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1/2 Na-T Project
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987 Posts
Discussion Starter · #1 · (Edited)
Well as most of you know I completed my 1/2 Na-t Conversion. For my oil feed I teed into the oil pressure sender port. For my return I used the oil cooler return port that is already on the 7MGE oil pan. I was told by a couple people it would work and by others it wouldn't work. Well after about a week my turbo seals are blown so I would say it didn't work :mad:. I tried to take a short cut and it ended up just creating more work in the end. So anyone attempting this conversion I would strongly urge you to take the time and either pull the engine or drop the front crossmember so you can remove the oil pan and have at least a 3/4 fitting welded on. Later.

Edit: If you don't have the resources to have a bung welded on, you can do as Jong did and use a fitting with a nut and rubberwashers on either side of the fitting. Here is a picture compliments of JONG!!

 

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greasemonkey
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3,134 Posts
well, for the 7mge/t guys, go to celicasupra.com. we do 5mgte conversions all the time and it is well known that that hole isnt large enough for an oil return. rabidchimp sells an oil line kit that is ss braided lines, the proper t fitting for pressure and comes wit hthe fitting that needs brazed or bolted to the pan after the proper hole/s have been drilled.
 
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Could say I told you so, but I wont.
You can weld a return in without removing the pan or dropping the crossmember.
I have explain how I done it in several posts.

Marty
 

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Republican
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8,421 Posts
This is why you gotta use -10 AN fittings or larger.
 

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1/2 Na-T Project
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987 Posts
Discussion Starter · #6 ·
TD42T said:
Could say I told you so, but I wont.
You can weld a return in without removing the pan or dropping the crossmember.
I have explain how I done it in several posts.

Marty
You did say that I needed a larger return but other people who had done the conversion did use this port without problems. I know you can weld the return on without dropping the crossmember but since I can't weld I would have to bring it somewhere. So I am just biting the bullet dropping the crossmember, removing the oil pan and taking it to a guy who tigged some stuff for me(aluminum bov flange on ic piping). So far I have not run into any problems dropping the front crossmember other then a snapped extension :). So far I disconnected the intermediate shaft for steering, dropped the shocks out of the shock towers, took off the front two crossmember nuts, and removed the two nuts for the engine mounts. I still need to disconnect brake lines from the body, disconnect the stiffener plates that run from the tranny to the engine block, disconnect sway bar end links from suspension, and take off the two remaing bolts and two nuts that are holding the front crossmemeber on. Later.
 

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Be original, not a copy
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861 Posts
You can use the stock oil cooler return for the turbo return but it is not recommended, at least not by me. Blowing the seals REALLY sounds more like a PCV system issue. Take the cap off of the oil fill and see if it smokes our of the tailpipe or whatever indicator you used to diagnose the turbo's seals. The CT-26 is internally orificed to prevent a crapload of pressure from going through the turbo which allows for a somewhat smaller return. BUT if you have a PCV that can not keep up with the blow-by (stock N/A PCV system does NOT work very well in turbo applications) then you will blow out the turbo seals because any crankcase pressure will keep the oil from draining from the turbo.
 

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1/2 Na-T Project
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987 Posts
Discussion Starter · #8 ·
Some people posted on supramania that once I fix my return the turbo seals should be fine, is this true?

Posted on SM:

"You'll probably find the oil level was above the port the Turbo is gravity drain so if the bottom of the return is blocked by oil it will back up and overflow the labyrinth seal and make smoke!

Good news is fix the drain the turbo should be fine!"

"People get all stressed about "seals" in a turbo there are usually 2 different seals one a plain piston ring type seal the other a labirynth seal each on their own not great but combined they work.

There's nothing to "Blow" as in a rubber lip seal and the only times they leak is if they've been cooked (Hot stop shut the motor off and the oil burns to the shaft/seal) sometimes they just plain wear out or if they've been flooded as in no return.

If it's the later it's usually good to go once you correct the return (It'll smoke a little till all the oil that's in the exhaust is burnt)."
 

