Hey all,

New here and to the world of automotive work. I've always wanted to learn how to do automotive work, and I've always loved F-150 trucks, so I went out and found myself an 85 f-150 inline 6 with the NP435 tranny. It's in great condition for the age and runs like to top, for the most part. I'm trying to ease myself into learning how everything works and how to do routine maintenance by going through and changing all the fluids. I've already done my first oil change and swapped the gear oil in the differential without any problems. When we transported the truck from where it was sitting in San Antonio (I'm in New Mexico) we removed the drive shaft for towing and I lost a bit of tranny fluid before I plugged it. Figured that gives me an excuse to change the transmission fluid out too.

I've done my homework online and read several places where you should remove the fill plug before draining the tranny, just in case it won't come off. Well, mine won't. I've tried every method I know, every wrench I own, and every curse word I know. I've soaked it in PB Blaster, wrenched on it with anything that will fit, hit the damn thing (and my wrenches) with a hammer, and even went out and bought a torch to heat up the case around the bolt. Nothing I've done budges the plug even a little bit, and I've done nothing but dig into the plug and start to round the corners. It's not round yet, I stopped before I screwed that pooch, but I don't have any tricks left in my bag. How do I get this damn thing off?

I've read that you can remove the shifter from the inside of the truck to fill it from the top, and I tried that as well. I stopped because none of my wrenches could get a good grip on it, and the force I was using seemed excessive. It seems like it would be incredibly hard to do with the tranny installed in the truck. It also looks like I'm not the first guy with this truck to have that idea, because the retainer looks like it's been manhandled quite a bit. Should I just go for it an have a replacement retainer on standby? Is this what I would be looking for: https://shop.broncograveyard.com/NP4...ctinfo/21006C/

I'd hate to have to bring the truck to a shop for this. I'm trying to learn all this stuff on my own and to be defeated by a fill plug less than a month after starting my project is... disheartening.

Thanks!

 

What type of plug is it? It has a square hole and a ratchet fits right into the hole? 3/8 or 1/2 drive?

 

My differential has the kind of plug you're talking about, but the tranny uses a square plug that's about 1/2". Like this one: NP435 NV4500 T18 T19 T98 TRANSMISSION FILL PLUG FITS CHEVY GMC DODGE FORD (17325) - TRP / APW

 

What kinds of wrenches have you been trying?

Do you have room for a good old-fashioned monkey wrench?:



The teeth on the jaws will grip tighter as more force is applied. Don't use an old beat-up wrench, as the teeth tend to wear down and be more prone to slippage. A new wrench with good sharp teeth will grip like no tomorrow. If you have enough room, you can even use a floor jack to apply pressure on the wrench handle.

If you can't get straight in with a monkey wrench, a plumber's basin wrench will reach into a tight spot at at angle. Here's one example. Get one made for small fittings, not larger pipes:

 

Thanks for the idea. I actually got an 18" monkey wrench today along with a propane torch to try to get it loose. Unless I'm using the wrench wrong, it seemed to want to round off the edges of the plug worse than the other tools I was using. I've tried vice grips, channel locks, crescent wrenches, the monkey wrench, and even a regular 5/8 open ended wrench that seemed to fit it very well. I was able to pound the 5/8 wrench on very tightly by tapping the end with a hammer and it didn't feel like it was trying to round the plug off when I tried to turn it. I was able to hang what seemed like almost half my body weight (I'm around 230) on that plug using the 5/8 wrench and it didn't move at all. That was after using PB and the torch. Unfortunately there isn't enough room to add a significant length of pipe or anything to the wrench so I could get more leverage.

I mean, righty tighty lefty loosey... right? I'm supposed to be going counter clockwise aren't I? I'm starting to question everything at this point.

 

That is the right way.
Try using MAP gas in place of propane as it has a hotter flame.
Don't heat the plug heat around the outside of it to expand the case not the plug.
Dave ----

 

I have been wrenching all my life and don't have to think about the right way to go, but when I am upside down laying on my back, I still to this day get mixed up and go the wrong way sometimes.

