Husqvarna 550xp mark2 weird high reving issue?

[Mark_Skyland]

Some of the mk 2 550xp's did have issues with the crank seal, I think that they we installed incorrectly at the factory so if it is leaking a new seal should sort the problem. Although, the bearing may be damaged to contamination and the air leak may have caused issue with overheating and possible piston/cylinder damage.

 

You really need to do a pressure test to confirm that its the seal that's leaking and causing the issue otherwise your wasting your time just replacing it, its always been the one flywheel side IME. Also any machines I've seen with a dodgy seal don't run OK one day then poor the next, they hang onto the revs once the throttle is released. 99% of the time the rest of the engine is OK but I think ive had one maybe two that have destroyed the bearing which turns into a really expensive repair if you're out of warranty but TBH the seal issue usually shows itself well within the warranty period depending on how often you use the saw etc. This usually happens when the operator has just kept using the saw for a long time with the issue. 

 

Note to the OP there are two types of seal for the 550xp depending on the serial number (and the bearing used) so check that with L&S first before buying.

 

 

[adw]

I couldn’t get a sensible answer to why you could not fit the new seal in the old bearing assuming the bearing was good, I have fitted many of these seals old and new into old and new bearings with no issue, I also remove the stupid plastic washer which in my opinion makes the situation worse, it is always the flywheel side seal that goes, there theory was it is very dry and dusty behind the flywheel, the resulting abrasion destroys the seal, the new bearing and seal are from a different supplier.

[adw]

20 hours ago, Mark_Skyland said:

Yes another waste of electronic kit IMO that will never earn its money back. I must have £1000+ of diagnostic kit that's only ever used to setup up new carbs. TBH I don't recall any instance that the kit has helped with repairing a machine.

In its defence, if you know what you are looking for it can help diagnose some issues, the fuel settings, especially the L setting gives a good idea of what the carb is doing, the settings run from 5 to 125 , so 5 is the electromagnet valve fully open, as rich as possible, so if we have a very low figure the engine is running very lean, possible air leak, blocked fuel filter etc.