Got hot after new thermostat and towing

RCS · **Joined:** Fri Feb 03, 2017 7:19 pm **Posts:** 85

I have never really towed with the KJ until this weekend. I didn't because I needed a new thermostat, had one but hadn't gotten around to changing it. Father's day weekend I decided to do it. Last week my wife's ball joint on her 2015 Cherokee went out and we where scheduled to go camping. I decided it would be a good chance to see how it would do. We went to Estes Park, about 95 miles away and up and over a pass. It is a 22 foot 3800 lb dry weight camper.

On the way there I was doing 70-75 turning only 2100 RPMs. I got 18 mpg, including going over the pass. The temp gauge went to high normal going over the pass so I turned the heater on and it came down. I was ecstatic. My wife's car gets 7-8 mpg pulling the camper, down hill with a tail wind. We were planning a trip to South Dakota because the MPG was so good.

On the way back no issues going over the mountains. When we hit the highway it would almost peg the H if I even thought about going over 60. I did not do a complete radiator flush when I changed the thermostat. Any ideas as to why it did this. When I bought this it had a new head and water pump. That was about 30,000 miles ago. I assumed they drained and flushed the radiator when they put the new head and water pump on. Planning to do a flush this coming weekend while changing the wife's ball joint.

WolverineFW · **Posted:** Mon Jun 24, 2019 1:19 pm

You might have a faulty fan clutch for the mechanical fan.

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TURBO-DIESEL-FREAK · **Joined:** Sat Apr 17, 2010 3:29 pm **Posts:** 1167

I tend to agree with WolverineFW.

A faulty fan clutch will not pull enough air through the radiator in high cooling system demand situations. It is your most likely problem. WWDiesel has a thread that discusses the use of a GM heavy duty fan clutch and 11 blade plastic fan. The apparently fit on exactly and do a better job than either the O.E. replacement parts or the Hayden fan clutch replacement. Here is that thread...

viewtopic.php?f=5&t=82941

Libertys have also been known to clog the radiator with debris from the outside and in between the radiator the A/C condenser and the intercooler. This will impede airflow, and cause an overheat condition in high demand situations just like a malfunctioning fan clutch will.

One more thing that can cause this is a worn out water pump. This is why the water pump is routinely changed when the timing belt is changed.

TKB4 · **Posted:** Tue Jun 25, 2019 2:37 am

I agree the fan clutch is the most likely culprit. Many have used the Hayden unit as a replacement, but note several have received defective ones brand new. Of course there are all sorts of electric fan alternatives written about here too. A good flushing certainly won't hurt just make sure to use the correct HOAT antifreeze afterwards like Zerex G-05. Good luck resolving your issue.

RCS · **Joined:** Fri Feb 03, 2017 7:19 pm **Posts:** 85

TURBO-DIESEL-FREAK wrote:

I tend to agree with WolverineFW.

A faulty fan clutch will not pull enough air through the radiator in high cooling system demand situations. It is your most likely problem. WWDiesel has a thread that discusses the use of a GM heavy duty fan clutch and 11 blade plastic fan. The apparently fit on exactly and do a better job than either the O.E. replacement parts or the Hayden fan clutch replacement. Here is that thread...

viewtopic.php?f=5&t=82941

Libertys have also been known to clog the radiator with debris from the outside and in between the radiator the A/C condenser and the intercooler. This will impede airflow, and cause an overheat condition in high demand situations just like a malfunctioning fan clutch will.

One more thing that can cause this is a worn out water pump. This is why the water pump is routinely changed when the timing belt is changed.

When the previous owner had a new head put on it, he replaced the water pump. I will look at the GM fan clutch.

RCS · **Joined:** Fri Feb 03, 2017 7:19 pm **Posts:** 85

Thanks for the GM recommendation. Since I am going to use this as a tow vehicle, I think I am going to do this mode if for no other reason than a precaution.

RCS · **Joined:** Fri Feb 03, 2017 7:19 pm **Posts:** 85

Out of curiosity, I have a Ford Taurus fan I was going to put in my CJ-8. Has anyone ever done this swap on a CRD?

