Safe ways of flushing my tranny at home

[heavyredchevy]

How can I safely remove all the old tranny fluid out of my 89 TH700R4. I have 155 K on the truck, and Im taking a 1500 mile trip on the 26th. I want to make sure the tranny is in good health.

Thanks

[slythee]

I've talked to several transmission guys and none of them can give a definite answer on whether flushing the trans is good or bad. The previous owner of my truck flushed it every 30k miles after he replaced it @ 100k miles. It's got 190k now and I won't do it again. I've had two Camaro's in the past and the transmission went out a week after I had the trans flushed on both of them. You'll have to pump fluid slowly through the trans for a while to flush all the fluid from the torque converter. High pressure could blow the friction material off the clutch plates, (they say). I don't think it can be done at home. The one thing I'd like to do is add an external filter and remove the internal one so it doesn't get clogged. And I'll be putting the old fuid back in.
The good thing is, if this can be a good thing, you can get a rebuilt trans from Jegs or Summit for about $750-$1200 and put it in yourself. It's a days work but it's not hard as long as you've got a transmission jack.

[MT-2500]

Originally Posted by heavyredchevy

How can I safely remove all the old tranny fluid out of my 89 TH700R4. I have 155 K on the truck, and Im taking a 1500 mile trip on the 26th. I want to make sure the tranny is in good health.

Thanks

A 5 gal. bucket and a hose from transmission pressure line into bucket is all you need for a flush machine.
Run cooler line into bucket and add fluid to transmission with engine at adle and flush away.
It will take about 18-20 qts fluid to get a good flush.
But if it is a high mileage transmission that has never been serviced it would be safer to stick with a pan drop and filter change.

To Flush or not To Flush ?
Just like Kenney Rodgers said you have got to know when to fold and when to hold.
If the fluid has high mileage 100K or over or is real dirty you had better hold.
On a trans that has had good regular service at 50K or sooner a flush is good.
But be ware of jiffie/quick/wallmart /fast lubes that offer power and fast flushes.
They have abused and over rated the trans flush.
They have a habit of using one fit all fluid out of the same barrel that fits all.
They just throw in a bottle of additive to make it fit all. Or worse they pitch in a bottle of cleaner or dope in it that can do more harm than good. And will tell you the filter does not need changing with a flush.
Just remember that all new fluid makes a high detergent cleaner that will break loose all varnish and dirt and grit in the trans and drop it in valve body and solenoids.
Always change the filter and go easy on or use no dope and cleaner.
Adjust/check the bands and linkage on the trans that have bands and adjustments.
Always use the trans fluid the trans/manf calls for. And be aware that some manf have changed the type of fluid specs since the trans was manf.
Some fords have changed the specs and a lot of cry/dodge have gone to the newer type of fluid on their trans service.
Also some fords have tsb’s and require a total complete trans flush to cure trans shifting problems. Some as low as 30K
If a person does not have a flush machine a old 5 gallon bucket and a couple of rubber hoses to connect to the cooler lines and with the other end in the bucket will make a good flush machine. Just put the hoses in the bucket and start the engine and start pouring fluid into the trans until the fluid running into the bucket gets good and clean.
It usually takes 16-20 qts. To get a good flush.
Flush or No flush always service the trans filter and trans on a good regular basic.
People that keep the serviced have a lot less trans problems.
Good Luck MT

[heavyredchevy]

Sounds like ill be doing the pan drop and fliter change. I have only had the truck for a year, and do not know of its past history, so i want to be on the safe side and service it myself.

whats your opinion on tranny additives?

Thanks for all your help.

[slythee]

Sorry, don't really know anything about them. My guess it that most are designed as temporary fixes for a bigger problem, but I don't know.

You might take it to a couple of transmission places and ask them to take it for drive and check it out. See what they say. I found one that would do it for free.

[glenncof]

I just had the tranny on a 1997 Tahoe (4L60E) rebuild at 125K.

I have done a slow flush process on a 1991 Range Rover (187K miles now on original trans.) which had a drain plug on the pan. Basically drained it every oil change and refilled. Only half comes out so it takes 5 changes to get it full renewed. After awhile do it every other or third oil change. It's it no brainer-simple at oil change. I started this at 120K but fluid was replaced at 60K.

On the Tahoe I did pull pan and replaced filter at 100K but didn't drain torque convertor. What a MESS !

Now I know better. Put in the drain plug on the first change. I would now have started at 30K miles. Filter on the Tahoe was not bad/clogged at 100K. I would not be too concerned about the filter but it's so much easier if pad is drained.

I have heard some many bad stories about a full flush at shops. Go with slow method and frequent changes.

[MT-2500]

Originally Posted by heavyredchevy

Sounds like ill be doing the pan drop and fliter change. I have only had the truck for a year, and do not know of its past history, so i want to be on the safe side and service it myself.

whats your opinion on tranny additives?

Thanks for all your help.

Say no to additives and dope.
Most will do more harm than good.
The best additive is a good clean new filter and new transmission fluid of the kind that it calls for. Yours should take dexron 111 transmission fluid.
Good luck.
MT

[heavyredchevy]

Sounds like a simple pan drop and filter change every now and then is the best way to go.

Thanks guys for all your help.