Overheating only on a load, heavy mods

OK...here it goes: I have a 1989 renix that pretty much has nothing old left on it. 6" lift with 35's and about 1000lbs over stock. engine is 4.0 with comp cam and polished and ported head, bored out throttle body, spacer, headers, and a high flow intake...blah blah blah... I know, but in troubleshooting my nightmare, this may come into play. so...cooling system mods: 3 row aluminum radiator, lower hose accordion style with spring. upper stock hose type. Flowkooler water pump and a flowkooler high flow thermostat hsg. 3 10" elect. fans, and a mr gasket type performance thermostat. there is the oem ac rad and a small oil cooler rad installed. I have also installed a
trans aluminum heat sink type cooler to disperse even more heat from the engine radiator. now under normal driving conditions, freeway city streets altitude, and offroading the system is perfect. It will
run at 195 to 210f. but when I need to climb on a load up to the mountains on a highway, it creeps up to 240 easy, and I have to pull over letting it run in park, cool off and try again. So if anyone out there has a clue, please help! Everything in the updated "open type" cooling system is new. oh and I ran thee head gasket test, and checked the manifold and the header and no leaks. all of my vacuum lines are new. all sensors are new. motor has 54K on it. Thank you for your time....

Cat converter clogging? Verify fuel pressure under load? Lean conditions can cause higher temps. Tried a different tstat? Another option is trying a coolant restrictor in the upper hose to allow the coolant more time in the radiator.

Brand new cat flowmaster...air fuel mixture rich to ideal


Sent from my iPhone using Tapatalk

I have tried no stat flange with hole, oem stat, super stat. 180, 190, 195....and on and on....the stat now seems to work the best under normal conditions.


Sent from my iPhone using Tapatalk

Many people have experienced how 3-row radiators and 3 electric fans are cooling downgrades compared to a stock 2-row hd radiator and the stock mechanical and electric fans. Others have found high flow water pumps and t-stat housings to move the coolant too fast to be properly cooled as well. If you go back to stock fan setup, get a 10-blade aux fan from a 97-01 cherokee and chop the connector off and solder on the renix connector(if you still have that old fan, if not, chop the plug off the donor jeep).


Sent from my iPhone using Tapatalk

If your coolant is moving too fast through the system it may not have sufficient time to absorb heat from the engine, likewise not enough time to release the heat while in the radiator. Factor in reduced airflow through the radiator and it goes from bad to worse.

Marketing hype vs. physics.

Yes I've heard that the coolant has to stay in the system longer to cool but what is heat transfer really but conduction, convection and radiation of electrons. The fluid in your system transfers those electrons based principally on the source-sink differential and the exchange material's transfer rate. An electron moves at varying speeds - Bohr's model has it moving at 2 million meter/second and with a mere 11 million eV boost you can get an electron to 99.9% of the speed of light. Though they move at varying speeds physicists accept that electrons move fast - really really fast. Far faster than the flow rate of the water pump. Your engine coolant's electrons do not know (or care) how fast you send them through the system - they just knows that the source is hotter than the sink and off they go.


Sent from my iPhone using Tapatalk

In a closed loop system if you keep the fluid in the heat exchanger you are simultaneously keeping it in the block longer. Unfortunately, the block is the part that is generating the heat. Sending hot coolant from your source (engine) through the heat exchanger (radiator) to the sink (air) will transfer heat as long as there is a temperature difference between the source and sink. The engine is still generating heat the whole time so why keep the coolant there any longer than you have to.


Sent from my iPhone using Tapatalk

This makes engineering sense to me...in racing these issues apply .... my jeep ran like crap with the inferior under designed cooling system...it works perfect in all conditions but one...heavy uphill load at moderate to high speeds...


Sent from my iPhone using Tapatalk

http://jeep-xj.info/HowtoRadiatorRestrictor.htm

Theory on paper is not always how it works in the real world. Try this. If it doesn't work you're only out a few bucks.

1989AMCXJ said:

Yes I've heard that the coolant has to stay in the system longer to cool but what is heat transfer really but conduction, convection and radiation of electrons. The fluid in your system transfers those electrons based principally on the source-sink differential and the exchange material's transfer rate. An electron moves at varying speeds - Bohr's model has it moving at 2 million meter/second and with a mere 11 million eV boost you can get an electron to 99.9% of the speed of light. Though they move at varying speeds physicists accept that electrons move fast - really really fast. Far faster than the flow rate of the water pump. Your engine coolant's electrons do not know (or care) how fast you send them through the system - they just knows that the source is hotter than the sink and off they go.


Sent from my iPhone using Tapatalk

Click to expand...

G C E

1989AMCXJ said:

In a closed loop system if you keep the fluid in the heat exchanger you are simultaneously keeping it in the block longer. Unfortunately, the block is the part that is generating the heat. Sending hot coolant from your source (engine) through the heat exchanger (radiator) to the sink (air) will transfer heat as long as there is a temperature difference between the source and sink. The engine is still generating heat the whole time so why keep the coolant there any longer than you have to.


Sent from my iPhone using Tapatalk

Click to expand...

Well, the whole reason for a t-stat is to heat up the coolant in the block while the coolant in the radiator cools off....and to do so in a controlled manner. If you don't, then the whole system will slowly heat up, unless you have a crazy large radiator for the engine size. You need a restriction that lets this happen.....that is why every engine has one...even boat motors where you have water -water heat sinks, which work much better.

