Exhaust question

"I just replaced my carburetor

"I just replaced my carburetor. (1976 120 Mercruiser.) I did the rough adjustment of the needle valves and it started right up.

I instinctively went and looked over the transom to make sure water was pumping out the propeller hub. (It was on the muffs.) It was. But exhaust and water also appeared to be coming out of the bellows between the transom and the outdrive. Bummer.

Then I noticed that the water coming out the propeller hub was oily and had a dull black layer floating on top of it.

My questions:

1) How long should that bellows last? (I just had all of the bellows replaced last year.)

2) Is the exhaust that oily and black because the mixture has not been adjusted or is something else wrong?

3) Should I shoot myself of my boat?

Thanks,

--FatBear"

"exhaust bellows should last m

"exhaust bellows should last maybe 4 to 10 years.
Because the exh bellows is such a pain to install, some use a little cheater that doesn't actually connect to the yoke. Maybe your guy put that type on in which case it would be normal for exhaust to exit there.
I wouldn't worry about black and oily - see how it runs down the lake first"

"Thanks for the lifespan info.

"Thanks for the lifespan info. It will help when I go talk to them about it.

The exhaust is also going through the prop hub, so I don't think they cheated it. (If I understand the cheat correctly.) Also, I know that they removed the outdrive to replace the bellows because they reversed two of the hydraulic lines which apparently blew out the seals on my admittedly ancient trim/tilt cylinders.

--FatBear"

Removing/Installing a Mercruis

Removing/Installing a Mercruiser outdrive does not require disconnecting any hydraulic lines.

Reversing lines would not blow seals if it was even possible to make that error.

"Yeah, I thought they could ju

"Yeah, I thought they could just remove the outer end of the hydraulic cylinders, myself, but for some reason they took them completely off.

It is actually easy to reverse the lines. There are four ports on the bottom of the transom part of the outdrive (the yoke?) Two on each side. The forward port on each side goes to the forward port on the hydraulic cylinder. The rear port on each side goes to the rear port of the cylinder. On my old cylinders, the two ports are very close together, so there were four hydraulic lines of equal length, with identical fittings. Easy to mix up. They mixed up one side and put the other side on correctly. This apparently had the effect of making the two cylinders fight each other. Maybe that won't harm new cylinders, but these were 32 years old. The weaker one lost the battle very quickly, the other seemed to work for a while before it gave out.

--FatBear"

"I just talked to the guy at t

"I just talked to the guy at the shop and he said that the exhaust has an over pressure cutout and that's probably what I was seeing. So false alarm on the exhaust leak.

--FatBear"

"2) Is the exhaust tha

"2) Is the exhaust that oily and black because the mixture has not been adjusted or is something else wrong?"

Mixture needs fine tuning along w/possibly the choke. Does it belch black sooty smoke when it starts? The choke is set too rich.

"Yep, it's black. I'l

"Yep, it's black. I'll go through the carburetor adjustment procedure in the next day or two when I get the time. Sounds like that should fix it. The boat ran fine until the carburetor stopped carbureting.

Thanks,

--FatBear"