Cold/dry start knock?

[PITT]

Hi Everyone,

I am a new member but have been viewing for a few months now. I have a 2003 dodge neon sxt with 82,000 on it. Recently i have developed a light cold start knocking sound, it last for about 2-5min and sometimes until warm, but always goes away. I know neons are known for valve tap, but this is a lower/middle knock. I have not dropped my pan yet to check if there is play in my rod bearings. Two weeks ago changed the oil- mobil super hm 5w30 and a purolator pureone filter, the engine sounds a little better . I was thinking about using a additive such as liqui moly mos2, due to the fact i heard it is good for cold starts. If anyone has any better options please let me know, i would greatly appreciate your feedback.

 

[Falken]

Maybe it is piston slap?

I was under the impression that piston slap usually plagues a specific engine from brand new.

Just guessing as it "goes away" after car warms up...

 

[ARCOgraphite]

No MoS2. Not for motor oil with filter. Maybe use a higher flow filter.

 

[Trav]

Originally Posted By: PITT
Recently i have developed a light cold start knocking sound, it last for about 2-5min and sometimes until warm, but always goes away.


Rod or main knock cold usually goes away within a couple of seconds then at some point in the not too distant future fail altogether.
A good indicator is with a mechanical oil pressure gauge, when the engine is overnight cold if the gauge stays down at the bottom for a few seconds then jumps to pressure, its usually rods or mains or possibly (remote) a defective ADBV.

A piston pin will make noise all the time and a failed ADBV will not go on for a couple of minutes just a few seconds.
A pitted cam or damaged lash adjuster/lifter can cause some noises that sound very similar. It can sound like its from the middle of the block.
I did a Subaru with what you would swear was bottom end or bad piston slap, it turned out to be a bad bearing on the roller rocker arm.

If it is piston slap there is nothing you can do about it, MoS2 wont do a thing for it, neither will any other additive. Hone/bore it and do a piston/ring job or live with it and forget it. They can go a long time with slap.
If it goes quiet when its warm i would forget it if its slap. Check it all out of course.

 

[4wheeldog]

Would you describe it more as a rattle, or an actual rythmic knock? A rattle could be a tensioner or something more external. A knock that goes away as the engine gets up to operating temperature would most likely be piston slap. Nothing oil related will really help this much, though it seldom develops into anything more than an annoyance.

 

[440Magnum]

Originally Posted By: PITT
Hi Everyone,

I am a new member but have been viewing for a few months now. I have a 2003 dodge neon sxt with 82,000 on it. Recently i have developed a light cold start knocking sound, it last for about 2-5min and sometimes until warm, but always goes away. I know neons are known for valve tap, but this is a lower/middle knock. I have not dropped my pan yet to check if there is play in my rod bearings. Two weeks ago changed the oil- mobil super hm 5w30 and a purolator pureone filter, the engine sounds a little better . I was thinking about using a additive such as liqui moly mos2, due to the fact i heard it is good for cold starts. If anyone has any better options please let me know, i would greatly appreciate your feedback.


Sounds more like piston slap to me. Rod knock will NOT gradually go away as the engine warms up, piston slap does (in fact that's pretty much a defining characteristic of piston slap.) Does it sound a little like a diesel engine idling? That's also characteristic of piston slap.

Piston slap is harmless, but annoying.

 

[IndyIan]

I would be surprised if there's anything wrong internally if its had reasonable oil changes. Those motors are pretty tough and I beat the tar out of mine on the track at 160,000 miles.
Have a close look at the accessories, maybe one of them is unhappy?
I did run some 40 weights in it as well, 5W40 syn would work as long as you don't make a habit of high revs on cold oil as it could build up in the valve cover. I ran some 15W40 for the summers I tracked it as well, but for normal driving its probably not helping anything.
A conventional high mileage 5W30 oil is probably the best idea though.

 

[Kamele0N]

Sludge under valve cover....oil lines around valve springs and tappets are blocked...and because of that oil takes a ?little longer to oil valvetrain........

 

[jk_636]

Originally Posted By: PITT
Hi Everyone,

I am a new member but have been viewing for a few months now. I have a 2003 dodge neon sxt with 82,000 on it. Recently i have developed a light cold start knocking sound, it last for about 2-5min and sometimes until warm, but always goes away. I know neons are known for valve tap, but this is a lower/middle knock. I have not dropped my pan yet to check if there is play in my rod bearings. Two weeks ago changed the oil- mobil super hm 5w30 and a purolator pureone filter, the engine sounds a little better . I was thinking about using a additive such as liqui moly mos2, due to the fact i heard it is good for cold starts. If anyone has any better options please let me know, i would greatly appreciate your feedback.


You replaced the oil and filter. That was going to be my first recomendation.

Try doing a 5 minute motor flush for the next few oil changes and add some MMO to the crankcase and run a couple short OCIs using premium fuel (V-power). See if that doesn't help.