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Discussion Starter · #1 ·
Hey guys
Anyone have this issue? When I turn the key to start the engine I get one thud sound like its to dead turn turn over, I turn key back off and repeat 5 or 6 times and then it finally turns over and starts like normal. When I get it started and drive it I dont have any issues and it starts first time, but when it sits for a week in between drives this sometimes happens. I put a new Odessey battery in and it still does it.
Any thoughts?
 

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My thought is the starter motor. Sounds like it's getting power from relay as it goes 'thud' but maybe the brushes get stuck and it needs a few tries. Try tapping the starter a few times (with a light to medium METAL hammer or if hard to reach, a metal hammer against a metal rod that reaches starter) before trying to turn it over the first time and see if it fires right up. If not, tap it again after the first 'thud' and if it starts, I'd say the starter motor.
 

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2021 Ram 2500 Tradesman Crew Cab 6.7 L Turbo Cummins 3.73
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You may have coolant leaking into a cylinder, that thud could be the piston hitting uncompressible fluid (coolant). You can bend a rod doing this. This is called hydrostatic lock. Once you turn it over, that fluid will be sent out the exhaust. You said it gets worse the longer the truck sits. When you turn off the truck, that coolant is very hot, and pressurized.

So, the question above is, ARE YOU LOSING COOLANT? If not, I would tackle the starter myself.

If you are losing coolant, you may have a bad head gasket or a cracked head.

Do an oil analysis, that will show traces of coolant in your oil if it's there.
 

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Though if it were mine, I'd try tapping the starter after an extended period of sitting. Then try to start. If still a 'thud', try tapping it again. After all, this is FREE. If it starts on the first or second time after a tap, I'd throw a starter at it... again, WAY cheaper than a head gasket (or 2 of them since you won't know which cylinder bank it is). Best of luck, keep us up to date with a final diag.
 

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Though if it were mine, I'd try tapping the starter after an extended period of sitting. Then try to start. If still a 'thud', try tapping it again. After all, this is FREE. If it starts on the first or second time after a tap, I'd throw a starter at it... again, WAY cheaper than a head gasket (or 2 of them since you won't know which cylinder bank it is). Best of luck, keep us up to date with a final diag.
There is also a kit you can buy from NAPA ($40 or so) that puts a glass filled with some blue liquid and a fitting to go on the radiator cap. Run the motor, if there is CO2 (from combustion) in the water jacket, the liquid turns green and the diagnosis is a head gasket. Otherwise, look elsewhere.
 

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@RAM259, how many miles do you have on your truck?
 

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Sounds just like mine in the beginning, and didn’t show in oil or on the ground. Eventually got worse and showed on side of block. I knew what it was the whole time, dealer couldn’t figure it out or agree with me. Which ended up being fine I got a completely brand new crate motor at 86,000
By didnt showin oil was that just visually looking or with actual oil analysis?
 

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No analysis done, but no film or discoloration in coolant. Eventually I had to take the coolant cap off when I parked for more than 10 minutes. Went from Very little coolant loss and strange starting to cap removal and hydrolocking in 5k.
 

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Hey guys
Anyone have this issue? When I turn the key to start the engine I get one thud sound like its to dead turn turn over, I turn key back off and repeat 5 or 6 times and then it finally turns over and starts like normal. When I get it started and drive it I dont have any issues and it starts first time, but when it sits for a week in between drives this sometimes happens. I put a new Odessey battery in and it still does it.
Any thoughts?
Hi: RAM259... This usually happens to me around 6am. I try to turn my wife over and I get one thud. I let 'er sit for a week but no go then either!!! The only issue I have is my bruised ego!!!
Dieseldragon North shore of Lake Erie.
 

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Discussion Starter · #20 ·
I am about ready to change my oil and send in to black stone. They have had all my changes. I am planning on pulling my trailer about 1200 miles in a week. If it needs to go to the shop I want to do it there. Any thoughts ?


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