BLUF: Knowing the difference between leaking and misting shocks will save your unit a lot of money.
Photo by Cpl. Michael Curvin
Damaged or leaky shock absorbers on your M-ATV MRAP make the vehicle NMC; however, it’s common to mistake “misting” for a leak.
Misting causes a thin film of oil on the outer surface of the shock. It isn’t considered a leak—it’s part of normal operations. PMCS Item 1 in WP 0060-12 of TM 9-2355-335-10 (Jan 22) clearly spells that out.
Oil film on shock absorber’s normal
You can blow through a lot of money needlessly replacing shocks for a leak that isn’t a leak. A front shock, NSN 2510-01-593-2843, costs just over $4,100. A single rear shock, NSN 2510-01-610-9572, is just under $4,400. Check carefully before deciding your vehicle needs new shocks.
If you’re still unsure whether the shock is leaking, notify your mechanic. He’ll check the nitrogen pressure using the shock absorber replacement (M16003) procedures in TM 9-2355-335-23&P in IETM EM 0426 (Jan 22). If the nitrogen level is too low and the shock isn’t performing well, he’ll install a new one.
If your mechanic decides not to replace the shock, he’ll need to record the current nitrogen pressure and then refill it to the required pressure listed in the IETM’S shock absorber replacement (M16003) guidance. At the next scheduled maintenance, he’ll need to reevaluate the shock to determine if it needs replacing.