okay let me start with the list of new parts:

thermostat (stant premium 195, drilled, hole at 12 o'clock) and housing
hoses (lower hose is NOT collapsing, if anything, its got a little bit of pressure in it)
radiator cap
water pump
radiator (advance auto parts)
temp sender for the gauge
fan clutch
serp belt
installed a fan shroud (didn't have one when i bought it)
electric fan works
rear hood lift
hood blanket removed
cat removed, running a strait pipe into a glass pack (sounds great, plenty of power)
cleaned overflow bottle and hose
Po did a full tune up
i installed a K&N panel into the factor box and i cleaned the TB
sea foamed the crankcase and intake and gas tank
fresh 10w30 rotella triple protection conventional, half a quart of lucas oil treatment, oversized motorcraft filter
trans fluid drained in at the plug and refilled, shifts perfectly
no brakes dragging
ujoints are in great shape, no binding. i can roll the jeep on flat ground in N by hand with ease.

jeep has just under 200k, and runs great, good oil pressure and runs smooth and quiet


okay, my jeep runs fairly consistently at 210 according the the gauge, which i believe to be accurate within a few degrees. on the highway it runs a little warm, sometimes 215, but usually 210. when parked (in traffic or in a drive through) temps slowly climb but i haven't sat in traffic long enough for them to climb passed 215-220 ish. when i slow down to get off an exit from the highway, temps go up to 215-220 ish. under hard acceleration, temps drop to 200 or so, then when i let off the gas to come down to the legal speed, temps climb back up to 215-220, then slowly drop back to 210ish after a mile or so.

I'm trying to get my temps more stable before the summer heat wave comes, and id like to see them a little lower that 210 if anything, not above. any suggestions?

 

I wanted to add, I flushed the system twice as well, and also filled 50/50 with green coolant. Planning to ad water wetter too.

 

Just curious but is your engine covered in grease from past or present oil leaks? Dual fans?

 

Also, 220 isn't absolutely horrible either, yes the water will boil off but I wouldn't think it'd overheat in that range.

If you want to be sure if your gauge is accurate you can find a temp gun and use that to compare the reading the what the gauge says. Who knows, the gauge may just be registering off even with a new sending unit and such.

 

I would not have drilled the thermostat. But that's minor.

Your head might have a hidden crack in it. My '92 still did the very same thing after I did all you did. Still did it after a professional total engine rebuild.

Head came back off. I junked it and had another used one rebuilt.

Problem solved.

 

Head gaskets can also cause weird temperature problems.

In some cases can test good cold but open up when hot.

I've even had engines with a blown head gasket leaking externally and internally, and a cracked head, and the engine ran great. Replaced the head and head gasket to resolve oil in the coolant and external leakage. Vehicle ran same before and after.

Engines can be weird.

 

The coolant should not boil at 220. The system is pressurized. Pressure raises the boiling point. This is why it's important to have a functioning radiator cap.

It actually shouldn't start boiling until it reaches around 260.

 

I meant if it was straight water, I know coolant raises the boiling point when mixed. 220 isn't really that high depending. His problem may not be with the cooling components but like mentioned earlier about a cracked head.

 

Pressurizing straight water raises the boiling point regardless of whether there is any coolant mixed with it. With a stock 12 lb cap at sea level, straight water wouldn't boil until it reaches 244 F. With a 16 lb cap (which is the recommended aftermarket option), it doesn't boil until 252 F.

When it comes to raising the boiling point, coolant only gives you about 10 degrees F. Pressure is more important to cooling than coolant is.

 

When I took off my head to replace the gasket that was leaking oil like crazy and when I did I noticed a crazy amount of deposits built up in the head that needed a ton of scrubbing and high hose pressure water to come off. Even if you flushed the system there could be some deposits like mine that is restricting flow.