XJ overheats, orange gunk in cooling

[AileniJones]

Just bought a clean 99 with only 102kmi on the clock. Shop has replaced the radiator, cap, and thermostat. Supposedly, it's always looked like this. It will idle forever, electric fan kicks on, a bit later, the needle will suddenly peg and blow coolant from the radiator cap.

Any thoughts would really help. Thank you!

 

[kevman65]

That looks a LOT like the residual after affects of barsleak or something similar. Probably had a radiator leak at one time.

 

[WJCO]

Use a laser to check the coolant temp. See if it's actually overheating or if it's excessive pressure getting into the cooling system. Only gets hot at idle or when driving too?

 

[GP NOIR]

Check for a blown head gasket, warped or cracked head.

 

[AZVAJKU]

Looks like someone mixed coolant types.

 

[Ddays]

Looks like someone mixed coolant types.

What I thought looking at the pics. OAT & HOAT dont play nice together

 

[GP NOIR]

My 4.0 did that when it blew a head gasket

 

[jeeeep]

My 4.0 did that when it blew a head gasket

I thought so as well but it doesn't look milky enough... but then again, the built-in phone filters may have adjusted the colors

 

[RJV]

Definitely looks like some bad coolant mix, I don't see any of the metallic glitter from a stop leak or something, but maybe the phone is filtering that out. How's the fan clutch and water pump? I'd do a coolant flush and make sure the fan clutch and water pump are good too. I know you said the t stat is new, but make sure it's a good one. On my 96 XJ, replacing the stock fan clutch with a new one from NAPA is what finally stopped it from overheating.