Universal 5432/M40 exhaust elbow?

[rwthomas1]

Looking at the exhaust on my 5432 last weekend it occurred to me that it could be improved. The exhaust exits the riser to a hose that is tapered and clamps to a 90* bronze plumbing fitting then to the waterlift muffler. The 90* fitting is a standard marine plumbing fitting with screw in hose barbs, etc. This fitting, assuming it is like every other fitting I have ever seen, will be quite restrictive to exhaust flow with the multiple interior convolutions and the harsh 90* turn. I am wondering if a heavy wall stainless steel mandrel bent 90* elbow could be substituted at this point? In theory, this would improve flow, should decrease backpressure, etc. This should allow the engine to make slightly more power at a given throttle setting due to decreased pumping losses, run cooler, and produce less soot. Any ideas/input on this one? Or do I have to be the guinea pig? RT

 

[stbdtack]

Ditch the 90 deg fitting and use hose to make the turn. Use the exhaust hose with the ribs and it can be bent into a pretty small radius. Vetus makes an excellent flexible exhaust hose. Outside is ribbed but inside is smooth.... also if you have the check valve fitting in the exhaust, get rid of it.
You're not the guinea pig it's been done many times....

 

[footrope]

SS elbow

This cost about $225. Two inch diameter.

 

[Dferr]

I also have the 90 degree bronze elbow, why was it installed? I was wondering about this my self.

Footrope, where did you find that mixing elbow?

Thanks,
Don

 

[stbdtack]

Great Craig......I thought I was content and life was good, now i have to have one of those.....

 

[rwthomas1]

What Craig has is a complete replacement for the mixing elbow. While a very nice piece, my elbow is only two seasons old so I think that will be fine for a while. I hadn't thought of simply bending the hose but I have a feeling that this would further restrict the already cramped access to the packing nut adjustment? I figured the stainless 90* would be simple and cheap enough. I will look into the Vetus hose or any other hose that would make that bend.

I know that some have upgraded the sizing of the exhaust hose all the way to the transom. What size is optimum and did the waterlift muffler get replaced to upsize the fittings on that too?

Thanks! RT

 

[Glyn Judson]

Increasing exhaust hose size.

Rob, I increased the size of my hoses aft of the muffler when I replaced it with a new one. I fitted a Vernalift with 2" barbs and the original Yanmar 2QM15 that came with the boat used 1 1/2" hose. When the boat was re-engined with a Yanmar 3GMF using 2" exhaust hose before I bought her, just the length from the engine to the muffler was increased but they stopped there. The original 8" steel pipe with welded ends began to rust away after 27 years and that's when I put the Vernalift in and discovered the two different hose sizes. It meant replacing the transom flange (comes out the port quarter on the E31) as well. Like so many projects on a boat, one task results in two or three along with it and this certainly was the case. Glyn Judson, E31 hull #55, Marina del Rey, CA

 

[stbdtack]

agreed, the factory elbow is good if its in good shape. I replaced my muffler with a Vetus and ran 2" hose all the way back to the transom. My hose was delaminated and collapsing on the inside. Vernalift mufflers are about $150 at west.

I dont think the bent hose affects the access to the stuffing box. You will be suprised how tightly you can bend the ribbed hose.

Most important is getting rid of that stupid check valve if you still have it

 

[footrope]

It was pricey - but I am intrigued by stbdtack's bent hose idea

I had the entire exhaust system upgraded from the original 1-1/4" to 2" in 2004. The elbow is bent from SS and is a custom job. I think it was a good idea. The small salt-water mixing fitting is on the wrong side of the elbow, by the way. It kind of bites into the insulation on the port side of the compartment. I also got a 3" heat exchanger at the same time.

This boat has been offshore and it had a full-flow (?) ball valve at the transom. So the valve, through-hull and muffler also got replaced.

A 2" diameter rubber, reinforced hose bends about 90 deg. and connects to the muffler from the smooth end of the elbow.

The overhaul was precipitated by delamination of the silicone liner in the short hose that went from the old elbow to the muffler. The back pressure blew the hose off the muffler and we got to sail into the dock. It took three passes - and luckily the wind in the harbor was only about 5-8. Outside it was blowing 20 knots.

 

[FrankJ]

EXHAUST LEAK on E38-200

Hi,
Its been a while since I've been here. I have an exhaust leak just outside the exhaust manifold, on my 5432 /M40 engine where the pipe connects to an elbow. The exhaust pipe comes up from the manifold to this 90degree elbow then connects to the exhaust hoes at the other end. Does someone know where i can get the 90 degree elbow ? Or would an elbow need to be fabricated.

Thanks
Frank

 

[Glyn Judson]

Exhaust elbows.

All, This might be slightly off topic but still in the ball park. Why don't I ever see bronze exhaust elbows? I'm sure there's a good reason I don't or we would see them everywhere. Anyone have a thought or answer? Thanks, Glyn Judson, E31 hull #55, Marina del Rey, CA

 

[Emerald]

All, This might be slightly off topic but still in the ball park. Why don't I ever see bronze exhaust elbows? I'm sure there's a good reason I don't or we would see them everywhere. Anyone have a thought or answer? Thanks, Glyn Judson, E31 hull #55, Marina del Rey, CA

I believe the bronze will become brittle with both the temperature and repeated heat cycling in the exhaust system.

 

[rwthomas1]

Frank,
How about some pics? I'm having trouble figuring out where you are talking about. FWIW, I ended up replacing the entire exhaust system when I put in the "new" used engine. Its now 2" from the engine to the transom. Made a big difference in power. RT

 

[FrankJ]

EXHAUST LEAK on E38-200

Hi

Attached are some pics of the exhaust system . The leak is just before the 90 degree elbow where the pipe threads into the elbow, ., see pic#3. Im using a mechanic for the first time and he's having a problem locating a complete setup, from the manifold to the exhaust pipe.(after the elbow).

Any thoughts, on where the parts would be available. Where was the custom pipe made? I'd appreciate assistance.

Frank
917 968-9724

 

[rwthomas1]

It would seem the 381 (mine) and the 380-200 are quite different in exhaust layout as I still cannot tell exactly what I am looking at. Looks as if the exhaust is wrapped and runs for a bit before the water is injected? That would explain the heat wrap. Unwrap that piping and see what under it. It may be common iron pipe. The cracked section is on the NPT threads of the male side. The broken piece can be extracted and just that section replaced, then you are back in business. Another pic, pull back a bit so we can see the orientation of all the parts, would help. RT