piston slap

[paul kellam]

will putting a hotter plug in the cylinder that has the noise make any differance? it should heat up faster?

[Shconer]

I'm not sure what you mean by heat up faster but a hotter spark plug will increase the spark plugs tip temperature and is not necessarily directly related to other engine temperatures. But if you have excessive piston to cylinder wall clearances or worn rings it may be beneficial as the hotter tip can burn off oil and carbon more effectively. But going to hot can cause premature ignition and engine damage.

[paul kellam]

here is the latest. 3 mechinics 1 mufflar shop man and other friends all goofed on this one. I decided that i would just have to live with the "piston slap" so i decided to go out and time the engine (Retard it) since i read that will make the engine run warmer. I timed
it to 9 degrees before TDC and guess what the piston slap is history. from what i can figure it was about 10 degrees advanced so long story short don't overlook the obvious.

[captchee]

Here is something to think about . Now I don’t want to burst your bubble and it could very well be that your timing has just been advance to far . But ,Do you have slap or don’t you ?. How long has this been happening ?
Retarding the timing can cosmetically cover up the problem .
if you have a wrist pin or rod bearing that’s worn , reducing the timing can make it sound better.
The reason for this is the closer you get to firing at TDC the more the bearings and rods become loaded and thus reducing the nock but it will still be there .
On older engine folks used to also go to a heavier viscosity oil as a fix as well . But in today’s engines with tighter tolerances ,this can cause the bearings to spin


Try this . Pull your dip stick and start the engine . Set the timing to factory specs

Now take the handle end of the dipstick and place it up against your ear..
Start with the cylinder the engine is timed to .
Place the pointed end at the top of the block just under the head by about 3 inches . You want to be about where the bottom of the piston would be at its furthest travel . To close to the head and your going to start hearing the valves working .
Listen for a thud . Thud , thud .sound . If its there you will here it through the dipstick . Check each cylinder that way.
Now start over but place the tip down below along where the crank sets in the block and again listen to each cylinder . Any damage to either the connecting rod bearing or wrist pin on any cylinder will be heard .
If the engine is timed correctly then every cylinder should have no noticeable change in the sound you hear.. If one has a louder noise then the others you know which cylinder you starting to have a problem on . You can actualy pin point the location of the problem using this method .


What im getting at is , this will help you decide if you fixed the problem or simply hid it for a while .
It will also help you diagnose the problem as to if its on the lower end or upper end .
As a side note , we used to fine tune out rocker settings this way on the old F heads . Even with the valve cover on you could hear specifically which valve had even the smallest clatter issues

[jtgh]

good write up capchee

but you can buy a mechanics stethoscope for $3 a most stores,.
you can find out what bearing is bad, PS or WP, or Alternator, in 1 instant.

no mech, would be with out this tool.

it is amazing what you can hear with this thing. Blows me away each time i use it.
works on axle too. I use it to find body noises, while other person drives.

Slap usaually is just during first 2 min warm up and can be ignored.
I owned many a Motorcycle with built in slap, YZ400 was one, new in box.
and all 2001 ford and chev and Chryster truckes with the new Higher Ring positions mandated buy inane EPA? google that.

the rods will double know, nah,knock, repeats

get the stethocope (non electronic ) and start probing.

cheers

hope you timing trick works.

[captchee]

yep a stethoscope is a good idea . but they are not always available .
but when one can be found , pick it up , they are much more sensitive then the method i described above .
But basically living in the sticks, which means sometimes you 100 miles from the nearest AP store , you learn to use what you have .