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Author Topic: Disconnecting an exhaust  (Read 2955 times)

AlisterL

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Disconnecting an exhaust
« on: February 09, 2009, 08:28:12 AM »

Greetings all,

I inherited a Stirling Models Chris Craft Corvette 42' model - the 48" version from my uncle and having reached a point of procrastination on my other build, I decided to take a look at the Corvette. To cut a short story shorter, I was intending to remove the engine - a Ohlsson & Rice Compact (not a Mk II or III) for cleanup etc and I got stuck at the exhaust. I must plead ignorance to things I/C - I've never built or operated one and that's my excuse for requiring help! So anyway, the engine won't come out 'cos the exhaust is attached to it and whilst the exhaust can be unsecured from the exhaust manifold, there isn't enough play in it to get it off.  And the exhaust won't come out through the transom due to the muffler. But the exhaust does appear to have a join in it as seen in the attached pic, so it must come apart somehow or it couldn't have been fitted in the first place!
How does this come apart? I have tried unscrewing the larger outer join tube relative to the inner tubes, but that started to get a bit ugly while using multi-grips and I did not want to scar it too much, plus it's debatable which way it might go. Should it slide? If so, it sure takes some effort, even after the application of CRC.

Any hints anyone?
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Alister

SteamboatPhil

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Re: Disconnecting an exhaust
« Reply #1 on: February 09, 2009, 02:28:15 PM »

I would have thought the exhust is bolted to a manifold on the cylinder head, and once that is off, all the pipe work should slid out, unless it has been soldered/ fixed in situ.
Any chance of a pic from the exhust outlet side ?
Phil
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Proteus

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Re: Disconnecting an exhaust
« Reply #2 on: February 09, 2009, 02:51:00 PM »

How about a picture of the exhust  manifold side.

Proteus
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AlisterL

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Re: Disconnecting an exhaust
« Reply #3 on: February 09, 2009, 08:26:10 PM »

I'll do a pic from the other side when I get home.

You can see, just, in the second pic where the exhaust takes a right angle turn, a rod poking out towards the side of the hull. This is threaded and had a nut and locknut on it which I have removed. That rod is too long to come out before hitting the side of the hull and there is not enough movement over the join between manifold and exhaust to separate the two. I think that the engine and exhaust have been put in as one piece and then attached to the exhaust outlet.

Thanks for looking chaps!

Alister.
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Alister

AlisterL

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Re: Disconnecting an exhaust
« Reply #4 on: February 10, 2009, 05:08:36 AM »

Pic of the engine from the other side - hopefully with a suitable amount of detail!
You can see at the bottom of the pic the threaded rod the comes out of the exhaust where it takes a right angle. On top of the manifold, just on the engine side of the exhaust, you can see a rounded head - I think that is the fitting the threaded screws into. The rod is too long to slide out before hitting the side of the hull and there isn't enough slop in the system to allow the exhaust to slide off the manifold either.
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Alister

SteamboatPhil

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Re: Disconnecting an exhaust
« Reply #5 on: February 10, 2009, 10:23:51 AM »

I think you may have to cut the rod, it looks to me as if that is a fitting bolt which fits into a nut inside the engine manifold, and pulls the exhaust into the exhaust stub. I would not cut the exhaust system as it looks custom made and is a lovely piece of work (I like chrome). I guess you have to work on the theory that some one put it together and got it in, therefore it has to come out reasonably easy (you would have hoped). Please keep us up to date, it has become an intriguing challenge  :-))
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andyn

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Re: Disconnecting an exhaust
« Reply #6 on: February 10, 2009, 04:58:02 PM »

Take out the rod and the manifold should slide out nicely. That 'Dustbin' exhaust will probably be way too noisy for the current regs, so you'll probably have to fit either a tuned pipe, or if you want to keep the original Paul down at Nimrif Models will chop it, fit a cone inside to silence it and weld it back up.
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Martin [Admin]

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Re: Disconnecting an exhaust
« Reply #7 on: February 10, 2009, 05:36:19 PM »

Can you get to all the engine mounting bolts?
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AlisterL

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Re: Disconnecting an exhaust
« Reply #8 on: February 10, 2009, 09:22:38 PM »

Guys,

thanks for your comments.

