what excitement, just about to round great whale island in the \bahamas when there is a strange knocking from the engine which had gone rather loud. Shut her down in the middle of a squall heading into the wind. Had alook down below and the threads of the pipe to the exhaust elbow(in fact the vertical pipe) had sheared off and was bouncing up and down. \\few choice words…
Anyway turned around and ran for cover, swooped into Green Turtle Cay under sail and dropped the hook. Then disembowelled my boat. Got the elbow off the engine and made friends with the locals. Set in vice and with careful hack sawing and a fine coal chisel drifted the remaining half inch of left over metalthread from the elbow. I thought it might not have come out but it did. Whew!
Cleaned everything up and there was sufficient thread left to reattach the standing pipe, (only just enough) \i shall have to replace as soon as I can but it will hold for the moment, until I get good info as to how best to fix.
I noted that the vertical pipe was cast iron and really heavy, it obviously had been whipping with the engine and just fatigued. it wasn’t braced except by the exhaust hose. Not really pleased with the whole set up.
Any advice at this time would be useful, is there a special pipe used for this, what about the weight and material issue, before I buy another piece of pipe assuming I can get it here it would be nice to have some answers.
Stewart,
In looking at your blog of 16 Feb 2009, your Yanmar 3YM30 has a tall vertical pipe between the top and bottom castings. The Yanmar website shows a short pipe, so it looks like the short SS standard pipe has been replaced with a taller pipe. I wonder if you’ve looked under the heat shield to check out the pipe? The standard SS pipe has standard threads on one end, and reverse threads on the other end, so the easiest way to get a longer pipe is to weld in a piece between the threads.
I was advised to lengthen the short ss pipe when I installed our 3GM30F in 1988, so had a marine exhaust shop weld a 10"-12" piece of SS in between the top and bottom threads. I used some scrap mild steel to make a brace that ran from the top of the pipe, down to the engine block’s lifting pad. I don’t know if such a brace is possible with the 3YM30, but it looks like a taller pipe requires it, because that top casting is quite heavy, If you can get a new Yanmar pipe (it’s only about 3" long, cut off the threads that you’ve lost and get that threaded piece welded back to your SS pipe, AND rig a brace the top of the pipe, you should be in good shape.
The picture shows a side-view of the slightly S-shaped, 2" wide brace. It’s bolted to a .5" wide strap that wraps around the top of the pipe.
you know the whole thing is pipe which would noramally be used with cast iron radiators and weighs an awful lot, not surprised why it broke. IN marsh \harbour the temp fix worked until we started the last bit in, and it let go then. We sailed into a busy hbr tacking right and left in between these mega yachts with my wife cursing me left and and right. Anyway dropped the hook in the middle after rounding up to applause from out next door neighbors who accused us of showing off.
Off to the hardware stores I guess to look for some moe radiator hose toix it again until such time as i can get the real things. I am still exhaustd and hopefully still married.
Stewart,
Check out the thread called “mixing elbow replacement”, started by Odyssey, latest date is 24 Dec 2010. He has a good pic of the standard Yanmar setup with the 2 castings and the short ss connecting pipe. At the end of the thread, check out the recent modification to Shaula’s riser/elbow.
Sorry to hear that the temporary fix didn’t last.
Dan
Ah I think I got it now, the pipe you talk about is ss, and I like the brace Dan very well done and I think I shall copy. Went to the hardware store here and found replacement pipe (galvanised) and all the fixing to go with it. I hve reinstalled and I suspect that is the way it has to be until I get back to civilisation and have a ss pipe fabricated and a brace to back it up. Looking for a good metal fab shop in Ft Lauderdale who can make up the parts, any suggestions. I assume it is all in SS what gauge would work best.
Stewart,
I’m glad to hear that you’ve got something that will work temporarily, until you get back to Florida. I don’t know the SS guage they used but it looked fairly heavy (about 2mm?). I don’t know the grade of SS either, but I could stop by the shop tomorrow and ask both questions. Ideally you should have it made up at a shop that specializes in marine exhaust.
You haven’t mentioned whether the the top end where the water is injected is the standard Yanmar casting, or something your installer fabricated? If you are using the Yanmar upper casting, all you need is that short Yanmar pipe with threads on each end, cut the pipe and weld in a SS piece of pipe. If you ARE dealing with a cobbled-up upper end, you could switch to the Yanmar upper casting.
If you have the shop weld up a setup like mine, I guess you’ll still need the Yanmar pipe for its threads for the lower casting. The all SS replacement of the top casting has several advantages, one of which is it’s a lot lighter than the Yanmar top casting. With the pipe extension, keeping weight down at the top is a plus, even with the brace.
Where is your water lift muffler located? The Feb 09 blog picture seems to show the exhaust hose heading aft at a high level? I wonder if the reason your engine installer used such a tall riser pipe was that he installed the muffler at such a high level? My advisor thought I needed the taller riser pipe in case the muffler filled and water backed up in its hose to where it could reach the top casting and head on down to the manifold. I guess cranking an engine that won’t start for more than a minute or so could cause this. Closing the intake seacock for extensive cranking is always advised for this reason. It’s possible that I didn’t need the extension because my water lift muffler is mounted low, just above the drive shaft. I wonder where other BCC’s mount their mufflers?
Let me know if you need more pictures of the brace.
Dan Shaula
There is not much of a riser on my Beta Marine exhaust so had to get the water lift low. The Vetus Waterlock muffler is a two piece tank to allow inlet and outlet angle adjustment. You don’t have to pull the shaft to mount the muffler under it. Split it in half and each piece will just go by the shaft. This photo on Flickr is not a great shot but you can see part of the muffler.
Moving right along, went to the local machine shop and had a brace fabicated yet to fit, made atemplate out of fibre board, braced with tape and hey ho we have a pattern, almost excatly the same as yours dan and many thanks for the idea. The ehaust is quite low set in below the laz floor. I don’t think any issues there, did you use a siphon break \dan, my riser must be 14 inches high.
The upper casting is really heavy on top of really heavy pipe, don’t know whether its Yanmar as such, it would be nice to clean the whole issue up, and get the weight out of it. Someone mentioned fibre glass heat resistant pipe which would solve the corrosion issue with ss. I am going to searh Yanmar for same.
Stewart,
OK on the brace! That should help a lot, and get you back to Florida.
If your upper casting looks like the one in the Odyssey photo, then it’s the standard Yanmar part. Fiberglass pipe that’s made with fire-retardant resin is available–the same material as the vernalift mufflers (by Centek) are made of. I think the resin doesn’t support a flame. However,that type of resin is not designed to support the hot exhaust gases that haven’t been mixed with the cooling water, at least not for very long.
We once had a problem with our raw water pump that resulted in no cooling water for 5 or so minutes. This happened repeatedly on startup before we figured out what the problem was (very worn pump body). The vernalift muffler handled the hot gasses OK, granted the engine was only running at idle. A friend has had his Vetus muffler melt out on him when his sea water inlet was plugged. He always carries a spare now. Do you know what type or brand of muffler you have? Under the lazarette floor is an interesting place for your muffler–I wonder if other BCC’s have done the same?
We have a siphon break on the cooling water hose between the heat exchanger and the upper casting–that’s a must. Our exhaust hose between the muffler and the transom loops up to just under deck level before exiting at just above the waterline. I don’t think a siphon break can be put in this hose (or is needed).
