liftedcherokee

OK, so hears the deal my 90 xj runs at 150 around town and on the highway (unusually low) but when i go offroad and put the car in 4 wheel drive it skyrockets to up to 260 like today when i was on the beach, any ideas on why it would run fine around town but when its in 4 wheel drive over heats???? btw it was 40 degrees out in NY and still got hot

highmileage

lower speed+higher RPM= heat
check you thermostat, temp sending unit, radiator core, fan clutch...... in the cold weather these things may be broken or clogged and show no signs of failure under normal operation. But when being worked they don't show up at all and wala overheating. or you could have a bad head or head gasket.

liftedcherokee

Thanks, i understand the concept im moving slower and higher rpm's with less wind =Heat, but it just seems to be too hot, also my eletric fan isnt working but i still think even with it working it would still overheat...someone said something about a closed cooling system and i may need a new resevoir tank and cap because it loses pressure is there any truth to that? Thanks for your help this is my DD so any help is awesome!

highmileage

I tried running w/o my electric fan one winter in MO when the temps were down around -10 ish and I was running way hotter than normal, hooked it back up and put a piece of plywood in the grill (worked way better, don't know why?) might need that elec fan working. On the closed cooling system if your bottle isn't leaking and the cap is holding you should be ok. could be air in your system. if your fan clutch is out w/o your elec fan you have no cooling air moving unless the vehicles in motion. just so you know too many trips to 260 the head will crack between the exhaust and intake on the #1, I have had the joy of this (bad thermostat). when being worked in this condition shows the same symptoms as what you are describing.

liftedcherokee

Thank you, i will try and get a new fan or atleast try and get mine going tomorrow and see how she does, unfortuantely she ran at 260 for a little while as i needed to get off the beach quickley to avoid a $1200 towing fee...hopefully the head isnt cracked and the headgasket doesnt blow (fingers crossed) but if she does i got the jeep cheap enough it would pay to fix, how much should a head and a head gasket run me if this is the case...btw she still runs mint and starts right up perfectely

highmileage

Well here's the kick in the pants.... 600.00 from a parts shop, 400 if you get lucky. If you can find a wrecked one a head can be 40 to 150, machining 40 to 60 just for a surface job (no valves). those are prices in KCMO not NYC. but check all of your cooling stuff before throwing in the towel for a head.

cruiser54

If you're running 150* around town, you have a bad thermostat. Should run 195*. You may have other cooling issues as well, but for sure a bad stat.

If the cap on your coolant reservoir/bottle is bad, it will also cause a boil-over. Only use the Napa 703-1396 on your bottle.

liftedcherokee

$600??? is that including labor because i have found some rebuilt heads for $300 and under,and i most deff check will check all of my cooling system later today or tomorrow

highmileage

dude if you need a head and you can get it for 300 jump on it

liftedcherokee

whats so special about the 1396 cap i just picked a cap up from napa today but it wasnt that part number should i return it and get that one?

99 Purple XJ

Before throwing parts at it take the time to figure out whats wrong with it and go from there and where in NY are you located if near me i wouldnt mind giving you a hand fixing it

cruiser54

It has better threads and grips even on an older bottle. It's rated at a higher pressure. It's lower profile and is less likely to contact the underside of the hood when the bottle expands. It's for a Volvo so Napa won't offer it up to you if you don't specifically ask for it by number. Return the one you got.