seals way before it should leak out through the thread fittings for the oil feed. This would not explain the leak at the oil inlet fitting. Regarding lines, if you want to stay with AN hose and fittings, I've been buying that stuff from Go-Autoworks - it's all Vibrant Performance stuff. You could also do a high pressure / temp oil-rated rubber hose for the return. A few other users here like @Txdragon are using that. How about the feed line - the oil could be leaking through the fitting there. Or, if the restrictor fitting has a different angle flare than the hose, it will never seal, regardless of how tight it is. AN is 37 a degree flare, SAE is a 45 degree flare. I wouldn't put it past a China turbo kit to put SAE flared fittings in the kit. You should also look at the CHRA to see if it is cracked where the restrictor threads in.

 

So I checked out the threads on turbo itself the threads look to be intact in it but it is hard to tell. Also I was thinking same thing that maybe thread isn’t quite the right one for turbo, because I didn’t buy it as a kit I bought everything separately, so the restrictor fitting is a AN I know for a fact, do you think I should try a SAE? Also the connection between feed line and fitting is 100% good no leaks there. Also if the fitting is correct should there be any need for any high rated Teflon tape or anything of that nature to make the seal good? Thanks.

 

eBay Turbos may not use the same standards ans the genuine article. It's very difficult to determine. However, for the sake of argument, let's say that it does use the same thread sizing and pitch. (whether you use a -4AN line or not isn't as relevant, only the restrictor's opening at the fitting itself. (BTW, that looks to be much larger than a .038" size restrictor opening. That looks to be over .065" or .080"... Which, for a -4AN line, is much larger than necessary).

Whatever you do, I would not recommending going to SAE fitting conversions. That's not where your issue lies. From what I can tell, your issue seems two-fold.

1) Wrong opening for a ball-bearing turbocharger (this is using the presumption that this e-Bay turbo uses similar bearing cage and tolerance as a Garrett unit) . This is the biggest unknown, and no amount of thread tape will solve this. If you put more on it, you could easily block the oil opening itself, causing the turbocharger to fail completely due to starvation.

2) The oil return line needs a lot of work, whether or not this is a JB or DBB unit, as this routing is not very good. (more from the fact that the turbo sits so low to the ground in relation to the oil pan (sump).


It's time to get some tools (even rent or borrow) to find out the thread pitch you're using and what that opening actually is. But at first flush, this looks like you have issues at "both ends" (pardon the pun )

As a comparison, here is what a true .030" opening on a 7/16-24 fitting for a genuine Garrett ball-bearing product.



This is a proper .030" 7/16-24 to -3AN conversion notice the smaller opening




This is the proper .030" to 7/16-24 to -4AN conversion. Much smaller than what you have pictured.




Your photo with the restrictor fitting opening on he "bottom" of the fitting, which could cause an oil back up. The leak may be from thread matching or over-filling of your large fitting opening.

Hard to say with eBay turbochargers, unless you can measure the components with the genuine article.

 

definitely re-do that drain line

 

So this is what fitting on turbo looks like, not sure if it will make the type of fitting needed more clear.

I have bought two new restrictor fittings, one 0.068” and one 0.038” because I don’t know brand of turbo so I’m not sure which restrictor is needed and also not sure how to find out also have purchased shorter drain line. I will let you know the results in a week or so.

 

That is not standard on any turbocharger made for aftermarket performance. As you said, changing this may not matter if the drain line route isn't changed either.

One more win for eBay by miy giving out vital information, when people concentrate so heavily on "the great deal!"..

 

AGREED...

I guess people like buying crap over and over again.

 

Yea will be buying better brand turbo whenever this one goes for sure, this situation is partially my fault though because I bought this used without knowledge of exact brand it was.

 

Even if you did know the retailer, unless the major components was from one of the major manufacturers, there's no guarantee that everything was going to fit, unless they provided those accessories for you. Then you can reverse-engineer from that point.

So, as of now, it's really a matter of fixing the drain line first, before investing in other restrictors and accessories. They may not fit this eBay unit.

At least you know not to do that again..

 

I understand you see people use those Ebay turbos and are able to get good numbers with them. That, I won't doubt at all. The overall durability and longevity will never be there...compared to actual brand name turbos. Had good results with PTE in my old setup and even better results on my current (Turbonetics).

 

So after all this info gathered and the thoughts on my drain line 😂 I have ordered a much shorter one from vibrant which should almost be the exact length I need to run it over the intercooler piping like it needs to be so it stays above oil pan. Have also ordered couple different fittings to see see if it was restrictor being to big and maybe drain being to long backing up, should all be coming In Mail next week. Hopefully this will solve my problem and it not be that the threads on this turbo are messed up and somehow allowing oil to spiral up and out. Will give update in a week or two. Thanks for the advice.

 

you need to adjust the fitting at the oil pan.

 

Yea I have adjusted oil pan fitting, to go upwards now in order to route over piping, but the one coming off turbo not sure if I should go just with a straight up connection with no angle fitting and then route it out from there or get a 90 degree fitting but I have also seen people saying not to use 90 degree fittings on drain lines. Would turn the 45 but it would make it so there would be a low spot in the drain line if I did that. Any thoughts ?

 

1. shorten the length of the oil return line
2. use a floor jack and "massage" the fitting at the oil pan upwards

I'm using a -10AN fitting at the oil pan but opted to use high-pressure hydraulic hose for my return line instead of braided SS lines. Works fine and DOES NOT LEAK

 

So it’s it took longer for drain line to come in than excpected but came today along with new fitting. Drain line is much shorter now, not perfect but for sure a better route, also got proper 0.030” restrictor fitting on. Let car run for about 5-10 minutes so oil could thin out some and saw no leaks, knock on wood. Getting it tuned tomorrow hoping everything holds up good. Thanks for the help everyone, much appreciated.