RobiHeat

It happened a few weeks ago. I was pulling my 2001 XJ into the garage and on shutdown, it puked coolant out from the radiator cap. Not good I thought. After waiting a little bit for the Jeep to cool down, I take of the cap to investigate. Coolant looks a little low and there is some brown sludge under the cap. Check oil at dipstick and oil fill, looks good. No milky residue or froth. Check resevoir, very very low. Almost nonexistent low. Also, the coolant at resevoir and at radiator fill neck is brownish. Could be rust or oil mixing. So I make a few calls to my buddies and have them look at it to see what their opinions were. After some talking we ended up overhauling the cooling system that weekend.

Drained coolant and did simple flush with water. Replaced upper and lower radiator hoses. The lower one with the spring had lots of rusting going on. Dropped in new radiator. Replaced heater hoses, inlet and outlet both had small flecks of rust in them. Removed waterpump. Woah. The impeller blades had all but rusted away. Could be the problem right there. Bolted new waterpump on. Fan clutch seemed okay, however, bought new one from NAPA and replaced it anyways for ****s and giggles. The hose connecting the resevoir to the radiator fill neck was totally plugged. I had to impale the sucker with a clothes hanger to loosen the rust particles. Gobs of the stuff came out Replaced t-stat.

Filled her back up with 50/50 green and start her up without the rad cap engaged. I hooked a Scangauge II to get second by second coolant temp updates. Around 175 she starts pushing coolant out the radiator fill neck. And at around 195 the t-stat opens and coolant starts flowing. Filled her back up and let her run for ten minutes. Shut her down. Reapeat process after she cools down. Everytime she pushes coolant out the neck. Oh and I replaced the rad cap for a new Stant 16psi from NAPA. Ended up driving her around for 20 minutes and she held staedy at 200 degrees. Figured it a job well done. Until morning came around.

Wake up and go and check the coolant one last time. Coolant in resevoir dropped and have a small leak under the Jeep. Check under the cap, still to the top. So I fill the resevoir back up and start her up. She still pushes coolant out the neck and then drops when t-stat opens. Let her run for about 20minutes and an air bubble surfaces. ****. I hit the throttle cable and the coolant sucks down but when the throttle is released a few bubbles come up. Great. So to make my long story a little shorter, I end up taking the Jeep to a reputable garage for a suspect cracked head or blown head gasket. He runs a compression test. Finds nothing. Pulls the valve cover off, no cracks visible anywhere. Runs a leakdown test on all cylinders twice, everything tests good. Motor looks and runs good. He does a chemical rad flush and a **** ton of brown gunk comes out of the system. He said after that he ran the Jeep around on pure water and then replaced with coolant. Said he was going to take the Jeep for another test run and would get the Jeep back to me. Never happened.

He calls me up and says after he replaced the the water for coolant she started overheating. About 240 degrees. So he ends up flushing again and again more brown stuff comes out with the flush. I believe he kept flushing and more and more stuff kept coming out. He is pretty positive I may have a blocked passage in the block somewhere. I asked again about having a cracked head and he swears the head isn't cracked. So, he is going to take the jeep apart and doubly make sure there isn't brown stuff anywhere. That includes pulling the cylinder head off and getting straight into the block. My question, finally!, is since the head is coming off anyways should I go ahead and take it to a machine shop and get it magnafluxed and check for straightness or shoild I take his word for it that the head isnt cracked? Thanks for reading.

Firestorm500

Obviously the cooling system was never serviced. You have a tremendous amount of buildup in there.

Before pulling the head, I think I would keep flushing with water and then draining. When it runs pretty clean, cap it off and drive it normally. If it still overheats, or the water level drops, start checking for combustion gasses in the coolant.