SteamBoatPhil - I don't want to cut it either! But there isn't enough room made (yet - there's a possibility!) in the frame to move the exhaust off the manifold. That's where Martin's idea might work - I believe I can get at the mounting bolts without too much trouble, but I think the problem there will be the inflexible exhaust pipe levering against the transom. I'm very wary of doing any damage that can't be easily repaired or hidden in some way. Phil, your statement that "as it went together and got in there, therefore it must come out" is the theory I am working on. Also the documentation I have for the engine suggests that the exhaust should be removed after every 25 hours of running and cleaned out - which supports that as well.
AndyN - I am sure you are correct about the rod and fitting the exhaust - but without modifying something (read cutting wood or metal) it wont come out. WRT the exhaust and noise regs - I'm in clean and green New Zealand and I don't know if such things apply! Which isn't to say you are incorrect either :)

I will try removing the engine mounting screws and see what happens - I guess I can lift it all until I hear wood cracking <shiver...> I also wondered about heating where I think the join is.

All comments and thoughts gratefully received!
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Alister

AlisterL

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Re: Disconnecting an exhaust
« Reply #9 on: February 10, 2009, 09:24:57 PM »

What I'm worried about is that, having never had to refurbish a model before, I don't want to go in rip, bust and hack causing more problems later on. So please forgive me if I seem a little reluctant to take a hacksaw to anything just yet!
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Alister

andyn

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Re: Disconnecting an exhaust
« Reply #10 on: February 10, 2009, 09:27:21 PM »

If it has O rings in there, they almost certainly will have perished by now. Which fortunately will be an advantage, because pulling hard on it will break them out easily.

What I'm worried about is that, having never had to refurbish a model before, I don't want to go in rip, bust and hack causing more problems later on. So please forgive me if I seem a little reluctant to take a hacksaw to anything just yet!

Thats fine, try to remove the engine mounting screws first. The engine should slide back off its coupling when the mounts and the coupling are undone.
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tobyker

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Re: Disconnecting an exhaust
« Reply #11 on: February 10, 2009, 11:24:35 PM »

If you get the mounting bolts out there might be enough flex in the exhaust pipe for you to wiggle the motor up and back and then withdraw it to port away from the silencer. Sounds like fun - do keep us posted with more pics please.
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AlisterL

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Re: Disconnecting an exhaust
« Reply #12 on: February 11, 2009, 09:20:50 AM »

Gents - problem solved!

Once the mounting bolts for the engine were removed, a quick wiggle and out it popped leaving the exhaust in place. I feel like I should have thought of that myself, but I was so focused on the exhaust I couldn't see the obvious solution. Some elbow grease, the multigrips (against my better judgement) and patience eventually saw the exhaust come apart where I thought it should and with minimal scarring, leaving just the external end in the transom with the joiner still on it. That came off with the help of some CRC and the presence of a smaller diameter hole through an internal frame to work against - I couldn't grab it by hand sufficiently well any other way. Now all is on the bench - photos of bits attached. For interest I have included some photos of other related bits including some damage (the sellotaped bits) caused quite possibly by a very young boy - lets just say "I have no recollection of those events Senator". You can also see where rust has started and where, on the shot of the inside of the hull, the varnish is peeling (on the left side). My next step will be to see if I can remove the foredeck and get at the clear plastic covering the portholes, remove it and clean up the rust.

Thanks to those who made suggestions - they are much appreciated.
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Alister

tobyker

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Re: Disconnecting an exhaust
« Reply #13 on: February 11, 2009, 09:38:33 PM »

Well done - she looks a lovely model. But do remember, when she's all back together, not to pull the starter viciously!
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AlisterL

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Re: Disconnecting an exhaust
« Reply #14 on: February 12, 2009, 01:24:00 AM »

LOL! Yes, I'll try to remember that :)

It is a nice model. I understand that my uncle and grandfather spent quite a bit of time removing weight from it for better performance etc.  I do recall seeing the radio that was originally used with it - a home made from instructions non-proprotional system - would have made getting the boat going the right direction a bit of fun...
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Alister

