Piston Slap - Does this cause damage?

Route--66--

Route--66--

Well-known member
Hi
Am pretty sure I have a bit of piston slap in my '65 200ci.
When starting from cold I can hear the 'clack-clack' noise .. not really loud or anything but is definitely there until it warms up ... after a few mins.. (it's not hydraulic lifters - I know what that sounds like).. also from other websites am 95% sure it's not rod-knock.
It's not massively loud and when warm it can't really be heard at all.
It doesn't burn any oil, even when I toe it and there doesn't seem to be any blow-by that I can detect.
I notice the spark plugs seem sooty though even though I'm currently running the mixture a bit lean (and read somewhere that carbon deposits can result from piston slap ???)
This has seemed to get worse since I bought the car in June 2011 .. although appreciate that as the days got colder into winter this would happen more... but could it also have something to do with me changing oil and filter(in that that may have de-gunked something?!)

So .. main question is ..
Is this damaging to the engine and should I do anything about it or is this "normal" for this engine.
Will it just get worse or could it cause a major failure. (oil pressure is ok)
Bearing in mind I am in the UK, so to get a new block shipped here would be toooo much!.. so if it is causing cylinder damage I suppose I need to get new pistons / rings sorted before it eats too much of the block rendering it not possible to re-bore??
Assume I can't possibly just fit new pistons & rings without taking the engine out ...???!
Thanks!
 
Piston slap is normal and common to engines that have high mileage and is a warning sign of bigger problems if not addressed soon. The pistons are just cast, with more clearance in the cylinders to make them slap, they are forced to rock in the bores much more than they were intended to. At first, pieces of the piston skirts can break off, which could have already happened, if the noise is more noticeable than you previously had. And from there you just have a more progressive breaking down of the pistons until one finally disintigrates completely and allows the connecting rod to take out a cylinder and everything else in its path. Of course thats the worse case scenario, but left unattended it can happen. You just don't know how long the pistons can take the added stresses of that once they start to crack and break apart.
 
8) yes, piston slap does cause damage. the issue is how much. and that depends on a lot of things;

how hard do you run the engine
how hard do you run the engine when cold
how much piston wall clearance is there
how long has it been going on
how well do you maintain the engine
what kind of oil are you using
 
Cheers guys
re: how I run it etc
I don't drive it hard hot or cold, use it for weekend cruising really.
Don't realllly remember any noise when I bought it 1500 miles ago .. although might have just got more tuned in to it perhaps.. and notice it more now...
since I've had it I changed the oil when I bought it and just changed it again after the 1500 miles..
am using 20/50.. a proper classic oil with high zddp(ore zdp .. the zinc stuff added anyway!)

Tried grounding each plug wire last night but no one cyl seeems to be making the noise - it sounds like number 1/2..maybe 3 .. BUT .. is there anything else at the front of the engine that could possibly make a similar noise that quietens down when it warms up .. doesn't seem to be coming from the timing chain ..
will remove the fan belt and run it a bit maybe Saturday to remove any chance of it being something to do with that but am 98% sure that's going to make no difference at all...

Cheers!
 
An exhaust leak at, near, around the manifold or down pipe will almost always quiet down as the car heats up and metal expands. When cold it can often sound like a loose/failing lifter.
A good exhaust shop should be able to poke under the bonnet with a stethoscope or some such and tell you very quickly if that's your issue. Hope it turns out to be something relatively minor (y)
 
Carried out a compression test this morning (with engine up to temperature)

Readings were all between 175-180psi (two centre pistons being the best readings by a bit) ..which I believe is pretty much correct..?

So... could the noise be piston slap even with good compression .. or is it less likely to be slap if this is the case..?

Cheers :) (y)
 
That's very good compression. I would think piston slap is not too likely and that the engine is not that high a mileage. (y) :nod:
 
Niiiice, that sounds hopeful cheers :D

.. The tester was last used probably in the 80's !! .. but was still very fresh in its original packaging so think it's reading right.. or at least very neat-to !

(y)
 
Have you listened to the fuel pump yet with a stethoscope or a length of broom handle? They can cause a noise like that. :nod:
 
yes thanks, the pump was the first thing I changed on it when I go the car 'cus it was making a real loud ticking noise!!
Cheers (y)
 
bubba22349":2j7k4kvp said:
That's very good compression. I would think piston slap is not too likely and that the engine is not that high a mileage. (y) :nod:
Click to expand...

