2.0 SOHC knocking

badgett · Post by **badgett** » Tue Feb 06, 2007 8:05 am

Every morning when I start my neon it knocks really loud. It stops once it warms up. It may not be a big deal but it sounds like the engine is going to fly apart. Any ideas ?

kc2005ptgt · Post by **kc2005ptgt** » Tue Feb 06, 2007 10:46 am

Heh - thats a neon for you. Seriously, it really is. We have noisy valvetrains, that is the problem. As long as it goes away and you wait 5 min when really cold out, then you should be cool.

Also, try switching over to synthetic oil, that may help a little. It did for me.

badgett · Post by **badgett** » Tue Feb 06, 2007 1:26 pm

Would it be ok to switch an engine over to synthetic that has always used conventional oil ? Should I use 5w30 or 10w40 for best protection ?

underway · Post by **underway** » Tue Feb 06, 2007 1:52 pm

also switching from platinum to maybe copper or sumthin like that for your spark plugs gets rid of alot of the knock ..assuming u have platinum in there now...neons dont like all the extra heat platinum causes

Cbussilver01es · Post by **Cbussilver01es** » Tue Feb 06, 2007 2:19 pm

kc2002acr wrote:Heh - thats a neon for you. Seriously, it really is. We have noisy valvetrains, that is the problem. As long as it goes away and you wait 5 min when really cold out, then you should be cool. Also, try switching over to synthetic oil, that may help a little. It did for me.

I SECOND !!! lol

fixitmattman · Post by **fixitmattman** » Tue Feb 06, 2007 2:24 pm

It's not the valvetrain as much as massive piston slap when cold. You'll find this is a pretty common issue. I should leave the block heater unplugged for a night and make a vid, the noise the car makes when cold is incredible. Once it warms up it's pretty good though.

Cbussilver01es · Post by **Cbussilver01es** » Tue Feb 06, 2007 2:31 pm

I know this may sound funny but I havent experienced piston slap yet in my car, and here in Columbus, its been -12 degrees for about the past week, lol I know its common, but I havent experienced it yet.

kc2005ptgt · Post by **kc2005ptgt** » Tue Feb 06, 2007 5:00 pm

Can you describe piston slap?

Nevermind, I think I found it on Allpar

Allpar wrote:I believe that "Piston slap" is when the skirt of the piston is draging, slaping, on the side of the cylinder wall. In an ideal situation the piston never touches the sides but is held away by the rings but because of increased clearances with age the piston wobbles in the cylinder. When the engine is cold it's worse. Aluminum has twice the expansion rate of iron and closes the gap when operation temp is reached.

But we don't live in an ideal world. On the 2.2/2.5 pistion rod there is a small hole that directs oil toward the cylinder wall to provide lubrication and a barrier against pistion drag. If hole is not pointed in the right direction you wind up with one pistion (No. 4) not geting the proper lub and it will cause excessive wear and then the slap which won't go away with heavier oil. I'd asume that if one of these holes became pluged (they're not directly pressurized by the pump) such wear could happen in any cylinder.

Had the case of a rebuilt engine with the rods put on backwards and it cost a complete rebuild. Noise was too low in the engine for a valve noise and had just had the head redone and too high pichted to be a rod or main. Still check the bottom end rods and mains and pulled the valve cover before commiting to pulling the pistions out and that's when I found the scuffed cylinder.

Is that pretty accurate??

Ifixyawata · Post by **Ifixyawata** » Tue Feb 06, 2007 6:24 pm

fixitmattman wrote:It's not the valvetrain as much as massive piston slap when cold. You'll find this is a pretty common issue. I should leave the block heater unplugged for a night and make a vid, the noise the car makes when cold is incredible. Once it warms up it's pretty good though.

Did your car come with a block heater or did you install it? I'd like to get some kinda overnight heater for the engine (over-day I guess it would be for me since I work midnights). It, like most neons, sounds like hell when I start it in this sub-zero temps.

Post by **racer12306** » Tue Feb 06, 2007 6:56 pm

as far as the synthetic goes. if the car was meticulously maintained then there shouldnt be a problem. but im still old school in those thoughts so if it were me i would stick with the conventional.

use 5w30. it flows better when cold. you already are having noise, no need to increase that noise from decreased lubrication that comes from waiting for the oil to get there. for your area 10w40 should be ok in the summer only, but it isnt needed.

fixitmattman · Post by **fixitmattman** » Tue Feb 06, 2007 7:11 pm

I've yet to come across a car up here that doesn't have a block heater installed in it. Most cars sold in Canada come with them as standard equipment. If you want to put one in, it's not hard at all. All you have to do is:

1) Get a block heater kit (comes with heater plug and cord)
2) Drain the coolant
3) Remove a freeze plug
4) Install the heater plug (replaces a freeze plug)
5) Top up coolant
6) Plug it in when it gets cold

As for the piston slap, that's mostly right.

There's a toggle point as the piston/conrod transitions from compression to power stroke at TDC. As this toggle/transition occurs the forces move from one side of the piston skirt to the other taking up the clearance on the other side. If it's really cold/excessive clearance, there is excessive noise from the force transition occuring. There's a lot of factors such as running clearance, piston alloy/thermal expansion, skirt length, wrist pin position, etc... that affect this noise. Most times this is remedied from a longer skirt, but not always, and a longer skirt has its own side effects as well. As it stands, it's a normal issue in the neons (hell most Chrysler 4 cylinders for that matter) and doens't cause any trouble other than annoying the hell out of you.

ACR MAN · Post by **ACR MAN** » Sat Feb 10, 2007 10:33 pm

fixitmattman wrote:I've yet to come across a car up here that doesn't have a block heater installed in it. Most cars sold in Canada come with them as standard equipment.

The block heater was standard equipment on 2nd gen neons (maybe 1st gens too) in the Canadian market. It was not a factory option in the neon for the US market, though. Odd...