blue236

I think I may need a coupler but I want to make sure that's the part before I spend the money and time replacing it. I'm smelling a little bit of rubber from the engine bay. I noticed my power steering belt is slipping a little so I was hoping that was the cause even though my limited knowledge told me it was probably the coupler. I was cruising at about 30 mph and my rpm's were reading at 4900, when it should be around 3000. I opened the engine hatch and smelled rubber but not necessarily in the back near the coupler. I then cruised at 1800 rpm's but the needle was revving up to 2100 or so for no reason then back down. Is there anything else that can cause this? I appreciate any and all input. I'm a novice when it comes to working on boats. It's a stock 7.4 liter mercruiser.

sunbather1969

If its that bad the coupler would have thrown rubber out of the area where the shaft goes through. But also you need to cure the ps belt.

blue236

I'm not seeing anything that is definitely rubber in the area below the motor and below the coupler. It's black down there in the very back, but no definite shards of rubber.

sunbather1969

It actually came out like paint on mine after it melted and slung all over the back area if you take your finger and rub it youll see what im talking about

PARASAIL941

Have you checked your prop hub? Hopefully the rubber smell is the belt and you just need the prop re-hubbed , Good luck!!!

Quinlan

iTrader: (1)

Mine coupler never slipped- it worked or it Didn't.

blue236

The prop hub is in good shape. I figured the belt is slipping because I saw a little black rubber dust that got flung off and onto my battery box in the engine bay. The belt slipping shouldn't cause the motor to rev up though, and the prop hub is fine.

Mr Maine

How do you know the prop hub is good? I would mark the hub and prop with a punch or sharpie marker then run it and see if it moves. Same with the engine coupler, although I agree if it is spun, there will be evidence rubber pieces and smell.

I spun a rubber hub in a mirage prop, there was no visible evidence that it was spun. Idled fine to about 1200rpm then would spin on the hub.

blue236

I guess I should have said the hub appears good. The hub is seperate from the prop, so I'm not sure where or how to mark it. The hub isn't worn out on the inside in the least so I don't know how it could spin. I had a prop with the hub all in one piece, and that was easy to mark. Had to rebuild the hub.

JaayTeee

Sounds like you might have snagged a piece of debris that stuck on the lower gear case and partially disrupted the water flow to the prop.

I've never seen a coupler or prop hub that would slip and still allow the boat to run much more than idle speed.