Starboard engine revs faster than port engine

[dsw222]

I have a 97 Challenger 1800 with the twin 110hp 787's

When i give both engines the same amount of throttle (i.e. move both throttle levers together in sync), the starboard engine will rev about 1000 RPM higher than the port engine... until I am at WOT, where they will both sync up and be around 7200

Does this just sound like I need to make a throttle cable adjustment? Or could there be something more serious wrong?

 

[Dr Honda]

Nope... sounds like one of your wear rings is a little more warn that the other, and it puts a little less load on the engine. So... it revs a little higher.

If they idle together, and peak together... the cables are fine.


One thing to try. Start both engines, and mash the throttle on the side that "Revs a little higher." I bet you will feel the cavatation without the second engine helping to push.

 

[dsw222]

Nope... sounds like one of your wear rings is a little more warn that the other, and it puts a little less load on the engine. So... it revs a little higher.

If they idle together, and peak together... the cables are fine.


One thing to try. Start both engines, and mash the throttle on the side that "Revs a little higher." I bet you will feel the cavatation without the second engine helping to push.

Thanks for replying to both of my threads (this one and the impeller question)! You are VERY helpful!

You mentioned that it sounds like one of the wear rings is more worn... one of them is cracked, and I believe that it is indeed the side where the engine revs faster. I didn't even think they were related... thanks for pointing that out!

It sounds like once I get new impellers installed with new wear rings, this problem should no longer be an issue (hopefully)

 

[pincusa]

I also have the same problem with mine, but both wear rings / props are new. I recall the manual says to adjust the throttle cables so at the same throttle position, they're both reving to 3500RPM. Now I only need small adjustments to get them both to sync at 5500RPM. WOT they're both running at ~7200 RPM

 

[dsw222]

I also have the same problem with mine, but both wear rings / props are new. I recall the manual says to adjust the throttle cables so at the same throttle position, they're both reving to 3500RPM. Now I only need small adjustments to get them both to sync at 5500RPM. WOT they're both running at ~7200 RPM

Do you mean that they're synced at 3500RPM but out of sync at 5500RPM?

If so, how do you make that adjustment? I only found the one way to adjust them in the shop manual (the way that you mentioned for 3500RPM)