Replacing hot section of T30 Exhaust

[BadaBing]

Now that was fun.

I just finished pulling the old exhaust sys out of the t30. Found all kind of new problems, Mr. Moyer a parts order will follow later today. Attached is a picture of what I took out. AS the exhaust leaves the manifold it moves horizontally about 1.5 ' then turned up to the bottom of the water lift muffler. Unlike what is described in the Atomic 4 Service and Overhaul Manual the water enters way up at the top of this assembly and the exhaust enters a good 1-1.5' above the manifold. The pipe that broke shows obvious signs of water inside it which I assume had a part in the failure.

Can anyone tell me if this looks like a factory assembly (with some added replacement pipe) Were these boats designed like this?

Thanks

Bill

[Kelly]

Hello Bill,

I believe your picture is showing a jacketed (double-walled) riser. The first picture below is of the same piece in my exhaust system. This riser precedes a muffler (mixer?), where the exhaust gases are combined with the cooling water before exiting by the transom. The wrapped pipe is the hot exhaust and the threaded connection just above where the wrapped pipe arrives in the riser is where the cooling water arrival was plumbed.

In the riser, the exhaust gases pass through a central pipe while an outer pipe contains the cooling water. I think that normally, the cooling water should be plumbed to the bottom of the outer pipe while the exit is near the top. Afterward, I'm not sure what your system looks like.

In the second picture, you can see the section of wrapped pipe exiting the riser (exhaust), continuing on to the muffler, while the cooling water exits here in the copper pipe and enters the muffler on the top (not visible).

Unless a muffler further down the line is overflowing and allowing water to back-up into the exhaust pipe, I think any water you found in the exhaust near the manifold may indicate a leak within your riser, between the concentric pipes, allowing water to trickle back down toward the engine. Or, maybe water is just condensing in the exhaust pipe?

Others will correct me here if I've got it wrong. You may want to pressure test the riser.

Best of luck,
Kelly in France

[BadaBing]

how hot should it be?

I had the old hot section double wrapped with header insulation, exactly the same stuff Mr. Moyer sells. Before I wrapped it with this it had some fiberglass insulation covered with a section of stove pipe.

Anyway even with the header insulation the hot section would get so hot that it started to scorch the bulkhead above it (about 3 " above) I just hooked a hose up to the manifold water inlet and outlet and ran the garden hose through it and there seems to be no restriction of the water flow. Any idea how hot is hot?

Thanks

Bill

btw I have become obsessed with this water lift issue. I saw in the Miss *** of the month a setup that had what looked like a horizontal water lift (? not actually lifting) just behind the manifold. I'm considering switching to a setup like that.

[Don Moyer]

Bill,

It's OK to use galvanized pipe to reconstruct a hot section although most boat builders in the 1970's used black iron pipe. You can also use stainless or brass for additional longevity.

As Kelly correctly points out, the small section of 3" diameter piping in your photograph appears more to be a double-walled section than a water-lift muffler. We're sort of left hanging in terms of what comes after this short double-walled section.

For future planning, in the event that this double-walled section does not pass a pressure test (20 or 25 psi should be sufficient), or there is something dysfunctional down stream of the double-walled section in your photograph, I'm attaching some technical files on replacing the entire system.

Regards,

Don

[BadaBing]

the rest of the story.

Don,

Thanks for your input and help. I would guess your correct that this isnt a true water lift muffler. The section in question is about 20" long and 3" or so in dia. It is in fact double walled. exhaust gasses enter at the bottom and travel up a 1.25" or so internal pipe to about 2" short of the top of the unit. then the insiode pipe seems to stop, around all this is the outerpipe you can see in the photo. The cooled exhaust gas/water exit the outer pipe at the base. Water from the exhaust manafold jacket enters at the top. I guess this is more of a heat exchanger only ment to cool the exhaust down. The attached dcrawing should help make this clearer. After the gas/water exits this "can" it enters a rubber pipe and goes to a small plastic muffler the after exiting the muffler through the hull above the waterline.

I assume this is howe it was built by Tartan back in 74, so far I havent found a T30 owner who could verify what they have. The system seemed to work fine foer the last 3 years I have had the boat so I expect I'll be putting it back togeather much the same as it was.

[BadaBing]

another view

this is another view of how it was.

[BadaBing]

almost finished

The new hot section is finished, still needs the header wrap insulation. I also found that the water jacket cover was leaking badly, after I removed the cover I found out why, 5 of the 8 bolts had rusted through to the point they were not threaded into the block, olny held in place bu some rust, naturally the other 3 bolts broke off.

I chased the threads to the 5 with a tap then set about trying to drill and easy out the remaining 3. No good no mater what after hours of attempts I gave up and just drilled them out with a bit sized for a 5/16 bolt, than ran the tap through with either cleaned the old threads or cut new ones. In one case this didnt work because the new bolt wouldnt tighten more then hand tight before spinning . I redrilled and tapped this to accept a 3/8 bolt. Everything seems to be working out just fine.

