Overheating problem on a 1988 cherokee with a 4.0 inline v-6

[nxm10]

The problem im having is my jeep keeps overheating pretty quickly either driving or sitting in traffic it has both an electric fan and a mechcanical fan. I replaced the Radiator last year, the Water pump, the Reservoir, Radiator Cap, Freezplug, Flushed the radiator, Flushed the heator core, Flushed the whole cooling system. Theres NO thermostat installed, and all of the hoses are clean and theres NO white smoke coming out of the exhaust and i also checked the oil and spark plugs and coolant and theres no signs at all of a blown head gasket.
Any ideas or help would be appreciated.

Thanks

[fredjacksonsan]

How quickly is it overheating? You said pretty quickly...are we talking 2 minutes or 15? Is there any bubbling?

First thing I'd try is a thermostat. Cooling tolerances are tight on this model, and keeping the water in the radiator a bit longer could help.



(apologies for initial post, missed the new radiator)

[nxm10]

Originally Posted by fredjacksonsan

How quickly is it overheating? You said pretty quickly...are we talking 2 minutes or 15? Is there any bubbling?

First thing I'd try is a thermostat. Cooling tolerances are tight on this model, and keeping the water in the radiator a bit longer could help.



(apologies for initial post, missed the new radiator)

It starts to overheat within about 5 or 10 minutes and sometimes it takes 15 or 20 minutes. Yea it boils over when it overheats. I took the thermostat out to get maximum coolant flow.

[inafogg]

It starts to overheat within about 5 or 10 minutes
thats way to fast,was all the repairs done to correct the O/H problem??
i know you are sure its not a h/g but... unless its an air bleed problem.
have you pressure tested the system,done a leak down??

[nxm10]

Originally Posted by inafogg

It starts to overheat within about 5 or 10 minutes
thats way to fast,was all the repairs done to correct the O/H problem??
i know you are sure its not a h/g but... unless its an air bleed problem.
have you pressure tested the system,done a leak down??

I have done everything i can think of to correct the overheating prob but everything i've done so far was to correct it. Im not sure what a air bleed problem is? I haven't pressure tested the system yet im also not sure what a a leak down is?

[Saudade]

First, taking out the thermostat is a bad thing. It regulates the *lowest* temp the engine coolant runs at and, unless stuck/blocked, has nothing to do with overheating.

If you are *certain* everything else is good, you may wish to take a close look at the coolant bottle and cap.

Renix era engines (Inline is not a V-6, it's an I-6) use a closed system and pressure must be maintained in the bottle on the firewall. Any pressure leak can result in boil over. You said rad cap but I'm assuming you mean the one on the plastic bottle. Aftermarket ones are crap. Get one from a dealer.

If you've mod'ed your system, you should explain what you've done.

Once you've verified all cooling components are good, your problem lies elsewhere.

[nxm10]

Originally Posted by Saudade

First, taking out the thermostat is a bad thing. It regulates the *lowest* temp the engine coolant runs at and, unless stuck/blocked, has nothing to do with overheating.

If you are *certain* everything else is good, you may wish to take a close look at the coolant bottle and cap.

Renix era engines (Inline is not a V-6, it's an I-6) use a closed system and pressure must be maintained in the bottle on the firewall. Any pressure leak can result in boil over. You said rad cap but I'm assuming you mean the one on the plastic bottle. Aftermarket ones are crap. Get one from a dealer.

If you've mod'ed your system, you should explain what you've done.

Once you've verified all cooling components are good, your problem lies elsewhere.

The coolant bottle and cap are new, There are no mods to the system. There is no shroud around the fan not sure if that affects anything at all?

[inafogg]

yes,the shroud is important,it directs the air inward to the
fan(its sucked in by the fan)no shroud no air beening directed

[denisond3]

While I agree the fan shroud should be there, and the thermostat should be in it, I think the lack of a fan shroud would have no affect once the car was travelling down the road at anything over 35-40 mph. I know what a 93 with the inline six looks like under the hood, but not an 88. Is it possible the radiator fan is the wrong one for the car? Radiator fans can run in either direction, depending whether its driven by the front or the back side of a serpentine belt. If the fan is meant to be a counter-rotating one, but is the normal-rotating one - it will not pull any air through the radiator.
I would also wonder if there is good air flow through the a.c. condenser in front of the radiator, or is it clogged up with insects and leaf bits?
If there was a headgasket starting to leak, it could be pumping hot gases into the water jacket. This would overpressure the radiator cap, and push water out of the system. It wouldnt necessarily result in white smoke out the tailpipe, or 'muck' showing up on the dipstick. After a little while it would have resulted in the water level in the head being low enough that the water pump wouldnt be circulating coolant properly. This would also happen if there was a crack in the head.
A compression test might be in order.