Hi guys,

I just purchased yesterday a 2001 F250 V-10 super duty with 125K miles.

I noticed that when I take off from a start, there is a couple of clunks that feel like a tranny slip. Then when I come to a complete stop, there is another clunk.

I read on the forums that it may be a U joint issue. I took it to a mechanic and he charged me $60 to diagnose the issue.

He said the problem was in the rear differential. That the pinion is the problem. He said its not an emergency to repair the differential right away. He said I don't have to worry about it until it is significantly a louder/harder clunk.

Is he correct in saying that I can continue to drive with this problem until it is finally gone completely bad? He said it will cost anywhere from $70 to $1500 to fix. And in most cases, its cheaper just to find a used rear assembly for about $1500 than to repair the differential case.

Can I PLEASE have your expert opinions? I don't know if I should continue to drive until it goes bad or repair it now and if I repair it now, what should the average price be?

Thanks in advance.

 

if you had a lot of slop with the pinion there would most likely be gear noise as well. usually on high mileage vehicles some slop develops in the diff carrier assembly but usually not a problem. also 1500$ sounds like to much money for a rear diff overhaul, even if the diff carrier needs to be replaced it should still be under 1000$. if he is saying its cheaper to replace the entire rear axle assembly id find another mechanic

 

Thanks for a reply Bill.

Not sure what your definition of A LOT of slop. But when I take off from a stop, i feel about 2-3 "bumps/slips". There are no sounds at high mileage. I used to have a vehicle that would make a grinding/howling sound from the differential, but this F250 does not have any gear noises while driving.

When I come to a stop, there will be another "clunk".

I will need t find a different mechanic based on your recommendation.

But do you think its safe to drive or should I get it fixed immediately to prevent more damage to other components or more damage to the differential itself?

 

If you have not already done so, I would lubricate the driveshaft splines in the slipjoint. This will cause the symptoms you have.Take a look at this:
2004 F250 Slip Yoke Service

 

You beat me too it....I would do this first and its something you can do yourself and wont cost a dime.

 

Sorry the link did not work, try this one:

2004 F250 Slip Yoke Service

 

also besides the slip joint if the rear leaf springs are very rusty and the nylon pads are gone that could cause the leaf's to bind on acceleration or de-acceleration causing that binding or slipping feel

 

Thanks for the link scratch. I will try it.

However, the mechanic actually got under the vehicle while his assistance drove forward and backwards and swears the sound is coming from the differential.

 

The sound may be coming from the differential but the slipjoint can cause it. From what that mechanic has told you I would look for another opinion. Besides lubing the slipjoint is cheap maintenance and is a known problem on these trucks. I believe there is even a TSB out on it.

 

had a the same problem and remove the slip joint front and back wil i was a it and no more problem!

 

Thanks Scratch. I read some of the other posts and they all have a Clunk.

However, when I take off, ,I don't get one clunk, its like 3 clunks.

Does anybody else have the 3 clunk and it turned out to still be the slipyoke?

 

Scratch,

I took the truck to Dan's Driveline here in Vegas and he looked at the truck. He said its not the slip yoke, that it has plenty of give. He said that the pinions are over tightened. That there is no freeplay.

The overtightened pinions is what is causing the clunking. They want $725 for parts, labor and tax. Does that sound like a fair price to replace the pinions?

 

that is more in line with the problem, some of the cost is new lube for the axle. See they will let you look at the gears while they have it open.

I would get this taken care of before they cannot adjust and have to replace.

 

I talked to the previous owner who drove it for a year and put 20K miles on it. He said it did the clunk when he purchased the truck. He said that's normal because the truck has so much power.

So with the pinion being overtightened for 20K miles, do you think there is already a lot of damage done, that just loosening the pinion is not recommended? Do you think it would be a better idea to have them replaced it with new pinions?

The tech at Dan's said that if he opens it up and it can just be loosened, then they will only charge me for labor. How much do you guess it would take? 1-2 hours? But I'm not sure if the pinions should just be replaced since its already opened.

 

Is your differential a limited slip (traction lock) or open type?