High Mileage Turbo 350 Filter Change.

[MarkIV396]

Pan Gasket on the Turbo 350 I have in the '70 C-10 is leaking + I would like to replace it and the Filter as well. Of course, If I replace the fluid with new -
I run the risk of Trashing the seal because of the detergent factor.

I would like to know what others have done. I see that Castrol has a Dextron III special formulated for High Mile Transmissions. Friend have told me that they would filter Old trans fluid & re-use it...

Not sure what to do. Castrol High Mileage still has some detergent in it...

Please give me your advice...

Thanks & have a great day!

Mark in Kansas.

[raycow]

This is the first I've heard about detergent oil being bad for seals. Could you please post a link to any site where you might have read about this?

Ray

[man-a-fre]

Use the new high mileage fluid it has a better seal conditioner package,don't put the used fluid back in that would not be wise filtered or not.

[MarkIV396]

Originally Posted by man-a-fre

Use the new high mileage fluid it has a better seal conditioner package,don't put the used fluid back in that would not be wise filtered or not.

Yeah, putting the old fluid really doesn't make alot of sense! Called my Old
Trans shop - but, they won't give me any recomendations - i'd have to bring it in.

So, Would the Castrol High mileage be the way to go? ANY brand other
recommendations ??

Thanks for the help!

-Mark.

[man-a-fre]

Castrol would work great.

[cparman]

Clean new fluid does have a detergent action to it. In my shop, I will caution people that IF we fix a pan gasket leak, we can also finish the transmissions ability to work. I see that you understand this, and I would suggest fixing the leak, as long as you understand that the next time the pan is off it will be a part of rebuilding it.

[MarkIV396]

I've tightened pan leak several times. I am thinking of backing bolts out slightly & pumping a ring of RTV sealant around the pan - then tighten to spec. Tired of this leaking on the drive & all the kitty litter!

???

Thanks,
Mark.

[stich626]

new fluid on a high mile tranny is it's death unless the tranny been serviced every 30k
it's a crap shoot..
good luck..
the high mile fuild is ok as it help the seals , for a while..

[AirSpeed]

Originally Posted by cparman

Clean new fluid does have a detergent action to it. In my shop, I will caution people that IF we fix a pan gasket leak, we can also finish the transmissions ability to work. I see that you understand this, and I would suggest fixing the leak, as long as you understand that the next time the pan is off it will be a part of rebuilding it.

Are you saying to not change trans fluid ever? I am not sure what you mean by fixing a leak may ruin the trans? Is that what you mean? Or am I misunderstanding? Thanks!

[Longhorn Man]

A tranny should be serviced every 30 to 50,000 miles. If you go 100,000 and try doing a fluid and filter, then when you put it in gear, it may not go. It may run for a while, and go out shortly thereafter.
I have always thought this was common knowledge, I've known is since I was a teenager, and seen it happen a few times first hand. However, it seems there's a LOT of people who have never even heard of it.
If you fear the trans is on its way out, or that this fluid change may kill it, then put it off till you are able to rebuild it. (Esp if this is your daily driver) Doing the kitty litter shuffle is better than thumbing a ride to work. You may do the fluid and filter and then it works great for another 50k+.

[sleepingbag]

What LHM said. Start saving for another tranny and let her mark her territory until you can replace it..

[WorkinLonghorn]

Couple of things; How many is "high mileage"?
In my limited experience with TH350 it is the ones that already show signs of impending trouble that need to continue running the old fluid, and that only means that it may last for a while longer. If the fluid is red/redish and not stinky go ahead and change it (don't "flush" it). I used the high mileage stuff once only and immediately I got a whining sound and a few thousand later it started misbehaving.Before I used the high mileage stuff it was perfect.
When the pan is leaking it is usually a mistake to just keep tightening the bolts as an overtightened bolt is a main CAUSE for pan leaks.When you drop the pan make sure that the areas around each bolt hole is very flat and if not you need to hammer it flat all around or it will continue leaking. Look in the pan and if you see large piles of friction material then maybe don't replace the fluid.Pour the old back in. If the piles are small and there isn't alot of metal particles (some amount is normal),then change the fluid.
If changing the fluid renders the truck non-operational, it would have gone out anyway in short order.

[Boog]

As my dad 'splained it to me so many years ago, a well worn auto tranny pump might lose it's fluid prime if you drain it and never pull again.
Now how do you define "well worn"? I don't know. Low mileage but rode hard or high mileage and rode normally? I define high miles on the 60's era vehicles as 150,000 and up as most didn't make it that far before a rebuild was due. Today's trucks are just getting broke in good at 150,000 miles.
I agree with the others if it's possible put off repairing that leak until such time as you might be able to build it proper.

