A 1985 4x4 f-150 i/6 starting to see leaking front the front differential, has ifs, i feel it may be the gaskets for the mileage on it . Seems there not an easy gasket replacement for this differential (bolted to the I beam) how can one take this axle apart to check for wear and tear and gasket redo.Is there a easy way to check for leaks and wear n tear any clues thanks TR

 

There isn't an easy way to service the front differential; it has to be removed from the car before it can be disassembled. If you plan to try replacing gaskets and seals, get a copy of the FORD service manual for your truck; the Chiltons or Haynes manuals won't do it. You can likely get a copy of the 1985 service manuals from Helms Inc., Service Publications, P.O. Box 07150, Detroit MI 48207. They also have a website. The price is probably about $100. The 1983 version has four manuals, an owners service book, a set of wiring diagrams and a book of specifications. If you plan to keep the rig, this is the best info you'll get. Helms is the firm that Ford selected to provide the factory service manual to those who need them. In the manual for your truck, there is a section on servicing the front differentials for the F-150 through F-350. If the gears and bearings are OK then disassembly, cleaning, gasket and seal replacement and reassembly is not too bad a job, once you get the differential out. But, getting the differential out and ready to work on requires removing the radius arm from the differential assembly. The two are held together with a big bolt that is torqued to over 200 ft lb (if I recall correctly). When I did the job, I had to borrow a 3' breaker bar to back the bolt out; my 1/2" wrench and bar wouldn't even touch the thing. I also had to look long and hard to find a torque wrench to tighten things up on reassembly.
My advice? If the assembly is not leaking too badly, let it alone and add oil as necessary to keep things lubed. Good luck.

 

I appreciate the help (info) Charles, this truck i bought new in sept of 1984 , soon to be 20 yrs old . 450,000 miles on it ,original engine --- only had the oil pump replaced in her at about 250,000 miles . (engine work)When the pump went out i was on the interstate and it knocked the timing out (what luck).Its been a very dependable vehicle still sharp looking and engines still strong.leaks some oil (not to worry for the mileage )and like a icon in this family . FORD makes a truck-----ive owned a few: debating the rebuild of the front diff will keep an eye on that leak thanks TR

 

You did mention a rebuild and I think this would be ideal for your situation. All that work just to replace a few gaskets is a lot of work, it would be wise to replae allteh bearings in the diff, if its apart you might as well since it's complicated to get it all off.

 

I agree that it would be a good time to replace bearings. You could replace all of them for a bit over $100. But, you would need the special tools to set the fore/aft clearance on the pinion. Moreover, I have never seen a part-time front differential (manual hubs) that had any appreciable wear on bearings or gears. Full time 4WD, yes, but part-time 4WD differentials get so little use that wear is not normally a factor. I would guess that few front differentials have been operated more than 5000 miles with the hubs engaged. I have seen front differentals damaged by water - people will run the axle under water and then not drain and refill as the manual recommends - but I have never seen any significant wear. Good luck.