D4-7u

My d4 has developed a leak of coolant. set for a year in shed pull it out to work on pony motor and notice anti-freeze weeping out of #2 exhaust. Got pony running today and cranked big motor and saw dripping of oilly like substance, I am pretty sure anti-freeze plus carbon,soot,fuel?. Do I pull head,look for cracks. leave head on and pull pre-combustion chambers? Can a novice spot a bad seal at the chambers? where can I buy a tool to pull Pre-combustion chambers? tractor seemed to be running fine when parked.
Thanks in advance.
Rick

Is the leak perhaps along the head gasket line between the block and head? Those engines use rubber grommets on brass ferrules to seal the coolant and oil passages through the head gasket and sometimes they seep a bit without causing a big problem. The D318 6 cylinder is noted for doing this.

If it's definitely coming out of the port, Have you removed the exhaust manifold to look down the port and see if you can see a source of the coolant like a crack etc.?

Did you notice any coolant in the oil pan. (might need to drain a small amount of oil to check what's in the bottom). What about bubbles in the coolant?

The tool to remove and replace the PC chambers isn't expensive and is available from CAT or aftermarket. Here's a link to an aftermarket set. You may need only the splined tool if you have one piece chambers. If you have the two piece type, you can still remove them with only the splined tool, but you need the other pieces to reinstall them. I don't think anyone still uses 2 piece chambers for replacements, only one piece now.
http://www.mbsmfg.com/caterpillar-precombustion-chember-toolspart5.html
It's easier with the head mounted on the engine still. Drain coolant! You will need a good 3/4" drive breaker bar or ratchet and a cheater bar to turn it though! The chambers are usually very tight and should come loose with a bang. If they don't that may be the root of your leak. A 3/4 drive or bigger impact wrench can take them out sometimes easier than the breaker bar and cheater. If it doesn't screw out easy, go back in and work it back and forth to try and save the threads in the head as much as possible. Once you have it out, inspect the seat and chamber carefully and make sure the surfaces are smooth enough to seal properly. Replace the o-ring seals at the top and then apply anti-seize to the threads before replacing the chambers with a new sealing ring.

Here's a thread about removing the different types of PC chambers, but it has a picture of the tools for your type too.
http://www.acmocbb.org/ACMOC_BB/showthread.php?t=7190&page=3&highlight=precombustion+chamber+tool