Scotty16

Took my XJ to the shop for a few things (no start and a leaky intake manifold gasket....not the cooling system) Apparently they tested the water mixture in my resivoir and said it was dirty so they flushed it and put a cleaner in...now they're like "it overheats at idle." Any ideas?? Temp was fine before they flushed and "cleaned"

Mendax13

i hope they didnt charge you for the flush since you didn't ask them to do it.

water pump bad?
t-stat bad?
clog?

djb383

Wouldn't a shop have an idea? Maybe find a new shop?

peep

I'd have concerns about what was authorized by yourself to service and what was done with out your consent. Next what is the cleaner? Deposits in cooling system are often calcium based and can require a caustic to clean out. What process was performed, what steps did they take. If you are sure no heat issues prior you could talk to them about what responsibility they intend to take if the cleaning process is suspect or performed incorrectly. The overheat at idle seems to lead to inefficiency of the rad. At idle the flow of fluid is less from the water pump, efficiency of a good rad compensates for low flow at idle as the coollant is within the rad longer and bleeds off more heat, if the rad is partially clogged not enough heat is being removed from the coolant. At higher rpm the fluid is in the rad for less time but returns to the rad sooner as more volume is being moved in a given time. To me the rad is more suspect than the pump or thermostat. Do you have confidence in the system components or knowledge of their condition. Still some concerns about unauthorized work. Talk it over with the shop. What do they think. Then take all the info you konw and make a decision.

Xj88

What yr is your xj?

tjwalker

A bad "fan clutch" is a very common cause of overheating at IDLE.

djb383

We know it went to a shop but we don't know what they really said.......at least from the way the op is worded.