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grinding noise on engine start

47K views 38 replies 20 participants last post by  4X4RDSTR 
#1 ·
So even though my Jeep is under warranty, I can't take it to the dealer because this only happens once every couple days so i wouldnt know how to prove it.

Basically, if I leave my jeep in the driveway for over 2days without running it, the morning I do start the engine, the second the engine starts there's a quick grinding that goes away in a split second. Only happens once and then its fine until the next morning...the rest of the day it sounds fine.

Is this normal? The noise kinda sounds like a zip tie being tightened (that's the only thing I can think to describe it as).

My jeep is only 3 months old with 3k miles, and its a 2010.

It happens so quickly... Just a split second when the engine starts... But its a sound I haven't heard in any other car I drove, so I got worried...
 
#4 ·
BLEGAN said:
is it a loud sound? the only thing i can think of is.. (and it sounds dumb) youre holding the key turned too long :p
JK's have the starting sequence computer controlled. For example when you turn the key for just a split second, the Jeep continues to crank till it engages.

That sound you hear is being discussed in another thread. A buzz type sound. Mine does more of a whine type deal on start-ups under about 15 degrees or so with a cold engine. I've only seen 2 JK's buzz at start-up and one had a starter slow to engage, the other had the fan make noise
 
#6 ·
I know the noise you speak of. You are not alone. It was happening to my 2011 on very cold mornings this winter after not being run for a day or so. A split sound grind then normal operation. Wouldn't do it the rest of the day. Have not heard it since the warmer weather arrived. I don't think I was holding the key in the start position any longer than usual either. Meh, plenty of warranty left on her so I'm not losing sleep over it. Yet another "Jeep thing" I suppose.
 
#7 ·
It really sounds like the starter is NOT disengaging at the appropriate time. I would definitely talk to the dealer about it. If you ignore it and it turns into something a bit more MAJOR...like flywheel teeth broken or starter going out......AFTER warranty period is up you will have no documentation that there WAS an issue.

Could be an issue with a relay being held on too long by the microprocessor ( internal timer value too large or output device faulty) OR a sticking relay after he microprocessor.
 
#8 ·
As much as you guys have explained so far... there's one thing wrong with some of your answers... I live in Florida. Our mornings are in the mid 70's, it isn't cold.
Could it be the fan starting up, or the AC? My roommate knows nothing about cars, but he told me his dad always says to turn the AC off when you turn the engine off... My AC is usually on.

Like I said earlier, it's less of a buzzing noise and more of a grinding noise, like the sound a zip-tie makes
 
#10 ·
mine does exact same thing when its really cold out!! i know you said its not cold were you are.
 
#11 ·
Not the cold. I'm in louisiana and mine does the same. Only on the first start of the day. Did not do it today though. I posted about it hoping someone else had the same issue and what it is.
 
#12 ·
I got that this morning for the first time. This morning was the first night outside of the garage and it was in the low 40's when I started the car. I'm going to leave it outside again tonight to see what it is. It sure doesn't sound like a starter motor grinding, in fact I'm not sure it was metal on metal grinding, more like plastic on metal. But I wasn't expecting to hear anything like that so I wasn't paying attention.

It sure got the "What the Hell!!!" juices flowing this morning.

Mike
 
#16 ·
OK, started it today without a/c on and no grind. Tomorrow I will start it with the a/c on.
 
#17 ·
Could it be related to the oil filter?
Maybe the drain back valve is allowing the oil to escape, so it takes a second or two for oil to get up there?
 
#18 ·
I changed my oil about 900 miles ago. I have a Bosch filter. Unless everybody else has Bosch I would rule that out.
 
#20 ·
Mine stared the noise when it was approx. 55f out. My son was using it and he had the a/c on because it got up to 80f or so the day before. So it sat out all night at 55f with the a/c in the on position. Got in it at 4pm temp approx 80f started it and the grind/buzz happened. My son was about 8 feet in front and I asked did you hear that? and he said yes. So the next day same thing happened. I haven't had the a/c on the past few days, had the sunrider open so I have not shut it off and left overnight w/a/c in on position. Gonna start it today and see but I forgot to turn a/c on before stopping last night.
 
