Carcrazi07 & beach8's 06 TJ unlimited

**stwilson74** · 07-18-2012, 08:58 AM

Originally Posted by beach8

Anybody got any ideas, this thing won't run below 210 deg, It's got a new radiator (single row stock replacement), water pump (good Bosch replacement with C.I. impeller) and 160 deg. thermostat. using a 16" electric fan. Do they all run this hot all the time, I'm thinking about a 3 row rad to help. I was thinking maybe a weepy head gasket but it doesn't overheat or use any coolant and holds a pressure test for 20 minutes. I'm afraid to take it out on the beach, that's the last place I want to be when it finally decides to get too hot!!

Is it going over 210? As long as it runs at 210 and stays there that is fine, mine has always run at 210 and has over 130,000 miles on it, it should be running anywhere from 205 to 210. That thermostat is way too low temp and may cause you some issues down the road, the computer and engine are set up for a 195 thermostat and your going to start throwing codes if the motor does start running too cool. Is there a good shroud on that fan to make sure your pulling air through the rad? Silly question, is the fan rotating the correct direction? In other words, if its behind the rad is it set up to pull? Make sure you have no air pockets in the system.

**beach8** · 07-18-2012, 02:36 PM

Maybe just slightly over 210, but hasn't overheated, I replaced the rad about 1 year ago because the top tank exploded, then it did the same thing last month and the store warrantied the rad but still never overheated, I went to a 13 PSI cap to keep the tank from exploding. (I've read somewhere that this is not that an uncommon problem) just uncomfortable with 210, It has a 16" electric fan with a variable speed controller that is working properly, blade rotation is correct, no air pockets and great flow thru the rad (as viewed through the open cap), just think that the rad could/should have more cooling capacity, the fans run all the time unless it sits at idle for a while, then they begin to cycle normally. I understand that its hot out so that doesn't help, once I get the cooling capacity right and the fan cycles normally I'll go back to a 180 or 195 stat so it won't throw codes. I just want to rule out blown head gasket/cracked cyl. head before I go to a two or three row rad. the good pressure test leads me to believe that there aren't any sealing problems with the engine, just needs more cooling capacity. what do you think or am I just being overcautious

**stwilson74** · 07-18-2012, 07:08 PM

I'd do compression tests and as long as those are good and the cooling system pressure test come back good I wouldn't worry too much and I'd keep the cooling system stuff, including rad cap and thermostat, stock. The higher pressure rad cap increases the boiling point of the coolant allowing it to circulate properly and provide cooling... once it boils your screwed.

**beach8** · 07-18-2012, 08:23 PM

yeah. I only went to the 13 psi cap instead of the 18 psi to keep the rad from exploding the top tank again, I heard it's not that uncommon on the plastic tanks on TJ's, maybe because of the odd shape of the tank makes for a weak area?? both times it's happened, it split in exactly the same place on the tank, the rest of the cooling system checks out OK and all cylinders are within 15 psi of each other, so that OK. the engine runs just fine in all other aspects

**Goonies.nsd** · 07-18-2012, 11:03 PM

The plastic tanks do suck. But a low psi cap can cause it to push coolant out when it shouldnt. If it calls for 16 or 18. You should run what it calls for. And like stwilson mentioned. 210 is normal. The sensors in the 4.0s are in the thermostat housing and is in the highest spot in the coolant system and near the hottest spot of the head. So 210 is not unusual. 220 is not unheard of when running A/C and the 90 degree days we have been having. Once it starts creeping over 220 than it a little to hot and time to turn off the A/C. Or turn the heat on. And about your concerns about the plastic side tank radiator. They do suck and dont last forever. The plastic and aluminum like to swell at different temps and eventually leak. But your more likely to have them fail from vibration or hard wheeling. They dont like the vibes. otherwise there OK.