Rear Differential "Clunk"

90

Asked by mimbres May 21, 2013 at 01:04 AM about the 2002 Ford Escape

Question type: Maintenance & Repair

AWD and get a clunk in rear differential that sounds exactly like a bad Ujoint but they have been checked and are good. Clunk occurs primarily when driving is started and going from rev to forward, another symptom is the "grabbing" of tires at low speed when steering wheel is turned (more than any "usual" AWD grab), in fact if wheel is turned a lot it seems to just about lock up the wheels, but don't notice that when in motion, just very low speed.
I made an extreme bonehead move when having to get the vehicle to town for different repair, I used a dollie and knew better but just forgot to remove rear driveshaft! Trans was in N, but at approx. 30mi it just locked up the rear wheels (and driveline) at about 35mph. I had the transfer case changed out and all Ujoints inspected. That cured a lot, but I still get that initial clunk at start, other than that it drives AOK and the clunk does not appear at any stop and start that comes after the initial start, though I believe it would if I were to go from R to D.
Does anyone have any advice other than installing a different differential??

10 Answers

90

Thanks for your reply. So far I've had the rear differential support bushings and related brackets installed. That may have made a "slight" difference but clunk still there. I will check the other items you mentioned. When I had the xfr case changed all new fluid was put in and new rear differential fluid as listed in manual. Not aware of any special additive but will surely check that out. Thanks again.

4 people found this helpful.
30

Just started having the same problem as you describe. Happens mostly when taking sharp turns. If I do circles slowly in a parking lot I can replicate the problem fairly easily. Dealer says this is a common problem with the Santa Fe AWD. It has to do with the AWD engaging and locking up. He said they even had one case where the rear wheel actually locked up entirely. Need the differential replaced. I am concerned though, he seemed off, like there was something he wasn't telling me. Not to mention the fact that I heard the mechanic ask him something about 2 different parts to order, and the service guy said Hyundai Canada will only pay for the one. What other parts would there be? Should I look for a second opinion from a non Hyundai mechanic.

3 people found this helpful.
90

Never a bad idea to get a second mechanic opinion. My best guess on that 2nd part is this - between the actual rear differential and the rear drive shaft (drive shaft bolts to it) is a part (sorry but been a while an can't remember the actual name), it is the area of the differential "yoke". This part transfers drive to the rear wheels when demanded in AWD and acts to synchronize correct inner and outer wheel speed in turns. Another big symptom you could check that did on mine was on "gravel", at very low speed, you'll hear the rear wheels engage and disengage so when it grabs the gravel will make a whooshing sound. It could be only that part and not the entire differential - a good mechanic will just take the differential fill plug off, smell it, and be able to tell if it smells "burnt", indicating differential is probably bad, but also might take the plate off to visually see the gears and look for any metal "pieces" floating around. Your symptoms are the same as mine, though I actually locked up my rear wheels and symptom occurred after that, but the cause, so I'd guess the same part for you, however, there are probably some electronic sensor, etc. that may be bad too. Again - looking at entire rear drive there is the differential, then a drive axle going to each wheel, on the front of the differential is the part with yoke which has the sensor that receives the signal from the computer to adjust inner and out wheel speed, that is the part. Now there are two types - one is fed by 1 wire and the other by 2 wires, mine was the 1 wire type and not sure which you have until you look at it. 2nd opinion may be good to find if it is only that part and not the entire differential, especially if Hyundai pays for that part and not the differential and you get stiffed paying for a differential when yours is ok and it's just that electronic yoke part. Sorry I can't remember it's exact name, you could search online or find mechanic with good repair manual that shows it in a diagram.

2 people found this helpful.
20

Just a side note: Ford doesn't make an AWD Escape. It does make front wheel drives and FOUR WHEEL DRIVES

2 people found this helpful.

The Escapes are not 4x4 but FWD with added rear drive. They are part time AWD.

7 people found this helpful.
90

Maybe, but my 2002 Esc has elec switch with selection for auto and 4wd. Sure seems like AWD in auto position as the car is "excellent" when driving in snow, no comparison to full time rear or fwd. Could be as you say and in the auto position it's fwd and switches to AWD when it senses the need?, but there is still a 4wd selection, never use it as the awd does the job.

2 people found this helpful.
20

My mechanic found a diff housing bolt inside the diff attached to the magnetic drain plug. Worth checking. Vehicle was making clunking sounds as described above.

2 people found this helpful.

I had several electronic issues which had no bearing on this issue, except when i replaced the GEM(with a used one from a wrecking yard) I started having issues with my ABS and began hearing CLUNKS in the rear end. Sounded a lot like a u joint going bad. but now that i think about it , the alarm issue. the ABS issue door locks etc all seem to be related to this used GEM. I have read and heard that it needs to be reprogrammed. This might be the case since it came out of a Mercury Mariner. So does the GEM control the rear end and need programming?

90

Sorry, can't help on that. Been some time ago with my problem. the low speed wheel "grabbing" turned out to be the electronic part in the rear yoke that controls the differing speeds of outer and inner tire rotation that occurs when cornering in AWD vehicles.

1 people found this helpful.
130

2018 Ford Escape AWD SEL —Same clunk and bind up during turns. Would take it in— might hear it then might not. Nobody would help. Finally a little shop figured it out. It’s the clutch to the rear differential unit— which wasn’t engaging to allow the outside wheel to rotate faster during a turn. (They unplugged something by the RDU and noise was gone but dashboard had lots of lights on like traction control and hill park assist) repligged it back in - lights were gone but noise back. Took it back to the Ford Dealer and they are replacing the RDU — covered under the power train warranty. I have a photo at home of part and what they unplugged.

13 people found this helpful.

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