#21 ·
Mine does it too. I haven't localized to the ac yet but one thing to keep in mind for all of you is that the ac pump does get engaged when you have it to the defrost or floor positions. It does this to pull moisture out of and not cool the air to aid the defrost process. So even though your ac button says off the pump is still engaged. I'm gonna put it on dash only vents to make sure the pump is off.
 
#23 ·
Keep us updated. I feel like if I address the issue to the dealer they'll just blame it on my offroad adventures, since first impression of my engine bay is quite filthy. But the issue has been going on since before I took the jeep offroad
 
#27 ·
OK I have narrowed it down to the a/c. When I last drove the jeep the a/c was on. Did not turn the a/c off when I turned the ignition off. Two days later started the jeep and grind noise. My theory is that there is head pressure on the compressor and when the jeep starts the belt cannot turn the compressor and the belt drags across the pulley causing the noise. I will experiment further and post. Oh yeah I am sure somebody will post that the compressor should not kick n when starting but I believe there is a fault with the system not Eliminating the compressor load at start causing the belt to vibrate.
 
#28 ·
So I have had it too

But only in the winter.

I think it has something to do with the blower. I say this because I have had the Jeep do this, turn off the heater and the noise stopped. Mine has only done it twice though so Im not to worried about it.

Just my $.02

Oh, and I have yet to use the A/C in my Jeep, if that adds anything.
 
#31 ·
chucky cheese said:
OK I have narrowed it down to the a/c. When I last drove the jeep the a/c was on. Did not turn the a/c off when I turned the ignition off. Two days later started the jeep and grind noise. My theory is that there is head pressure on the compressor and when the jeep starts the belt cannot turn the compressor and the belt drags across the pulley causing the noise. I will experiment further and post. Oh yeah I am sure somebody will post that the compressor should not kick n when starting but I believe there is a fault with the system not Eliminating the compressor load at start causing the belt to vibrate.
Damn that's some pretty good thinking. I'm trying to remember if my heater was on when mine squealed. I USUALLY shut that and the radio off, but I'm not 100%

You should pop the hood before start up and have someone fire it up. Might be able to get the area it's happening in.

I wish I could play too. It's just not cold enough for mine to do it. Next few days I'm getting lows in the 20's...we'll see
 
#32 ·
That's my plan. It is hard to coordinate someone to help when it only does it once when sitting 24 hours. Also gotta remember to shut it off the day before w/ a/c on.
 
#33 ·
All right the latest. turned off w/ a/c on yesterday, this afternoon started jeep and grind happened with a bonus! When the fan blower came on (there is a couple of seconds delay before it starts) there was a second split second grind. So it has something to do with the fan belt and the load on it when starting. I do not have the grind when the compressor is not engaged at starting so I have narrowed it down to either the a/c compressor is engaging at start, the belt or tensioner is at fault so it could be in the electronics that is not eliminating the compressor at start or faulty belt tensioner. Now I have never had a problem starting a vehicle with the a/c on. I tried my dodge van and it starts then a few seconds later the compressor kicks in. My thinking is the electronics are not eliminating the compressor load at start. From other posts Or the lack of posts about this makes me think it is a problem on certain jeeps. I do not want to make a special trip to the dealer for this so I will wait until I have a real problem before I go. I have not yet had a visual on this. It seems my wife has to put on makeup before she goes outside so I really don't have the time to wait for her to get prettied up to come out to start it. But when the planets line up and the moon is in Uranus (thats why it smells like cheese) and the makeup and outfit is perfect I will get her to sashay out and start it as I have the hood open and observe and being careful to observe from the side so as she cannot cash in on my life insurance! So for now TATA ,God speed and cio!
 
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