Need to install new blowers, insulation, ignition and finish cleaning out the bilge and we should be good to go. Also installing a new oil pressure gauge, temp gauge and a new tach (the old tach seems to work when it feels l like it so I cant trust it)

If everything goes as hoped I'' be ready to give her a try by Sat AM.


Attached are a couple pictures. I'll wrap thia project up

[BadaBing]

more pics of the project

a couple shots from the head

[Kelly]

Assembling hot section exhaust pipes

Hello Bill,

Nice job on your project. I'll bet you feel more confident about using your engine now that everything has been inspected, cleaned and repaired (if necessary).

One question: how did you assemble the threaded parts of your hot section piping? Did you put them together dry or with some sort of sealant?

I'm about to do the same and despite some threads on the subject here in the forum which seem to indicate that no sealant is necessary, can a dry fit ensure no leaking of exhaust fumes?

Thanks,
Kelly

[BadaBing]

thread seal

Kelly,

I was told the same thing that no sealent was necessary. BUT plumbing and I dont get along very well so I tend to do a bit more then is necessary to insure things dont leak. I couldnt find a true thread sealent that was rated to stand up to the amount of heat this section develops so I used exhaust system repair puddy. Its made for exhaust pipes, mufflers to be exact, so I assume it will handle the heat. If none is required it wont make any differiance, if there is a slight need then I thingk this should do the trick.

I also had done 2 acid flushes prior to putting all my hose connexctions back togeather. I used a drill pump to pump in the acid, then flushed with fresh water then did another flush, then ran fresh water through till only clear water and no more scale came out.


I finished the wrap and wet echaust hose connection on Sat. and cranker her up for a spell to warm the oil. Wanting to clean her out inside I did 3 oil changes with about 30 -45 min of run time between changes. She seems to run much cooler now.

Since I have it torn apart I am also replasing all guages and replaces all hoses. I still need to finish up the guages and am making a slight modification to both the auto and manual builge pumps. As soon as these are finished (today?) we'll be giving her a trial on the bay at the next high tide.

Bill

[BadaBing]

just under 6 years

Just under 6 years and that shiny new hot section has failed. We had been out on a few day sail and noticed the smell of exhaust while motoring. The dull headache was a give away.

Today I dove into finding the problem and discovered that the failure was at the connection between the flange and the first section of brass pipe. I was all set to blame to problem on electrolysis and dissimilar metals until I cut the section in two found that the inside of the pope was all like new.

However the outside 1/3 of the pipe had given way to what seems to be heat deterioration. It just flakes off in my hands and is dark gray to black. The hot section was wrapped in heat tape wrap. Im thinking the heat tape (exhaust tape held too much heat in and caused the pipe to break down.

Given the reports that black pile lasts 6-7 years and the added cost of brass pipe (or is it bronze?) I'm redoing the project in home depot black pipe this time.

[ndutton]

It's very interesting reading through this old thread and realizing how far we've progressed with various exhaust systems. Early in the thread there's a mystical nature to the type of exhaust system when today most would recognize it instantly as a standpipe. The mention of galvanized pipe as acceptable for a hot section would never pass muster today.

Speaking of which, neither brass nor bronze are USCG compliant materials for hot sections either.

[BadaBing]

new-new T30 exhaust

Finished the second hot section replacement. This time just went with black pipe. \While I had the exhaust out of the boat I decided to ditch the useless little muffler. I dont know it Tartan installed these as factory items or if back in the glory days of T30 racing some "racer" added this to be slick about running the kicker.

Here is what I found after running with no muffler.
#1. down below, when under power, there is actually LESS engine noise. Strange but noticeably true.
#2. There seems to be significantly less exhaust system back pressure. This make sense because we have removed the obstruction of the rubber/plastic baffles in a muffler. Ergo, the little 40 years old engine spend less energy on exhaling so it has more energy to give the prop. (the reason that race vehicles run no mufflers)
#3. Out side the boat, actually in a dink, just beside the exhaust port, while at cruising rpm crossing the bay. The voice of the A4/ T30 is a bit deeper and richer BUT not noticeably louder. I didn't put a sound meter there to see how much it changes, I don't have one. But all we really care about is what it sounds like or how loud. I doubt anyone would know that I have removed the muffler.

[Ball Racing]

My bronze pipe did the exact same.
At the time I did not know is was not USCG approved.
I made a new one out of Iron pipe for now, and am going to make one out of stainless.

[BadaBing]

Because I had it all apart to replace e.the head I decided tos h pet life the hot section I replaced in 2013. At his point another $25 in pipe and.fittings is a small change order. I also gave a slight down flow.from the exhaust manifold.flange to the elbow there the pipe turns.up to the stand pipe. ITS not.much of a.dip b it enough to.collect.a.cup or so of s seawater.that might otherwise slide back into the manifold if some spray happens to Punxsutawney inside the center exhaust type in the stand pipe..this also brought cnn t the hot pipe an inch lower from the plywood bulkhead and will allow for some extra insulation. THE I mounted the stand pipe a couple.in he's higher to causebansteeper down angle to the hull exhaust fitting. I WANT TO G E T THAT H OTNSTUFF.OUT OF MY COMPARTMENT.