Your truck came with 75-140 synthetic from factory. Pinion seal? Leaking all of a sudden? HMMMM.. Unit is designed for 75-140 synth.

 

Yeah, that's why I asked. It says it on the axle tag as well. These guys work on a lot of Ford trucks so I didn't argue when they put 80-90 in it. I'm going to wipe it off and see if it still leaks. If it does I'll take it to my local 4WD shop, Holbrook specialties and see what they say.

 

Holbrook is going to look at my rear diff tomorrow. The noise was more amplified outside my truck, standing in their shop bay. Definitely needs new bearings in the rear diff, pinion seal and who knows what else.

I asked about the synthetic, they told me Ford only does that because of fuel economy. Also, synthetic is worse for the clutch packs in the limited slip than regular 80-90 gear oil is. They recommended I stick with 80-90 in the rear end when this is all said and done.

 

They use 75-140 synthetic because of the demands and heat inside there. Esp when towing...After 60,000 miles or so the diff bearings usually start pitting. I replaced mine at 80k or there abouts. You may have bad pinion bearings also. I wouldn't use anything other than the recomended fluid..


Dick

 

Verdict is in. The whole rear end is shot. Carrier needs replaced, carrier bearings were pitted out horribly, pinion bearing is shot and was loose sliding up and down the pinion shaft. Bunch of other stuff wrong, clutches in the limited slip all worn out. The took it out and showed me. They said the carrier actually fell out of the housing when they pulled the diff cover. I took photos of the components (which didn't turn out too well) they looked awful. Ring and pinion were both marred and pitted up. A lot of the components lost their "case hardening".

Shop told me and showed me there was water in the differential. Said they couldn't tell if it was ever serviced. I trust this shop, they do excellent work and have a stellar reputation for not telling you to do something that doesn't need done. And they did have a good explanation for the 80-90 weight oil, very technical. These gentlemen have been doing rear ends and other 4WD stuff since 1969 - they talk way over my head and they know their stuff. Glad I found out now rather than on some long trip. It's going to cost me 1275.00 to get the work I need done, but at least it'll solve the problems.

BTW thank you for your help with these problems. I might drop by there tomorrow and give them the diff oil (synthetic) I want used.

 

This mechanic who works on "a lot of Ford trucks" didn't see this when they took the cover off to check the tone ring?

 

Don't go putting that LS back in it get a gear unit or locker..

 

I went with a regular open carrier, no limited slip. When the time comes I'll get a locker, but for right now I don't care.

Yes, you would think the previous mechanics who worked on the truck would have seen all the problems in the rear end. I had a conversation with the owner about that.

Back to my original problem - it was not the VSS. I had to pull my cluster out and have it repaired by a speedometer shop. What they told me is there's a chip inside the cluster which is in charge of reading the speedometer signal and converting it to what's shown on the speedometer. This chip apparently went bad - and it is a common problem. So that's fixed now.

I have a speedometer, a new rear differential, a working horn and working cruise control. I am hopeful this spate of repairs can hold me for the next couple years. I don't drive that much, so I like my odds. Thanks to everyone for their help.

 

Thanks for updating us... Good luck..


Dick

 

Here is my story, this morning went out to hook boat to truck to go fishing, noticed water on driver floor mat and battery was dead, weird I thought. Jump started and off we went, noticed OD light flashing and no speed odometer. Back from trip and trans worked fine. Researched internet and most info pointed to speed sensor on rear differential. Cleaned connections and inspected wires all looked good, still had problem. Pulled speed sensor out to look at and clean, after removing I heard my door chime go off??? It did this several times and then the door locks started to go on and off, really weird, disconnected batteries. Researched alittle more and found post in this forum about water in GEM. Well pulled that apart and water was dripping out of it, so my water leak is running down into this box. Letting it dry and will report back.

 

So I dried everything out over night, let a hair dryer run a couple of hours to make sure all water was gone. Also took cover off of GEM and looked inside where circuit board is, no signs of water. Put all back together. Test drive good, speedo works and no more flashing OD light, trans shifting good. Spent hours with a hose and sprinkler trying to find where water came in at, could not find any leak. It is raining pretty good today so will be out to look again this afternoon.

 

Also forgot to mention that fuse #3 was blown, it is a 20 amp that runs cigarette lighter and OBDII. I take it was from the water in the GEM connections??

 

windshield water?

 

Very time consuming and frustrating. I could only produce water after a heavy rain, I think i am down to the weather stripping on the cab near the rear door corner. No matter how much water I put on it either through a hose or sprinkler I cannot get it to leak. I sprayed windex along top of door onto weather stripping and then used low pressure shop air along inside of door and could produce bubbles in one location in weather stripping. Don't know if this is a good way or not but trying anything at this point. I am down to replacing the weather strip and/or reseal front windshield.

 

I am not sure by reading this but the vss is on the transmission not the differential. ABS sensor is on the differential. I just changed out all my gauges with autometer.Their speedometer needed a clean signal from the transmission in order to work.