cleaning heat exchanger circuit

[jim rosenthal]

After my port engine was damaged, repaired with new parts, I found it runs a bit warmer than the stbd. To be sure, the water temp here is 85F, but I'd like to bring it down to what the stbd engine runs at. So I'm getting ready to flush the system- made up a new bucket and pump kit, etc.

When I did this before, I flushed it backwards- the flush went in the showerhead supply hose, and came out through the return fuel cooler (I think- it's been a while) I have a choice of ways to do this- forwards or backwards.

So, any opinions on how to hook the system up to flush the entire seawater circuit? What's best? Forward (normal direction of flow), backwards (as above), or "it doesn't matter"?

Sound off and let me know what you all think.

 

[jim rosenthal]

I should mention that the coolant level is up where it should be, the impeller is new, and the flow of water out the exhaust is actually a bit more than the other engine.

 

[SKYCHENEY]

Why didn't you send out the heat exchanger to be cleaned when you had everything apart to do the repairs?

 

[jim rosenthal]

It wasn't due for it. They were sent out a couple of years ago. Of course, I wish I'd done it, but there was no reason to suspect that it was running warm. It may come to that, but it would be nice if it could be cleaned in place as I'm planning.

 

[Dan Mapes]

Doesn't the direction have something to do with which port is highest? Having it go out the highest port might enable more air to escape and yield a better flush.
How much was changed on the engine? Tstat? Will you pull the impeller and recover the pump so you can do the "whole deal"?

 

[jim rosenthal]

To flush it going forwards, the flush solution would go into the return fuel cooler and exit at the showerhead hose, diverted back in the reservoir bucket of the cleaning solution. Flushing it backwards would mean going into the showerhead hose and recovering it from the return fuel cooler. This is what I'm inclined to do because with that method the flush solution is running downhill all the way.

The impeller is new, actually, and the water output at the transom is plentiful. Recovering the solution from the return fuel cooler leaves the raw water pump out of the circuit; I'll just shut the sea cock before disconnecting the pump output to the return fuel cooler.

 

[SKYCHENEY]

Just saw the HE off of a 12v71 what was pulled and there were pieces of old zincs plugging the water exit by half. I don't think flushing would have done a thing for that. Hopefully yours is not that bad.

 

[Chasemmc]

Not to hijack the thread. But didn't someone document the process with pix. I need to do mine as well

 

[jim rosenthal]

Some flushing solutions dissolve zincs. I'm planningon replacing them after flush is done. BEfore I start, I'll pull out what's in there and use blank plugs while fliushing.

 

[Briankinley2004]

I always pull the zincs off the plugs before I start and remove the impeller. R A Clarkson says this helps with the ball valves by cleaning them. I have flushed both directions. I think the best practice would be to flush one direction then the other but then you would have to re-route your pump. I'm in the "doesn't matter" camp but part of me thinks back flushing would be better as it may push out pieces of debris lodged in the vanes that may be acid resistant (impeller parts?).

Not to hijack your thread but am curious if anyone knows the additive you can put in the freshwater side in lieu of anti freeze. I am in FL where freezing is not an issue and hear that running straight water with an anti corrosion additive will get you 5 degrees cooler. I am thinking Pen Cool but that may be an anti freeze.

Good luck with the flushing. I think you will benefit either direction

 

[Dan Mapes]

I always pull the zincs off the plugs before I start and remove the impeller. R A Clarkson says this helps with the ball valves by cleaning them. I have flushed both directions. I think the best practice would be to flush one direction then the other but then you would have to re-route your pump. I'm in the "doesn't matter" camp but part of me thinks back flushing would be better as it may push out pieces of debris lodged in the vanes that may be acid resistant (impeller parts?).

Not to hijack your thread but am curious if anyone knows the additive you can put in the freshwater side in lieu of anti freeze. I am in FL where freezing is not an issue and hear that running straight water with an anti corrosion additive will get you 5 degrees cooler. I am thinking Pen Cool but that may be an anti freeze.

Good luck with the flushing. I think you will benefit either direction

Running with water is definitely going to let the engine run cooler, which begs the question, is the mix the same in the engine that is running warmer?

 

[Airpilot]

I chased creeping temps for years and finally pulled the heat exchangers and took them to a radiator shop to be cleaned and pressure tested. Both engines now run at 173 degrees at 90% thrust.

 

[jim rosenthal]

I just completed setting up the plumbing for this task. I decided to flush forwards, as it was easier to set the system up. However, since both hoses are 3/4", I can actually reverse them and backflush it also. I may do that.

I also pulled the zincs out, and found that there was very little left of the heat exchanger zinc- but I can't get a new zinc in there. The brass plugs are back in, without zincs, we'll see if flushing the system clears out whatever it preventing a new zinc from going in the HE. I hope so.

I recall being told that Os-Pho would dissolve zincs- does Barnacle Buster dissolve zincs as well?

I'll probably do the flushing tomorrow, as I'm tired from working on it today, and I don't think I'll leave the boat while it's going on. Plus I still have some fittings to seal with Teflon tape. It took a lot of fittings to hook it all up.

 

[whoover]

Dr. Jim, I do know that muratic acid will melt zincs. I used it to clean out broken zinc from the plugs, it was the mild solution for toilet cleaning.

Walt Hoover

 

[jim rosenthal]

Thank you. I have around here somewhere, also Os-Pho as well.

More interesting developments, as follows:

I completed setting up the flushing circuit today. It consisted of two 3/4" hoses, the first connected to the output of a small (750 gph) SeaFlo bilge pup mounted in the bottom of a 5 gallon plastic bucket. The second was connected to the hose which runs to the seawater discharge entry of the showerhead. So where the seawater would normally have just entered the showerhead and exited out the transom, it went into another 3.4" hose and was diverted back into the bucket. After verifying that everything was tight, I started the little pump up, adding 3 gallons of fresh water and three bottle of Barnacle Buster concentrate. After a few moments, the solution began to turn dark, and it bubbled or foamed a little.

All went well until the friend who was helping me noticed that the level of water and BB in the bucket was dropping. Over the next hour, while checking for any possible leaks, I periodically added water, probably to total a couple of gallons.

There are no external leaks. There is no leakage of flush solution, or anything else, in the bilge pan below the engine. The coolant tank level, the antifreeze circuit, has not risen any higher. I have no idea where the additional flush solution went. Nothing was coming out the transom exhaust pipes.

After about an hour, I shut the pump off. There is very little left in the bucket. The sea valve is closed. The bilges are dry. The engine oil level is normal.

Possibilities:

-water is going into the combustion spaces of the engine. Hard to imagine as it ran fine once reassembled. I have not test run it, and I won't until I talk with The Cummins people at T&S.

-there is a leak between the seawater side of the system and the freshwater side. I suppose this is possible, but thecoolant level in the overflow tank hasn't changed.

-Cummins B engines have a rather large seawater aftercooler. Perhaps all that solution just filled it up. I don't know.

Ideas, impressions, etc, welcome.

-the oil level has not changed, nor is there any water in the crankcase that I can see.

 

[Briankinley2004]

Do you have the dripless shaft seals that use the raw water circuit to lubricate? If so that hose needs to be removed and capped.

 

[jim rosenthal]

Brian, I never thought of that. I DO have dripless shaft seals, and they tap off the gear cooler. I'll bet that's where the cleaning solution was going. Thanks for the suggestion.

 

[jim rosenthal]

Looks like that was indeed what it was. I am putting everything back together and hope to run the boat this week- today is out as they have a tornado watch posted through this evening. Uh Oh. in the next few days.