I tried oil down the bores to see if this would reduce the noise -- think it did lessen the noise so maybe is that.
I retried compression test on no.2 which took the result from 178(ish) PSI to just under 200 .. so an improvement of +20psi..

Would that indicate too much difference .. i.e. there is too much gap?

I also hear that rings can get carboned up .. my plugs are pretty much always carboned up .. so could the slap be because the rings are too 'stuck' in their channels on the piston and unable to expand .. IF this is the case can I pour something down to 'clean' them..
Cheers!
 
Yeah that's a big jump in compression (with oil) means rings are weak. Your are getting very high compression readings with the gauge too maybe it's not very accurate has it been dropped or damaged? :unsure:
 
ooo rats ... that can't be a good thing :/
mm.. the gauge is over 20yrs old :/ !! .. although still in good condition .. but either way it still shows too much of a difference by the sound of it :/
Cheers
 
Trying removing one spark plug wire at a time with the engine running. This will remove the spark load from that cylinder and quiten down the noise. If it does quiten down, this will point to items such as the piston, rod bearing, wrist pin as being the problem with that cylinder. It likely would not be lifter, rocker arm, etc..since they are not affected by the spark load of the cylinder.This will also help confirm or eliminate items not associated with the rods and pistons if it doesn't change the noise, like fuel pump, crank thrust(thrust bearing gone),etc.
 
Just returning to this topic after a bit of time-out.
I still have the piston slap noise until the engine warms up, after which it's really smooth and quiet.
The noise sounds the same as in this video (even to the point that it makes no 'slap' noise for a few seconds on initial cold start-up (don't understand why not????) although certainly not as loud as this;
http://www.youtube.com/watch?v=geDRmNKH0Pg

The bottom end is quiet .. can I just change the pistons or maybe put new rings in (as previously mentioned it burns no oil at all)
.. or do I have to go to the great expense of taking it to have the engine pulled, rebored, crank reground, new shells etc etc :/
.. am trying to not rebuild unless necessary as just shipping a rebuild kit from usa costs $1200 (a third of which is shipping and import duty :arg: ) .. then at least another $1500 to get it installed.. :/

rbhom;
how hard do you run the engine - Not hard
how hard do you run the engine when cold - Very lightly - let it warm up on the drive for a minute or so first
how much piston wall clearance is there (no idea .. not had it apart)
how long has it been going on - I think since I had the car 18 months ago
how well do you maintain the engine - regular oil and filter change - changed twice in 1700 miles probably a 3rd time before 2k
what kind of oil are you using - 20/50 with high zddp; http://www.classic-oils.net/Product-351/Products-by-Manufacturer/Millers/Millers-Pistoneeze-20W50

Cheers!
 
Just Putting in new rings will not help, as to if you could just change the pistions (with new rings) maybe. The trouble is to find out you would need to open it up look at the pistons and measure them and the bores. If the slap is because of a cracked piston skirt than it would probably fix it. Is the import cost as much if you bought the parts from Austria? There was an old time way to fix them if the pistions were still fairly good shape, they would knurl the skirts to tighten up the clearance. Back in the day when there was little money to keep the family car running it was quite common on a low budget rebuild of rings, bearings, and a valve job. Good luck
 
You'll probably find that once you tear into the engine, the block will need to be bored, the crankshaft reground, rods reconditioned, etc... :banghead: . Once they begin to make noise for as long as you say this one has, and you keep driving it without attending to it, it will likely have other problems you will have to address as well. It would probably be a good idea to have a plan "B" if the cost of fixing this engine is more than you want to spend.
 
you say you have high cabon on the plugs, this tells me you are running very rich on fuel. does the engine have a PCV valve? if so is it clear (blow through it)? check to see if the choke is opening all the way. If the plugs are oily you have a ring problem, if dry it is unburnt fuel causing carbon buildup. to remove the carbon buildup on the pistons,
1. remove air cleaner
2. coke, beer etc, can full of clean water
3. with hot engine, hold trottle open to about 2500 rpm
4. gentely pour the water down the carb, but DON'T let it stall out
5. rev engine higher then let drop a bit and rev again while the water in entering the carb.
when the water is gone, let it idle for a bit, and see if the knocking is gone. if so you need to reduce the jet size in the carb to lean it out. Plugs should have a tan color if running proporly.
 
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