1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Engine Fan Positioning And Airflow

Discussion in 'Intermediate CJ-5/6/7/8' started by Stakebed, Sep 30, 2022.

  1. Oct 4, 2022
    Stakebed

    Stakebed Member

    Lake Co....
    Joined:
    Aug 2, 2022
    Messages:
    656
    A lot of questions, I'll try to answer them all.

    1-ideally past the engine and under the vehicle. Yes, the engine compartment is crowded. My mechanic (who is a Jeep guy) says he's seen more crowded engine compartments that don't have airflow/cooling issues. I've wondered about airflow on the passenger side with those dual compressors and dual battery box.

    2 & 3 Hwy 29 between Kelseyville and the Hwy 175 turnoff. A long-ish steep hill right outside K'ville and then fairly flat but still uphill grade after that. Maybe I'd have to video record the route and post a link to YouTube.

    3-As soon as I turn off Hwy 29 onto Hwy 175, the road is slower. Max speed is 45 but most is 35 and less. Very twisty, country road. Cools down on that road. Down to 180° within a few miles. BTW, driving into town, the reverse on my overheating route, no engine temp over 180-ish.

    4-No

    5 & 5 again-No

    6-with grille in place, I cannot get my fingers into the radiator. I have had the fan suck a paper rag into the radiator area.

    7-Yes I can hear the fan clutch engaging the fan when cold and when hot.

    8-I keep forgetting to check ign timing.

    9-Radiator was rodded out in Aug. Shop owner said it was unnecessary. Maybe 5% plugged before he worked on it.

    10-Coolant new when I reassembled cooling system late Aug. New hoses and thermostat as well (even though you didn't ask).

    11-Well that is a puzzlement. I see one sensor on the thermostat housing. I'm thinking that's for the fuel injection. Not sure where the gauge sensor is...yet. As you noted, it's a crowded engine compartment.

    12-Tried to. As I stated, I've probed various areas. Cylinder heads are the hottest. Intake manifold and thermostat housing are cooler than the heads. Radiator is coolest at maybe 187-190 when gauge shows 210. I've now forgotten the other probed numbers as I tested a month ago.
     
  2. Oct 4, 2022
    Stakebed

    Stakebed Member

    Lake Co....
    Joined:
    Aug 2, 2022
    Messages:
    656
    1 month old for both.
     
    Jw60 likes this.
  3. Oct 4, 2022
    Norcal69

    Norcal69 Out of the box thinker 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Northern California
    Joined:
    Sep 6, 2014
    Messages:
    3,549
    I have driven the roads that you speak of.
    Your answer to my post just described perfect cooling system operation.
    Verify the timing is correct and leave the rest alone. Everything is operating as it should.
     
    Last edited: Oct 4, 2022
    Downs likes this.
  4. Oct 4, 2022
    Stakebed

    Stakebed Member

    Lake Co....
    Joined:
    Aug 2, 2022
    Messages:
    656
    During test at mechanic's shop for combustion gases in coolant, he siphoned out coolant to get it below radiator neck. While running the engine, no bubbles. LOTS of coolant flow as well. The moment he shut off the engine, bubbles came up into the radiator neck. His test device showed no evidence of combustion gases in coolant.
     
  5. Oct 4, 2022
    Stakebed

    Stakebed Member

    Lake Co....
    Joined:
    Aug 2, 2022
    Messages:
    656
    No way. You drive Lake Co? Gee, should I feel sorry for you? :D
    I'll have to respectfully disagree about normal function. I have a LOT of vehicles that do not increase in temp over that route.
     
  6. Oct 5, 2022
    73cj5

    73cj5 Member

    Maine
    Joined:
    Jan 15, 2004
    Messages:
    903
    If it's getting too hot at highway speeds its not an issue with the fan / clutch. The fan and clutch really don't do much over 15/20 mph at that point the air being pushed through the grill significantly outpaces the fan.

    How is the condition of the radiator? Is the correct one for a V8? Anything blocking the grill?
     
  7. Oct 5, 2022
    Ol Fogie

    Ol Fogie 74 cj5 304, 1943 mb

    Southern...
    Joined:
    Nov 24, 2019
    Messages:
    1,765
    Just pondering your problem.:confused: have you replaced any gaskets on the engine lately? like head gaskets, water pump, or intake gaskets. My dad changed a head gasket once on a truck engine during the winter .No problems. Then in early summer the truck would run hot at highway speeds. Long story short after many trials finally found the replacement head gasket had smaller holes where the coolant passed from the block to the head reducing the volume flow. :bananatool:.
     
  8. Oct 5, 2022
    Stakebed

    Stakebed Member

    Lake Co....
    Joined:
    Aug 2, 2022
    Messages:
    656
    Freshly rodded out as I wrote above.
    Yes it is.
    Yeah, the winch is kinda large. A Warn HS9500i fast speed. I'm looking at trying to re-engineer the mounting system so i can lower it a couple of inches. 20220923_145525.jpg

    That's a good story.
    I have only replaced the thermostat gasket. But after steam cleaning, I can see the cylinder heads are dark blue. So maybe the heads were serviced in the past. I dunno.
     
