Cruisers Forum
 


Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 16-04-2021, 06:13   #1
Registered User

Join Date: Oct 2017
Location: Detroit
Boat: O'Day 30 CB
Posts: 52
Exhaust hose reducer?

My new-to-me O'Day 30 with a 2QM15, is getting splashed at the end of the month. As part of the refit, I replaced the 40 year old exhaust hose. The old stuff was apparently compliant enough to attach to the lift muffler (2") and the transom fitting (1.5"). The new hose will not compress enough to grab the 1.5" fitting.

Easy enough, I ordered a reducer, which is now in limbo somewhere. The boat is 3 hours away, and this weekend is really my only chance to start her, have time to fix anything, and still make my launch date.

I'd REALLY like to start the motor (I've never seen it run) before I launch. Can I wrap the 1.5" transom fitting with something so I can temporarily attach the exhaust? I just want proof of life- I'm not going to motoring for days :-)

Thanks!
kayakerChuck is online now   Reply With Quote
Old 16-04-2021, 06:16   #2
Registered User
 
pcmm's Avatar

Join Date: May 2014
Location: Whitby, Canada
Boat: Morgan Out Island 41
Posts: 1,394
Images: 2
Re: Exhaust hose reducer?

Instead of ordering a reducer, why not order a 2" exhaust transom fitting. Its not ideal to introduce restrictions in the exhaust. and by changing out the fitting you remove a joint from the system.
pcmm is offline   Reply With Quote
Old 16-04-2021, 06:46   #3
Senior Cruiser
 
tkeithlu's Avatar

Cruisers Forum Supporter

Join Date: Feb 2012
Location: Carrabelle, Florida
Boat: Fiberglas shattering 44' steel trawler
Posts: 3,192
Re: Exhaust hose reducer?

pcmm has it. Introducing a constriction in the exhaust changes the backpressure, which in turn alters the evacuation of spent gases from the cylinders. That reduces the amount of nice fresh clean air in the next load being compressed. In nearly all cases less back pressure is best; The only engine I've ever met that needed backpressure was a two-cycle motocross bike that used resonance in the (very loud) pipe to capture the next load in the cylinder. Note that racing engines don't have pipes....
__________________
Never let anything mechanical know that you are in a hurry.
tkeithlu is offline   Reply With Quote
Old 16-04-2021, 06:58   #4
Registered User

Join Date: Oct 2017
Location: Detroit
Boat: O'Day 30 CB
Posts: 52
Re: Exhaust hose reducer?

I agree that the transom fitting should be swapped out for the correct size. It's also been this way for 40 years- it will be OK for another season.

Currently, the boat is 3 hours away, just off Lake Michigan. It's cold. Messing with epoxy & such to move bolt holes is going to take more time than I am devote to it now. Next year, the boat will be 1 mile from my home & shop. I'll correct a WHOLE LOT of evils. For now, I'm basically only interested in making her safe so I can get her home. I have a very small window to work on her.

I'm thinking I can just wrap shrink tape or something around the transom fitting- good enough for a few minute test run while on the hard.
kayakerChuck is online now   Reply With Quote
Old 16-04-2021, 07:58   #5
Registered User
 
Bill O's Avatar

Join Date: Jul 2015
Boat: Bruce Bingham Christina 49
Posts: 1,994
Re: Exhaust hose reducer?

I agree w/all the previous posts of getting the proper sized transom fitting (2").

You could jury rig it. Do you have any of the old 1.5" exhaust hose still? Cut off a piece and place over inside flange for a spacer. If you have normal 1.5" exhaust hose, the OD should be ~1.875" and may be enough now to clamp the 2" hose down. If still a little floppy, add some aluminum tape wrap on the 1.5" hose.

Again, this is only a temporary fix to test your motor.
__________________
Bill O.
KB3YMH
https://phoenixketch.blogspot.com/
Bill O is offline   Reply With Quote
Old 16-04-2021, 22:37   #6
Marine Service Provider

Join Date: Sep 2014
Location: Auckland, NZ
Boat: Compass 790 , 7.9 metres or 26 ft
Posts: 2,222
Re: Exhaust hose reducer?

If you have any fibreglass tape, that & RTV silicone will work for years to fill the gap. If you have time to let the silicone go off just the silicone will work. Current silicone gap filler at least 3 years old on our exhaust hose.

We have basically a 1/2 of a 2QM15 ( YSM8 ) seem to be pretty good engines apart from the parts pricing.

Failure points are exhaust elbows & oil pump clearances. I'd check the oil pump clearances if the oil light is slow to go off after starting FYI.
Good luck
Compass790 is offline   Reply With Quote
Old 17-04-2021, 00:53   #7
Registered User

Join Date: Nov 2013
Location: Nice, France
Boat: Hunter Marine 38
Posts: 1,092
Re: Exhaust hose reducer?

Because of the water injection exhaust gases are very low temperature. For your startup trial use whatever reasonable solution you have at hand and it will hold. Exhaust gas temperature is around 40C right after the elbow, at the transom it should be even lower.
sailormed is offline   Reply With Quote
Old 19-04-2021, 18:42   #8
Registered User

Join Date: Oct 2017
Location: Detroit
Boat: O'Day 30 CB
Posts: 52
Re: Exhaust hose reducer?

A bit of plastic tape wrapped around the exhaust fitting did the trick nicely.

A 5 gallon bucket run through showed me that I had some loose raw water and exhaust fittings, and that the motor starts and runs nicely. I can relax a bit before launch!

Thanks all!

(New thread with new questions coming. Thanks for helping to erase my ignorance!)
kayakerChuck is online now   Reply With Quote
Reply

Tags
exhaust

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Possible Rust Reducer. Patrigo Construction, Maintenance & Refit 10 19-09-2020 23:21
Looking for source for bronze reducer 1" to 1/2" summercamp Construction, Maintenance & Refit 8 01-05-2018 12:23
Shore Water Pressure Reducer Safety schoonerdog Plumbing Systems and Fixtures 30 11-08-2011 08:47
New Prop, Shaft . . . Nylon Reducer ? Anzo Propellers & Drive Systems 4 20-09-2010 16:19
US hose on metric hose barb coot Construction, Maintenance & Refit 5 04-03-2006 20:22

Advertise Here


All times are GMT -7. The time now is 18:43.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.