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Category: Dodge
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Experience:  30 years experience, ase certified,shop owner
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2009 Dodge Ram 1500: 5.7 Hemi..its cold the is a loud knocking sound

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When I put my 2009 Dodge Ram 1500 5.7 Hemi in gear when its cold the is a loud knocking sound. What is it?

I'm Neal and I am here to assist you. Only accept when you are happy with my assistance. If I can't help I will open your Question to other experts.


I think what you are hearing is cold piston slap which is due to the engine design using a piston that is short and has the pin high up in the piston which allows some rocking, especially when cold. They do use a moly coating on the piston skirts to reduce this, but it is still going to occur to some extent.


How cold is it when you are noticing this?

Customer: replied 5 years ago.
I put in the info the dealer had eliminated the engine. It does it on any cold start 30 degrees or 95 degrees. Doesn't make the noise until you put it in gear. Piston slap would occur even without it being in gear when cold.

I'm sorry I misread your question as far as being in gear. The only other thing I have been running into is exhaust manifold leaks. But it ddoes not sound like this is your issue.


Can you describe the noise anymore or can you tell the area it is coming from?

Customer: replied 5 years ago.
From inside it sounds like an exhaust leak. They have already replaced the bad manifold bolts and checked for a cracked manifold which are known problems. It goes away after it gets warm but as soon as it cools down "its back" and only does it when in gear. They now say its normal because they say they have one on the lot doing the same thing. I know they don't get paid for looking for a problem so they don't want to spend any more time on it. The noise is so loud its embarassing.
Based on that I would say it is an exhaust leak then, you can actually hear it so you have a good perspective there and that makes sense that it goes away when it warms up. Just because there is another one on the lot with an exhaust leak does not make it ok. If they will not make it right, you can get with dodge corporate and make a complaint on the dealer and they will usually help get it resolved.
Customer: replied 5 years ago.
I fiured that much. Is there someone else who might have a better idea?
Customer: replied 5 years ago.
Relist: Other.
Answers were not any info I didn't have
Welcome to just I'm here to help you and your 100% satisfaction is my goal.We can determine exactly what the causes , if you have an exhaust leak and the engine is cold you can use what they call a smoke test are we use a defined vacuum leaks in evaporative emissions system or the heating and cooling system it can also be used to find exhaust leaks what you would do is use a smoke machine and fill the exhaust looking for any leaks up around the exhaust manifolds or exhaust pipes . They would be very easy to spot . If you think that we may have an internal noise in the lower part of the engine being a piston slap for example simply place the engine gear then disabled in each cylinder one at a time by either disabling disconnecting the fuel injector or disabling the spark to each cylinder and if the noise goes away on one particular cylinder this is a good indication that you have a loose piston . As you say it would be a little rare for it to happen only in gear but remember you have a different load on the engine when it's in gear and not to contribute to the noise also . If none of those prove to be conclusive we will have to test further
Dodge expert, ASE Cert Technician
Category: Dodge
Satisfied Customers: 10370
Experience: 30 years experience, ase certified,shop owner
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Customer: replied 5 years ago.

I have contacted Chrysler and they are contacting the dealer. They aren't really happy that the dealer didn't exercise their proceedures and contact them for help in resolving this instead of the answer "We have another one doing the same thing, must be normal" Thanks for the help.

Okay thank you just let me know if there's anything else you need