 

 

I cant imagine you would strip the fill plug with a wrench, the fill plugs are huge. Use the open end, 11/16 or whatever it is, put a pipe on the other end and it should come off. Maybe the previous owner thought it would be genius to out loctite on it or something. Heat is a good backup plan.

To get my shifter off i use a large channel lock, open it just enough to get the stick inside of it, place most of my bodyweight on one hand on the channel locks to press the cup down, and the other hand on the handle of the locks to pop it counterclockwise and it will come out. It will require quite a bit of weight to push the cup down though, I can usually get it in the first 2 or 3 tries now that i know how to do it. You just want to go hulk on it and get it out without too many tries as you can mess the shifter up eventually causing it not to shift anymore (happened to me a few weeks ago when I asked a buddy to remove it and he wasn't pushing down enough and I had to put a spare in). If you have never had one like this out before google np435 shifter and you will see how it works.

Also you are turning it counterclockwise..... we've all screw that up sometimes.....

 

Here's what I tried today. I put the 5/8 open wrench on it, pounded it on good with a hammer, and then got a bottle jack underneath it. No dice. It actually started lifting the front of the truck before my jack topped out and I got so nervous about the amount of pressure I was using that I stopped. I tried breaking it forward as well by tightening it, but it didn't help.

Not sure where to go from here.

 

Get a metal pipe and use it on the wrench for more leverage. After that start looking towards heat...

 

Already applied heat around the plug with a small propane torch. I don't have the equipment to do much more. Unfortunately the only impact I have is a cordless, and it won't fit. I did put a pipe on the end and try that way, but due to the angle of the plug and how loosely the pipe fits the wrench, I run out of vertical space towards the front of the truck before the plug would start moving.

 

A tranny shop would be a better option than totally destroying that plug. A previous mechanic or owner obviously overtightened the plug. It doesn't need much torque to seal because of the tapered threads.

I don't think that an open end wrench like you have is going to do the job. The wrench spreads with pressure on tight bolts and plugs and tends to round off, as you have probably found.

Another suggestion is to use an 18" pipe wrench with a 3 foot pipe extension slid over the handle. Hardware and home stores sell electrical and plumbing pipe that would be large enough (probably 1-¼"pipe size would be about right) to make a cheater bar.

 

My surefire go-to? Brute force and ignorance! 60% of the time it works every time.

I think you're on the right track. Do you need the truck as a daily driver or can you let it sit for a day or two? If the latter, here's my suggestion:

Apply some penetrating oil liberally. Use something like Kroil or PB Blaster. WD40? Ain't gonna cut it. Use a product specifically designed as a penetrating oil. Spray it on there and let it sit for several hours at least, overnight if possible. Reapply as needed to keep it soaked. The stuff works slowly, so give it time.

It seems your wrench is getting a good grip, so hammer it back on there. If not, use a plumber's monkey wrench, with good sharp teeth for maximum grip. Put your jack under the wrench again. Per your picture, you're going the correct way to loosen the plug. If needed, put a stout block under the jack to give a little more travel.

Jack up the handle again to apply some turning pressure on the plug. How much? I'd say just to the point of being scared, and then a tiny bit more. Wheels off the ground? That's way too much. I bet if you unloaded the suspension about an inch, that would be just right.

Working carefully, mindful the wrench could slip and the truck will drop, set up a little vibration. Smack the plug with a medium hammer three or four times. Smack the plug, not the wrench. Use a short spacer, like a socket, if needed. Then walk away. Go in the house and break out your Matlock DVD boxed set and watch a couple of episodes for a couple of hours. Then go back out and reapply the oil and smack the plug three more times. And then walk away again. Resist the urge to keep trying constantly. Let the oil, constant pressure, and occasional vibration do the heavy work. Repeat as necessary.

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I have had success using a spray called "freeze off" on a Wagoneer that was more rust than truck. It cools the bolt down so much it's frosted. Its supposed to form cracks in the rust that allows the oil to penetrate deeper. Time and lots of oil combined with everyone's tips should hopefully do the trick.