My Xterra heats up when I pull a grade, and won't cool once I get off the grade- have to pull over let it cool off. Also boils and dumps coolant to puke tank when I shut the engine off, requiring refilling of radiator. I recently have had radiator and thermostat replaced and a coolant hose replaced that blew on most recent 10 day trip to Norcal. 200K on motor - still runs well otherwise. Ideas???

Maybe waterpump or blown head gasket.

Is there oil in the coolant?

No oil in coolant or coolant in oil. WP & TB changed @ 145K- ish. 205K on the vehicle. Could the AC fan be failing to come on? What conditions made the AC fan kick on? Can't imagine that would afffect temp @ high speed, tho.

Depending on how many times you've "boiled it" over there is damn good chance the head gaskets are blow and the heads are warpped due to overheating.


Next thing to do is to make sure there proper air flow across the condensor and radaitor.

The condensor sits in front of the radaitor, if the condensor fins are plugged up with drit and debris it could cause restrictive air flow to the radaitor which sits just behind it.

Other than that you may have an issue with the fan clutch not enguaging enough to pull more air when needed across the radaitor and condensor

Fan clutch replaced 3 months ago. Will check condenser for clogging. What am I looking at in terms of $ for a head gasket job? 1200? My mechanic changed out the radiator / thermostat 2 weeks ago, as I was loosing coolant and overheating ... whould he not have checked the condensor & fan, and pressure tested the thing for leaks? I suppose it could leak when hot and hold pressure when cold if there's a crack somewhere. I love the wheels, but I've put 2K into this baby in the last 3 months - I guess I'm dreaming thinking I'll get a break!

P.S. - drove 'er around today in 100 plus heat - no problems, but no long hills and no significant cargo load. Noticed when idling @ operating temp. (not overheating) a significant temperature difference between top & bottom rad hoses. Top one - quite warm (not too hot to touch) Bottom - barely warm. Could this indicate a stat problem?

I recently had the same sort of problem. Do you have an engine coolant code popping? I replaced the coolant sensor. Turns out the thermostat was stuck and when I pulled it out there was a bunch of crap built up behind it. Flushed everything out, replace the thermostat, fixed the problem........Mine wasn't over heating, just running a little hotter than normal.

For the record, the top and bottom hoses SHOULD be different temps, as one is the hot water from the hot engine, going into the radiator to be cooled, and, the other is the cooled water going back to the engine.

If they were the same temp, the water is not being cooled (If both warm), or, the water is not going from the (HOT) engine into the radiator, etc. IE: If the engine is COLD enough to not open the thermostat...the hoses could be the same temp...but once the engine NEEDS cooling, the two hoses should get into their "One hot/one cold" routine.