Oscar Will

On an earlier conversion we found an overheat problem at higher speeds caused by air "stacking up" in the engine compartment... you can force all the cool air you want at the radiator but if it can't pass through and exit somewhere... the cooling system won't be able to do the job.

Avarookie

iTrader: (8)

I think he posted that he actually removed the hood and still had issues, no? LSXranger may have a good idea, by simply adding some washers (cheap test) and jacking up the rear of the hood. With my hot issues I had with my SS, I pulled the weather strips from the hood seal all the way around just to see f it helped.

I wonder if he is going in to a lean condition, that would account for heat under heavy load under prolonged duration.

Definitely a WTF situation, time and testing will tell.... problem is finding the issue, then the correct solution.

Jeepthing

Jeep has been dyno'd and was running lean, big tires and 5K+ elevation don't help, then tuned with HP tuners. I may revisit the tuning just because, wouldn't hurt.

I did test without the hood, negligible difference. I added hood vents just to be safe. I do wonder about venting the inner fenders though, a lot of hot air could be allowed to exit the engine compartment with them.

Having extra accessories under the hood definitely makes things tight. Never an issue with the stock engine...but more power means more heat...

The fan shroud will be removed and the fan mounted directly to the radiator as I think the shroud is hurting air flow. Finding time to make the change, as well as ordering the rubber seal for the shroud from SPAL, are my biggest hurdles.

Thanks again to all!

sparkwirez06

iTrader: (18)

if your fans are controlled by the computer, it will shut off your fans at a certain speed,
the natural air flow should take over. seems to be where your problem starts!

Jeepthing

Normal highway driving the temps are well within check, the only issue is at higher load going uphill or driving aggressively. This to me essentially means I have no "reserve" cooling capacity, and in this specific case I think its air flow related.

I have been trying to determine if my fan does in fact turn off at a certain speed. I have heard mixed info in regards to under what circumstances the fan shuts off. The ECM has been tuned and a couple parameters changed for tire size, gearing, etc, not sure if the fan has been messed with.

Avarookie

iTrader: (8)

If you do not have access to someone who can read your computer when you need them to, just temporarily add a light to it. You can set it up either way, when the fan shuts off or turns on, up to you. It's the same as using a shift light or line lock or the sort. It either will receive a signal and turn on, or lose the signal and turn off. that will let you when it is happening, you can the check what other things are happening at or very near the same time.

Jeepthing

Thanks avarookie, I will be adding at least a temporary light so I can understand better what's going on with the fan at higher speeds.

Haven't had time the past week to make any changes. Been driving the Jeep and temps are "OK" but I would still like to get temps down about 10 degrees across the board. The removal of the fan shroud doors definitely did help, not sure if removing the shroud entirely will just move my problem to a low speed issue. The temps still come down once the fan turns on at lower speeds but it does take a bit longer.

Punisher8738

iTrader: (1)

How much of a difference did removing the shroud doors?

lsxRanger94

Sounds like you need to turn the fans on a bit sooner at low speed.

Jeepthing

The max I saw on the highway was 219, so down about 5 degrees. This is testing on the same portion of highway each time. I believe that when I am in the mountains ascending some of the passes the temps will get higher. This is without A/C on and "unloaded" as well. My goal is to be able to tow a small trailer at some point as well.

Currently the fan turns on at 210 and off at 195 or so. If I were to drop the fan ON temp down how far should I go? I wouldn't think I would want to drop it much since I am still running the stock thermostat. My thought is drop to 205 maybe?

I am considering drilling a few holes in the thermostat to help coolant flow, should know pretty quickly if it helps or hurts. This would then tell me if my issue is coolant flow or air flow related...or possibly both.

lsxRanger94

Drilling holes typically takes longer for the vehicle to warm up and helps slightly with burping the air out of the system. I think the factory t-stat opens at 187. So on at 190-195 off at 180.

Jeepthing

Considering I am filling the system with a vacuum tool I don't think air in the system is an issue. I was under the impression that adding the holes will add to coolant flow while at the same time slowing warm up times. I'm not too concerned with warm up time but extra coolant flow may help??? I know using a restrictor in place of the tstat has been mentioned but to me that seems like a good method for testing if coolant flow is an issue but not a good permanent solution.

From my very scientific pot of boiling water test the tstat does open at 187 or so, but is not fully open until closer to 195-200. My question on lowering the fan settings is how will this effect high speed if anything?? On paper I don't see that it would do much but I could certainly be wrong...any ideas there?

lsxRanger94

In a previous post you said not running the fan caused temp to reach 235. you didn't mention how many miles were on the water pump or if it was new. Also you didn't say if the radiator you have was sized for the 5.3 or the engine you replaced. Lowering the fan temp will also lower under hood temps, which in turn helps the engine run cooler.

Jeepthing

The water pump is new as are all engine accessories, radiator is a new two core aluminum from Novak with SPAL 16" fan and shroud. I mentioned the details very early on in the thread but not recently, probably should have mentioned the details again to keep things up to date.

My newest thought is that removing the shroud entirely could help at high speeds even more than just removing the shroud "doors". Then lower the fan settings to help keep things cooler overall. Those two combined may help enough alone.

Ultimately I need to have time to make changes and test, which is working thus far, but not happening quickly due to family and work...

lsxRanger94

I just looked @ the novak site. The FX3300-T doesn't show any doors on the shroud.

lsxRanger94

http://www.novak-adapt.com/knowledge/cooling.htm

Jeepthing

I have been in contact with Novak on an almost daily basis with my issues. I originally had their single core radiator with a full shroud that did not have the "doors" in it. After some testing they recommended upgrading to their newest two core radiator and shroud with "doors". From my last conversation they are now working on an even newer shroud with rubber "flaps" on the shroud instead of doors. This newest style is similar to how many production cars are set-up (Volvo and Saab to name two). I modified my original shroud and added the rubber flaps from a Volvo and they didn't help. Removing the doors on the newer shroud did drop temps by about 5 degrees which is helpful but not enough.

Thanks again to all who have been sharing their insight, it is appreciated.

Pop N Wood

iTrader: (1)

I keep logging on here waiting for the all fixed post.

Keep at it and good luck.

Turning the fans on below the thermostat temp is counterproductive. Just means once you heat up they will never turn off.

In your case a lower temp thermostat isn't going to help the overheating problem. Once it opens and temps go up past the opening point then it has done all it can do.

Jeepthing

Trust me I wish it was an easy fix and I had moved on to other projects but sadly that is not the case.

After more research etc I think some overall changes are going to be made hoping that each makes an incremental drop in temp. I am looking into a "shorter" winch, relocating the trans cooler, adding vents to the inner fenders, and generally trying to get more air in and out of the engine compartment.

Looked at an 06' Silverado recently to see how its cooling situation was laid out and I will say the Jeep is at a HUGE disadvantage to the 5.3's intended home. The radiator in the truck must be three times the size with dual electric fans, and gobs more room in the engine compartment.

I will get it figured out just will take time and money...like every other project

slogo

have you done the block test to see if you are getting exhaust gasses into your coolant
system?