Odd "running hot/overheating" issue (i searched)

Hey all got a weird scenario on a jeep i a working on (i searched but couldn't find anything similar to my situation...) 1999 Jeep Cherokee Sport 4.0 auto 6.5" long arm lift 35's 4.56's locked front and rear...lol

Well anyways jeep has a CSF 3-core radiator, as of right now brand new rad cap, brand new t-stat, and brand new coolant temp sensor, auxiliary fan works, has an electric fan in place of mechanical one that runs all the time, had a flowkooler water pump installed along with a new camshaft...

if you let it sit there and idle, or in drive-thru/traffic it will run hot and its between 20-30* outside and it gets to the point where aux. fan kicks on which is 225* i think and its just sitting there so if it were hot out it would overheat badly....bled the system with one of those nifty funnels with rad cap adapters, and also did a block test to see if headgasket was screwed (its not)


opinions please

Water pumps turns the correct direction ? Full time e-fan big enough to replace the CFM's of the mechanical clutch fan ?

Tim_MN said:

Water pumps turns the correct direction ? Full time e-fan big enough to replace the CFM's of the mechanical clutch fan ?

Click to expand...

every person i talks to mention a reversed water pump...lol and i have considered it many times but i looked at flowkooler and hesco no jeep 4.0 used a non counterclockwise rotation pump...and i considered the fan not being big enough but its running hot idling so even the mechanical fan wouldn't really be doing anything as its a thermostatic clutch a properly running engine wont gain temp at idle over what its supposed to be at i think

I remember a guy having the same issue with all of the same high end cooling products.

He came to the conclusion the between the CSF 3 Row, FloKooler water pump, Hesco thermostat housing blah blah blah That the coolant was flowing to fast through the entire system to get a chance to cool down. YMMV

Ill try to find the post.

bugout said:

I remember a guy having the same issue with all of the same high end cooling products.

He came to the conclusion the between the CSF 3 Row, FloKooler water pump, Hesco thermostat housing blah blah blah That the coolant was flowing to fast through the entire system to get a chance to cool down. YMMV

Ill try to find the post.

Click to expand...

i kinda feel like the water pump is spinning to fast and not being overly effective and that the coolant isn't getting through the 3-rows fast enough another buddy of mine had the 3-row and im pretty sure the flowkooler and he would overheat on the trail all the time...meanwhile my xj had all newer stock stuff and would only run a tiny bit hot on a 90*+ day crawling in 4-lo fan would kick on and it would be fine

http://www.naxja.org/forum/showthread.php?t=1100194

http://www.naxja.org/forum/showthread.php?t=1104444

All of these folks did EVERYTHING to their cooling systems. High flow this, faster this, 3 row this. Living in SW FL (swampland 100% humidity and 95-100 degree weather for several months straight.

After flushing the hell out of my old system to knock as much loose as possible from the heater core and block, I replaced everything with stock stuff from NAPA and BAM problem solved. In the summer time I never saw 220 again and now that were having out winter weather (70% humidity with a low of 50 at night and a high of 70 during the day LOL) It takes forever for it to get up to 210. Where before it hung out at 230+ in traffic.

Also, Since I started a drain and fill routine with my AW4, which at 215k I honestly believe it had the original tranny fluid in it, my temps are running steadily lower and lower. YMMV

Just because...
I run a full flush and fill every other year. Every other flush is a chemical clean as well.

Plus, I only use steam distilled water in the system to keep out the minerals that love to precipitate out of solution and gum up the works.

Expensive? You bet it is.
Less expensive and frustrating than a clogged cooling system? You bet it is.

Which would you prefer? Battling it or, simply running the routine maintenance?

O-Gauge Steamer said:

Just because...
I run a full flush and fill every other year. Every other flush is a chemical clean as well.

Plus, I only use steam distilled water in the system to keep out the minerals that love to precipitate out of solution and gum up the works.

Expensive? You bet it is.
Less expensive and frustrating than a clogged cooling system? You bet it is.

Which would you prefer? Battling it or, simply running the routine maintenance?

