High speed over heating

I have a 90 xj with4.0 it has an automatic. At high speeds or when roping in the mud. the temprature tends to get fairly high. I cant remember exactly how hot but fairly close to the dangerous end of the guage. When at normal speed (70)and idle the temp never moves above normal. Im currently in Iraq so i have no acces to my truck, or any way of communicating with the auto shop. Is there possably a way to make the aux fan turn on when the temp gets high. Also the engine has less than 75,000 miles on a rebuild.

When at high speeds, the fans do next to nothing compared to the air forced through the radiator by the forward velocity of the vehicle. Sounds like a clogged radiator.

When romping in the mud, I would expect the temps to climb. You can rig a manual switch to turn on your aux fan. There are several threads that explain how this is done. A quick search should turn them up.

RR3

Ralph said:

When at high speeds, the fans do next to nothing compared to the air forced through the radiator by the forward velocity of the vehicle. Sounds like a clogged radiator.

When romping in the mud, I would expect the temps to climb. You can rig a manual switch to turn on your aux fan. There are several threads that explain how this is done. A quick search should turn them up.

RR3

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Hey thanks alot that was fast.
Ryan

Jeepin_rebel said:

Hey thanks alot that was fast.
Ryan

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Yeah, the general "rule of thumb" is if it runs hotter on the highway, its a waterpump or coolant flow issue. I just had the same problem on my Honda. Ran just fine in town, got hot on the highway.

IE: at highway speeds, the car is making more heat and should be circulating the coolant to compensate for it. If the flow is disrupted by a clog, corrosion, or weak waterpump..............it will run hot.

I would also suggest doing a presure test on it when you can. A leaking head gasket can cause high speed heating.

I´ve taken radiators out for whatever. Looked clean from the outside, washing them of the vehicle, without the A/C condensor in the way. I`ve gotten an amazing amount of crude out of there. Especially mud, between the rows, hard to see.
Clogged radiator (inside or outside), air (or exhaust gases) trapped in the hoses or block, spring slipping in the bottom radiator hose and allowing the pump to suck it flat. Have all caused me problems in the past. Overheating at high speeds, can also be an indicator of a lean burning motor. Not enough fuel,or to hot of a plug, can cause some serious damage, fairly quickly. Can heat up your motor considerably. Bone white plugs, sometimes blistering, can be an indicator of lean burn. A good running XJ, burns pretty lean anyway (at highway speeds), sometimes hard to tell, if it´s too lean, until it´s too late (sindged valves or piston). No speed limits here, tempting to overdo it sometimes.

I looked at the plugs when i changed them right befor i got deplioed and saw nothing out of the norm. However the thought never crossed my mind about the hoses colapsing. I have no idea why i didnt think of that. Im also going to look into having the radiator dipped. Hopefully that will clear up my problem. Again thx for all the help

Ryan