dasswright

Greetings . I'll start with history and the issues I've been having. I don't have much experience with auto Dyi but I'm definitely on the road of educating myself of taking care of things myself; had my 04 f150 lariat 4x4 about 6 months and now has around 135k miles. . Recently stepped up with a 2.5 level kit and 35" Trail grappler M/T. I live in the country and drive a lot of dirt road. Few months ago I was having trouble getting the 4x to disengage, but went back to 2x after a few. Now I've got nothing. No light on the dash. Yesterday I unplugged the vacuum hose at the firewall solenoid and the front driveshaft would not turn by hand. Put hose back on and driveshaft would turn free. That's as far as I've got with the 4x diag. A more concerning issue I've been having is I recently started noticing a hum. One similar I've had before when rear diffs start to go out. I pulled the rear diff cover , and everything seemed fine. Changed gear oil following advice of a thread on here. No metal shavings except a little on the fill plug. But all looked good to me. Still have the hum. Can really notice the sound when I'm driving and give it a short burst of throttle. Next I'm going to change fluid in front diff and transfer case. I would really like to get this issue taken care of myself if possible and before the situation degenerates and becomes more of an expensive problem. I may be best taking it in to a shop, but really can't afford it, and am trying to do more myself. Any advice on things to check out? Look for? It's tough to describe the situation. And one other thing. I have a diablo sport tuner . There was a day when I changed the gearing ratio to 4:10 setting after I got bigger tires thinking it may help with power loss. But put it back to factory soon after. May that have started this?or played a role . Been a good 6 weeks since . Been mainly running it at factory setting with a little experimentation here and there. Any info advice / constructive criticism would be highly appreciated! Update::: the problem has been diagnosed as rear diff/axle bearing. Need master bearing kit. Pinion axle bearings . Have 3.73 rear diff running 35" m/t. Would it be good to regear to4:10 or 4:56? I also have ocaasional hard shift from first to second gear. That was happening before I went to 35s... Have 135k miles othe truck. And really hoping to get 300k+ like I did with my 01 f150.. Also have a ticking sound from the engine. Read about this a lot with no real solution in mind.. It's always something ey. One step at a time - thx!
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tareed94

Not trying to insult your intelligence but I have to ask. Could the humming sound be the MT tires? Mine hum/howl at speed. As far as the 4x4 goes, I've heard the solenoids at the hubs can go out so that could be your issue.

dasswright

I really wish the sound was just the tires. But absolutely sure it's a different sound. Took it in to a shop today and up in the air. The unhealthy sound is definitely coming from the rear differential. I just opened it and changed oil. Gears looked good to me. The shop guys are recommending a bearing kit. They wanted 800 to do the axle or diff bearings. Do I've begun looking into how to do this myself... Think and hope you're right about the selinoid for 4x... Thanks for your input. Appreciate

tareed94

Yikes. That's not TOO high though. I have no idea what is involved in doing that. Hopefully it's the solenoid.

Do you have a limited slip rear differential? Did you add the correct amount of friction modifier?

dasswright

Yeah. The 4x I feel will not be a big deal.. The rear diff. I added 6ozs. Which some say 4 some say 7. I'm really in a tough spot here as the diff him is getting worse and worse to a bad sound almost constantly . I've been babying trying to figure how to best solve this. I happen to be at my second home ish. Out in the middle of nowhere. But in a small town waiting to handle this. Been looking for rear diff at salvage. Found for roughly 6-800. But quite a mission to get it with a failing vehicle and only other transport is motorbike. Unless I had a friend help which they all have busy lives and wouldn't want to ask to drive 8 hours to get a rear. So. I'm wondering why this happened and if I replace bearings in rear, which is supposedly the prob . Will it just go out again? Now that I'm running 35"s this all started after getting new tires and pulling a heavy trailer long distance. Wondering if my lifestyle is just too much for this rear. Maybe I should be looking into re gearing? After the tires and lift I noticed a substantial power loss and started to take it easy on truck. Thinking maybe it would stress trans, rear, or motor and create problems... I'm not super mechanic guy by any means.,so just trying to figure all this out and how to find best solution without a lot of money .. Any thoughts ideas , input advice? Anybody? Thanks for all so far. I'm all alone in a place where I don't really know anyone far from the city without many options/resources.. Very thankful for this site.

tareed94

What gears are currently in it? If you're towing and on 35's id suggest 3.73's or 4.08's. I'm not an expert on gears though.

