Knocking sound at cold start. Any ideas?

[22rubi1202]

Hello all. Just wanted to get some opinions on what I’m hearing. When I first start my truck after sitting for some time I hear a knocking sound. It not right away and depending on where I’m parked I can’t hear it at all. I can hold the brake and give it a little gas and can hear it. Then once it’s fully up to temp and drove around a bit it’s quiet. Any ideas are welcomed. By the way it a 24 Mojave with 8000ish miles.

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[DylanM]

The description sounds like piston slap.

 

[FLACRACKER]

Can you confirm the noise is from the engine bay, or else where ?

 

[22rubi1202]

The description sounds like piston slap.

Any ideas what causes it? Is it something that needs immediate attention or something I can do to quiet it down?

 

[22rubi1202]

Can you confirm the noise is from the engine bay, or else where ?

No I can’t.

 

[FLACRACKER]

What about after shutting the engine down after warm up, then restarting? Any trail rides lately?

 

[22rubi1202]

What about after shutting the engine down after warm up, then restarting? Any trail rides lately?

As far as I can tell after shutting it down and restarting it’s still quiet. No trail rides ever in it.

 

[FLACRACKER]

I know with mine, when starting cold, the valves did a little " ticking " when starting up, till the oil pressure came up. If there are no "idiot" lights displaying and the oil level is good, belts are tight, I would relax. It probably would not hurt to drop by a reputable shop to get someone to check it out. A few dollars is better than a thousand !

 

[22rubi1202]

I know with mine, when starting cold, the valves did a little " ticking " when starting up, till the oil pressure came up. If there are no "idiot" lights displaying and the oil level is good, belts are tight, I would relax. It probably would not hurt to drop by a reputable shop to get someone to check it out. A few dollars is better than a thousand !

Yeah I hear ya.

 

[yoda13]

Mine does this too. Once it’s up to operating temp, it’s quiet. When it’s warm, it’s extremely quiet. I’ve been keeping a journal. Mine started as soon as the temp dropped below 50 at night. If it’s a warm night, it doesn’t do it when you start it the next morning. Local jeep shop couldn’t hear the tick when I took it by there, even with a stethoscope. His conclusion was also piston slap. I am living with it, as none of the three jeep dealers will look at it unless there is a check engine light on

 

[Jonesc00666]

It is tappet/lifter noise because oil is bleeding back to galleries is usually the cause. My 3.0 liter does it when it is below 30 degrees. My oil pressure is over 80 when it is this cold. If I put it in gear it gets worse. I have learned through the years on this vehicle (2021 Eco Diesel) and other vehicles that I must allow it to idle for a few minutes before I put it in gear. With the 2021 Gladiator. I just remote start it as I am putting on my boots and walk out and get in. That short time means I don't have to wait.

 

[22rubi1202]

It is tappet/lifter noise because oil is bleeding back to galleries is usually the cause. My 3.0 liter does it when it is below 30 degrees. My oil pressure is over 80 when it is this cold. If I put it in gear it gets worse. I have learned through the years on this vehicle (2021 Eco Diesel) and other vehicles that I must allow it to idle for a few minutes before I put it in gear. With the 2021 Gladiator. I just remote start it as I am putting on my boots and walk out and get in. That short time means I don't have to wait.

That sounds about what it is. Taping sound that goes away at operating temperature. Some times it sounds a lot worse when parked in a parking lot around other vehicles. At home I have a gravel parking area and I don’t usually hear it that bad.

 

[22rubi1202]

Took mine in on Friday and of course they said they couldn’t hear it. Went to leave and I heard it and got the service manager. He acted like he heard it but said he didn’t hear anything out of the ordinary for these engines. Pretty much got the idea we ain’t gonna do anything till there’s a code or light. Then proceeds to tell me that me doing my own maintenance could hurt me if something happens down the road. They have told me that before but I just ignored him. So now I don’t know if I should continue to do my own maintenance or let them do it.

 

[Jonesc00666]

That sounds about what it is. Taping sound that goes away at operating temperature. Some times it sounds a lot worse when parked in a parking lot around other vehicles. At home I have a gravel parking area and I don’t usually hear it that bad.

I also saw on another forum that the auto tensioner for timing chain uses oil. When it is cold not enough oil gets there till end. This would make sense also. I still think mine is tappets. And first time I heard it it really freaked me out a little.

 

[22rubi1202]

I also saw on another forum that the auto tensioner for timing chain uses oil. When it is cold not enough oil gets there till end. This would make sense also. I still think mine is tappets. And first time I heard it it really freaked me out a little.

Yeah tell me about it. I thought what the heck is that. But they pretend to not hear it and that it is normal.

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