I've got my radiator woes solved, but before I install the new radiator I want to flush the block of crap. When I removed the old radiator, the hoses had your basic mud mixture in them. I don't think there was much water in the cooling system.

So I intend to flush the block. Many blocks contain a block drain plug, to allow coolant to be drained when changed. I'm not finding one on my XJ 4.0. I'd really like to run a hose of fresh water thru the system to clean out as much crud as I can before I install (and foul up) a new radiator.

Is there a block coolant drain plug? Can anybody clue me in to it's location?

 

I know the earlier blocks had a coolant drain plug behind the exhaust collector-ish, it took an 8m/m square drive (which can be easily fabricated from an 8m/m or 5/16" hex key, as I've explained before.)

The plug may be threaded 3/8" NPT - I haven't been able to confirm this. If it is, it may be replaced with a standard hardware store part - which will have a protruding square drive (probably 3/8") or a recessed square drive (definitely 3/8".) The recessed drive will accept the drive nub of a 3/8" socket wrench readily - the protruding wrenching head is square, and you'll want an open end wrench or a crescent to remove it.

 

Does "earlier" include 98'? The parts catalog doesn't list a plug for the block for this year, which I find odd. I'll look down there, but I can't recall seeing one, which has me befuddled. Thanks.