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Rattle slop in piston ring?

6K views 14 replies 7 participants last post by  Homer 
#1 ·
Ok my baja has a rattle/vibration, thought i had an idea what it was but when i fixed that it was still there, I have since investigated further and found that the noise was coming from internal in the engine.

On further investigation i have found that when looking down the exhaust outlet that the noise is the piston ring slopping up and down in its slot!

If i get a replacement piston ring will this fix the problem?
 
#2 ·
It wont be that!

Chances are the bearings are flogged in the bottom end and the crank is ratteling up and down.

I have seen a lot of guys run with this problem and they don't even know it.

This noise can come if you use a thinner head gasket in your engine as sometimes after use it gets a little lip at TDC and when you put the thinner gasket in the piston will clip the lip.

thirdly, if you change cranks (especially a stroker) the same as the above applies.

If you want to experiment with gaskets use the thinnest first or use the longest stroke crank first because you can always work your way down the bore but once you get a lip that part becomes usless.

Let me know what you think.
 
#3 ·
It was making the noise stock! have rebuilt the bottom end its now as tight as a nuns nasty, the only changes from stock are a copper gasket, replaced bearings and seals and your teflon zero drag seals, as i said it was making the same noise prior to the rebuild, i can actually see the ring sloping up and down as it makes the noise
 
#4 ·
buggered if i know! pulled the head off the thing and every thing is tight but the ring seems to be able to slop up and down in its slot!:bang: ahh bugger it I'm just going to run it until it dies hopefully not at origin but if so looks like ill be doing a rebuild down there fingers crossed it last!!
 
#5 ·
is the ring the right size for it maybe a new one could fix it ...you said you rebuilt the bottom end how did the bearings look i think maybe dave was talking about the bearing on the bottom of the conrod ..big end bearing of the con-rod....but if you say that you can see the piston ring slop then maybe try a new piston and ring....

ambro
 
#7 ·
The bearings in the big end and piston end all look ok and there doesn't appear to be any slop between the piston and crank shaft or crank bearings. the only place is the ring! I haven't changed the ring but picked up one from dps tonight but apparently there were two different thickness rings in the 26cc cy that came in the ss kit, Kris only had the thicker rings and when i tried to swap it mine obviously came with the thinner one, think kris said the one he supplied was .80 but they also came with a .60 which is what mine is as the .80 didn't fit, Other than the bit of up and down movement which appears to be causing the noise everything looked good and the car runs well, its got me stuffed, to be honest i just wanted it to be 110% for origin, if i was just racing / bashing up here i would drive it to it shat its self!
 
#9 ·
if it was like that from new could just be one of those piston,s just not machined properly i would probably get a new piston as well and matching ring and check that its has or has not got the slop in it..take your one out and check it up against another piston and ring.....

ambro

That's a good bit of advice, know anybody with an old SS head kit that might let you borrow the piston out of it?
 
#11 ·
hey guys pulled the ****er apart again and have put the ESP in, gave it a run yesterday after noon and have managed to turn the parents front yard into a dust bowl, need to run another half a tank run in and drop it off at Kris's thanks for all the suggestions will have the head and piston at origin so you can have a look cheers , By the way the ESP ****en hammers so ill be the guy doing donuts at every corner:D
 
#12 ·
By the way the ESP ****en hammers so ill be the guy doing donuts at every corner:D
When you say it "****en hammers" how powerful is it?
I bought the same head kit as you and have just built it and to be honest, I thought it was going to be a lot quicker than it is...
Its still running a bit rich though...
We will have to compare them in Sydney!
What pipe are you running?
Cory
 
#13 ·
Mate running a rear dom (rovan clone) its definitely punchier in the bottom end but runs out of a bit of puff at the top end which i expected given it has a longer stroke hence why i purchased several different gear sets, not sure what gears i'm going to run at origin but at this stage thinking stock as there track is short but will be good to see the two together
 
#14 ·
Mate running a rear dom (rovan clone) its definitely punchier in the bottom end but runs out of a bit of puff at the top end which i expected given it has a longer stroke hence why i purchased several different gear sets, not sure what gears i'm going to run at origin but at this stage thinking stock as there track is short but will be good to see the two together
If it was me, I'd use the powerful bottom end to it's advantage and try the next taller gear ratio from stock. If you have plenty of torque, taller gears will help put the power to the ground better without wheel spin and give you more speed.

Thats what I did when i ran my 30.5 however the rear dom was a mid-top end pipe which helped the top end power of the engine.
 
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