WWDiesel · **Posted:** Tue Jun 25, 2019 3:35 pm

RCS wrote:

Out of curiosity, I have a Ford Taurus fan I was going to put in my CJ-8. Has anyone ever done this swap on a CRD?

Its been done and there are several threads on LOST that discuss the Taurus fan mode.
Someone even used Volvo fan which they stated was the same motor as the Taurus.
Do a search by pasting this in your search bar: > Taurus install site:www.lostjeeps.com/forum/ <

As for me, it is very hard to beat the GM heavy duty V8 fan and fan clutch combo. It moves a lot of air flow.

RCS · **Joined:** Fri Feb 03, 2017 7:19 pm **Posts:** 85

WWDiesel wrote:

RCS wrote:

Out of curiosity, I have a Ford Taurus fan I was going to put in my CJ-8. Has anyone ever done this swap on a CRD?

Its been done and there are several threads on LOST that discuss the Taurus fan mode.
Someone even used Volvo fan which they stated was the same motor as the Taurus.
Do a search by pasting this in your search bar: > Taurus install site:www.lostjeeps.com/forum/ <

As for me, it is very hard to beat the GM heavy duty V8 fan and fan clutch combo. It moves a lot of air flow.

Under stand completely. I am still considering you GM mod. I am now thinking about the electric because it would be nice to turn it off during the winter for the extra heat. So, more air in the summer towing the camper, less in the winter for extra heat. Is that too much to ask for?

WWDiesel · **Posted:** Tue Jun 25, 2019 10:11 pm

RCS wrote:

Under stand completely. I am still considering you GM mod. I am now thinking about the electric because it would be nice to turn it off during the winter for the extra heat. So, more air in the summer towing the camper, less in the winter for extra heat. Is that too much to ask for?

I don't profess to be a thermodynamics engineer, but quite a few on here have stated that the mechanical fans moves a lot more air flow than an electrical fan can provide.

If I lived in a very cold winter time climate, I would simply remove the mechanical fan for winter driving and then put it back for warm weather driving.
It is very easy to R&R if you have split the fan shroud into two pieces like many of us have done. Need more info doing that, just holler.

TKB4 · **Posted:** Wed Jun 26, 2019 3:15 am

I leave the fan off the one I drive all year round even with AC in 100 degree weather it does ok . If I tow anything bigger than a light John Boat in summer though it definitely needs the fan.

RCS · **Joined:** Fri Feb 03, 2017 7:19 pm **Posts:** 85

WWDiesel wrote:

RCS wrote:

Under stand completely. I am still considering you GM mod. I am now thinking about the electric because it would be nice to turn it off during the winter for the extra heat. So, more air in the summer towing the camper, less in the winter for extra heat. Is that too much to ask for?

I don't profess to be a thermodynamics engineer, but quite a few on here have stated that the mechanical fans moves a lot more air flow than an electrical fan can provide.

If I lived in a very cold winter time climate, I would simply remove the mechanical fan for winter driving and then put it back for warm weather driving.
It is very easy to R&R if you have split the fan shroud into two pieces like many of us have done. Need more info doing that, just holler.

Do you have a picture of where you cut the shroud?

ebbnflow · **Posted:** Wed Jun 26, 2019 9:35 pm

RCS wrote:

WWDiesel wrote:

RCS wrote:

Under stand completely. I am still considering you GM mod. I am now thinking about the electric because it would be nice to turn it off during the winter for the extra heat. So, more air in the summer towing the camper, less in the winter for extra heat. Is that too much to ask for?

I don't profess to be a thermodynamics engineer, but quite a few on here have stated that the mechanical fans moves a lot more air flow than an electrical fan can provide.

If I lived in a very cold winter time climate, I would simply remove the mechanical fan for winter driving and then put it back for warm weather driving.
It is very easy to R&R if you have split the fan shroud into two pieces like many of us have done. Need more info doing that, just holler.

Do you have a picture of where you cut the shroud?

Cut it off below the mounting bolts holes and toss the bottom half. Put the top half back on and you're good to go.