SteamboatPhil

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Re: Disconnecting an exhaust
« Reply #15 on: February 12, 2009, 12:06:25 PM »

See I knew it had to come out (the simple way it would appear) she is a nice looking boat I must say, can't wait to see pics of the refurbished boat on the water. Keep up with the good work. :-)) :-)) :-))
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AlisterL

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Re: Disconnecting an exhaust
« Reply #16 on: February 12, 2009, 08:36:48 PM »

You were right Phil!
I think the really simple way - that was initially intended - was to slide the joiner along the exhaust one way or the other, lift the exhaust up vertically and slide it off the manifold. The problem with sliding the joiner was that the O rings had got themselves a little stuck. They seem to be still on good condition and with a little clean up on the outside of the exhaust and it's extension they now move quite easily.
I don't have timeframe to complete the refurbishment - I'll have to see what bits it's needs.
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Alister

Bill D203

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Re: Disconnecting an exhaust
« Reply #17 on: February 17, 2009, 04:32:25 PM »

Take out the rod and the manifold should slide out nicely. That 'Dustbin' exhaust will probably be way too noisy for the current regs, so you'll probably have to fit either a tuned pipe, or if you want to keep the original Paul down at Nimrif Models will chop it, fit a cone inside to silence it and weld it back up.
" CUURENT REGS" Andy what are you on about???? Omra set there own noise level controls.  Some local councils/ parks wardens also set limits. As you know in the USA they do not make any attempted to cut the noise down.  Can you tell me where i find a copy of " The Current REGS" apart from the OMRA rule book???

Your boat looks very nice, I see from the photos that it has a rice engine. They are good little engines, I think they are a few years old now. Have you had a chance to run it? Please take some video of it so we can all enjoy it when you do get it back in the water. Re cleaning out the pipe. Modern fuel and 2 stroke oil should mean you will not have to clear the Ex pipe to often. The best way to clean it out is to soak it in petrol for a few hours then set light to it. (under controlled)  This burns all the unwanted oil from the inside of the pipe. Then if you can blow it out with an air line blower it should be good to go again.  Have fun with what looks like a very nice boat. :-))
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AlisterL

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Re: Disconnecting an exhaust
« Reply #18 on: February 17, 2009, 08:08:12 PM »


...They are good little engines, I think they are a few years old now. Have you had a chance to run it? Please take some video of it so we can all enjoy it when you do get it back in the water. Re cleaning out the pipe. Modern fuel and 2 stroke oil should mean you will not have to clear the Ex pipe to often. The best way to clean it out is to soak it in petrol for a few hours then set light to it. (under controlled)  This burns all the unwanted oil from the inside of the pipe. Then if you can blow it out with an air line blower it should be good to go again.  Have fun with what looks like a very nice boat. :-))
[/quote]

Thanks Bill. I haven't run the engine myself, my uncle said that the fuel filter needed to be replaced, and having now got it out, I've been concentrating on the hull and deck - but now I need to go and beg for funds, so it may be a while before much progress is made. As far as I'm aware the boat hasn't been near the water since the early 70's.
As for filling the exhaust with fuel and lighting it - that sounds brave, to say the least!
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Alister

Bill D203

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Re: Disconnecting an exhaust
« Reply #19 on: February 17, 2009, 08:53:09 PM »

Alister.
Is the pipe blocked???? What it says on the engine case is for a canister type Ex pipe which would have come with the engine. Clearly yours is not. If you blow down it it should be clear we no back pressure. If its OK then leave it alone. I use to have a 125cc 2stroke motor bike, every 6 mouths i had to take the guts out of it and burn it off using petrol. Oh happy days now long gone.
Anyway good luck with the boat, stick with it. It is worth saving :-))
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andyn

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Re: Disconnecting an exhaust
« Reply #20 on: February 17, 2009, 09:39:31 PM »

" CURRENT REGS" Andy what are you on about????

I do mean the OMRA book, but due to noise complaints etc it changed not all that long ago. Therefore producing the Current bit...
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