760T Black Coolant

760Towner · Post by **760Towner** » 27 Oct 2009, 02:19

The interior of the coolant reservoir is black. The black material was somewhat greasy but more like a fine black powder. I removed and washed it and filled with 50/50 antifreeze and water solution. Nxt time I checked the liquid was green color but the interior of the reservoir was black again.

I talked to two mechanics:
One said it may be oil from deteriorating head gasket (terrible problem that won't be worth fixing) or may be exhaust or oil from the Turbo (easier to fix and may be worth it)

Another tested the water in the reservoir and ascertained it is not oil or exhaust fumes. He suggested the black powdery residue may be from lining of hoses I recently replaced or "Stop Leak" solution I may have poured in the reservoir months earlier. I plan to flush the system and monitor. I'll let this site know what I find next.

Post by **billofdurham** » 27 Oct 2009, 12:01

This is of interest to all owners so please do keep us updated.

Bill.

DeRail · Post by **DeRail** » 27 Oct 2009, 19:58

If he tested the reservoir for oil contamination, would this cover transmission oil as well? I've heard that the coolant will turn sludgy if your radiator develops an internal leak and the ATF mixes with the coolant. Be sure to check that out because coolant is especially dangerous to your autobox!

As far as the stop leak product, I've heard of people using the home-version which is just throwing black pepper into the cooling system. I wonder if the pre-bought stop leak stuff is of the same consistency once broken down?

-Darrell