Problem with heat exchanger outflow

[Strait Shooter]

I installed a "red dot" type heater on my boat today. The hoses from the engines heat exchanger to the heating unit and hot water heater never even got warm.

My first thought was a thermostat failed in the closed position. Then I started thinking maybe it's the heat exchanger itself. How can I tell what's going on? I have felt the engine runs hot since I purchased the boat. It runs at 190 according to its own gauge.

Should I simply remove the thermostat and test it? What else should I check, and how? I've been searching threads but haven't seen anything. Any help would be appreciated.

It's a Perkins M50.


John

[DeepFrz]

Show us a diagram of how you have the hoses run. I don't think you should be running any lines from the heat exchanger to the hot water tank and boat heater. However if the hoses are run properly you may need to install a booster pump. There is a current thread "where is the heater" I think is the name that may be of interest.

http://www.cruisersforum.com/forums/...-115837-2.html

[Strait Shooter]

I'm not sure how to draft something up that will display here. I'll figure out that in a bit I guess. I can see its usefullness.

You're correct, the hoses are not coming from the heat exchanger. They are coming from the block. One is coming from a gooseneck fitting which I'm assuming is housing a thermostat, and the other is off a simple fitting on the side of the block.

I routed the hose from the gooseneck fitting (water pump right below it) to the heater. From the other side of the heater I ran it to the hot water heater. From the other side of that I ran it back to the secondary hose fitting on the side of the engine.

Does that make sense?

Thanks....

[Blue Stocking]

Check that you have the flow direction, output and return, correctly positioned. If this engine has both hoses exiting and return to a single fitting there may be a flow direction butterfly type valve which prevents flow if installed backwards.

[Strait Shooter]

Originally Posted by Blue Stocking

Check that you have the flow direction, output and return, correctly positioned. If this engine has both hoses exiting and return to a single fitting there may be a flow direction butterfly type valve which prevents flow if installed backwards.

I'll check that in the engine manual. Good idea!

Thanks!

The title of this thread really needs to be edited, sorry for the confusion.

[DeepFrz]

I assume that the hot water heater worked before installing the boat heater, is that correct? If so then possibly flow through boat heater is wrong direction or as I said before you may need an auxiliary pump.

You can message the Ops with the new title if you like. Just click on the little red triangle, bottom left of the post.

[Strait Shooter]

Originally Posted by DeepFrz

I assume that the hot water heater worked before installing the boat heater, is that correct? If so then possibly flow through boat heater is wrong direction or as I said before you may need an auxiliary pump.

I didn't think flow would be an issue. I checked all inlets/outlets for markings and found none. I think the hose off the gooseneck, above the water pump is the driving hose. Pretty common in most machines, no? I noticed a bleed air valve on the heaters coils, I should bleed that as well.

I honestly never checked the hot water heater when engine driven. It was only used at the dock, and worked there. This could have been going on for a while.

I noticed that the coolant in the heat exchanger didn't seem to be "flowing", but rather acted like a choppy sea.

[Strait Shooter]

Originally Posted by Blue Stocking

Check that you have the flow direction, output and return, correctly positioned. If this engine has both hoses exiting and return to a single fitting.

Nope, two fittings...... And I think that the engine is the only component in this that is flow directional. I think the appliances don't care. But I could be wrong...... Again!

[DeepFrz]

I think I am wrong about the flow through the appliances being directional.

It is possible that the water pump (coolant) in the engine is not working properly and needs replacement. I'm not sure how you would check that.

[Strait Shooter]

Originally Posted by DeepFrz

I think I am wrong about the flow through the appliances being directional.

It is possible that the water pump (coolant) in the engine is not working properly and needs replacement. I'm not sure how you would check that.

And wouldn't a thermostat stuck in the closed position act the same way as a broke water pump? I believe so!

I still think testing the thermostat is the first step here.

[DeepFrz]

Yes, you are probably right.

There was another recent thread where the fix to a thermostat that wasn't opening properly was to drill a 1/16" hole in the thermostat to allow some coolant to circulate through it.

[Strait Shooter]

Well, thanks for the help. Hopefully it will be an relatively easy fix.

[zeehag]

inside the heat exchanger is a brass tube with passages. these passages should be open. if they are clogged they will not work. water wont flow. you may want to take the heat exchanger apart to inspect the innards.

[Oregon Waterman]

My Vetus/Mitsu has a clean-out arrangement on the exchanger. It has become a 40 hour service thing as sea grass has blown around the dock.

[rolandcavanagh]

My experience is that the hoses for the auxiliary devices (heater, hot water heater) come off below (before) the thermostat, and return to a lower pressure point on the block. I'd be looking for a plug in the original hot water heater, or a bad coolant pump, but as I once discovered on my GB, a badly installed hose (one with a plastic cap still on the fitting, one with the hose crushed into the fitting) is a possibility. I'd disconnect the hose starting at the pressure (top) fitting and start the engine briefly with my thumb over it and assess the pressure and flow, then work my way through the system.