overheating of a 258
1986cj7
Senior Jeeper
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- Location
- southeast missouri
- Vehicle(s)
- 1986 cj7 258, t-176 4-speed, d-300, moser one piece axle in back in amc 20,G2 4.10 gears front and back, detroit truetac front and back,G2 4340 chromoly front axles in a d-30, 4" rough country lift, 33" tires
I've had this jeep for 4 years and didn't drive much but on back roads and though town. Till the water pump blew a hole in it so I replaced the water pump, i've made sure I have the right pump the v-belt not serpenten belt. Now when i drive it on the interstate for more than 10 miles on the highway it would boil over so i replaced the cap. Still over heated changed out thermostat was stuck open, still overheating checked the thermostat in boiling water 195 opened up at 200. Put all new hoses in they were dry rotted. Still over heats. Flushed out rad and motor and heater coil with stuff you can buy at auto zone. Still overheated. Had rad boiled out still overheats. Had the rad shop check temp differance on top and bottom rad hoses, when hot top was 200 bottom was 160. replaced temp sending unit, it is electrical. No water in oil, or rad. since i replaced the cap it will leak out steam but won't boil over most of the time. Now i've hear to differant stories about rad hose temp diffearance the rad shop said the rad is doing its job. But a mechanic I know said he thinks the rad is still clogged up should only be a diffrance of 20 degress, 30 at most. Now there is a cold spot in the middle of the rad. sides are hot. So who do i belief on the temp differance. could the middle still be clogged but then why is the temp differance so high and still overheating? I know that flow matters the more water flow the better. also put new fan shourd on. No fan clutch fan bolted staight to pulley on water pump. Thought about a high out put water pump not sure yet. This motor has compression of 135-120 when cold with all plugs out,and 145-115 when hot I know the rings are bad cause i have alot of blow-by. Could the motor just be shot the odometer has 189000 on it but when i bought the jeep it had 33" tires on it and 2.73 gears which thew off the miles by 20% did the math. So who knows how many miles it has on it. Will try a new rad shop and see if the can test the flow of the water pump. Don't know if this motor has been mod. could .030 bored over cause this over heating cause this and is there a way to check this out with out taking the head off and messureing the cylinder? Lost and confussed in missouri someone help out of ideas. Oh and last but not least i've changed the gearing from 2.73 to 4.10. Seams to heat up alittle faster now with higher rpms. Sorry for such a long theard just trying to put all the info out as possible. Thanks in advance.