Mariner 350 Exhaust leak

[SanJuanDreamer]

They're made of rubber, I was hoping to cut them out and replace with new ones, but I cant find a direct replacement. I emailed Carver, see if they have a couple or can recommend a OEM Exhaust tip. Pretty sure even if I removed all the screws, that 5200 in there will really be tough, might break something. The book calls for PN 5159000 Flng: Exhaust 5in 45 degree.

[bud37]

Judging by the stain colour,....do you know for sure the leak is coming from the outside or from the exhaust port itself (waste water from the engine) ?? Could there already be a crack in the port.??Yeah I agree it would be great to get a new one and cut out and replace.....could be tricky with it being rubber though.....I will have to take a closer look at our boat.....maybe you could replace with a like kind aftermarket that would fit the hole.....I know this isn't a great help but sometimes talking things thru gives you an idea...

To add, I had much the same thing with an 83 Mariner...took the complete exhaust apart and put new screws and caulking, new hoses done in 1990, a little heat helped get it apart...was transom exhaust though but the same idea.

[mjk1040]

May I suggest this approach? Remove the hose from the manifold to the muffler. Remove clamps, heat ends with a heat gun. Get one of those rubber strap wrenches to twist this hose to break it free and remove it. Then remove the bolts from the thru haul flange. A 1/4" drive deep sockets, some long extensions and a swivel to get to the inside nuts and a friend with a screw driver on the outside. Using the heat gun warm the flange on the outside. Sharpen a 2" putty knife and slide it between the flange and the hull little by little to break the 5200 sealant. Warm some more and try pushing the muffler to the outside and the flange away from the haul. If successful clean area good. re-seal with 5200 and put 5 new SS bolts in and start them. Some say you should just bring the flange up to the bead of 5200 and let set for 24 hrs or longer and tighten down the next day or so. Giving the 5200 time to form a gasket if you will, other wise you will squeeze most of it out and not leave much to seal the area. I feel your pain on this project. But now's the time to do it on the dry. Good Luck. Mike

[Viper]

Can anybody confirm whether this model has a core in this location? If so and there's been a leak for a while, the core may need attention if it wasn't sealed properly around the opening.

It'll be so much easier if everything is out of there so you can lie down and get to the side of the hull. Break the inside seal all around the exhaust hose at the joints with a mechanic's hose pick. It'll take a bit of muscle but it will come off. Putting it back together won't be a walk in the park either.

[Viper]

Source of the post....Some say you should just bring the flange up to the bead of 5200 and let set for 24 hrs or longer and tighten down the next day or so. Giving the 5200 time to form a gasket if you will, other wise you will squeeze most of it out and not leave much to seal the area....

That is the proper way to re-bed something however, only if the item is being thru-bolted. If just using screws this method shouldn't be used otherwise you'll break the seal around the screw when you go to tighten it the rest of the way. When doing the final tightening on the thru-bolt, you must not let the bolt turn or again, you'll break the seal. Tighten the nut without allowing the bolt to turn.

When using either a screw or bolt, you should always ream out the top of the hole so there is a bevel there under the item being fastened. This serves to hold a good bead of sealant at the top of the hole around the fastener that will not get squeezed out because it will be lower than the top surface. In fiberglass, this bevel will also prevent cracks radiating from the hole. A practice that should be used every time you drill a hole in fiberglass for a fastener.

[SanJuanDreamer]

In case anyone cares...Part number 8120
They're at Marine East and cost $104ea....thank goodness as I'm tired of paying out the ars for simple things...
http://www.marineeast.com/a_sch/sch_det ... &pid=08_01

[bud37]

Cool...now get in there and get dirty ,LOL.....If it were me I would just cut the exhaust hose near the port and put new, it is almost 20 years old and probably needs it anyway, that will make it much easier to get apart and reassemble.....

[mjk1040]

Thanks Viper for the clarification on the re-sealing technique. I only mentioned the bolt the method since that appeared to be what we were working with. Mike

[Viper]

Source of the post.... I only mentioned the bolt the method since that appeared to be what we were working with. Mike

Yep, I just thought I'd warn about when using screws for the benefit of anybody who might have a project using screws so they don't try to do it the same way as bolts. Glad you brought it up Mike, not many people know that's the way it should be done. It's so automatic with me that I didn't think to mention it.

[Viper]

While we're on caulking, a very good alternative to products you get in a tube is butyl tape. I've used this type of product on several projects and find myself using it more often now. It has a few advantages over caulking like no mess, no cure time, and no waste like you get with partially used tubes of caulking. No matter how hard you tighten things up, you can't squeeze it all out, there will always be a thin elastic/flexible amount between the two mating surfaces. It's great for bedding hardware including railing stanchions and the job noted above.

https://www.westmarine.com/buy/incom--butyl-caulking-tape--P015730286