Smoke coming off heat exchanger??

[j_king]

Hi guys,

I have recently done a bunch of work to my atomic 4 as it was not running when i tried to start it up this season. I have not owned the boat for very long and it has been a bit of a project. I have some smoke coming from the right side of the engine compartment once the engine is running for about 5 minutes. I initially thought it was an exhaust manifold leak so I replaced the manifold gasket and the flange gasket that leads to the pipe. I started it up again and the smoke came back one the engine warmed a bit. I honestly think I see it coming off of the heat exchange unit, it does not seem to be coming from the exhaust or the valve cover or further below. My best guess at the moment is that the exhaust manifold is heating up so much its causing some sort of burning on the heat exchange unit (maybe the paint?). It has never done this before but I have not really run the engine very long in the past. Maybe the exchanger has failed?

When the engine is at idle I am seeing only 100 degrees on the temp gauge. But if i shut off the engine after 5 minutes of running the temp spikes to 180 which might be normal im not sure. There is good water flow coming out of the exhaust


So some other things that I have done that im not sure would have any effect would be;

new 55 amp alternator
Took apart carb and cleaned it and new gaskets
removed old fuel put new fuel in
New fuel pump and inline primer
New fuel filter
engine re wire
Auto charging relay to charge house and starting
new raw and fresh water impellers
oil change
added 50/50 coolant when i did the manifold gasket
new coolant hose

The other thing I'm thinking might be an issue is the new larger alternator? After I installed it the engine seems to make a small clunk when the alternator kicks in. I'm pretty lost to why this smoking is happening?

Any insight would be greatly appreciated

Jon
Pearson 33

[Al Schober]

Jon,
It would help if you could take a photo, load it into Paint, and add an arrow showing where the smoke is coming from.
I can see the high end of the exhaust manifold getting hot. Several A4 owners have rerouted the coolant hose to go from the t'stat outlet to the LOW end of the manifold, forcing air and water out of the high end.
If you have a heat exchanger, it should NOT be getting hot enough to smoke!

[j_king]

Hi Al,

Thanks for the response, I've attached some photos

[edwardc]

The "smoke" you're seeing is steam. Looks like your heat exchanger has two burst seams (freeze damage?). You can see the corrosion around both of them from the escaping moisture.

The upper seam could probably be brazed shut, but the lower one is more troublesome, as it is actually a seat for a gasket under the round end plate, which must seal tightly. It will be difficult to beat it back into round and still get it flat enough to seal. A machine shop could help, but honestly, by that time, you're probably better off just replacing the HX.

[j_king]

Thanks Edward,

I tend to agree with you considering how warped it is. I think I will source a new one.

[tenders]

A+ on those blue silicone cooling hoses. They’re fantastic - they stay flexible for years and years.

[capnward]

Thanks for the photos, they really help. The gap around the cap on the bent end of the HX sure looks like it must be leaking. I'm surprised you don't report it blowing water all over the engine. When water hits a hot manifold it will create steam. I know from hard experience.
When you attach the new HX,
https://moyermarine.com/product/heat...y-cfwk_02_265/ (which is oriented vertically, unlike the one you have),
be sure to mount it further from the manifold. My first impression from your photo was that the black hose is lying right on the manifold, and that you may be burning that hose, which would create smoke. Your second photo shows maybe 3/16" of clearance there, but it still looks too close to a hot manifold, IMO. That is the hot end of the manifold, which can easily get hot enough to make a hose smoke if in direct contact. It will burn that hose before it burns the paint on the HX.
The engine spiking to 180 after shutdown is no cause for alarm. That is because the coolant flow has stopped but the engine is still hot, so water caught in the engine will get hot. If your engine runs too hot it reaches the boiling point and you will hear it bubbling up into the HX, and you will see it flowing into that sriracha jar. However, 180 is high for an engine that had been running for five minutes at 100. If you can run for long periods at idle with the temperature at 100, your HX is working fine. 100 seems low to me, but I have a 160 thermostat.
The curved bracket on which the HX seems to be resting looks like it was meant to be mounted on a bulkhead, not the manifold. The HX was apparently meant to fit into that curve, instead it rests on the point of the curve to get it away from the manifold. If your HX doesn't leak, it should be mounted elsewhere.

[edwardc]

If you like the horizontal style HX with integral tank, you may be able to source a near-exact replacement from Sen-Dure:

https://heatexchangershop.com/wp-content/uploads/Sen-DureCatalog.pdf

Otherwise, get the vertical one MMI sells:

https://moyermarine.com/product/heat-exchanger-only-cfwk_02_265/

Its well supported with caps & gaskets available.

[j_king]

Hey Guys,

So i replaced the HX on the engine... Unfortunately I still have smoke/steam coming from that right side of the engine. The smoke could be steam I'm really not to sure, it doesn't smell like exhaust really and there isn't much color to it. Is it possible that it is coming from the freeze plugs on the manifold or maybe the manifold is cracked? I really can't seem to pin point the smoke very well as it seems to happen only when I rev over 1000 rpm for a bit and its very minimal. Sometimes it looks like the manifold is just steaming. The new heat exchanger works great and the engine seems to be running nicely even with this problem, I just would like to resolve the smoke issue before i head out for my 12 Nm trip down the river to the ocean

Thanks again !!

Jon

[j_king]

Some more pictures to show the new HX and manifold

[Hawkeye54]

Smoke coming off . . .

May I suggest a rerouting or protecting that red wire in the upper picture - it appears to pass near the hose clamp and under the free end ? I would be concerned that the wire may chafe due to vibration







Rick

[j_king]

Hey rick thanks for the suggestion, this photo was mid install of the HX, that wire is secured now

[JOHN COOKSON]

Is water dripping off the blue hose onto the manifold an artifact? Maybe it has been fixed already?

ex TRUE GRIT

[Peter]

You seem to not have the standard “slash tube” that comes from the valve cover and leads to the flame arrester on the carb. Is it possible you have a lot of blow-by and that piece of grey plumbing you have instead is leaking?

Peter