Piston slap. Seriously???

[lionheart002]

Hi all. Just noticed my B200F has got a piston slap when cold. Apparently it is a common thing and is caused by poor engine design(insufficient piston cooling due to lack of piston oil squerters) . Does your engine have it? How does it affect the engine longevity? Always wanted to have a 740, since I was a kid. Bit disappointed mine has it. Still planning on keeping it though.

[Pete940]

My B200E had it, quite badly when cold. Nothing to worry about in my opinion. They run fine regardless.

[Laird Scooby]

Hi all. Just noticed my B200F has got a piston slap when cold. Apparently it is a common thing and is caused by poor engine design(insufficient piston cooling due to lack of piston oil squerters) . Does your engine have it? How does it affect the engine longevity? Always wanted to have a 740, since I was a kid. Bit disappointed mine has it. Still planning on keeping it though.

What you could try is running it on 20W50 oil instead, that may help alleviate it somewhat. On an engine in good condition, 10W40 semi-synth would be the way to go with a red block, as yours is showing some signs of wear, the 20W50 mineral or semi-synth might just be enough to keep it quiet and prevent further wear.

Don't forget the red block comes from the old B18/B20 engines used in the 120/140 series back in the 60s and would have had 20W50 as the specified oil back then. As such, going to 20W50 in your "modern" red block shouldn't be a problem. ;) :D

[lionheart002]

Thanks guys. I am planning on trying Lucas oil additive at first. At the moment it is 10W40 in it.

[Clan]

Hi all. Just noticed my B200F has got a piston slap when cold. Apparently it is a common thing and is caused by poor engine design(insufficient piston cooling due to lack of piston oil squerters) . Does your engine have it? How does it affect the engine longevity? Always wanted to have a 740, since I was a kid. Bit disappointed mine has it. Still planning on keeping it though.

The only times I have noticed this is after the engine has been overheated , and only on No 4 cylinder ! No problem though .. never known of it suddenly developing with no reason ..

[classicswede]

Lack of oil squirters are not the cause of the issue, it is much more down to piston design. Squirters can slow it down

They can go on a very long time with piston slap

[TheLeeds]

What you could try is running it on 20W50 oil instead...........

Yep. That should work.

Many years ago, I bought an old 1.6 crossflow off a boy racer, to fit into a MK2 Fiesta. He assured me it had never been thrashed, but he lied. The clutch was burnt out, and it had very poor compression because the rings were gummed up, and I noticed there was a lot of scoring on the piston skirts when I had it apart to replace the rings.
I put new big end shells and a new oil pump on it as well, but I didn't want to keep thowing money at it, so I didn't replace the pistons.

When it was all back together, it was amazing, and great fun in a bog standard Fiesta shell that didn't even have servo brakes. The tailgate badge still said, 'Fiesta Popular', and it had the poverty spec metal bumpers and horrible aftermarket plastic wheel trims, so people never realized until it was too late that they were never going to catch up with it away from traffic lights and on slip roads.

The only downside was the piston slap when cold. I cured it by putting 20/50 GTX magnatec oil in.

[AllHailKingVolvo]

I agree with the above, put some heavier grade oil in it and don't worry about it. I've had three B200Fs, two (including my current 744) had very minimal slap when cold and one (my second 745) would clatter like a shopping trolley full of tin cans on the cobbles for a good couple of minutes on a winter's morning.

It would always settle down when warm though and it didn't affect the running or performance at all. I put slightly heavier oil in it which ameliorated most of the noise and the car is now owned by my mother in law...still running like a peach despite close to a quarter of a million miles on it (The car!).

[MiniNinjaRob]

What does piston slap sound like?

[Laird Scooby]

You'll get several replies i'm sure but to my mind, it's always been a medium sort of knocking, not as heavy as big end knock or as light and "tinkly" as little end knock, usually happens under load when cold and eases/disappears when hot.