  9. Oct 5, 2022
    Sierra Bum

    Sierra Bum Member

    The High Sierra
    Joined:
    Oct 23, 2017
    Messages:
    329
    I'm not chiming in here as some sort of expert, but only because I've been down the searching-for-cooling-gremlins road a few times. My jeep does not have a V8 nor is it an intermediate. However I did have the run-away, running-hot-slow-creep, which made me uncomfortable. It would normally run fine, but get too hot for my tastes on long climbs both on road and 4-wheeling.... 200, then 210, then 220...and so on. I never overheated only because I would always get nervous, stop and cool off before that happened. Its a long story but I tried everything I could think of. I was just wanting it to stabilize around 190 and stay close to that.

    The abridged version in phases of experimentation and in no particular order: Clean out system; Replace old parts such as thermostat; New radiator; New fan; New shroud; Fan spacer; Different fan; Electric puller fan; 2 electric puller fans; High flow water pump; etc, etc... And things continued basically the same. So I removed the winch. No change. Frustrating.

    For me, under-hood temps are HOT because I have headers. And so reluctantly I installed hood vents/louvers. That helped with air flow and under-hood temps. I can feel that hot air escaping. In a limited space environment, I was negotiating the subtle nuances of heat, heat retention, heat dissipation, air flow, etc...

    In the end, the start of the solution was a combination of new everything listed here. New aluminum high volume 3 row radiator; Mechanical fan with sealed shroud 1" off radiator; high flow H20 pump; Hood vents. ------with all this the problem improved but still ensued.

    So finally, I custom installed an additional high CFM electric fan on the front of the radiator as a pusher. That did it. I put it on a manual rocker switch and since I'm used to obsessively watching my temps, it works for me. I turn it on when I want it (when it gets to around 200). I can leave it on when I'm parked to cool things off. A guy could pretty easily set it up with a thermostatic switch to come on-off automatically. In hot conditions on the trail, even on slow, working-hard, tough climbs it's running around 190. And so YES, It has both mechanical and electric fans. It also has a pretty beefy electrical system, so no issues there. This is not everyone's ideal solution but it works well for me.

    If you want to try it, affectionately known as finger cutters/choppers, these things move some air : PermaCool
     
    Last edited: Oct 5, 2022
    Stakebed likes this.
  10. Oct 5, 2022
    73cj5

    73cj5 Member

    Maine
    Joined:
    Jan 15, 2004
    Messages:
    903
    It's blocking a good portion of the grill.

    A lifted V8 Jeep running fast up a grade with thin Colorado air is approaching the limits of the factory cooling system to begin with.

    Try temporarily removing the winch and see if that makes a difference.
     
    Stakebed likes this.
  11. Oct 5, 2022
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
    Joined:
    Aug 3, 2003
    Messages:
    9,754
    High altitude will result in an over-rich mixture. I "blued" the exhaust pipes on my Harley that way.

    Check your plugs to see?
     
  12. Oct 5, 2022
    Stakebed

    Stakebed Member

    Lake Co....
    Joined:
    Aug 2, 2022
    Messages:
    656
    I'm not in Colorado. Lake Co, CA. 1600-2600'.

    I do intend to remove the winch temporarily as a further test.
     
  13. Oct 7, 2022
    Downs

    Downs Rattlecan All The Things!

    Hunt County Texas
    Joined:
    Jul 25, 2020
    Messages:
    579
    At the speeds he's running and worried about his 215 temp, no amount of extra fan will help, at those road speeds there's already more air moving though the grille and radiator than any fan could hope to move. The viscous fan clutch is a proven design that works, and on these Jeeps was actually part of the heavy duty cooling package or if you had optional AC. If you had a spacer and fixed fan, that was considered standard duty. If he was having low speed and idle over heating issues I'd lean towards an airflow issue, but I wouldn't say swap to a fixed fan I'd be saying take a hard look at his fan clutch.





    Your engine temps are fine, and you will chase your tail to the ends of the earth on this if you obsess over it, I see it all the time in XJ groups. It sounds from your description of your test route and speeds that the system is doing exactly what it's supposed to do. At the speeds you're talking about your "overheating" happening, your fan is playing almost no role in cooling at that point. There's far more air coming though the front of the Jeep than a fan could hope ot move.

    FWIW, when these left the factory they would have been running a 195 thermostat and by the FSM the thermostat would have been considered to be functioning normally if it was "fully open" at 219 degrees. There's a chart from Continental Engines floating around that shows the relation between coolant temperature and increased engine wear. A 180 is the lowest I would go for the sake of that. Sounds like you already have a 180 in it from the sounds of previous posts.