Click to expand...

O-Guage, what kind of chemical flush do you run???

X2 on the distilled water. This far south with all of the salt water intrusion from the canals, you HAVE to!

Just your average top of the line Prestone.
http://www.amazon.com/Prestone-AS107-Super-Radiator-Flush/dp/B000BPSVWI

This type requires 3 to 6 hours of run time.

When I got this jeep, one of the first things I did (after replacing the PS pump which was hemorrhaging fluid as fast as it was poured in...) was to do a flush and fill.

As for the chemical to use for cleaning, I actually started with Vinegar. Vinegar is very Old School (OK for me, I'm a very Old Guy!) and works nicely to descale an engine. The mild acid cuts the crud. And, you can dump it anywhere as it is biodegradable...

What I found was scary to say the least. I have better descriptions but you can not post that kind of language.... The "coolant" that came out was black. Eventually, after going through several cycles of Preston chem clean, I replaced the radiator. It would not come clean.

So... Broke open the input side tank and found mud and scraps of silicon sealant everywhere. The silicon was blocking about half of the tubes. Not good.

Now, when I flush the system, it is a nice clean green colour. It has been suggested to me that I back off the schedule. Go to every three years with a chem clean every six. I just can't do it. The last thing I want is to start up the issue again. Plus, with the aluminium radiator in place no chances are being taken.

I would like to offer a suggestion that you folk can take for whatever it is worth to you.

When using silicon sealants, apply the sealant to the part with your finger. IMO all that is needed is an extremely thin coat. If you can see it on the part, that is enough.

Consider this, if the sealant squishes out of the joint on the outside of the engine, it is also doing it on the inside of the engine. Where it can break off and go places it should not ought to go.

Again, IMO, it is the single greatest mistake made by folk.

The radiator I pulled apart I should have photographed to evidence. It was beyond horrible. It certainly looked like it had been filled with unfiltered well water. How else can so much dirt get in that it settles out onto everything?

Shouldn't the fan kick on around 210? 225 seems kinda high. Also, I've had a brand new thermostat fail on me, might want to confirm that its opening all the way.

The actual set point in the PCM is 116(C) on and 112(C) off.

This is not an opinion, I am looking at the code in my PCM...

The data is located in the section named "Environment".

O-Gauge Steamer said:

The actual set point in the PCM is 116(C) on and 112(C) off.

This is not an opinion, I am looking at the code in my PCM...

The data is located in the section named "Environment".

Click to expand...

what year? my 99 kicks on right when it hits 210 on my gauge. 116c is 240f...id be worried about getting it that hot.

'98. But, all of the '96-'01 are the same.

The data in the PCM contains two sets of Fan Controls. The set points I first listed and the second set of controls (subtitled "Low") which have the following set points:
Off at 103(C)
On at 106(C)

So then those are the set used. I posted the wrong data set by mistake.

My abject apologies to all...

And my thanks for catching that for me.

Sorry I was wrong about when fan kicks on and coolant is premixed 50/50....

O-Gauge Steamer said:

Just your average top of the line Prestone.
http://www.amazon.com/Prestone-AS107-Super-Radiator-Flush/dp/B000BPSVWI

This type requires 3 to 6 hours of run time.

When I got this jeep, one of the first things I did (after replacing the PS pump which was hemorrhaging fluid as fast as it was poured in...) was to do a flush and fill.

As for the chemical to use for cleaning, I actually started with Vinegar. Vinegar is very Old School (OK for me, I'm a very Old Guy!) and works nicely to descale an engine. The mild acid cuts the crud. And, you can dump it anywhere as it is biodegradable...

What I found was scary to say the least. I have better descriptions but you can not post that kind of language.... The "coolant" that came out was black. Eventually, after going through several cycles of Preston chem clean, I replaced the radiator. It would not come clean.

So... Broke open the input side tank and found mud and scraps of silicon sealant everywhere. The silicon was blocking about half of the tubes. Not good.

