CJ7 360 still overheating

onestophop

CJ7, 360 Howell EFI, 727 Auto. Over the last two years (when I got it on the rode) the jeep overheats in about 35 minutes on the road or a little longer if at idle. In winter up to an hour. It has a new 3 Core, new waterpump, currently 160 degree thermostat and tried 195. Reptuable service center tested for exhaust gasses and said none were present. I sent the heads out last week to be checked. They rebuilt them checked for cracks. He said the heads looked good other than a couple of exhaust valves were a little burned. The block was supposed to have been boiled, but I took out one of the drain plugs and there was pieces of rust or something clogging the hole. I pulled the engine and popped the freeze plugs and flushed it all out. It runs for about 40 minutes still overheats. New hoses with springs, tried bypassing the heatercore. I really don't know what to do next. No body lift, mechanical fan, fan is 1 7/8 from center of radiator.

jeepsr4ever

Try replacing your fan...sometimes its something simple. You could have problems elsewhere but I would start there

onestophop

I had the oe clutch stlye on and I switched last year to an aluminum flex fan. Hasn't change the overheating issues though. Even the shop that did the test for exhaust gasses said they wouldn't diagnose any more because it isn't factory drivetrain. Well it was factory in the waggy it came from. Called several other shops to here that needs to go to a 4wd shop because it has 37's. Come on. I would drop it off at a reputable shop to fix this problem if one was willing to do it. I'm in the St. Louis/Illinois Metro area and still don't know where to take it.

jeepsr4ever

hmm have you tried changing your timing?

onestophop

Yes, but I did advanced the timing just a little because with the Howell EFI system it seems to run better. I still don't think it is as good when I had my Edelbrock 4bbl for that's for another topic. I know it could be something simple, but maybe I'm overlooking it because I seem to keep rechecking the same things.

toolong

don't take any offence, but did you bleeded air from the system properly? I say that because, been there done that! now I use a device who looks like a big funnel connected on top of the radiator and full of water and I leave it on top until the engine is at running temp or no bubbles coming up, success every times now for me and my friends, just my 10 c.

youdidwhat

could your temp sensor be wrong... do you have a reverse rotation pump? I.E. engine is counter clock wise, pump is clock wise. or the fan flex blades have flattened... HUmmm sounds like you just about replaced everything else..

Goose

Ok.. seems like we need a little more info..you say it will overheat in 30-40 minutes?? that seems pretty slow for a mechanical issue.. (blockage etc..) I would expect it to begin overheating as soon as the thermostat opened in that case. also when it does overheat.. does anything you can do cool it down?? like downshift to bring the rpm up or anything like that?? Cause the odd part about what you are saying is 35 minutes?? if it will hold the temp down for 35 minutes it should hold it forever.. It really sounds to me like somehow you are just becoming heat soaked and unable to dissapate (I know it sounds like an ad for kaopectate) and I would just go back over all the system.. without ever saying naaah I replaced that it isn it.. cause after replacing 5 bad pumps in a row on a 3.5l intrepid I take nothing for granted.

ironman_gq

could the efi be leaning the motor out for some reason like a bad o2 sensor. that could cause the motor to overheat. the ecm could also need to be adjusted to correct any fuel problems

AMX69PHATTY

Yeah, if it goes lean it will get hot, and you mentioned some burnt valves. Running rich smells bad, but runs cooler. Doesn't the ECM run in "automatic" mode until the O2 sensors gets heated up to temp ? Something like 800 degrees before O2 takes over and controlls mixture. Maybe once it kicks in, it's leaning it out and making it get hot ...... Also when started cold, it richens the mixture like a choke on a carb. As it warms up, it leans down the mixture. With an EFI, engine temp, Manifold Air Pressure, O2, etc all change mixture. Maybe one of these inputs are falsely leaning out the mixture. I forget which exhaust gas increases as the mixture gets lean.

Goose

Yea, I would also wonder about the mix.. it just doesn't seem to fit with the "cooling system " type symptoms

Holeshot

Does it still have the fan shroud? As far as replacing the fan - wouldn't it be cool (anyway) to have a high CFM electric fan with a thermostat???

onestophop

I've driven it several times now on the road and it may be the fan flattening out. I took it out for about an hour on the trail and didn't overheat. I need to check this more though. I changed a few different thermostat's around without checking each one individually but I don't think that was it. Usually it overheats on the road and maybe I don't let it cool down long enought before hitting the trail and it overheating again. I'm trailering it this weekend to wheel and will post up with results. Thanks for the posts.

warhammercustoms

I realize this is an old thread but I need to make a few posts before I can post pics on this site. What dis you end up finding on this problem. You never did say if you were running the shroud. Jeeps with AMC V8's WILL overheat or run hot without the fan shroud.

Patf10

i dunno i have never ran the fan shroud and i have never had a problem over heating. Maybe with the two row rads. I have talked to a few people who dont run the shroud and have no problems

fifesjeep

On the old 304, clutch fan etc... no shroud she maintained 180-185* I did have a overheating problem with this 401 (Virgin Bore) when I first got it... it had some issues... Mostly timing, she was running lean, the carb was siliconed to the intake and the fuel dissolved the silicone, A can of B12 let me know real quick... the intake valley seals weren't sealed, they used the rubber seals instead of a good 1/4"-5/16" tall bead of high temp silicone. It had a shroud but the shroud didn't cover the fan so it wasn't drawing enough air through the fins... It had a flex fan on it with a short spacer... I yanked that stuff off and put on a dual flex-a-lite fan... All good now... Before I did anything to the motor it would idle for about 15-20 minutes and would get up to 210*+... I rotated the distributor about 90* so that I could get more timing to set-it where it ran smooth etc... I have a Holley Offroad Truck Avenger 670 and I'm always adjusting the carb... One month it'll be alright the next month or two she's running kinda rich... I have the fuel/air mixture screws marked to be aligned to the carb... As a matter of fact she's running a little rich, not bad though.. better a little rich than too lean.. :oops:

hohner0006

Try replacing the waterpump....I had a similar problem and (after replacing everything else) replaced the WP and problem solved. The only thing we could figure was the impellor was loosening up at the shaft at higher temp and not spinning correctly. My second time (on a different vehicle) ended up being a partial blockage somewhere inside the system. I used water and a high pressure air hose to back flush the system multiple times. Some crap ended up coming out of the engine and my heating issue was solved. Good luck!!