Hopefully the other replies will be either very similar or just different enough to give you a really good idea! ;) :D

[TheLeeds]

What does piston slap sound like?
On that Fiesta engine, it was a kind of supressed intermittent clatter, slightly more noticeable on the overrun after being revved. Not all that loud, and nothing like the distinct loud tap / knock you'd get if the big ends were going. It was certainly nothing that would cause alarm or make you think the engine was about to self destruct. I only knew what was causing it because I'd made the choice not to throw money at the project indefinitely. I could have carried on and put new pistons in, had the block rebored, done the main bearing shells etc, but you've got to draw the line somewhere, and I wanted to fit the engine and drive the car.

It sounded a bit like dropping a small screwed up bit of bacofoil into an empty tin.
It's caused by slight wear round the lower part of the piston, and the noise you hear, if any, is the sound of the side of the piston, briefly making contact with the cylinder bore. Thick oil stays around slightly longer and reduces or prevents this contact, and supresses the sound. I did about 30,000 on the engine I'd rebuilt using the original scored pistons, and I never had any problems with it, other than the car eventually rusting away.

https://www.saabcentral.com/phpgallery/albums/album87/piston_skirts.jpg

[Laird Scooby]

Great write up! ^^^^^^ :thumbs_up: ;) :D

[Clan]

On that Fiesta engine, it was a kind of supressed intermittent clatter, slightly more noticeable on the overrun after being revved. Not all that loud, and nothing like the distinct loud tap / knock you'd get if the big ends were going. It was certainly nothing that would cause alarm or make you think the engine was about to self destruct. I only knew what was causing it because I'd made the choice not to throw money at the project indefinitely. I could have carried on and put new pistons in, had the block rebored, done the main bearing shells etc, but you've got to draw the line somewhere, and I wanted to fit the engine and drive the car.

It sounded a bit like dropping a small screwed up bit of bacofoil into an empty tin.
It's caused by slight wear round the lower part of the piston, and the noise you hear, if any, is the sound of the side of the piston, briefly making contact with the cylinder bore. Thick oil stays around slightly longer and reduces or prevents this contact, and supresses the sound. I did about 30,000 on the engine I'd rebuilt using the original scored pistons, and I never had any problems with it, other than the car eventually rusting away.

https://www.saabcentral.com/phpgallery/albums/album87/piston_skirts.jpg

As I first said above, this is usually caused after the engine has overheated , That piston above has clearly overheated and expanded too much.
The piston slap is usually worse when cold and a hollow light rattle and the tone of it can be altered by the position / load of the throttle , You could almost play a tune with the throttle pedal , there is one position where the engine neither brakes or accelerates where the noise goes ...

[Stephen Edwin]

The only engine distress sound I can vouch for is an A Series broken crankshaft.

THUMP !!! THUMP !!! THUMP !!! THUMP !!! THUMP !!!
THUMP !!! THUMP !!! THUMP !!! THUMP !!! THUMP !!!
THUMP !!! THUMP !!! THUMP !!! THUMP !!! THUMP !!!
THUMP !!! THUMP !!! THUMP !!! THUMP !!! THUMP !!!
THUMP !!! THUMP !!! THUMP !!! THUMP !!! THUMP !!!
THUMP !!! THUMP !!! THUMP !!! THUMP !!! THUMP !!!

ad infinitum if allowed to continue ....




I far prefer the call of the bittern. Audible for miles across the marshes.

Boom !!!


.

[MiniNinjaRob]

Thanks, I'm always paranoid about noises, nothing wrong with mine, its just the sound of the engine! (local volvo experts say it sounds great BTW)

[lionheart002]

Made a video, so you can hear it. If you haven't heard a piston slap so far... Can't say it is too bad...

https://youtu.be/_xCOjbiy54o

[Laird Scooby]

Made a video, so you can hear it. If you haven't heard a piston slap so far... Can't say it is too bad...

https://youtu.be/_xCOjbiy54o

Thanks for that - puts into real noise what my description couldn't say with words! :thumbs_up: ;) :D

[AllHailKingVolvo]

Thanks for that - puts into real noise what my description couldn't say with words! :thumbs_up: ;) :D


That doesn't sound too bad to me, just sounds like a cold B200F...perhaps they're all a bit piston slappy when cold. More or less the same as all three B200F cars I've owned 🙂