Now, when I flush the system, it is a nice clean green colour. It has been suggested to me that I back off the schedule. Go to every three years with a chem clean every six. I just can't do it. The last thing I want is to start up the issue again. Plus, with the aluminium radiator in place no chances are being taken.

I would like to offer a suggestion that you folk can take for whatever it is worth to you.

When using silicon sealants, apply the sealant to the part with your finger. IMO all that is needed is an extremely thin coat. If you can see it on the part, that is enough.

Consider this, if the sealant squishes out of the joint on the outside of the engine, it is also doing it on the inside of the engine. Where it can break off and go places it should not ought to go.

Again, IMO, it is the single greatest mistake made by folk.

The radiator I pulled apart I should have photographed to evidence. It was beyond horrible. It certainly looked like it had been filled with unfiltered well water. How else can so much dirt get in that it settles out onto everything?

Click to expand...

0-Gauge,

Exactly what are you doing with the vinegar? Concentration, duration etc...???

i have a 96, it will run warm 225-230 or so on the interstate. get done to city driving temp stay normal. a friend of mine told me the other day that he read a post on another sight that said check the MAP sensor. it could cause it to run lean( i think)

I'm not talking about interstate driving, driving on the road this thing maintains normal operation temp as soon as your in a stopped idle position temp starts rising (parked in driveway, drive-thru, wheeling 4-lo crawling...) coolant is clean and green thermostat is working, new coolant temp sensor, good rad cap...

mcguyver_xj said:

I'm not talking about interstate driving, driving on the road this thing maintains normal operation temp as soon as your in a stopped idle position temp starts rising (parked in driveway, drive-thru, wheeling 4-lo crawling...) coolant is clean and green thermostat is working, new coolant temp sensor, good rad cap...

Click to expand...

Unfortunately there is no quick fix suggestion for this problem and these things are a pain in the arse.

Me and a lot of others have gotten burned by aftermarket crap in this area. Since it only overheats when sitting idle its a pretty good indication that the problem is airflow across the radiator or water flow.

I would just try a stock mechanical fan and shroud if you have one laying around and a stock water pump. My money would be on the fan.

Also, I'm not a subscriber to the water moving too fast theory that some people have. Faster water is always better =) But if your pump is cavitating then that's a different beast all together.

i'm thinking it's an air flow issue. at idle, the only airflow comes from the fan. if it isnt large enough or shrouded correctly the heat will build up in the system. an idling engine will absolutely continue to build heat well beyond normal if the heat isnt removed. driving under a load will only do it faster.
i have always run stock components on XJ cooling systems because i'm not an engineer who knows how to take all the variables into account to maximize the desired effect of modifications. there are far more "my modified cooling system is overheating" threads here on than "my stock system is overheating" .. i took a simple lesson from that years ago.
go back to a stock mechanical fan, or look at the CFM rating on the Efan and replace it with a better one. it needs to fit snug against the radiator and run all the time..
it is a frustrating process of elimination to reverse engineer multiple modifications to find the cause, let us know what you find.

I couldn't agree with you more sidriptide, and I am an engineer with a masters degree. I really hate that about the aftermarket performance market. Think about it, who designed the better water pump for this specific application, Chrysler with 1000s of engineers who have a product sold in the millions and tested in the field for over 10 years or flowkooler. Not to mention that I'll wager anything that Chrysler knows more about what materials interact with the fluids in bad way. Not all green stuff is created equal.

But as for the OP of this thread. I really think it's worth it to clean the radiator fins and AC condensor fins really well and try a stock mechanical clutch fan with shroud. While you have the fan out, take a garden hose to the backside of the radiator and blow it out the front.

Also if you have done grill and headerpanel modifications, check for hot air blowing out the front around the radiator (this would be in the wrong direction and it would help to seal these front gaps, use duct tape for testing

Keep in mind that to move air across the radiator you need low pressure air behind and high pressure in front of the radiator, this is what the fan is for. But to do this the air in the engine compartment has to exit somewhere, it should be out the bottom but if there is too much stuff blocking it from moving out the bottom it won't be as efficient. Everything has to work together and you have to look at it from all angles