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Stringer 800 and 305 V8 exhaust hose replacement question

gcban

Member
"I need all of your expert OM

"I need all of your expert OMC help with my 1985 Trophy (V-8 5.0/305cid GM engine and 800 stringer outdrive) exhaust hose replacement. I need to replace the wet exhaust hose that comes from the exhaust manifold risers to the elbow tube and also the hose that attaches from the elbow tube to the bell housing on both sides. All 4 hoses are 3.5 inch ID exhaust hose. Lower hose is 2.5 inches long, upper hose is 4.25 inches long. Both hoses on each side are straight, no bends required.

I put my boat in Lake Washington last weekend and heard water tricking into the bilge. Starboard lower hose was leaking near the clamp, tightened it which did not help. Started engine and that stopped water leak but then you have small exhaust hiss coming into the engine compartment. Pulled the boat out of the water immediately after that. Looks like the failure of this hose or the clamp could put in underwater quickly.

My question is this. Do I absolutely have to use the OEM (909232 & 909371) hoses as published or can I just make exact duplicate lengths with some Shields Marine Nautiflex Wet Exhaust hose? This is my first inboard/outboard boat with a wet exhaust system and I prefer not to leave the proper selection of these hoses to my beginner’s dumb luck! I don’t see what the problem would be with the Shields bulk exhaust hose cut to size but like I said, I am new to this. I welcome any comments, feedback, suggestions or even mild ridicule and scolding as long as it helps me get the job done right.

Thanks to all of you for being so helpful to someone new to this like myself. It is truly appreciated. (picture attached, parts # 18 and 19)



Gerry
219704.jpg
Exhaust V8 GM and manifold pic
 
"those OEM hoses are $45 and $

"those OEM hoses are $45 and $26...why risk sinking the boat or damaging the engine? you can order them right here at marineengine.com
they're in stock.

did your original hoses melt during an overheat?

I ask that because the exhaust flappers (water shutters) in the stringer intermediate seal pretty tight... if water was running in, I wonder if the flapper on that side might be melted.
regardless, when you change that hose next time, look in with a bright light if you can down the exhaust ports at the water shutters."
 
"Hy Stat,

Thanks for the re


"Hy Stat,

Thanks for the response. The hoses that are currently on the boat did not melt but it looks like they may be getting small cracks at the very end of them near the clamps. The previous owner must have replaced them sometime ago. I recently had then off to change the riser gaskets and that one must not be seating well anymore. Both Sides have standard (Hose) clamps on them which I also want to change out to something more heavy duty.

I now know that there are flappers in the intermediate that I did not know were there thanks to you (told you I was new). Where are they located and can they be seen (and replaced) from the outside of the intermediate if I raise the outdrive up and look into the exhaust port? I have attached the only photo I have of the exhaust port from the outside angle. I will take a look inside the inside port when I take the hoses off next week. (Have to head down to AZ tonight).

Thanks again!

Gerry
219708.jpg
Exhaust Port - 800 stringer
 
you don't want to know wha

you don't want to know what's involved in changing the flappers... the engine has to come out so lets hope they are ok. -if you stick a long screwdriver down the exhaust ports from inside the boat you can push them open and then pull the tool out quickly and you hear the springs flap them shut with a rubbery thud.

#42 in this pic is the water shutter or flapper

http://shop2.evinrude.com/Scripts/I...65\12.TIF&ilSC=31&ilIV=0&ilBR=0&ilIF=P&ilRE=8
 
"Hy Stat,

Put off my return


"Hy Stat,

Put off my return to AZ to take my hoses off and inspect. Going to start raining for several days starting tomorrow and my boat is in outdoor storage where I work on it. Your suspicions were partially correct. The starboard flapper is not seating correctly and when it snaps back I can still see a small gap between the tube and the flapper face. Does not look like it is melted, just not seating right. Almost like it is not quite level on the face of the flapper. The port side flapper seats flush when it closes. Both sides seem to have equal tension on the flappers so I don’t know what the deal is. (Picture attached).

I am going to order the hoses and think I might even replace the starboard metal exhaust tube between the hoses. It looks a little rough and beat up around the lower edge. I don’t have the capability of engine removal.

Would having this boat in the water full-time be a bad thing with this flapper not sealing tight? I have been getting the boat ready for parking it full time in a covered marina slip so I can get more use out of it.

As usual your comments and guidance are humbly accepted and appreciated. Thanks!

Gerry

219744.jpg
Starboard_flapper
 
"I don't think that flappe

"I don't think that flapper will cause any issues for mooring - it will still do it's main job of stopping wave wash from back-flooding the engine when you come off plane. not worth pulling the engine for. It's not technically supposed to keep the boat afloat...your new hoses will do that.

Mind you your boat must sit very low in the water for those ducts to be lower than the waterline...

waterline is below the exhaust ducts of the intermediate on my boat...interesting... have you ever cut any test holes in the floor to look for waterlogged foam etc in your boat? or maybe you have a rearward fuel tank - mine is in bow, + my engine is only a V6
I know I have removed all the exhaust in the lake before and no water came in... mind you my dock is in an area with no waves.

Are you sure that "duct" in the above pic is not porous from the corrosion? It sure is nasty looking... makes me glad it's all fresh water where I boat"
 
"I know what you mean about th

"I know what you mean about the salt water damage. What the picture does not show is even though the lip is partially corroded on the bell housing exhaust flange, where the exhaust hose seats and clamps onto it is in fine shape. No doubt that the bell housing will have to be changed out in the next few seasons.

I have a 305 V-8 engine and my gas tank (64 gallons) sits directly in front of the engine so lots of weight in the aft part of the boat. Boat gets up and moves once up on plane, trim tabs help a lot on this boat. Cruises about 38 knots at 3200 rpm and 1/2 tank of gas with 4 people in it. At WOT (4500 rpm) it hits around 47 knots. It probably does sit lower in the water than your boat does. As for the waterlogged foam comment I would not know where to start to see if that is going on.

Once I install the new hoses I will take it back out to Lake Washington for a quick sea trial and photograph how low it sits in the water at the outdrive area. Will post the picture after it’s done. Thanks again for your help and insight.

Gerry"
 
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