Piston slap

[Grottie Yachtie]

I am running volvo md2030's in my cat. When starting up, the stb motor is fine but the port motor has a noise to it which I think is piston slap. The noise goes away after 5-10mins running. It doesn't blow any smoke. The engine has done just under 2000hrs. Should I be concerned about this and is there any remedy or quick fix? Would appreciate any info.

Grottie Yachtie

[sony2000]

I don't think that slap goes away when warmed up.
If the lifters are hydraulic, then a lifter is sticking.
Change the oil and add a little thicker SAE.

[Dave_S]

I don't know much about diesels but performance engines with forged pistons rattle when cold until they warm up then they are good to go.

Is it a new noise? If so I'd be concerned that it might be more serious.

Piston slap is a more hollow sound than a rattle. How sure are you it's piston slap? Piston slap is when piston skirt flops to the other side of the bore when the piston is changing direction. If it goes away when it warms up, I would be very kind to it until it warms up and I wouldn't be to worried about it but would keep an ear on it to see if it gets worse. A rattle is usually a big end bearing and should be fixed straight away.

[a64pilot]

A dirty injector will cause a cold motor to sound exactly like it has piston slap, old cure was to run some auto tranny fluid in the fuel, now there are specialized cleaners, it's just varnish on the tip is all.
Piston slap is usually caused by a short skirt piston and especially if it's a loose fit, short skirt Pistons are all the rage now for less friction and more efficient and better fuel mileage spark ignition engines, however I do not think any Diesels are built with short skirts, least not any older Diesels..

Google LS engine piston slap for some excellent explanations, even videos of the noise

[SDChristian]

Pistons can wiggle until they heat up and expand, which eliminates the extra space.

[rognvald]

Piston slap in a 2000 hour engine? Possible, but not probable. But, before I would get too involved, I would want to know what's been your oil maintenance schedule? Do you change filters with every oil change? Do you have the same oil(weight, grade, brand) in both engines? Engines with serious problems are not self-healing and there's no such thing as a "mechanic in a bottle," however, I have seen many engines with "noises" miraculously self heal when run properly and maintained under the proper oil regime. Before I would spend any serious time or money on the offending engine, I would service the engine with the recommended factory oil/filter and while underway, run the engine through varied rpm's especially up to max rpms over the next month. If it gets worse, go to plan B but, you might be surprised that your sound "magically" disappears. When it comes to engines(major expense), I always begin with the most simple, obvious things first before spending big money and time. I hope this helps.