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Be original, not a copy
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The CT-26 has a labyrnith oil seal on the turbine and an O-ring or "C-clip" on the compressor side (depends on the source of the CT-26). More than likely fixing the oil return will solve the problem. What oil are you using and at what oil pressure? Sometimes running too "thick" of an oil will also cause drainback problems.
 

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1/2 Na-T Project
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Discussion Starter · #10 · (Edited)
DeanMarcum said:
The CT-26 has a labyrnith oil seal on the turbine and an O-ring or "C-clip" on the compressor side (depends on the source of the CT-26). More than likely fixing the oil return will solve the problem. What oil are you using and at what oil pressure? Sometimes running too "thick" of an oil will also cause drainback problems.
I am using Mobil 1 10w-30, so I don't think it is my oil thickness that would cause a problem :). I am running stock oil pressure whatever that is, with no modifications to the oil pump.
 

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Can't wait for Spring!
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When i first did my conversion i stupidly used a T'd oil filter relocation kit for the oil feed. That overfed the turbo and the oil pushed past the seals. I T-d into the oil pressure sending unit and it has worked like a charm.

he pulled off his lower IC and it was full of oil.

However, i agree with DM again on this one, maybe that port is fine and you have too much blowby. you said you just stuffed your can with stuff and that made it go away, or did it make it less noticable. You may have just put a bandaid on a severed arm. ( wierd analogy)

I was hoping that port would work out for ya. But i think the main reason it didn't work out was all that blow-by you've got. sucks ass i know, but you may have to face the facts... you have an assload of un-normal blowby.

And i know you are in the middle of installing a bung into the pan now, but what if there is all that crankcase pressure, it won't help at all by having a slightly larger drain will it?

sorry man
 

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1JZ BLING!
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This is why the oil line kit comes with a -10AN weld on drain fitting. You need good flow.

Did anyone who said it would work have that same setup to prove that it did? Or did you take advice from a bunch of people who have never done NA/T?

Take internet advice with a grain of salt. Only accept advice from those who have done the subject at hand themselves, not what someone heard or what their brother's girlfriend's uncle said.
 

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1/2 Na-T Project
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987 Posts
Discussion Starter · #13 ·
SlimFastSupra said:
This is why the oil line kit comes with a -10AN weld on drain fitting. You need good flow.

Did anyone who said it would work have that same setup to prove that it did? Or did you take advice from a bunch of people who have never done NA/T?

Take internet advice with a grain of salt. Only accept advice from those who have done the subject at hand themselves, not what someone heard or what their brother's girlfriend's uncle said.
http://www.supraforums.com/forum/showthread.php?t=235973&highlight=1%2F2+na-t+oil+return
 

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1/2 Na-T Project
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987 Posts
Discussion Starter · #14 ·
jong said:
I was hoping that port would work out for ya. But i think the main reason it didn't work out was all that blow-by you've got. sucks ass i know, but you may have to face the facts... you have an assload of un-normal blowby.

And i know you are in the middle of installing a bung into the pan now, but what if there is all that crankcase pressure, it won't help at all by having a slightly larger drain will it?

sorry man

I am wondering the same thing, I will be doing a compression test in the next few days, so pretty much if my compression numbers are low then the rings are worn and causing excessive blowby? I already did a block test and it came up negative for any combustion gases in the cooling system.
 

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Can't wait for Spring!
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well, like DM said, you can have good compression and still have excessive blow by
 

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1/2 Na-T Project
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987 Posts
Discussion Starter · #16 ·
Guess we will see what happens when I do the compression test. Could I do a leakdown test by just filling each cylinder with compressed air and listen to where the air is coming out if at all(ie exhaust, valve covers, oil dipstick)?
 

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wastegate hose is pulled
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JT87NA said:
Guess we will see what happens when I do the compression test. Could I do a leakdown test by just filling each cylinder with compressed air and listen to where the air is coming out if at all(ie exhaust, valve covers, oil dipstick)?
If your crankcase is pressurized, you already know it is coming past the rings. The leakdown test, in this case, is to quantify the percentage of leakdown and identify problem cylinders. You'll need a proper leakdown tester to accomplish this.
 
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