Try running your engine with no t-stat or flow restriction and let us know how it works.

1989AMCXJ said:

This makes engineering sense to me...in racing these issues apply .... my jeep ran like crap with the inferior under designed cooling system...it works perfect in all conditions but one...heavy uphill load at moderate to high speeds...


Sent from my iPhone using Tapatalk

Click to expand...

Funny...both of mine run fine........guess you need to go back and do some re-engineering since you ain't got it right yet if it overheats at all.

neither of mine overheat in any condition......using that 'inferior under designed' cooling system, and they got many, many miles on them.......


Sounds to me like you're trying to re-invent the wheel, but can't figure out how to make it roll yet.....

added to the above

see above

1989AMCXJ said:

Yes I've heard that the coolant has to stay in the system longer to cool but what is heat transfer really but conduction, convection and radiation of electrons. The fluid in your system transfers those electrons based principally on the source-sink differential and the exchange material's transfer rate. An electron moves at varying speeds - Bohr's model has it moving at 2 million meter/second and with a mere 11 million eV boost you can get an electron to 99.9% of the speed of light. Though they move at varying speeds physicists accept that electrons move fast - really really fast. Far faster than the flow rate of the water pump. Your engine coolant's electrons do not know (or care) how fast you send them through the system - they just knows that the source is hotter than the sink and off they go.


Sent from my iPhone using Tapatalk

Click to expand...

https://www.flowkoolerwaterpumps.com/cooling_faq.html



Nominated.

the last thing I want to do is re invent the wheel...I seriously am not trying to be an ass...I have been trying to improve a faulty system for quite some time now. when I lifted this XJ, put on 35's, bumpers, winch, armor, 4:88 gears. lockers, etc. The all new parts factory cooling system simply failed. it's just a plain fact. so piece by piece, I would update each part of the cooling system to find improvements. Each time I made a change, it would improve, run cooler, more efficient, and even better mpg. In all conditions but one...up a grade...I live at 7000 feet in the mountains, and even up here I get 18mpg on the streets, which is amazing to me. the last time I had the heat up issue, it was the lower hose that was collapsing, restricting the flow rate...so if I put in a restricter, wouldn't that do the same thing? Thank you again for your time...

thanks for the link about the restricter...I will try it...

I doubt you get 18MPG, check your speedomoeter/odometer error

I have a factory open system in my Jeep on 35s, 4.88, slightly tired engine and can run up 18, 330, and 38 as fast as is safe at I'll get to about 215 degrees. My stocker Jeep gets to about 205 in the same conditions.

Factory water pump, cheap aluminum radiator (but a CSF all-brass would do just as well and be built better), factory electric fan plus ZJ fan clutch (although at +35 speeds fans are out of the equation).

What gear are you trying to climb in? You very well could be getting this heat from your transmission. I spend most of my time going up the mountain in second gear with brief stints in 3rd or even 1st around the tight hairpins, lugging the engine generates a lot of heat from both the engine and transmission. Keep your engine speed between 2500 - 4000, 3000 minimum when going uphill.

Bent said:

If your coolant is moving too fast through the system it may not have sufficient time to absorb heat from the engine, likewise not enough time to release the heat while in the radiator.

Marketing hype vs. physics.

Click to expand...

I'd think that would just max out the systems ability to transfer heat since it's continuous. Not really a bad thing just diminishing returns once your reach a certain point.

Anyway my "Heavy modded" 4.6 renix runs great in 100 degree weather in a rock race with stock renix cooling (except fans) I promise the design of the system is not at fault here.

Bent said:

https://www.flowkoolerwaterpumps.com/cooling_faq.html

Click to expand...

LOL

1989AMCXJ said:

the last thing I want to do is re invent the wheel...I seriously am not trying to be an ass...I have been trying to improve a faulty system for quite some time now. when I lifted this XJ, put on 35's, bumpers, winch, armor, 4:88 gears. lockers, etc. The all new parts factory cooling system simply failed. it's just a plain fact. so piece by piece, I would update each part of the cooling system to find improvements. Each time I made a change, it would improve, run cooler, more efficient, and even better mpg. In all conditions but one...up a grade...I live at 7000 feet in the mountains, and even up here I get 18mpg on the streets, which is amazing to me. the last time I had the heat up issue, it was the lower hose that was collapsing, restricting the flow rate...so if I put in a restricter, wouldn't that do the same thing? Thank you again for your time...

Click to expand...

yes & no.....it will hurt you far more since it is on the suction side of the pump, which make sit easier for the pump to cavitate. You need it on the pressure side.



And as for the flow-rate thru the system thing.....think of this.........what cools you off more when you are hot....running thru an air conditioned room, or walking slowly thru it ??

OK so I built the nylon washer just like the website said, installed it and proceeded to go up a long steep incline (Onyx Summit). Results: It actually helped quite a bit! Not 100% resolved, but a big difference none the less...I still have some CFM's to make up as well. One of my three cheapy Chinese fans is fading and the others...well not to good. So I will be installing 3 new SPAL fans in there place ( I can finally afford it). The cheap fans are six years old...time to go...So thanks everyone so far for heading me in the right direction...I really appreciate it. I will post my results after the higher CFM's are in place...


Sent from my iPhone using Tapatalk