I am having some work done on my truck (the front cover gasket) and i only have enough extra $ to do one these. My truck has 66k on it , it is a 97., 4.2 with a 5sp.

So what is your thoughts.

 

F150nky,

How many miles on your truck and has it either ever been done previously?

John

 

It has 66k on it , and it neither have never been done.

Just to add another wrinkle, if i was going to do one or the other myself which is the least difficult to do.

 

I'd have the tranny fluid done by your mechanic. A flush would be best if you can afford it. The rear diff is a lot easier to do by yourself.

 

Rear is easier in my opinion. Only because I'm unsure where the fill hole is on the tranny. And how easy it is to fill. If you you buy one of those suction gun/gear lube changers at Autozone/pep boys etc. Then I'd say do them both yourself. The rear is easy to do, I did mine and put on a Trick Flow Diff cover. Just drive it awhile first to warm it up. Unbolt the cover and let it drain into a pan. Scrap the old RTV sealant off, put a fresh bead around the cover, and bolt back into place. Pull the check plug out from the driveshaft side of the diff with a 3/8 extendsion and use the suction gun to push in the new fluid. When it starts to drain out the hole, you've added enough oil. Plug it back up and you're done. 30 minuts at the most. The only thing will be the fluid. Check you manual and see what type you need. Mine uses 75-140 synthetic. You'll need about 3 quarts or so for the 8.8 rear. I use redline and got it at summitracing.com, $7.95 each. You could also go to the dealer, but a little more expensive. Valvoline is making a new synthetic 75-140 but have been unable to find it locally. It's on their website.

Good Luck,

John

 

He's got a 5 speed, no flush and fill needed.

 

Do them both yourself. It is very easy to do. I just did mine about 3 weeks ago. I too have the 4.2 5-speed. The transmission has two plugs on the left side (drivers side) they are both labled, at least on mine they were (I have an 01) one says fill, and the other drain. It is a little diffuclt to fill, but can be done no big problem.

The manual calls for 3.75qts of trans fluid. I found it took just about 4qts. You do it the same as the rear-end. Once you put the drain plug back on you fill it till it starts leaking out the fill hole.

So you don't have to worry about over filling either the rear-end or manual trans.

NOTE: as far as when you go to fill them the truck should be level. I was able to do both my trans and rear-end without lifting the truck off the ground. If you do lift the truck off the ground then you could end up either not putting enough fluid in, or overfilling one or both of them.

I used Royal Purple 75w-140 gear oil for the rear. I bought 4qts so I would have at least 1 qt as a spare. It will take just about 3 qts to do the rear. I bought Royal Purple max ATF trans fluid ($7.36qt) and I bought 5qts of that, same reason to have 1qt as a spare. I paid like $7.36qt at northernautoparts.com.

Remember if you have limited slip rear-end to get 4oz of the friction modifier. Royal Purple as well as some of the others like Redline, Amsoil etc will tell you that you don't need the friction modifier, but I asked Mike (Superchips forum) and he told me they ALWAYS use friction modifier in their L/S rear-ends regardless of what the bottle may say.

 

you fill where the tranny dipstick is i believe at least in automatics, ive never done any work on manuals sorry. But that guys right about doing both. The differential is a relatively cheap and easy thing to get done. You just need a 3 dollar gasket, about 3-4 quarts of diff fluid and some of the blue gasket sealer stuff. Just undo the back let all the crap come out, clean up with brake-cleen. close it with blue gasket stuff and the new gasket and put new oil in. Transmission is a little harder i think esp if you have a torque converter but im doing mine next weekend with a little valve work, im not expecting much trouble.

 

Something I forgot to mention is don't be concerned if you can not find a gasket (for the rear-end). I could not find one here in New Hampshire, no Ford dealer had them or auto part stores. The Ford dealers told me they come from the factory with NO gasket only RTV sealer.

When I did mine I found that to be true and they don't even have much RTV from the factory. I used the high temp RED gasket sealer just to be safe. All you need is about 1/8" to 1/4" at the most bead all the way around the cover and it seals fine. I have no leaks at all.

As far as the manual trans there is no dip stick. You have to get under the truck to get to the "fill" and "drain" plugs. I don't think it took me more the 2 hours to do both the trans and rear-end and that was taking my time cleaning everything up afterwards.

 

I just did my rear diff on my 98 f-150. I got my 3 qts of royal purple 85-140 ($8/qt) and the gasket ($7) at my local NAPA store. I also got a $3 plastic pump at auto zone that attaches to a one gallon jug (like prestone anit-freeze) and attached some clear tubing to the pump to pump it into the rear diff. You could probably do this for your tranny too.

 

WOW!! This board truly is a wealth of knowledge. A big thank you for the help. Wish me luck on the front cover gasket, the more i peel that onion the worse it gets.

 

If your doing the rear-end for the first time I would highly recommend taking the cover completely off to drain. You will find that towards the back of the rear-end, next to where the cover is there is a valley, can't think of a better name, but it holds approx. 1 cup of gear oil. You will want to slaush that out, or use some paper towels to soak it up so all the old fluid is out. While you have the cover off try to look at the teeth the best you can and make sure everything looks good, no chipped teeth etc.

The pump sounds like a great idea. I didn't use one and found that filling the rear-end was easy without one. They make the gear oil bottles where they work well. However, for the transmission it may prove to work very well. When I filled my transmission I used what is about a 8" long plastic tube that connects to the bottle of trans fluid. I bought it at the auto store. It worked pretty good but I would bet the pump would work much better. I can say there is no way you can get the trans fluid in the transmission without a pump or the tube thing I described.