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WWDiesel · **Posted:** Wed Jun 26, 2019 10:21 pm

RCS wrote:

WWDiesel wrote:

RCS wrote:

Under stand completely. I am still considering you GM mod. I am now thinking about the electric because it would be nice to turn it off during the winter for the extra heat. So, more air in the summer towing the camper, less in the winter for extra heat. Is that too much to ask for?

I don't profess to be a thermodynamics engineer, but quite a few on here have stated that the mechanical fans moves a lot more air flow than an electrical fan can provide.
If I lived in a very cold winter time climate, I would simply remove the mechanical fan for winter driving and then put it back for warm weather driving.
It is very easy to R&R if you have split the fan shroud into two pieces like many of us have done. Need more info doing that, just holler.

Do you have a picture of where you cut the shroud?

Plenty of threads on LOST on the subject.
Basically cut the shroud at the half way mark.

See this:> viewtopic.php?p=916154&sid=37b8b2273aae8b55507272958f8d4bb2#p916154

RCS · **Joined:** Fri Feb 03, 2017 7:19 pm **Posts:** 85

Went to NAPA and they did not have the fan or clutch, said it would be a couple days to get it in. I went by Advanced auto (CarQuest) and they had the clutch in stock for $57.00. The part number is 215158. The fan will be here at lunch.

TKB4 · **Posted:** Thu Jun 27, 2019 3:32 pm

History: one of the original fan shroud mods was termed the AUSSIE shroud mod . Later IRUNMILES had a post in the Tech section about it.

One big problem is most people remove it to do the modification by removing the fan with then modify it for next time, which is one of the whole reasons for doing it in the first place.

I modify it in place. I use one of the vibratory cutting tools and be careful with it and you can cut it off without removing anything else. Takes about 15 minutes or less. I guess you could use a small rotary wheel cutting tool but much higher risk of cutting something else too. I did it first time by removing both but after that did 4 more my way which is much easier.

RCS · **Joined:** Fri Feb 03, 2017 7:19 pm **Posts:** 85

I was wondering if I really needed the bottom and could get away with just the top for safety. Picked up my fan on the way home. That thing is a beast compared to what is in there.

WWDiesel · **Posted:** Fri Jun 28, 2019 1:20 am

RCS wrote:

I was wondering if I really needed the bottom and could get away with just the top for safety. Picked up my fan on the way home. That thing is a beast compared to what is in there.

Well remember, it is for a big 6.0L GM V8 with HD cooling, AC, and towing package. :lol:

Don't forget to get the four bolts for bolting the fan to the fan clutch, they are larger than the OEM Jeep bolts.
Grade 5 Hex Head - 10mm x 1.5 x 18mm. Final installation will require the use of a washer and loctite.
or
A GM dealer may be able to supply you with the four bolts:
Fan Blade Bolt - GM (11516869)

RCS · **Joined:** Fri Feb 03, 2017 7:19 pm **Posts:** 85

I am getting the bolts at lunch. Tomorrow I will put the new ball joint in the wife's car, flush my radiator, put the new fan and clutch on and hopefully upload the new tune from yeti. After that I will book a camp site at Curt Gowdy state park in Wyoming for mid July.

GordnadoCRD · **Posted:** Fri Jun 28, 2019 4:56 pm

I also vote for the clutch+fan mod.
The part numbers I used are in my sig info.
One reason it pulls so much more air is the fan is about 1/3 the weight of the oem heavy steel fan. Sooo much less inertia that the clutch has to overcome!
With the turn ratio being direct and overdriven from the crankshaft speed, the lightness will also produce less load on the engine, although at lower (cruising) RPM, the difference isn't going to be much.
Unless you are surrounded by people willing to put their hands into the fan area of a running engine, the safety guard on top isn't making much difference for safety. What it DOES do, is direct the hot air from the cooling stack in a lower direction... around the sides and under the cover of the engine.
Supposedly this is to keep the wiring loom cool.

What the shroud as a whole does, is
1) prevent hot air recirculation in the front of the engine.
2) allow a round fan to draw air through a square radiator evenly. This improves cooling by 21.5% minimum. The bigger the radiator / smaller the fan diameter the higher this figure will be.

Got hot after new thermostat and towing

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