[Longhorn Man]

just like you never throw leather sneakers in the washer, unless you have another pair to wear to the gym tomorow.

[05crewcab]

I'm gonna call BS on fresh trans fluid killing the trans until someone can provide definitive proof.

Fresh fluid is always better than old dirty fluid. If it wasn't we'd never need to change our oil, power steering, brake fluid, or gear lube.

Any trans that is such high mile and so under serviced should probably just be rebuilt anyway...it's already on it way out when you put the new fluid in it, but the fluid isn't the cause of it's demise.

[Longhorn Man]

no one said it's the fluid's fault.
It's the lack of solid particles in the fluid.
When you get ice in the driveway, you throw sand down to increase traction between your tire and the ground. Dirty fluid pumps solids onto the clutch packs and gives it enough bite to move.
Yeah sure, any trans that dies after getting serviced needed rebuilding already, bu that's beside the point.
I have personally seen it at least 4 times first hand. So personally, I know for a fact it can happen. You can believe it, or don't. I didn't document anything or get photos, but it happened.

[05crewcab]

Yep, I understand that old dirty fluid can hold an already weak trans together. In a healthy trans though, there is no reason not to change the fluid at proper intervals.

And I'm not saying trans death by fluid change doesn't happen, but should we be scared to change our trans fluid? Probably not.

If the current fluid isn't super nasty and trans seems to perform well, go ahead and replace the fluid and filter while fixing a leak, just be prepared for the off chance it won't come back to life after the blood transfusion.

[WorkinLonghorn]

It is about the viscosity. With old clutches and bands all worn down and cracked the ancient fluid will have lost a lot of it's viscosity and the cluthes will just barely engage. Then you add new fluid with the proper "thickness" and suddenly the clutches just don't quite have enough grab. They start slipping on the thicker fluid and as soon as that happens the resulting heat finishes off a clutch or band and it won't shift.

[stich626]

Originally Posted by 05crewcab

I'm gonna call BS on fresh trans fluid killing the trans until someone can provide definitive proof.

Fresh fluid is always better than old dirty fluid. If it wasn't we'd never need to change our oil, power steering, brake fluid, or gear lube.

Any trans that is such high mile and so under serviced should probably just be rebuilt anyway...it's already on it way out when you put the new fluid in it, but the fluid isn't the cause of it's demise.

THIS IS COMMON KNOWLEDGE..
most tranny's never see a normal fluid changes (30-40k)
also most no one ,out side those that are motorheads and the person that brings their truck to the dealer ..
A tranny with 90k on it and never had a fluid change,, will die afterwards..
ask any tech.. most will not touch a high mile car if there is no record of the tranny getting normal service..
I've had to tell a berson that just bought a car/truck that this may kill the tranny if it was never serviced...
and then watch them come back , yelling that WE. broke it..
think of it these was ,as seen as you where calling b/s.
what happens to an engine that never got oil changes and is full of sludge ,and you flush it???
there is a reason, g.m. puts a time line on tranny service..
and if anyone thinks the new cars 100k service is the way to go..
remember,after 100k they don't fix it, YOU DO..
even new cars/trucks should be done every 40k..

[05crewcab]

Originally Posted by stich626

THIS IS COMMON KNOWLEDGE..
most tranny's never see a normal fluid changes (30-40k)
also most no one ,out side those that are motorheads and the person that brings their truck to the dealer ..
A tranny with 90k on it and never had a fluid change,, will die afterwards..
ask any tech.. most will not touch a high mile car if there is no record of the tranny getting normal service..
I've had to tell a berson that just bought a car/truck that this may kill the tranny if it was never serviced...
and then watch them come back , yelling that WE. broke it..
think of it these was ,as seen as you where calling b/s.
what happens to an engine that never got oil changes and is full of sludge ,and you flush it???
there is a reason, g.m. puts a time line on tranny service..
and if anyone thinks the new cars 100k service is the way to go..
remember,after 100k they don't fix it, YOU DO..
even new cars/trucks should be done every 40k..

I think we argee with eachother? I am all about regular service, infact I am too anal about it on my diesel... I was just pointing out the fact that people are too quick to blame the fluid change rather than the lack of service for the demise of their tranny.

I also think 100k scheduled service (hell the german cars dont even have dipsticks...they call it lifetime fluid) is a BAD idea...of course, then again, the car makers just expect people to pay to put new transmissions in at 100k, when in reality a regularly serviced trans that doesn't get beat will last 3 times that long. The worst thing is that 99% people just bend over and take it.

