How can I keep my 2.9 cool?

[jkufen]

I tried to search through the forum for threads but really didnt find anything that answered my question. What can I do to try and cool down my 2.9? I never had an issue with the heat before but over the past few weeks it has been running hotter than usual. We all know that the 2.9 is notorious for running hot. I flushed my radiator and put new coolant in the radiator. Is there a different degree thermostat I can put in it? Would an electric fan be better? What are some of yalls tricks that yall used? I spend on average 2 days a week in the mud which usually involves me and the B2 at high rpms so I really want to make sure that I can do what I can to help keep it cool as possible.

 

[superds]

How do you know it's running hot? What temp is it running at? Is it staying around 210 F? Are you basing this on the factory gauge? Are you sure it still works properly?

One thing you can do is upgrade radiators. Spec out an HD radiator from a 90-92 4.0 Ranger or 91-94 Explorer (other models/years may work also, but I know those are a pretty straightforward swap, only the bottom mounting holes need to be modified slightly to work in your BII).

The electric fan probably isn't much of an upgrade for cooling capacity. Most aftermarket electric fans don't flow as much as a factory mechanical. Make sure the fan shroud is in place, if not that will make your cooling system less efficient since the air isn't being directed through the radiator as well.

 

[Twister]

If you want to run an electric fan, grab one from a Taurus, they move tons of air.

Sent from, wait how did this get here?

 

[jkufen]

I am going by the factory gauge. I assume its working properly. It rises like it should but no im not certain that it is exact.

 

[adsm08]

The factory temp gauge is an idiot light. It only knows cold, OK, and too hot. If it says C, it is cold. If it is between the lines, it is OK, if it says too hot, then you have a problem.

 

[yehaadon]

I also flushed the radiator on one I had, took it out flushed it seemd ok. got warm again, a guy from here told me to feel my radiator for cold spots, and sure enough , that was it. I bought a new radiator, hoses and transcooler, changed thermostat to the cooler one and never had another problem. The old one would work alright if I was on the hwy, at a regular speed, but slow down or stop and it started warming up. these motors will not take heat well, If you keep them cool they will run great.

 

[jkufen]

What degree thermostat should I get? I havent changed the thermostat yet. I have seen the different degree thermostats but wasnt sure if higher the degree the cooler it would run or the hotter. My factory gauge stays in between the normal lines but it stays up at the 3/4 mark on the hot side.

 

[Shran]

One thing you can do is upgrade radiators. Spec out an HD radiator from a 90-92 4.0 Ranger or 91-94 Explorer

NO, do not do this. The factory radiator on a 2.9 is PLENTY. A 4.0 radiator is not an upgrade, you are gaining a huge amount of coolant and a 2.9 won't keep it hot enough. The coolant temp sensor will read cold all the time and your gas mileage will go straight down the shitter.

Myself and others have done this and it turns a 25mpg engine into an 11mpg turd!

What degree thermostat should I get? I havent changed the thermostat yet. I have seen the different degree thermostats but wasnt sure if higher the degree the cooler it would run or the hotter. My factory gauge stays in between the normal lines but it stays up at the 3/4 mark on the hot side.

Factory spec 195* thermostat should be fine, if it's overheating with that, you have a problem elsewhere.

 

[superds]

Eh, the Explorer radiator is working ok for me, the one I used was for an Explorer with a manual transmission and A/C, single core. It's aluminum/plastic tank and it was significantly less expensive than the copper/brass ones available. Engine heats up to normal operating temp (as indicated by my aftermarket temp gauge) and stays pretty close to normal.

I also don't daily drive this vehicle and I've never checked the fuel economy on it so I dont know what effect radiator would have on fuel economy.

 

[kimcrwbr1]

It could be a few things, plugged radiator, thermostat, fan clutch or water pump impeller. Have you changed the radiator cap lately if the system goes into a high pressure where the overflow is not working correct that can also cause cooling issues. I would start with the cheap stuff first radiator cap. thermostat 195 deg and fan clutch. When your running high revs at slow speeds yes you need to increase air flow through the radiator to exchange the heat it produces. Also was there alot of rust in the radiator if so there is probably alot of rust in the block also. get a new water pump and blast the block out good with high pressure water before you put the new pump on. If stock its a 27 year old motor do you know how old the water pump is?

 

[jkufen]

No not real sure how old the water pumps or thermostat is. Today it ran nice and cool right in the middle of the gauge. I am wanting to replace the thermostat and water pump but since it does keep me ok most the time I have bigger fish to fry unfortunately. I have heard the horror stories with high heat and the 2.9s so I am cautious

 

[AllanD]

The 2.9 is not "Famous for running hot" it is however famous for cracking if it is run hot.

What it is less than famous for is instrument issues.

THE wire to check is the ground between the back side of the driver's side
cylinder head and the retaining stud on the wiper motor

This ground is often the culprit.

