258 cooling prob

[MacGyver]

I am running the 258 I6, I got from Gopher motors about two years ago. Since then I have removed all of the emission controls, the catalytic converter, and replace the stock air cleaner assembly with a K&N air cleaner and filter. The engine runs amazingly well!

The Jeep runs real hot, doesn't overheat (until I get it off-road) just creeps up to 260 or so (right to the red). I figured, flush the radiator right? I bought all the right chemicals and flushed it very thoroughly, and then flushed it again. filled her back up with 50/50 mix, and she still overheats.

I am guessing bad radiator right? Maybe if I am upgrading, I should go with aluminum? how about different fan? Any thoughts would really help.

Thanks,

Jason

[jeepsr4ever]

Jason I have seen everything that can go wrong and overheat a 258 in my experience with them, lets see if we can go through a check list and check the simple cheap items


1. Fan shroud! gotta have it, also are you running headers?
2. Fan clutch..is it good?
3. Thermostat.....are yousure the dang jeep has one init, they over heat without them
4. Is your radiator clogged with mud
5. where are you at for timing?
6. how much of an overbore do you have
7. What size is you radiator ie.....2core....3core
8. does your oil look milky at all?
9. Whats your compression rating for your pistons?


260 is WAY to hot for any motor that uses conventional oils at 240 degrees oil starts to loose its lubricity. It is probly something stupid simple. A decent trick is to take and remove the 2 bottom bolts from teh radiator and loosen the 2 top ones add a .5" spacer between radiator mounting flange and front clip and bolt it back together (watch out for clearance) This tips your radiator slightly and gives you better air flow throught eh cooling fins of your radiator.

[MacGyver]

1. yes I have a fan shroud, no on the header.
2. The fan blows lots of air, so I assume its good. I could try holding it?
3. Cheap part, so I will replace it..see if this helps. It only has 15,000 miles on it though
4. radiator is clean, except I put a branch through it. Right between two of the verticle veins. No leaking, and the problem was there before the hole was.
5. I will have the local mechanic run a timing light, but that was just done about 15k ago, that was before the engine mods that I have done.
6. no overbore
7. its the origina stock radiator, I don't know what came stock however?
8. oil looks goos, no water in it.
9. I don't know the compression rating of the pistons, but there same as OE.

I haven't heard the trick with angling the radiator back, I like it though! kinda like the miliatry HMMWV?

[jeepsr4ever]

hmm i wonder about your radiator then, might want to try a couple of pints of super coolant as well

[281 quadcam]

i had nearly the same issue... i had no shroud, junkyard was empty and for 80 bucks i could do better things like not spend 80 on a plastic thingy.... so i pulled a big block 440 fan from an old mopar, just barely had to enlarge the holes for it to bolt to the water pump... a spacer for it to come away from the belts...

http://members.aol.com/imnotryan/post/fan2.jpg

never had another cooling issue... gained some power from the flex fans blades and lighter weight - but thats arguable lol :wink:

[mrtazwrench]

I'VE ALSO SEEN IT WHERE THERE IS ENOUGH COROSIN IN THE FINS THAT THERE IS NO HEAT TRANSFER FROM THE TUBES.

[Holeshot]

I would either buy a new one (nice aluminum crossflow for < $200) or have the radiator "rodded out", that's where they de-solder the top and bottom and shove a rod through each passage. Prob with that is that if the rad is starting to get "rotten". Another prob is that a lot of the guys that have been doing that seem to have developed health problems.

My 400 horse 360 used to get REAL hot, had the radiator rodded and never had another problem (matter of fact it runs too cold). Entirely stock cooling sys.

[jeepsr4ever]

281

Man that fan looks really close, Reminds me of my first 7 with a 6 and broken motor mounts, would pop the oil filter while it scraped the radiator when i lugged up hills.... :shock:

[mrtazwrench]

HAD THE CLOSE FAN ON MY 440 MOPAR, PILED THE BRAKES, FAN IN RAD, THE ONLY TIME THAT CAR NEVER MADE IT HOME, SPUN A BEARING IN THE 383 IT HAD STILL COASTED INTO THE DRIVEWAY THEN IT WAS LOCKED UP, ALSO HAD 2 TRANNYS GO STILL MADE IT HOME.

[mrtazwrench]

:shock: JUST NOTICED I HAVE A NEW RANK! :mrgreen:

[Rocky]

Does removing all the emission controls include removing the EGR? The EGR helps the engine run cooler, plus the carbs on EGR models are jetted to run with an EGR. This could be part of the source of your overheating.
Just yanking the emission controls off an engine doesn't always improve performance. (Plus, what one of us is so special that we can pollute more than everybody else??)

