Classy Comanche Posted December 17, 2022 Share Posted December 17, 2022 Hey guys so this is one of those things that has started happening out of the blue. When I turn my heat on. Low, mid or high I will occasionally get squeaking noises that cease. It'll do it sometime later and cease again. I can't pinpoint it because it mainly does it when driving. I'm about 99.99% sure it's not the serpentine belt because it doesn't squeal when doing a cold start and its like 2 months old. I don't really know since I drove to work this morning scratching my head. Heat blows nice and hot. Make you sweat if you ain't careful. I didn't know if you guys had a idea or had this happen? Thanks! Link to comment Share on other sites More sharing options...
fiatslug87 Posted December 17, 2022 Share Posted December 17, 2022 Maybe the blower motor. Put a long screw driver on it and the handle to your ear (or a mechanic’s stethoscope if you have one) and listen for the noise. It’s under the expansion tank. Link to comment Share on other sites More sharing options...
Classy Comanche Posted December 17, 2022 Author Share Posted December 17, 2022 I'll have to do that on one of my days off. I did crank it up, put the heat on mid and let it idle in park and I was giving it gas and as I gave it gas 2 out of the 14 times I feathered it it would begin to squeal and stop or I would be going up rpms about 1100-1200 and it would squeal for half a second then quit. Definitely not saying it's not the blower motor but that is my observation. Tomorrow morning I'll drive to work with no heat, and be freezing admittedly. But for science! I'll see if it does it then. Link to comment Share on other sites More sharing options...
Minuit Posted December 17, 2022 Share Posted December 17, 2022 Check for oily residue on the serpentine belt. You may also want to check or have checked the belt tension. Is your AC operational? Throughout my MJ ownership, that's been the one consistent source of belt squeals - the refrigerant oil leaks through the front compressor seal onto the belt and pulleys. Link to comment Share on other sites More sharing options...
Classy Comanche Posted December 17, 2022 Author Share Posted December 17, 2022 So I can confirm 100% with no doubt in my mind that there is no squeak when the heat is off. It's quiet as can be. When I got to close to work I turned the heat on low and it squeaked for roughly 2 seconds and quit. I turned the heat up and it was quiet for a while. Then it started doing it again. So when it started again I immediately turned the heat off and when I did the squeak immediately stopped. My AC does work to my knowledge. I had it recharged this summer. So it specifically squeaks when the heat is on. I don't think it's my blower motor because it's not a high pitched whirr like a constant wheeze sound. This almost sounds like every full rotation of the engine it squeaks then does eventually stop. Heat blows hot and good. This here does have me scratching my head. I'll take a peek and see if there's oily residue on my belt and such. I'll also have the mechanic take a look at my tensioner when I go back for a personal inspection soon. Link to comment Share on other sites More sharing options...
Minuit Posted December 17, 2022 Share Posted December 17, 2022 Record the noise. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 17, 2022 Share Posted December 17, 2022 Tighten the belt. Link to comment Share on other sites More sharing options...
PIKE Posted December 17, 2022 Share Posted December 17, 2022 https://www.gates.com/gb/en/power-transmission/power-transmission-tools-and-merchandisers/power-transmission-tools.p.7401-000000-000003.v.7401-00072.html Link to comment Share on other sites More sharing options...
scguy Posted December 17, 2022 Share Posted December 17, 2022 Unplug your compressor and try it with the heat on again. Link to comment Share on other sites More sharing options...
Classy Comanche Posted December 17, 2022 Author Share Posted December 17, 2022 I'll record the noise best I can when I can. I'll mess with it and check around as you guys suggested. I also need to take it by the shop for a new exhaust anyway so I'll have them check the compressor and such Link to comment Share on other sites More sharing options...
cruiser54 Posted December 20, 2022 Share Posted December 20, 2022 Tighten the belt. Link to comment Share on other sites More sharing options...
Minuit Posted December 20, 2022 Share Posted December 20, 2022 Tighten the belt. If noise persists, record noise and seek further counsel. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 20, 2022 Share Posted December 20, 2022 THIS^^^^^^^^ Link to comment Share on other sites More sharing options...
