470 cooling system clean up

[NWVintage]

So, I got this boat last year but I had an issue with the temp on my last outing (killed the engine at about 190deg and got home on the kicker). Hence, I am going through the cooling system properly.

I currently have all of the coolant out of the system. I installed a backflush port in one of my heater hoses and ran water through it for 30 min or so to really get everything out that I could. Then I pulled the heat exchanger (looks good other than a small amount of scale) and the exhaust riser (bought a new one - old was in sad shape). I pulled the ends off the manifold. Everything actually looks pretty clean and only the riser was significantly rusty. I replaced the impeller in the drive last year and it pumps water nicely.

My questions are two:

1. What should I use to flush/descale the raw water side of the exchanger? I have a pump and was thinkning of using a bucket and a couple hoses to pump a descaler through but what product to use? Is lime-a-way or CLR ok?
2. Is there anything that I haven't though to check? I am going to recheck the thermostat orientation, just to be sure that this wasn't my issue...

 

[alldodge]

Re: 470 cooling system clean up

1. What should I use to flush/descale the raw water side of the exchanger? I have a pump and was thinkning of using a bucket and a couple hoses to pump a descaler through but what product to use? Is lime-a-way or CLR ok?
2. Is there anything that I haven't though to check? I am going to recheck the thermostat orientation, just to be sure that this wasn't my issue...

I would suggest taking the exchanger to a local radiator shop and let them clean and pressure test it. They have the tanks and all the expertise to clean the exchanger and shouldn't cost more than a radiator.

Looks like you looked throught the system pretty well, hope someone else here will look over your request and see if there is something we may have over looked.

 

[stonyloam]

Re: 470 cooling system clean up

You can use a long brush to clean the tubes.

 

[NWVintage]

Re: 470 cooling system clean up

I realize its been a few months but thank you both for your input/ideas. After researching what was available in my area, I was reminded that I really wish I lived somewhere a little less urban - I couldn't find a shop anywhere in Seattle that even seemed to know what a heat exchanger was! After much consideration whether to take it out to a more rural area, where people know about motors, and research into the cost of either that route or replacing parts, I decided that I should just clean it as best I could. The exchanger itself was pretty clean and I used a dental instrument to scape the scale off of the inside of the manifold and thermostat housing. I had to replace the riser and ended up having to take the manifold to a machine shop to remove a broke bolt with a broken bolt extractor in it... It all ended up costing about $500 and was a total PITA but it works now and will not likely need attention again (other than coolant changes and raw water flushes after each outing) in the time that I own the vessel.

 

[Live-liner]

Re: 470 cooling system clean up

I flushed my exchanger with water then filled with CLR and let soak for about five hours. It really cleaned up nice, then pressure checked and re-installed. I did this on both the coolant and water sides, it made a huge differance.

 

[Volphin]

Re: 470 cooling system clean up

Glad you guys posted this up. Is there any advice on how often the heat exchanger should be cleaned? I've often wondered that myself...

 

[SuperDave3113]

Re: 470 cooling system clean up

I had overheating problems with my 470 also. Impeller had gone out. What I had was a piece of impeller stuck in the port between the outdrive and the gimble housing. I can remember why I had pulled the outdrive but when I did there was a large piece jammed in there.

 

[stonyloam]

Re: 470 cooling system clean up

One of the best ways to prevent overheating problems is to change the impeller every other year. The vast majority of 470 overheating problems are worn impellers.

 

[Live-liner]

Re: 470 cooling system clean up

Taking the noticable positive effect into account, I will add it to the Spring maintenance every two years. With the exchanger out of the way, it opens up that whole side of the motor and makes life so much easier when changing hoses, servicing starter, etc. even just cleaning the port side of compartment and bilge.