Drive chain plus three shaft seals for the Mercedes 4MATIC transfer case on ML, GL, GLE and R-Class, the fix for the classic grinding and 4MATIC codes.
A Mercedes ML350, GL450 or R350 that makes a loud ratcheting or grinding noise under acceleration, clunks on takeoff, or lights up 4MATIC and ESP warnings usually has a stretched chain in the single-speed transfer case. This kit puts a new drive chain and three new shaft seals into that case, replacing chain reference 1642820182 and cross-referencing the 251 280 xx 00 transfer case family, so a case with good sprockets and bearings can go back in service instead of being replaced.
On the W164 ML, X164 GL and W251 R-Class, the transfer case bolts to the back of the automatic and splits torque to the rear propshaft and the front propshaft. The rear output runs straight through; the front output is driven by a chain that wraps the main sprocket and a lower sprocket on the front output shaft. That chain carries every bit of torque that goes to the front axle, and there is no tensioner. As the pins and link holes wear, the chain grows longer, slaps the plastic guide, and finally rides up over a sprocket tooth. That jump is the ratchet you hear. Owners on MBWorld describe it as loud enough to feel, first under hard throttle and later under light throttle as the wear gets worse.
The three shaft seals keep the small fluid fill in the case. A case that has been weeping fluid runs the chain and bearings hotter and wears them faster, so the seals belong in the same job.
Rule out the transmission and the propshafts first. A worn center support bearing or front shaft joint can also clunk, and our 722.9 common problems guide covers transmission complaints that get blamed on the transfer case and the reverse. Drain the transfer case and check the magnet, then look for fluid at the case seam rather than at the transmission pan; our 722.9 leak guide shows where the transmission itself leaks. If the noise is the classic chain skip, the chain is the part that has failed.
The listing covers 4MATIC ML350, ML500, ML550 and ML63; GL450 and GL550; GLE350, GLE400 and GLE43; GLS450; and R350, across the W164 ML, X164 GL, W251 R-Class and the later W166 and X166 bodies. It replaces chain 1642820182 and 1642820082 and lists transfer case numbers 2512801800, 2512800700, 2512801200, 2512802700 and 2512803100, with seals 0149971346 and 0169973646. Read the number on your transfer case tag and match it to that list before ordering. It fits the single-speed case only; GL models built outside the US with the two-speed off-road package use a different case. For a 2003-up W163 ML, see our HV-091 transfer case chain, which lists that body.
If the front shaft joint is worn, pair the job with a W164 and X164 front driveshaft or a center support bearing while the propshafts are already down.
| Replaces | 1642820182, 1642820082, 2512801800, 2512800700, 2512801200, 2512802700, 2512803100 |
| Seals | 0149971346, 0169973646 |
| Includes | Transfer case drive chain, 3 shaft seals |
| Fits | Mercedes-Benz W164 ML, X164 GL, W251 R-Class, W166 ML/GLE, X166 GL/GLS 4MATIC |
| Weight | 4.91 lb |
| Condition | New |
The single-speed 4MATIC case used on W164 ML, X164 GL, W251 R-Class and the later W166 and X166 ML, GL, GLE and GLS. Match the number on your case tag to the cross-reference list: 2512801800, 2512800700, 2512801200, 2512802700 or 2512803100.
A ratcheting or grinding noise from the center of the vehicle, first under hard acceleration and then under lighter throttle as the chain gets longer. Many owners also notice a clunk on takeoff and 4MATIC or ESP warnings.
Only if they are worn. Check the teeth for hooking or sharp, thinned tips and look at the plastic chain guide. If the chain was skipping for a long time, the sprockets and guide often show damage and should be replaced with the chain.
No. With the rear propshaft unbolted, the rear case half comes off underneath the vehicle and the chain and sprockets lift out together. Plan on a lift and the correct sealant for the case seam.
The case has its own fill, separate from the transmission. Use the Mercedes-approved fluid listed for your transfer case and fill to the fill plug, not the transmission dipstick tube.