How much would it cost to get a tear end shipped to you? I'm sure it's not cheap, but it'd be easier than phoning a friend. I think you could get away with replacing the bearings and being fine, if that's the issue. That could just be a symptom. How many miles are on the truck?

shannonC

If your noise is for sure in the rear diff then your looking at pinion and side bearings. Easy job for a seasoned tech but could wreak havoc on a diy. A lot goes into it. Setting bearing preload,making sure your backlash is right between ring and pinion gear,not getting the side shims mixed up. It can be done but I would definitely use air or power tools. The crush sleeve on a 9.75 rear diff is a pita to crush.
As for the 4x issue you need to find a shop or dealer that will check for codes in the 4X4 module and go from there. They will be C18?? codes. Most common issue on the older 4X4 systems is the IWE solenoid on the firewall.

dasswright

From what I've gathered this far. You seem to be right on. I've talked to nearly every mechanic in the area. There are a couple that don't want to get involved ; and my buddy said he can only think of one or two techs that could handle the job. So the DIY is def out of the question. I was kinda unhappy hearing it would be 800 in labor for the rear diff bearing job. But then found a guy that seems good and said he do it for 300 in labor. So that's a relief . Didn't want to spend 8 for bearings when I can get an entire rear end for that. Anyway, appreciate the input ShannonC .

shannonC

No problem bud. You can usually find a competent tech to do it on the side for about 2-3 hundred bucks.

dasswright

Yeah. I've looked around quite abit. I'm in the are of my second home , which is remote. Don't really know many people in the area, talked to my buddy's buddy who is the only mechanic I know of personally but he's got other stuff to deal with. But he recommended a shop he used to work for and the owner is the one that quoted 3 for the labor. But not till sometime next week. So I'm grateful for that. The 8 the other shop qouted kinda bummed me out. Anyway, my concern now, is once I get this rear to a healthy state, how long will it last? I'm running these 35" mud tires which I love. I live 7 miles down a dirt road which can get bad, so I need big man tires and 4x4. The previous owners of this truck likely never serviced the differentials . So I'm hoping that's the cause. But I'm thinking the new use of these big tires are likely putting a lot of stress on drivetrain Trans engine etc. . So maybe I should be looking at re gearing front and rear diffs? I do a lot of driving. I'm nomadic by nature. Drive lots of highway , off road, and Mtn highway and even some city. Any advice on how to get this truck set up for the long haul? Should I be considering gears? Heard about 4:10 and 4:56. 4:10 doesn't do that much and 4:56 may slow my top end . I'd like to be able to travel at 75mph with no worries. Also. I've got a few days before I can get my rear bearings done and the hum grind seems to be getting worse. I had a rear on my Tacoma just straight brake coming out of a stop sign. The last mech I talked to said the noise would become unbearably loud before it broke and left me stranded. I know I should drive as little as possible but wondering how long I have and what sort of other damage may occur if I put more mile on it? Been babying it and not really driving. Thinking about adding some Lucas heavy oil stabilizer. As I've read this may help alittle? The sound is not horribly loud and when driving I try to take it easy and find that place where it's the least loud and stressed . Sorry I'm rambling. Appreciate any info ideas advice. I'm not a mechanic by any means but really trying to learn and handle more situations and avoid issues with my own hands. Grateful for this resource and not feeling all alone on the matter...