But remove, wire-brush then reinstall the sender unit


DO NOT use "Teflon tape" on the sender unit, it MUST make good
electrical contact.

 

[lil_Blue_Ford]

NO, do not do this. The factory radiator on a 2.9 is PLENTY. A 4.0 radiator is not an upgrade, you are gaining a huge amount of coolant and a 2.9 won't keep it hot enough. The coolant temp sensor will read cold all the time and your gas mileage will go straight down the shitter.

Myself and others have done this and it turns a 25mpg engine into an 11mpg turd!



Factory spec 195* thermostat should be fine, if it's overheating with that, you have a problem elsewhere.

First I've heard of this....

I put a 180* T-stat in my choptop and a radiator out of an Explorer (no modifications required other than I had to change my lower rad hose). I've been running an aftermarket temp gauge and gets up to 180* and stays there no problem. I also put a new water pump on it a couple years ago. I was getting 18 mpg with it around town with the old bias ply 33's and all. And yes, I did correct for tire size and gear ratio.

 

[4x4junkie]

Yep, that's blasphemy.

I have the two-core Explorer radiator ('94 w/auto & AC) and a 195° thermostat for my BII's 2.9L. I get low-20s MPG easy on the freeway even with my big 35" MT/Rs.
An engine not reaching it's proper operating temperature means there's an obvious thermostat problem (that or it's like -55° out). The thermostat is supposed to allow only a certain amount of coolant through the engine for it to remain at the thermostat-set temp (the amount of coolant within the radiator itself is irrelevant).


To the OP,
The Explorer radiator swap is all bolt-in IIRC other than you have to swap the lower radiator hose for it to mate up with the Ex radiator's angled lower port. Also, I've heard some say their upper hose gets pretty close to the alternator after the swap, however mine seems to have plenty of clearance (my BII had the swap already done when I got it).

 

[Elutheros]

I love the Explorer 4.0 radiator and I'm running an electric Volvo fan. The only issue that bugs me is cruising at around 70, the temp may climb up to the "o" in Norm on the guage--not all the time and not because of outside temp. I think the water pump starts to cavitate sometimes and can't flow water as it should. At low speeds the electric fan does a great job of keeping the temp on the "R" or below it in the Norm range.

 

[PetesPonies]

First of all . . wow, do we have some inaccurate info being slayed around as gospel. A properly designed cooling system will overcool an engine if allowed. If it cannot do that, then it is not properly sized. Fact, forget everything else, this is gospel.
Second, as junkie said, the thermostat will then control the operating temperature of the engine by controlling the temperature of the coolant. Typically the operating temperature will be about 7 degrees over the rating of the thermostat.
Adding a 4.0 radiator is a decent choice, however a proper operating 2.9 radiator should keep a proper operating 2.9 engine cool. So you decide where the problem is. The 4.0 radiator will certainly do the job and WILL NOT cause any temperature problems with the 2.9. I happen to be using a 4.0 radiator with my V8 swap and it does just fine.

 

[70roadrunner]

you said you go mudding a couple times a week. is the radiator clogged with mud? have a buddy shine a light through the radiator and see if you can see the light. if you cant see through it, air cant flow through it

 

[4.0B2]

I like the Taurus 3.8L e-fans... wire the low side on a temp switch and wire the high side on a toggle switch and to your a/c... The low will move enough air to keep it cool for normal driving in most cases and the high is great for trails or really really hot days.


but yes, you should be able to use the stock system and keep it cool. Try bypassing your heater core and doing it again, if it's partially stopped up... you'll see the difference. maybe have a radiator flush done... check all your hoses and stuff.

 

[Shran]

A properly designed cooling system will overcool an engine if allowed. If it cannot do that, then it is not properly sized. Fact, forget everything else, this is gospel.
Second, as junkie said, the thermostat will then control the operating temperature of the engine by controlling the temperature of the coolant

This is key information here - properly designed cooling system is the important part.

The 4.0 radiator swap ads a large volume of coolant, given fact. Therefore it takes longer to heat it to operating temperature. Because of this, the thermostat stays closed for longer intervals, allowing the water in the radiator to cool much more than it normally would. When the thermostat opens you get a huge rush of cold coolant.

Keep in mind we are talking about fuel injected engines that partially rely on coolant temperature to set the fuel/air mixture. We're not off in carburetor land where anything goes. That huge rush of coolant has a dramatic effect on your coolant temp sensor.

Y'all can tell me I'm wrong all you want, I've done the swap three times in three different vehicles with the same results. There is some science behind the reason why every vehicle doesn't have a huge radiator.

 

[PetesPonies]

I initial burst of cold coolant into the system may temporarily cause the thermostat to close, but this is normal. It happens anyway when they first open. And this goes away as the temperature settles in. Not an issue.