I have a 1987 Merc. Colony Park with the 5.0L V8 with 120k miles.
This problem seems to be getting worse over the last four years.
The cooling system has a rusty looking muddy sludge in it.
Recently, I was going to change the head gaskets, but in the process of
tearing down the accessory stuff I found that the water pump was not
very good. Went deeper and found the timing chain was shot. Fixed
that and found the freeze plugs shot. Fixed that. The dealer told me
that the head gaskets should not need changing, so I put the thing back
together with new belts and hoses.
That was two weeks ago and I completely flushed cooling system, too.
Looked in the radiator and found more "muddy sludge". I mean this
stuff looks like butterscotch pudding!
Anybody know what is causing this?