Hi,

New to the forum but looking at buying a 2000 F-150 XLT Ext cab 4x4 with a posi rear end and 94000 miles . As it sat at the dealer it had a problem in the rear end which the salesman made me well aware of before I took it for a ride. I'm told there is some kind of clutch assembly in the posi rear end to compensate the rear wheels in cornering and when taken for a test ride you can feel it vibrate for a second or two in the turns. He said they tried changing the oil and it didn't fix it so now he's going to have it sent out to be repaired. Does this sound correct and if so is this a vehicle I should stay away from? I'm planning on using it to tow a 5500 lb trailer. Any comments, advice or suggestions would be greatly appreciated.

Thanks,
Jim

 

Welcome ! It's called a limited slip differential. It's a great option, if it's not fried. It requires a limited slip additive when the lube is changed or lube that includes it. The problem description is common. It may need the additive or it may need a new LS clutch pack. The clutch pack is a relatively expensive repair that requires the rear end to be half-way torn down. If the problem is corrected, there are no related issues to question.

 

welcome to the boards i'd have to agree with max...sounds like its doing what its supposed to...is this a ford dealer your dealing with?...zap!

 

Its not a Ford dealer but the clutch pack is what he said was going to have to be replaced. He said they had tried changing the grease (like max said) without success so this was the next step. Does this seam like a normal wear item at 94000 miles? It has a hitch but the paint wear on the inside of the reciever seems to indicate it wasn't used much (or at all) and I'm wondering if this is an indication of hard use. I'm planning on towing and don't want to buy a lemon.

 

To evaluate the situation, someone would need first-hand knowledge as to whether the correct lube and additive was used at the last fill. Yes, it's quite possible to need a clutch pack at that mileage for a number of reasons. Typically, used car dealers do everything they can initially to hide problems from consumers in an attempt to minimize costs and maximize profit. If possible, it's done at the consumer's expense.

 

Thanks Max,

So if he has documentation of the clutch pack being replaced, and it riding OK, I should be good to go with the rear end. I know what your saying about used car dealers but he was pretty up front with the problem and quite frankly, I may not even have noticed it if he didn't mention it. One other thing did arise. The service engine light came on. Know of anything (or sensor failure) these engines are notorious for? Any other "Nickel & Dime stuff I might be expecting with this year and mileage truck?

 

You're very welcome ! If they actually do it and the mechanic knows what he's doing, it's completely routine. As for the check engine light, the truck will need the code/codes read to surmise the problem. There are many reasons the CEL light can come on and it is just guesswork until you know the codes. Personally, I would consider any truck with almost 100,000 miles on it in 5 years a risk in many aspects. Nickel and dime stuff would be the least of my worries. I would have an independent mechanic evalute the entire truck. I would hope to get maintenance records, a CARFAX, and an Oasis report. I would check for body repair and rust. There have been several issues with that year. Off the top of my head, a few are: door cracks, worn front suspension components due to lack of grease fittings, minimal spark plug threads in heads risking spark plug blowout/thread damage, lower door and tailgate rust, incorrect radiators in the Class III supercooling package, differential whine on the 5.4 w/9.75" rear, and cruise control recall. You could read for hours here on any of these topics if you search them.

 

ask if you can test drive the truck alone or with a wife or something. then go to a autozone or someplace that will check the engine code here first. it may be as simple as a tb cleaning or maf cleaning.

 

The clutchpack shudder is a common problem with LS differentials. It is common on the new F150. Mine were replaced ar 4,000 miles. The first attempt to correct the problem is to replace the grease with a synthetic and put an friction "enhancer" from Ford in it to make the grease slicker. The problem is not slippage but the lack of slipping. The truck may have been this way since new. It bothers some people and not others.