overheating of a 258

[1986cj7]

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.

 

[JR74CJ5]

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 measuring the cylinder?

Possible...

May need to put a larger Radiator in, or new radiator (if clogged) How does the radiator look? Are all the "fins" looking good and not flattened out blocking air flow?

At high RPM's the motor obviously is working harder, but at higher speeds, the air should be moving better through the radiator.

I have seen some posts talking about venting the motor area with hood louvers, winches blocking airflow, etc.

Sounds like you have tried quite a lot of things though, may just need to do some out of the box thinking / upgrades.

The gearing may help as it would lower your RPM's I believe...

Good Luck man,
~ JR

 

[Old Dog]

If I'm reading the first couple line right it didn't start overheating till you changer the water pump.? If thats the case I'd say you got a bad pump.

 

[Petescj]

If I'm reading the first couple line right it didn't start overheating till you changer the water pump.? If thats the case I'd say you got a bad pump.

Agreed. Just cause its new , or most likely remanufactured ,doesnt mean it works. If it started overheating right away and that was the only thing that changed well?? One other thing I can think of is does it have a fan shroud? If not it really should.

 

[CjDan]

maybe something is wrong with your gauge or the wiring???

 

[IOPort51]

I would swap the pump. any chance you got the stat in backwards?? I have to ask.
something changed when you lost the pump.

 

[1986cj7]

This is the problem I really didn't drive it much but on weekends and on backroads really never ran on highway speeds much till pump ate the bigone so not sure if this was a problem that was there to begin with. I bought the jeep in january here in missouri and didn't get hot cause of the cold. This rad has been boiled out but who knows how well. The rad shop said it had 5 gals a min of flow. I've been told that the 4cylinder and 6 cylinder ueses the same rad. Now it is a two core cap in the middle, not the hd 3core cap on the drivers side. Also not sure of the motor if it has mods, the guy I bought it from said he really only used it to drive in the woods and cut firewood, and he bought it from the original owner. I'm going to have a differant rad shop one that I was referred to not just one out of the yellow pages. Take a look and see if they can do a flow test of the pump and whole system.

 

[1986cj7]

Well I've had 3 differant thremos in at with spring and pellet to the motor, the 195 seemed to work the best it is also the oem. What I have founded out is that some or most of rad shops just boil out the rad. Some shops do what is rodding the rad by taking the rad apart and running a cleaning rod though the tubes. This shop I am now dealing with this is the process they use. He also said that if the rad was not salvage able being that maybe there are to many leakes from the cleaning of the tubes, and better or cheaper to get a new rad he wouldn't charge for the cleaning. This may sound like he's just trying to sell new rads but he gave me the prices of the new rads. I guess the morale of the story is to get as much info as possible and referances on the work of the shop and not just let your fingers do the walking in the yellow pages anyone and get in there. But a good rep is what you need to look for. So after this process is done which this shop should have done by Monday after i take it out and give it to them. I guess we'll see. LIVE AND LEARN I GUESS!!!!!!!!

 

[littleriverrat1]

I am inclined to go along with Old Dog and Pete on this, Depending on where you got your new pump, getting a lemon at the parts store is NOT uncommon. The other issue that sticks in my mind is how hot did it get? While compression and no water in oil are good signs it is also common to develop a HD Gasket leak that result in exhaust gases leaking into your water jacket thus causing a pressure problem that will lower your cooling efficiancy. Might let her get up to OP temp, with the cap off and see if your "Blowing bubbles.

 

[1986cj7]

I am inclined to go along with Old Dog and Pete on this, Depending on where you got your new pump, getting a lemon at the parts store is NOT uncommon. The other issue that sticks in my mind is how hot did it get? While compression and no water in oil are good signs it is also common to develop a HD Gasket leak that result in exhaust gases leaking into your water jacket thus causing a pressure problem that will lower your cooling efficiancy. Might let her get up to OP temp, with the cap off and see if your "Blowing bubbles.

I've have done this add dont see any bubbles being blown in the water when I say water I mean water have had this thing apart so many times could do in my sleep by now lol. This pump is new not refurbished but new parts can fail out of the box like you say and if the rodding out doesn't work I will try a new pump there only about $40 so Its cheap and worth a shot. Well it needed everything else done anyway so we will see thanks for all the input.

 

[littleriverrat1]

Be sure to keep us updated and lets know where the "FIX" takes place. I'm a sucker for info and advice, sense they're most times free and can be put in a vault for future use.

 

[1986cj7]

I've got the rad back from the shop and they said the middle was clogged with junk. This could explain the reason the middle of the rad was cool to the touch but outside was hot just a troubleshooting aid in future. So this will hopefully fix the overheating issue. Will be putting on the rad today after a funneral. Will see how it runs. The process of rodding sounds to be better then just boiling. This process at this shop was also cheapr then boiling out buy $5 even though they had to take the rad apart. In the future this is the way to go. Also getting refferances form mechanics helps with the rep of a shop.

 

[1986cj7]

Well after all this is turns out that the rad was the problem even after being boiled out it still had a bunch of build up in the middle of the rad. Causing the rad to only be using the outside edges to try and cool the whole motor. Lession learned depending on how old your rad or condition its in check on a process called rodding that involves taking the rad apart and running cleaning rods down the tubes to completely clean the tubes of build up. This process was even cheaper then boiling out the rad by $5 go figure. I also recommend getting refereances on a shops rep if possible also this is usefull info. Most of you out there probablly know all this. I had to learn the hard way. Hope this is good info for others. One last thing I learned was that the buildup of white junk is called sodder bloom it is corosion bettewen the sodder of the rad and coolant.

 

[littleriverrat1]

Good deal Man! Glad to know your back up and running "Cool" again. And thanks for posting your fix. I'm sure that CJ is ready to be back on the road, nobody likes being stuck, much less stuck in the Shop!