Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Piston Slap

I had a noise develop earlier in the summer and after a lot of toing and froing it has been diagnosed as piston slap.
The car is about 6000 miles old, is this a common problem?
A quick bit of Googling and it is not obvious.
Thanks

Yours would be the first of which I am aware. And to be manifest at only 6k miles means the engine must have originally been built with very with very loose piston to cylinder wall clearance, and should have been somewhat noisy from new. Piston slap is a "soft" sound generally only audible for a short while at start up until the engine fully warms through. If the noise persists with a fully warm engine, it is more likely to be related to the Centa drive coupling which are famous for various maladies and sounds most usually related to the rubber drive rollers breaking up.

And it occurs to me that if you have an early car, you may still have the original Harley-Davidson torque compensator, which needs periodic greasing or they can get pretty noisy. Most early cars have been converted to the Centa rubber roller cush drive.

Thanks for the response.
We are pretty sure that it is the engine. The transmission has just been upgraded with a Bleazey upgrade and that is now wonderfully smooth.
Car is 2017 and so not an early one. Seems like my initial brief research was right and piston slap does not seem to be common.

Could it be knocking? Have you tried changing the spark plugs?

Check if there is any play of the Centa with the crankshaft by trying to rock the Centa through the Bleazey access hole. If it rotates, it means your crank-Centa connection is bad and needs a new connector (ie engine out again)...

I have heard of one engine that had new barrels and pistons under warranty for "piston slap" but that is the only one, so not a common problem. As you have just had the Bleazey Centa fitted (I assume the problem was not there before?) that could well be the source of the noise, as Paul V suggests. The Centa spline adaptor requires careful fitting, something complicated by the S&S crank splines not being made to very close tolerances it seems.

You can confirm any play in the Centa by removing the camchest cover and putting a socket on the end of the crank pinion retaining bolt and an Allen key on one of the screws on the outer edge of the Centa case. Hold the crank still with the socket and wiggle the Centa housing with the Allen key, any play should be apparent. If you have any play, that is the problem and the engine needs to come out again to fix it.

How old/miles/km's is the Bleazey upgrade and which roller type are you using - Original Bleazey or original Morgan?

Hi Fasteddie,

we just repairing an Euro 4 M3W. That one had noises as well. We started to take off cylinder heads and found that all valves have been too hot and now need replacing.
The cause have been both melted pre cats in the exhaust manifolds. Because they are melted, the engine couldn`t get rid of the exhaust gases what did cause that the valves
don`t seal anymore. Just a thought. On those M3W`s everything can happen....
Regards
Frank
Morgan Park

Hello again, thanks for the responses. Sorry for the delay in getting back but have been away.
The noise predated the Bleazey conversion which was recent. The liners are scored and apparently we have billet pistons when usually they are forged?
Judging from all your replies and the lack of any other threads or internet news on this subject it seems that it is pretty rare.

Eddie. I might be wrong but I reckon there are quite a few 3 wheelers out there with a bit of slap, you either put it out of your mind and use it or a strip down and a big job. Phil's car sounded like a bag of spanners when I drove it compared to my mate's I even commented on it he didn't seem that concerned and had quite a high mileage from memory. Em