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High temp woes

V

Vitzaa

NAXJA Forum User
Location
Los angeles
Hey guys!

Got another problem with my rig... :mad:

'01 xj, Russ's 87 octane 4.6 stroker (3k miles). Novac ax15, 4.88 gears, 35" tires. 5,800lbs (armor, RTT, toolbox and tools)

Been running hot since before the engine rebuild, still ran hot after rebuild. Flushed/back flushed the heater core a dozen times and got a ton of crud out. Figured radiator clogged up so threw in a new mishimoto rad. Still heating up so figured it might be the dual Cali cats (200k miles), replaced those as well and am still running hot.

Non highway temps are 210-220's
Highway temps 240-245 (2,500 rpm)
Coasting down the offramp drops me to 220
At idle, temps creep and hover around mid 220's

Ngk plugs, one step cooler
New fan clutch
New silicone hoses
New 180deg tstat
Flushed system and ran thermocure a week, got more junk out, nothing large
G05 coolant
Water pump is a flowkooler

Temps at radiator inlet are about 20 degrees hotter than radiator outlet while at idle and temp sensor showing 220

Electric fan works

Passenger side of head measured 190's at idle (forgot exact number.



Not really sure what to do from here...

Thinking of replacing the water pump as I've read the flowkooler can cause some cavitation at higher rpm, but it shouldn't be an issue at 2,500 right?

Run thermocure again in case there are blockages?

Hood vents?

Replace temp sensor on tstat housing?

Go two steps cooler than stock on the plugs?

I'm just kinda stumped. I know the hopped up motor and weight are a factor but I feel like it shouldn't be in the 240's...
 
195 stant superstat first. Regular water pump is probably a good idea. There have been reports of the misimoto radiators have poorly cut cores and restricting water flow. I'd try a the largest stock style radiator you can find. Plastic tanked ones actually hold up better in my experience.
 
I would definately be suspicious of the water pump.
 
The stant thermostat I believe is made my motorad, which is what's in there now... I doubt it being 195 would make a difference to the higher temps...
I also contacted mishimoto and sent some info in for a replacement

Rcp, hey man! Thanks for popping in! Which direction you recommend I go with the water pump? Stock or another brand high flow?
 
I've had great results with my Hesco pump!
 
Your's is a common trait of a wrong rotation so be careful of that!
 
No, flow is still in the same direction, it just causes cavitation.
 
RCP Phx said:
Your's is a common trait of a wrong rotation so be careful of that!
Click to expand...

You know, I'm starting to wonder why Jeep changed the rotation direction of the water pump when they derived the 4.0 from the 4.2 - is the serpentine belt routing really that different?
 
Vitzaa said:
Looks like backorder til October. Can't find one anywhere online either... Bah.

Any other quality brands?
Click to expand...

I have had good luck with AC Delco Gold/Professional water pumps. They are new, not rebuilt.

Had a similar problem with my son's '95. Turned out to be a stuck thermostat. We tested it before installing, but it failed almost immediately. Tested and installed a failsafe Motor Rad off Amazon. Problem solved.
 
Last edited:
Vitzaa said:
Hey guys!

Got another problem with my rig... :mad:

'01 xj, Russ's 87 octane 4.6 stroker (3k miles). Novac ax15, 4.88 gears, 35" tires. 5,800lbs (armor, RTT, toolbox and tools)

Been running hot since before the engine rebuild, still ran hot after rebuild. Flushed/back flushed the heater core a dozen times and got a ton of crud out. Figured radiator clogged up so threw in a new mishimoto rad. Still heating up so figured it might be the dual Cali cats (200k miles), replaced those as well and am still running hot.

Non highway temps are 210-220's
Highway temps 240-245 (2,500 rpm)
Coasting down the offramp drops me to 220
At idle, temps creep and hover around mid 220's

Ngk plugs, one step cooler
New fan clutch
New silicone hoses
New 180deg tstat
Flushed system and ran thermocure a week, got more junk out, nothing large
G05 coolant
Water pump is a flowkooler

Temps at radiator inlet are about 20 degrees hotter than radiator outlet while at idle and temp sensor showing 220

Electric fan works

Passenger side of head measured 190's at idle (forgot exact number.



Not really sure what to do from here...

Thinking of replacing the water pump as I've read the flowkooler can cause some cavitation at higher rpm, but it shouldn't be an issue at 2,500 right?

Run thermocure again in case there are blockages?

Hood vents?

Replace temp sensor on tstat housing?

Go two steps cooler than stock on the plugs?

I'm just kinda stumped. I know the hopped up motor and weight are a factor but I feel like it shouldn't be in the 240's...
Click to expand...

Remove your hood and test. If it helps, then you know hood vents would help too (not as much of course).
 
Hey guys, figured I'd throw an update on here in case things come up on a future search...

Replaced the pump, fin direction was identical to my previous pump. Made no difference.

Black and forward flushed the heater core and radiator, barely anything came out. Maybe half a teaspoon of stuff, looked like rust/calcium and some small dust like metal particles (radiator has a magnetic drain plug which has a TON of the particles).

I then purchased one of those back flush things which incorporated an air hose for compressed air. Used it and an absolute sh|t ton of junk came out when using compressed air. Wish I caught it in a bucket but it literally looked brown for a second til the air sent it flying. Back flushed the heater core as well and same deal, bunch of crap.
Went back and forth on the rad/heater core til water was running clear... I'm thinking mishimoto radiators have smaller passages which clog up easier.

I also ended up installing a coolant filter on the heater core return hose (from core to water pump). Haven't opened it up yet so will see how much it collected...

I'm running the zyrex g05 coolant so I'm hoping it'll stop any corrosion going on in the block. The hopefully the machine shop that machined the block gave it a hot bath but who knows... Anyone know what the deal is with the metallic particles? Electrolysis?

My heat is also not as hot as it used to be before the coolant filter. I have a wix filter in it and there and I don't think it's up to par on moving as much fluid, going to call Donaldson and get a recommendation on one of their filters that would hopefully move more fluid. Heater core isn't leaking either (from what I can tell so far, been a couple hundred miles) and I'm sure the system purged all air bubbles at this point...haven't seen things get above 200 (180 degree tstat). Will see how things go on a hot day with some highway uphill driving.

Anyways, if anyone's running hot and not having luck reverse flushing, incorporate compressed air and that should do it.
 
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