Help with my cooling issues

This is my dd jeep
Specs: 1996 4.0 lifted 4.10s auto.

It used to cool awesome with a decent AC but that all changed when the stock plastic radiator started to leak.

I decided to replace it with an old stock radiator I had laying around. I opted to go ahead and replace the exhaust manifold at the same since it has been cracked for sometime.

After I pull the manifolds I notice that one of the freeze plugs was leaking so I opted to replace all 5 on the side with new brass plugs. I also deep cleaned my intake manifold as it was very nasty. Also added a throttle body spacer that I had laying around.

Put a new 190 degree thermostat. Water pump was replaced 2 years ago.

I bypass my radiator with an external tranny cooler. I placed it in front of the mechanical fan side.

Now that all of that is replaced I'm having serious cooling problems. Just cruising around town Jeep stays right above 210 with the AC off and air temp is 90s. Run the AC at all and it will overheat.

Cruise interstate with AC off it goes right at 210 sometimes right below. If I turn AC on at all it approaches 260 very fast.

Took a recent trip to Nashville up the interstate with the AC off it never really got above 210 but as soon as I stopped to fuel up after driving 70mph for 2 hours I noticed the overflow bottle slowly boiling over. Odd....


Could it be the fan clutch? Is a zj clutch worth it? Will it rob lots of power?

Is it okay to have the cooler in front of the mechanical fan? Should it be in front of the electric fan?

Should I ditch the used radiator and go with a new one? Don't want to spend the money on a 3 row so I'm thinking the all metal 2 row from Napa. This jeep won't be around long...

Cliff notes for those that don't like a long read.

Replaced:
Cracked radiator with spare used stock radiator
Thermostat with 190
Freeze plugs with new brass ones
Exhaust manifold
Added tranny cooler infront of mechanical fan and bypassed radiator.

Might have air trapped, mine did almost the same thing.

You should have the single write temp sender in the back of the head.
Park it on a hill with the ass uphill, take rad cap off and pull the temp sender, coolant will come out pretty quick. This should get any air out.

Yes I have both temp sensors thermostat housing and the sensor on the head.. What is the purpose of the one on the head if I have the one on the housing?

Head one is for the gauge.

*89Laredo* said:

Might have air trapped, mine did almost the same thing.

You should have the single write temp sender in the back of the head.
Park it on a hill with the ass uphill, take rad cap off and pull the temp sender, coolant will come out pretty quick. This should get any air out.

Click to expand...

Wouldn't coolant just come out of the radiator and be replaced with air coming in through the temp sender hole?

No
I've personally done it.

Coolant will come out with quite a bit of force with 2 gallons and the force of gravity behind it.
You don't need a huge hill, just have the rear a couple inches higher than front.

*89Laredo* said:

No
I've personally done it.

Coolant will come out with quite a bit of force with 2 gallons and the force of gravity behind it.
You don't need a huge hill, just have the rear a couple inches higher than front.

Click to expand...

Hmm thanks. I'll try that tonight.

Fan clutch would help more at low speeds. You either have air in the system or that old radiator is clogged

256offroad said:

This is my dd jeep
Specs: 1996 4.0 lifted 4.10s auto.


Replaced:
Cracked radiator with spare used stock radiator

Click to expand...

Why did you have a spare used one? (I know why i do, it was changed out cause it was old and bad)

Is it clean or plugged?

scottmcneal said:

Why did you have a spare used one? (I know why i do, it was changed out cause it was old and bad)

Is it clean or plugged?

Click to expand...

I parted my old wheeling rig and it worked fine in that jeep.

bled some more air out of the system. When I got home and put a fan on the motor to help cool it down I came back out after dinner and both radiator hoses were flat as a board. so i check the overflow hose for blockages and found a huge peice of plastic blocking the hose. got that out and replaced the radiator cap.

still no change in the cooling system.

I plan on replacing the radiator with an all metal 2 core as well as a zj fan clutch.

256offroad said:

bled some more air out of the system. When I got home and put a fan on the motor to help cool it down I came back out after dinner and both radiator hoses were flat as a board. so i check the overflow hose for blockages and found a huge peice of plastic blocking the hose. got that out and replaced the radiator cap.

still no change in the cooling system.

I plan on replacing the radiator with an all metal 2 core as well as a zj fan clutch.

Click to expand...

change the radiator....ones that come out of my wheeling rigs typically have tons of junk in them.


the air bubbles shouldn't be a huge issue, theyll work their way out after a week or so just keep filling it up when its cold.

tranny cooler shouldnt be a huge deal, as long as its not covering a huge area.

checked the waterpump yet? they become pretty inefficient with very little bearing play or leak through the bearing housing. you could boil the thermostat too to ensure proper opening.

are you losing coolant at all? or just when it boils out.

shortxjdoug said:

change the radiator....ones that come out of my wheeling rigs typically have tons of junk in them.


the air bubbles shouldn't be a huge issue, theyll work their way out after a week or so just keep filling it up when its cold.

tranny cooler shouldnt be a huge deal, as long as its not covering a huge area.

checked the waterpump yet? they become pretty inefficient with very little bearing play or leak through the bearing housing. you could boil the thermostat too to ensure proper opening.

are you losing coolant at all? or just when it boils out.

Click to expand...

Yeah I'm figuring it may be the radiator. That old wheeling rig was pretty nasty and abused.

I'm only losing coolant when it boiled.

I'm hoping to swap the radiator out and fan clutch tomorrow.

is it better to replace the mech. fan with a dual electric one? just wondering

I replaced the water pump, new thermostat, new cap, added a trans cooler with fan away from radiator, burped, and still get 220 230 temps! Any other suggestions? I di get a ZJ fan and clutch which I'll mount soon!

Boss Cherokee said:

I replaced the water pump, new thermostat, new cap, added a trans cooler with fan away from radiator, burped, and still get 220 230 temps! Any other suggestions? I di get a ZJ fan and clutch which I'll mount soon!

Click to expand...

Yeah, check your sender...went through the same thing and turns out my parts store sending unit was way off.

Bought a factory (dealer) part and all is within spec....infrared (sp?) is an invaluable diagnostic tool!

Hans

Oatmeal said:

Yeah, check your sender...went through the same thing and turns out my parts store sending unit was way off.

Bought a factory (dealer) part and all is within spec....infrared (sp?) is an invaluable diagnostic tool!

Hans

Click to expand...

Is it a cheapie Harbor Freight infrared sensor? If so I may pick one up if it works well for you!

Boss Cherokee said:

Is it a cheapie Harbor Freight infrared sensor? If so I may pick one up if it works well for you!

Click to expand...

Yep, it's not a bad little unit.

Check their circulars for sales....got mine on sale plus 20% off with one of their coupons

You know what really sucked, though....all the times I would shut off the AC and turn on the heater to keep it from overheating, only to find out it was fine the whole time!

Hans

Oatmeal said:

Yep, it's not a bad little unit.

Check their circulars for sales....got mine on sale plus 20% off with one of their coupons

You know what really sucked, though....all the times I would shut off the AC and turn on the heater to keep it from overheating, only to find out it was fine the whole time!

Hans

Click to expand...

I caught my self doing the same thing a few days ago!!