[MacGyver]

Does removing all the emission controls include removing the EGR? The EGR helps the engine run cooler, plus the carbs on EGR models are jetted to run with an EGR. This could be part of the source of your overheating.
Just yanking the emission controls off an engine doesn't always improve performance. (Plus, what one of us is so special that we can pollute more than everybody else??)

I haven't heard/didn't know that the EGR helps cooling? I thought the EGR just recirculated exhaust gases to further burn it off to a more purified pollutant?

I agree that I do not have the right to increase the pollution that is emitted by my 6 cyl. However, my priorities are not to create a vehicle that is environmentally friendly, rather I am attempting to make an off-road vehicle. If I can do this, and still minimize the pollution to the environment that's a bonus. I am a huge supporter of tread lightly and other responsible off-road organizations, and appreciate well-managed and responsible participants in this sport, I just have not yet evolved to make modifications to my Jeep to decrease pollution. I hope that I can one-day spend the time and money to create a pollution-free ORV.

Do you have some tips or tricks that I may start towards this now? I am looking forward to one-day swaping my carter carbed-258 for a clean-running fuel injected power plant, but money has not yet permitted this.

[281 quadcam]

i had about an inch there... i never encountered any problems in the offroad runs i made in it - however i do see your point...

just another option - perhaps what i did was better suited for a street jeep...

[Rocky]

The purpose of an EGR is to cool combustion by introducing a small and controlled quantity of exhaust gas into the fuel/air charge. It is not a device to burn off unburnt fuel from the exhaust. Not only does it reduce certain polluntants, but it also causes the engine to run cooler.
One air-cooled engine specialist I know runs individual temp sensors on every cylinder, and installs a cockpit controlled EGR which, when used in conjunction with a cockpit controlled aircraft-style oil cooler, gives the ability to push extra performance from the engine, while actually upping reliability.

EGRs can be both good for performance as well as helping to control emissions. Same goes for cats. (At low revs, a little back pressure is necessary to keep the incoming charge from blowing out with the exhaust...running a cat can sometimes actually produce more low end power.)
On a carbed engine, it's important to have a carb with the right flow and jetting for the engine. It ought to be in good shape, and tuned properly, as should the ignition system. A hotter ignition can help reduce emissions, by reducing misfires. (TFI or HEI, spiral wound wires, capcitive discharge ignition, etc. run w/ standard copper core, not platinum plugs. ...Platinum plugs fire more easily, so will give a surer spark on a standard ignition, but a standard plug fires hotter, so with enough juice, it'll give the better spark.)
If your vehicle came with an air pump, leave it on... or put it back on. It only uses a small bit of power, and in conjunction with the cat, helps remove a lot of pollutants.

Bottom line: if you're not racing, the small effect that many pollution control devices have on most engines is usually too little to be noticed. The gains to all of us in cleaner air are too great to overlooked.
For alternatives to carbed engines, look into EFI, or an LPG conversion.

[MacGyver]

Thanks for the tips Rocky, I will look into some of those mods

[frank]

It does actually overheat right, as in boiling over, spewing antifreeze?
Sometimes gauges are not all that accurate.

[281 quadcam]

the last couple runs before i decided to rip the 258 out for a ford small block - the temperature gauge would SHOOT to red hot as soon as i turned on the jeep - even before i started the motor... this is an instrumentation failure as sure as any...

be sure that you are also not experiencing an instrumentation issue... a bad transitor somewhere can cause it to fluctuate from hot too cold, or to read to hot, and back over a course of a few minutes... sometimes a gauge can report all kinds of strange things like fluctuation, slight or severe... not all instrument failures result in an obvious way like mine did.

[73hornut]

Hey Macgyver. I didn't see you mention what your thermostat is or if you have one. A common missconception is to run a lower thermostat, 160 instead of 180, if you are over heating. Either you are running to low of a thermo, or it is sticking open. The problem with running to low of a temperature thermo is that when your engine reaches that temp the thermo just stays open. Running a higher thermo lets the coolant stay in the radiator longer so it gets cooled down, Which is what causes the thermo to close. I run a 195 in everything I own and an overflow recovery bottle. If you aren't running the recovery bottle alittle coolant boils out everytime you shut off the engine after it's gotten warm. Eventually your coolant gets to low and you overheat alot easeir.

[MacGyver]

Thanks for all of the replies. I am running a 195 (it might have been 185?) thermostat, and I do have the cooling bottle.

tomarrow, I am looking at timing, and mixture. I think my Jeep is breathing a little better and may be running lean with all of the air leaks sealed up.