    Now there's a chance that the thermostat isn't opening fully, I'm not sure if it was tested prior to install but a 180 won't fully open at 180, 180 is when it starts to open, then it's fully open around 195 or 200.

    Here are the steps for testing a thermostat from the Factory Service Manual

    Another thing. A "rule of thumb" when troubleshooting cooling system is:

    If it's getting hot at idle or low speeds, it's typically an airflow issue. Clogged radiator fins, bad fan clutch, loose drive belt, stuff like that.

    If it's getting hot at higher speeds, it's typically a water flow issue, stuck or partially open thermostat, collapsing coolant lines (the lower can collapse at higher engine speeds), cloogged internal passages in the radiator or engine, bad or going bad water pump, stuff like that.

    Now that's not a hard fast deal, there are things that could cause overheating all time that are in both of those lists if it's bad enough. Just something to think about.

    As for sensor placement. The thermostat housing is the stock place the original gauge would have gotten it's info from, I'm assuming yours is getting the info from there as well. So that's another thing to keep in mind, that by the time the coolant has reached the thermostat, it's as hot as it's going to get, it's already made it's trip though the block and heads and has picked up as much heat as it can before getting there. So your coolant temps going into the water pump from the radiator are going to be much lower. I'd suggest grabbing an IR heat gun and "shooting" temps at various spots. It might make your anxiety subside to see how cool the coolant is in various spots of the route.
     
    Dale Park, Stakebed, Fireball and 2 others like this.
  14. Oct 12, 2022
    Keys5a

    Keys5a Sponsor

    Florida Keys
    Joined:
    Jan 23, 2014
    Messages:
    4,170
    Down’s reply above touches on another variable that hasn’t been discussed. That is the water pump itself. I learned a lesson decades ago that has always stuck with me.
    My mom’s BMW 2002 (only 4 or 5 years old at the time) had the original water pump start leaking at the weep hole. No overheating issues, just a small leak. I ordered a new pump (aftermarket) and installed it. No more leaks, but the car ran hotter at highway speeds. The faster, or longer the trip, the hotter it climbed, never quite reaching the red (hot) zone of the gauge. Previously, the car almost never climbed past the half-gauge mark. This went on for a month.
    My dad brought home a factory BMW branded water pump and I installed that. The temp never ran past the mid-gauge point after that.
    There are “better” high flow water pumps available for AMC V8s. I have one installed on a 360 (Flow Cooler maybe?) Your rise in temperature at road speed on uphill climbs isn’t very alarming to me, but tells you are near the cooling capacity of your components. If you are really bothered by the temp rise, look into a high performance/ high flow water pump.
    By the way, I am a believer in fan clutches provided they are working as designed, and ALWAYS have a close-fitted shroud for the radiator.
    -Donny
     
    Norcal69, 47v6 and Stakebed like this.
  15. Oct 13, 2022
    Norcal69

    Norcal69 Out of the box thinker 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Northern California
    Joined:
    Sep 6, 2014
    Messages:
    3,549
    Good thinking.
    I have an Edelbrock water pump in the stack of components for my 440" AMC build.
     
    Stakebed likes this.
  16. Oct 14, 2022
    Dale Park

    Dale Park Member

    Utah
    Joined:
    Feb 15, 2021
    Messages:
    112
    I would like to know what "high flow" water pumps Keys was talking about. You could also have a water pump where the impeller is the issue and might be free wheeling on the shaft where it does not spin up after a certain point. I still think your issue is either the fan clutch or water pump or thermostat Your temp spread was quite a bit different between radiator, thermostat housing and heads.
     
  17. Oct 14, 2022
    Stakebed

    Stakebed Member

    Lake Co....
    Joined:
    Aug 2, 2022
    Messages:
    656
    As a reminder, plenty of water flow. 20220914_151001.jpg

    I cannot load my video of the water flow. Trust me, LOTS of water.

    In other news, I drove the Yellowjacket to SF today. The Waldo Grade is a loooong steep grade. But with fog washing over the Marin headlands the air temp was probably in the fifties with Lots of moisture. Engine temp never went over 180°.
     
    Ol Fogie likes this.
  18. Oct 15, 2022
    Caharry73

    Caharry73 New Member

    Boise, Idaho
    Joined:
    Sep 24, 2022
    Messages:
    5
    Most people on the AMC forum as well as people in my AMC club say that an AMC can run 220 all day long with no problems, anything above 230 is when you should get cincerned.
     
    Norcal69 and Stakebed like this.
  19. Oct 15, 2022
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
    Messages:
    12,529
    Maybe you posted it but what is your coolant mix ratio? Full water? 50/50? That can make a significant impact on cooling efficiency.
     
  20. Oct 15, 2022
    Stakebed

    Stakebed Member

    Lake Co....
    Joined:
    Aug 2, 2022
    Messages:
    656
    50/50 with long life antifreeze
     
New Posts