[blackedoutharley]

Originally Posted by MarkIV396

I've tightened pan leak several times. I am thinking of backing bolts out slightly & pumping a ring of RTV sealant around the pan - then tighten to spec. Tired of this leaking on the drive & all the kitty litter!

???

Thanks,
Mark.

Just an fyi..... tranny fluid turns RTV to jelly and will actually leak more.

What I have always done was to apply a small amount of grease to the pan for the gasket to stick to just to hold it in place during installation.

As far as fresh fluid killing a transmission; it is true that the new fluid is not the culprit but actually the instigator. Think of an engine with a lot of gunk build up from lack of proper oil changes... If you get it good and hot and then drain it, or god forbid actually flush it, the thing is going to smoke beyond belief.
Think of transmission fluid as highly refined detergent motor oil (for laymens terms), when you drain all the oil from one that was not taken care of properly, you basically are removing the stuff that holds it together and it could result in loss of pump pressure.

I think, without seeing it myself mind you, that if the fluid is still "pink" and not burnt you should be able to do a fluid and filter change with no problem. If it is leaking badly you have effectively already changed the fluid by replacing what has leaked out.

The only product that I have ever seen help older transmissions is called K&W Trans X.
I had 904 Torqueflight that was failing to go into reverse and high gear. Did the trans service and added a quart of this stuff and drove it for another 18 months until I could afford to rebuild it.

http://www.midwayautosupply.com/pm-1...-can-2032.aspx

I would replace one quart of atf for this stuff when you refill after a filter change.

YMMV.

[Longhorn Man]

I highly recomend NOT putting any additives in your trans. If it is a junk trans that needs rebuilt (slipping/missing gears) and you KNOW you'll end up rebuilding it, then mechanic in a can might get it limping for a while. Possibly a long time. However... a good trans does not need it, and the friction modifiers in the additives will damage and shorten the life of a good trans.
Now, if you need to make your slipping junk trans work for a little longer, you can use the additives, and most of them do actually work. But don't expect it to FIX anything.

[benoit454]

ford is terrible for transmissions to go out if the fluid isn't changed and somebody decides to. I've seen handfulls do it. Our trans guy said it just eats the clutches up.

He said gm usually doesn't do it.

I would beleive it too because I got a junkyard th350, unknown year and mileage, didn't have hardly any fluid in the pan, not even a mouthful probably. I put it in the car, filled it up with 5 quarts or dexron 2 or 3 forget which, started it up and tried to move the car, didn't want to move, ended up filling the whole system took about 12 quarts total, tried to move it and it acted funny, ran it on jackstands and when we'd manually shift thru the gears it'd work fine, but in drive it did not want to shift. It finally started to shift into 2nd, then finally into 3rd. Never had a problem since. It only took about one trip to get it working too. I put in a new filter as soon as I got it and put it in the car, along with the fluid, about a year or so later I removed it, put in a 2k stall and b&m stage 2 shift kit, filled it up with type f fluid, and ran it. Never had a problem since either.

[Lugnut64052]

Originally Posted by 05crewcab

I'm gonna call BS on fresh trans fluid killing the trans until someone can provide definitive proof.

It's no B.S. I've personally seen it happen, more than once.
The seals get all stiff and hard in an old, neglected transmission, and it needs that thick, dirty fluid to help keep the seals sealing. Putting clean (and therefore lower viscosity) fluid into an old transmission is a sure way to get some seal leakage and clutch slippage going. The transmission will then roast itself in short order.

And don't put any leak seal additives in it. Sealer just swells the seals, turns them into mush, and still kills the unit.

IF, you change the fluid every 30k to 50k miles you can keep doing it for the life of the transmission. If you ran it up to 100k, just leave the old fluid in it, and run it out.

Personally, I'd fix the leaking gasket (installed dry! no big silicone booger) and dump the old fluid back in.

[benoit454]

Well if you drop the pan it only takes about 5 quarts of fluid to fill it and around 12 total so that's 7 quarts of old still in it to help.

I too have seen many die from fluid changes, don't beleive me, get you an old ford like a front wheel drive tempo or something that hasn't been changed, but it working perfectly, change it and see what happens. It'll die and not very long either.

No chevrolet haven't had do it that much but ford yes plenty, we lived across from a trans shop for years and hung out there alot. The guy who built them told us that fords get eat up by new fluid, happens all the time.

Now on dad's old 84 truck with a non lockup th350 it did mess up, but not like ford, we had it out to switch motors, cleaned it up, put in a b&m shift kit, filled it with new fluid, torque converter snout had broke so had to have a new pump put in it, once we put it back in it never worked right. it would drive, but no power and always lugged the engine, wouldn't run over 60 on the highway with your foot on the floor, motor wasn't revved way up either, but it ran like driving with the brakes on.