Author Topic: Rebuilt turbo 400, what type of fluid should i use?  (Read 19644 times)

Offline ncguy89

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Rebuilt turbo 400, what type of fluid should i use?
« on: May 10, 2012, 05:10:47 PM »
hey guys just got my turbo 400 rebuilt from cooks racing in cowpens sc. he recommended me using a good brand type F fluid in the trans but iv always used dex/merc fluid in gm trannys. what do yall recommend me using. its going in a 4wd truck that will see offroading quit often but street driven daily too!! i figured with the heat from offroading at slow speeds synthetic would be best but man that stuffs expensive!!!
1987 v20 - 350 tbi with towing cam, hummer wheels, stock otherwise

1984 chevy c-10 shortbed - kidney foundation truck (for my father)

Offline DustyRusty

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #1 on: May 10, 2012, 05:22:31 PM »
I would go with what the trans builder advised.  I would also get a high quality aftermarket transmission cooler to add in series downstream of your cooler in the radiator.  That should help quite a lot. I've never used synthetics so can't comment on its use.
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Offline Lt.Del

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #2 on: May 10, 2012, 05:26:00 PM »
i second the idea of a trans cooler--great insurance. However, I've always installed them prior the radiator, so the fluid will cool down with external cooler, then go thru radiator cooler, then back to trans.

Offline ncguy89

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #3 on: May 10, 2012, 05:29:50 PM »
i am going to buy a trans cooler to mount in front of the radiator instead of running it through the radiator. there a certain brand to recommend? and also im going to order new lines to install before i install the new transmission. so you would use what the builder recommends?
« Last Edit: May 10, 2012, 05:31:30 PM by ncguy89 »
1987 v20 - 350 tbi with towing cam, hummer wheels, stock otherwise

1984 chevy c-10 shortbed - kidney foundation truck (for my father)

Offline werewolfx13

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #4 on: May 10, 2012, 10:27:04 PM »
Don't bypass the stock cooler, no aftermarket cooler cools the fluid as fast as the liquid quench effect in the radiator.  Transmission > radiator>aftermarket cooler>transmission. Think about it this way...if you heat up a piece of metal to 350*F, and hold it in front of a fan, will it take longer to cool to 250* than if you plunked it into 200* water? But take that piece of metal and plunk it in 200* water, THEN hold it in front of a fan, and it will cool off further than the liquid would have accomplished alone.
Chris
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Offline ncguy89

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #5 on: May 11, 2012, 12:58:15 AM »
so how would i run it? hook the main line to the radiator then hook the return line out of the radiator through the cooler then to the return line going into the transmission? also where should i moung the aftermarket cooler? first time using one so kinda new to it.
1987 v20 - 350 tbi with towing cam, hummer wheels, stock otherwise

1984 chevy c-10 shortbed - kidney foundation truck (for my father)

Offline bd

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #6 on: May 11, 2012, 01:08:25 AM »
Synthetic oil is expensive, but so is your transmission.  Synthetic oils tolerate heat significantly better than conventional oils.

Here's one possibility (but not the only one):
http://www.redlineoil.com/product.aspx?pid=52&pcid=9

I agree with adding a dry cooler to supplement your factory wet cooler.  Install the dry cooler downstream from the wet cooler.  In addition, consider installing a temp gauge between the transmission outlet and cooler inlet.

so how would i run it? hook the main line to the radiator then hook the return line out of the radiator through the cooler then to the return line going into the transmission? also where should i moung the aftermarket cooler? first time using one so kinda new to it.

You've got the right idea.  Use the largest cooler that will fit in the available space in front of the radiator and A/C condenser that is directly in the air flow.  Leave at least 1" of unobstructed space between the trans cooler and the condenser or radiator.  Mount the cooler to the radiator support.
Rich
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In other words... if people learn by making mistakes, by now I should know just about everything!!!
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Offline 454Man

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #7 on: May 11, 2012, 05:48:54 AM »
On a street application is there a need for a trans cooler with a fan mounted to it like the B&M?

Offline bd

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #8 on: May 11, 2012, 09:39:35 AM »
On a street application is there a need for a trans cooler with a fan mounted to it like the B&M?

IMO, on a street app it doesn't hurt, but isn't necessary if the cooler is mounted in the airstream with unobstructed airflow.  There's only so much room between the radiator and the grille.  On our trucks, maintain a minimum hose ID of 5/16" (for a long run, 3/8" - 1/2" (-8 AN) is better).
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline ehjorten

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #9 on: May 11, 2012, 02:06:07 PM »
I'm going to go against the grain here on this thread and say don't use type F.  The type F has been know to soften and swell seals.  It also is more viscous and has friction modifiers that make a transmission shift harder with it in it.  It is my impression that tranny rebuilders like to say use Type F because it is going to shift harder than if you had Dexron/Mecron and usually when you have an old transmission rebuilt you are looking to firm-up the shifts.  The fact is that all TH400s had Dexron/Mecron in them from the factory, not Type F.  Even Ford switched away from Type F to Dexron/Mecron.
-Erik-
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Offline ncguy89

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #10 on: May 11, 2012, 10:21:27 PM »
well im going to remove the ac condenser so maybe that will make room for the trans cooler. also im not fully understanding where i should put the temp gauge. put it inline with the fluid coming FROM the transmission or TO the transmission from the cooler?  iv heard alot of guys around here using type F in rebuilt 400's so im going to stick with what my builder said.  also im putting new lines on when i install the transmission, does anybody have any good ideas on flushing the radiator cooler for the transmission out so i dont mix type F with dex/merc? thanks for all the advice guys!!!
1987 v20 - 350 tbi with towing cam, hummer wheels, stock otherwise

1984 chevy c-10 shortbed - kidney foundation truck (for my father)

Offline 454Man

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Re: Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #11 on: May 11, 2012, 11:12:36 PM »
On a street application is there a need for a trans cooler with a fan mounted to it like the B&M?

IMO, on a street app it doesn't hurt, but isn't necessary if the cooler is mounted in the airstream with unobstructed airflow.  There's only so much room between the radiator and the grille.  On our trucks, maintain a minimum hose ID of 5/16" (for a long run, 3/8" - 1/2" (-8 AN) is better).
thanks for the response

Offline bd

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #12 on: May 12, 2012, 02:03:38 AM »
...im not fully understanding where i should put the temp gauge. put it inline with the fluid coming FROM the transmission or TO the transmission from the cooler?

The fluid will be hottest coming FROM the transmission, so that's where you install the sensor, in line.  That gives you the most accurate indication of actual transmission temperature.

...does anybody have any good ideas on flushing the radiator cooler...

You can use aerosol flush marketed specifically for trans coolers ($$$), or you might be able to use painters naphtha with ~100 PSI shop air and an A/C flushing gun tool (flamable).

well im going to remove the ac condenser so maybe that will make room for the trans cooler....

On our trucks you should have plenty of room even if you don't remove the condenser.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline VileZambonie

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Re: Rebuilt turbo 400, what type of fluid should i use?
« Reply #13 on: May 12, 2012, 08:42:33 AM »
Don't use type F and keep in mind it's incompatible with dex. Running type f was an old school way to get firmer shifts. Run the auxiliary cooler in addition to the factory cooler but make sure you flush the lines and the cooler before you reinstall.

As far as the oil cooler goes an auxiliary cooler should be installed AFTER the radiator cooler on the return side. So connect to the top outlet at the radiator and then go into the aux cooler and back to the trans. The only time you would want to install it b4 the rad cooler would be EXTREMELY cold climates.


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