Swap done, Dauntless runs hot down road

One of the biggest reasons behind putting the Dauntless in my CJ2A was because the old L-head ran hot when I tried to go down the road. Lack of power was the other reason. The power problem is cured! WOW!

Unfortunatley I'm still getting up to 200F before I'm even a couple miles from my house. I don't know how hot it will get. I haven't tried any long drives. I saw 220F on the return trip. It seems to cool off really fast if I slow down, but the temp comes right back when I speed up.

Here's my data:

The radiator was replaced when I got this Jeep 2 years ago and it saw limited use with the L-head. It's a 2 core. I had the lower outlet swapped to the passenger side for the Dauntless last week. There has been no damage to the radiator at all. It's still basically like new.

The engine is out of a Commando and it seems to run fine. I have done the bare minimum to the motor. The bypass hose looked bad, so I changed it out. The water pump was really stiff so it got replaced with a rebuilt pump from Napa. The carb was rebuilt becuase it had troubles.

I have no idea what thermostat may be in this motor. I doubt that it's stuck becuase the radiator gets plenty hot, but I may change it anyways.

The 'horse hair' between the grill and radiator was long gone. I put some floor mat material in it's place this afternoon and tried again, still got hot.

Currently there's no fan at all. I need to pick up some new nylon mount ties for the electric fan. It's only fits in front of the grill. I will get this done tomorrow night. I would think that th air going through the grill would be enough when driving at 50 mph. Am I wrong?

There's no unusual exhaust restriction. I'm using the stock manifolds and I pieced my system together from 2" mandrel bends. Turbo muffler.

Does anybody have any ideas other than thermostat, fan and flush the system? How hot does your Dauntless run on the road?

Does anyone have any reccomendations on a really good radiator flush product? When I was a kid I used to use some stuff that came in 2 parts. You put part A in the radiator with water int he system and idled for 10 minutes, then added part B to neutralize the PH of part A, idled a few more minutes and then dumped it. I remember this stuff working great, but I haven't seen anything like it for years.

 

You have to run some sort of fan to get the air through the radiator. If you can get your electric fan working and it still gets hot, I would suspect the thermostat.

 

180* is stock. you need a fan to cool the radiator, other wise you are limited to about 35mph to get ideal cooling. also what is your coolant/water ratio? should be 50-50 to get best results. water pump might be spinning too fast/slow for :v6:/2 core radiaitor.

 

Thanks guys. I'll put the fan in it tomorrow.

Coolant is 50/50 - I'm in Minnesota We had snow flakes falling from the sky last week.

I'm not taking it 4 wheeling until memorial weekend, so I've got some time to work out the bugs. I'll try the fan first then dig deeper if I have to.

 

obviously the fan and the t/stat would be the place to start, as they both need attention/replacement.
one item often overlooked is the radiator cap
the 4 cyl flatfender radiators used a large diameter, low pressure cap.
4lb and 6lb caps were very common
as recently as 2 years ago I found a 10lb, large diameter cap to fit mine.
This was not that easy to find, so keep looking for a good parts guy that can help you.
every pound of pressure knocks off 3-4 degrees in temperature
I recently (this month) replaced my 20 year old radiator with a new 4 cyl radiator; along with the lower outlet mod, I also had my radiator modified (new neck opening) to accept the smaller standard size rad cap, and can now run a 16lb cap.
If you can "block" off the top and side gaps bewteen the radiator and grille, this will help also as air flow will go the path of least resistance.
The changes I have made should help with highway speeds, 5:38s, and 31" tires. I would only get warm while towing the Bantam on warm days out here; never got hot while Jeeping.
I have run 5, 6, and 7 blade fixed steel fans over the years; always figured more was better.

 

Stock on the Dauntless was a 195* not a 180*, I run a 180* though and recommend it now.
At Tellico it would run 195-230 in the woods but never knocked pinged or even idled rough, on the highway at 70 mph driving the 175 miles home it rarely made it to the 180* mark and going down a long hill would actually drop to 150* on the temp gauge (new Autometer) Flush the system good and put your fan on. Also where is your temperature probe located on the engine, they actually varied, the 70 and 71 models were on the back of the block on the passenger side, others were on the thermostat housing. I actually believe that the back of the block gives a false reading at slow speeds as the water there is not circulated well and pools there at slow engine speed due to the water pump turning slow and not forcing the water out of this confined area!
I also run a 5 bladed 13" flex fan. i think I am also going to put an oil cooler on the motor to aid in cooling in the woods.