Classy Comanche Posted December 21, 2022 Author Share Posted December 21, 2022 I've been trying to get it on video but when I fumble for my phone while driving it stops or it'll do it for a split second and stop. It's a very high pitched squeak sound. Definitely does it when it makes a full engine rotation. I'll have it tightened up and go from there. The belt is new after all. Once again this morning it did it and no I couldn't catch it on video because I fumbled for my phone and fell in the floorboard. Great. So I did just turn the heat off and once again immediately stopped. But this go around I'll have said camera ready so all I have to do is press record Link to comment Share on other sites More sharing options...
cruiser54 Posted December 21, 2022 Share Posted December 21, 2022 Tighten the belt. Link to comment Share on other sites More sharing options...
jpnjake Posted December 22, 2022 Share Posted December 22, 2022 On 12/17/2022 at 8:38 AM, cruiser54 said: Tighten the belt. On 12/17/2022 at 9:18 AM, PIKE said: https://www.gates.com/gb/en/power-transmission/power-transmission-tools-and-merchandisers/power-transmission-tools.p.7401-000000-000003.v.7401-00072.html On 12/20/2022 at 7:23 AM, cruiser54 said: Tighten the belt. On 12/20/2022 at 7:58 AM, Minuit said: Tighten the belt. If noise persists, record noise and seek further counsel. On 12/20/2022 at 8:47 AM, cruiser54 said: THIS^^^^^^^^ 43 minutes ago, cruiser54 said: Tighten the belt. Tighten the belt. I can’t believe nobody suggested this yet Link to comment Share on other sites More sharing options...
Classy Comanche Posted December 22, 2022 Author Share Posted December 22, 2022 Lol yes I'll certainly tighten the belt. I do believe that is the reason it's doing what it is doing as so you guys, and thank you! However. I did manage to capture the sound on my way home. I was driving, phone was positioned right above my radio. It was also raining and I had the wipers on. So I do apologize for those sounds but I did capture the squeaking sound! It sounds like baby birds. The heat was on the setting max and the level was low. 20221221_191140.mp4 Link to comment Share on other sites More sharing options...
cruiser54 Posted December 22, 2022 Share Posted December 22, 2022 Tighten the belt. Link to comment Share on other sites More sharing options...
Classy Comanche Posted December 22, 2022 Author Share Posted December 22, 2022 I am. I was just showing the high pitched squeak I've been talking about and missing for you fellas to listen to. I thank yall! I'll have it all tightened up in no time! Link to comment Share on other sites More sharing options...
AZJeff Posted December 22, 2022 Share Posted December 22, 2022 The 4.0 in the MJ and XJ models is VERY sensitive to lack of proper belt tension. On top of this, they seem to need a hellacious amount of tension compared to some other vehicles. This means that many DIY guys under-tighten the belt, and noise ensues. Add in belt aging, and crud on the belt and/or pulleys, and it can be really annoying. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 23, 2022 Share Posted December 23, 2022 I wish someone had mentioned belt tension earlier on. Link to comment Share on other sites More sharing options...
fiatslug87 Posted December 23, 2022 Share Posted December 23, 2022 I think the belt is too tight. Link to comment Share on other sites More sharing options...
jpnjake Posted December 23, 2022 Share Posted December 23, 2022 2 hours ago, cruiser54 said: I wish someone had mentioned belt tension earlier on. Someone should’ve really thought of that maybe next time someone can suggest it Link to comment Share on other sites More sharing options...
Manche757 Posted December 23, 2022 Share Posted December 23, 2022 Don't forget to loosen your belt when you sit down for Christmas dinner. Link to comment Share on other sites More sharing options...
Minuit Posted December 23, 2022 Share Posted December 23, 2022 16 hours ago, AZJeff said: The 4.0 in the MJ and XJ models is VERY sensitive to lack of proper belt tension. On top of this, they seem to need a hellacious amount of tension compared to some other vehicles. This means that many DIY guys under-tighten the belt, and noise ensues. Add in belt aging, and crud on the belt and/or pulleys, and it can be really annoying. I know we're joking around a little bit here, but Add in the janky manual tensioner setup that is somewhat prone to being damaged, and it can be annoying to get right. Link to comment Share on other sites More sharing options...
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