Slapping sound when starting sometimes

[chrisbh17]

this is pretty well spot on.

If I drive the truck from work to home, the next morning I do not hear that noise.

If I start up my truck just for a few minutes (for example to turn it around and back it up in the drive way), it will make the sound the next morning.

So, it appears the hemi doesn't like to just be started and ran for a few minutes. It needs driven, rpm's up and that oil pressure up and circulated.

What I dont get is WHY that is....my experience is if i wait longer than 30-60 minutes after a 'quick turn it around' trip, no noise! Why is it only an issue within a certain amount of time after that quick turn it around trip? Almost like there is some programming that's causing it.

 

[gregs2018ram]

I was just thinking oil isn't getting fully pumped to the very top of the engine with a quick turn on/trip

What I dont get is WHY that is....my experience is if i wait longer than 30-60 minutes after a 'quick turn it around' trip, no noise! Why is it only an issue within a certain amount of time after that quick turn it around trip? Almost like there is some programming that's causing it.

 

[chrisbh17]

I was just thinking oil isn't getting fully pumped to the very top of the engine with a quick turn on/trip

Yeah I get that part but the part I dont get is if that happens but I let the truck sit overnight, my next start will NOT make the noise. The oil never reached "up" from the quick turn around the night before, but something on startup after the truck sits for longer than an hour makes it react differently so there is no noise.

 

[gregs2018ram]

Guess we'll worry ourselves to death on why this noise happens. Not something i'm taking in for them to look at though because it doesn't do it all the time.

Silverado v8's have the same noise every morning on start. There was an explanation but I can't find it.

Yeah I get that part but the part I dont get is if that happens but I let the truck sit overnight, my next start will NOT make the noise. The oil never reached "up" from the quick turn around the night before, but something on startup after the truck sits for longer than an hour makes it react differently so there is no noise.

 

[gregs2018ram]

almost like the injectors or lifters rattling for a slight moment, but appear to be a tick. for a few moments until oil pressure max's.

On the Silverado, here was the explanation. ******I spoke with my dealer service and the advised me that it was normal oil pump repressurizing after the truck would sit for few hours or first start after night. ******** Sort of like a "rasping" noise in the Chevy V8.*****The oil pump design has changed from a gerotor gear type pump to a two speed vane type pump for fuel economy reasons. At temperatures of 32°F (0°C) or colder, when the engine has been sitting for a few hours it is possible to have air enter the pump through normal oil drainback. Upon startup the owner may hear a short Rrrrp or Rasp coming from the front of the engine. It is most often heard during a remote start. There is nothing wrong with the oil pump or oil system. No repairs should be attempted for this condition.

 

[Addicted2fishing]

Is this after the truck has been driven for a while where speed and rpm's have been up

or

is this the way it sounds after you've been on a short trip or just moving the truck around in your yard/driveway and you restarted it later?

To be honest I’ve had both. If I wash my vehicles I’ll wheel my ram onto the road. Wash the vehicle and move truck into driveway. I’ve had it happen for that. Or after sitting for a few days. Or if I’ve been doing errands and drop something off at home and go back out after 30 min or so it’ll do it. It’s been so random


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[Arth]

After reading what others said about Red Line, and my oil filter leaking, I switched to RL 5w30 and I haven't noticed this noise anymore either. Might be the temperature but I know for sure the engine has quieted down at 700 miles of the oil being in there. I will be sticking with 5w30 RL for now.

Mine hasn't done that with any of the 5/30's that tried, and now that I have 5/30 redline in it it is super quiet. JMO but I think the 20wts are just too thin and drain off leaving no protection on cold starts.

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[Fitz-0518]

I may have read every post on this subject in the forum archives. The conclusion "I" came to, is that some of our 5.7 and 6.4 engines experience O/N drain down that results in less than needed start up lubrication. I have also read here and in other publications that the 6.4 oil pressure, at start up, is in the 50's. It drops to the 40's and as low as 30's when the MDS activates. Have not been able to nail down a credible technical source to confirm that. I am am convinced that a 0-40 oil in the "warmer climates" is too thin at start up. Week after next I will drain the PUP 0-40 and try 5-40 Redline. RP or Amsoil filter. Our 6.4 with 5800 miles has the valve train dry start noise for about 1-2 seconds. If we do not start for 2 days, the noise last 4-5 seconds. My hope is, that RL has a different base oil formula than PUP, that adheres better at shut off. Will see.

Edit; One other fact that may be helpful. When I fill the crankcase, I use exactly 7.5 qrts in the 6.4. When I check the oil level in the morning before start up, it shows, over full. When I check the oil level after driving and let it sit for a while. Oil level is right between the two dots. It is another reason why I suspect that finding an oil that has better cling or adhesion property's may help that short dry start noise.

 

[Joes1500]

My 17 does the same ****. I run amsoil in it with there filter. It still does it but not as long. I always figured it was the lifters bleeding off from sitting. The old ford 300 6cyl , and some of the 302s were famous for it.

Be curious to know if the guys that have switched to the hellcat lifters still have this noise?