 

I did not know that. My radiator has the normal sized cap, but I had a 7psi cap on it. Ill throw a 16 psi cap on it and see what happens.

Good to know! A 195 degree thermostat would certainly account for the rapid rise to 200F. I'll pick up a 180 degree thermostat tomorrow.

Thanks again everyone. Hopefully these things will fix it.

 

I run a 4-5 psi cap on mine and run at around 185 all day (except when the brakes are locked up . But I do have that 2700 cfm fan that makes my jeep sound like a jet If the timing is out of whack, it makes the temp go sky high, might be something to check. Are you running the stock distributor, or HEI like mine?

 

I think there is a 180 in mine. It can get to 200 tho... Stock 4 blade fan on mine isn't even close to the radiator. Small electric stuck in front for those long crawl sessions. I would have thought that the air blast would have been sufficient as well.
-Hill

 

I've got the original radiator for the dauntless with the 180 thermostat and stock fan. However, I added an 1,800 cfm flexalite electric fan. Mine would run at 180 all day long until the daytime temps went above 80 deg. Then it would heat to just over 200. Now, when it gets to 200, I turn on the electric fan and it goes to 180 within a minute or two and stays there.

 

I've been flushing it all night. All Fleet Farm had for radiator flush was Gunk brand. Did that twice following directions on the bottle. Also tried vinegar once - couldn't hurt and might help loosen any calcium based scale. Got some crud out, but no huge chunks. Just silt.

After flushing I put in a 160 degree thermostat, thinking that a dramatic change would be good for diagnosis and I will put a 180 in later. Also put the fan on. Doesn't seem to be a lot better. Still creeps up at fast idle. Didn't even try to drive it.

I think the radiator might have a bunch of rust and scale in it from the old L-head. That motor was crusty inside the water passages. The radiator doesn't seem to be hot everywhere, but it's kind of hard to judge with my bare hands. The motor has one of those plastic back flush fittings in the heater lines. I'm going to try that tomorrow night. Seems a little plausible that it might help becuase it will be pushing water back in the lower hose with all the force my garden hose can muster. Hopefully any scale got looser tonight, rather than sliding further in. Basically, I'm planning on one more night of denial. If (when) nothing gets better tomorrow night, I'll give in to reality and have a radiator shop rod out the cores

By the way, noticed that it's a three core not a two core. That really should be enough - if it was working right.

 

marginally speaking, you need 225 square inches of radiator surface fin area (H x W)
my core meausres 20 x 13 (approx) which equals 260 square inches
19 x 13 equals only 228 square inches
so size does matter
obviously bigger is better

 

If the radiator is flowing, as evidenced by water moving quickly once the thermostat is fully open and you are still running hot, then I would look for a blockage somewhere. The 225 is not a difficult engine to cool. I used my Lhead radiator for a couple years before switching mine out and that 4 cyl radiator worked fine except when crawling. However, you said something about the radiator not being hot everywhere. Cool, or cooler spots in it can mean some blockage there where water isn't flowing. I would be sure and check behind the thermostat as well after your done flushing. the top hose is the return hose and anything that could have come loose could be sitting behind the thermostat.
Beyond that, you definately need a fan. If you were running hot before the swap, your problem is in the radiator, and with a lack of a fan, that will only get worse with a larger engine.

 

It's flushed. I'm wet, but it's flushed. Got this idea from reading the FSM. Seems they used to use a flushing system that combined water with blasts of compressed air. Hooked the hose up and ran it full blast, then opened the pet**** and put the air gun over the pet**** and pulled the trigger. Old Faithful erupted and I was thankful that it was at least 66 degrees here. Repeated several times. I'm pretty sure chunks of stuff came out, but it was hard to see it in the eruption.Found one big chunk that must have been stop leak. The rest of it just disappeared with the water. I'm sure there was rust and scale too.

The radiator flows great now. I can stand there with the thermostat open and rev the motor to the redline with the cap off. The water just rushes by faster. There's no restriction to flowing down the tubes at all as far as I can tell.

It still creeped up to 200F though. The last thing on my list is a much better fan. The radiator was plenty hot, there just wasn't enough air to remove the heat. I'm going to order the monster fan Oldjeep runs right now. I suspect that will be the end of my problems. I'll switch back to a 180 degree thermostat if the fan is able to keep things below that temp.

Thanks for the help guys.

 

Check the lower hose. It should feel cooler than the upper hose (and top of radiator). Just another way af varifiying if it's cooling enough.