Raw Water System Plugged

[Sir Rondo Normal]

I wonder if anyone here has any experience with a raw water cooling system plugging up.
My engine is a volvo penta MD17C and I've just replaced the water pump">raw water pump and I'm still not getting any water out the exhaust. I also found a plugged fitting on the outlet of the transmission and cleared that. It was like cement.
Now the new pump is in and the lines are clear to the engine and I'm just wondering where the system is most likely to plugged now, in the heat exchanger or in the water jacket?
Either way isn't good.
Hopefully though, I can find a used heat exchanger if needed.

Thanks

[sabray]

Exhaust elbow, exchanger and hose delamination . Maybe not in that order.

[Sir Rondo Normal]

Oh ya, I also just replaced the elbow. Thanks, have you been through this before?

[Sir Rondo Normal]

Is there anything I can try to flush the system with that will eat its way through, like Draino for raw water cooling systems?

[sailcruiser]

Is this mineral type cement stuff? Maybe white vinegar in short intervals? I know it helps keep heads clear of mineralization. May be worth a shot. Does your MD17 have a separate seacock or does it cool through a saildrive? SC

[Sir Rondo Normal]

The system is seacock > sea strainer > transmission > raw water pump > manifold. What about muriatic acid? Maybe I'll try the vinegar first though

[sailcruiser]

I did a quick Google since I may face this myself someday. I found a reference to a product called Rydlime.

"There are different liquid descaling products available. Most are extremely caustic to work with, tough on the environment, and probably should not be used often on metal surfaces. In tests at Practical Sailor we found that Rydlyme Marine, which is milder, non-toxic, non-corrosive, and biodegradable, works just as well if left in place longer—say 15 minutes, as opposed to 3-4 minutes for harsher products. The Rydlyme won’t hurt hoses, seals, gaskets, impellers, or other soft parts, and it can be handled and disposed of safely.


Read more:http://www.boats.com/blog/2010/11/wi...#ixzz1jyMukSA1


http://rydlymemarine.com/

No experience with it but it appears you can read more from Practical Sailor. Hope this helps a bit.
SC

[sailcruiser]

I think muratic acid would work but tough on the environment and on you. I go for less toxic first and vinegar is cheap. If you try the above product let me know what you thought. (Rydlime) I also have a MD17 so I try to watch threads around them. Always something to learn. :-) SC

[Sir Rondo Normal]

Originally Posted by sailcruiser

I think muratic acid would work but tough on the environment and on you. I go for less toxic first and vinegar is cheap. If you try the above product let me know what you thought. (Rydlime) I also have a MD17 so I try to watch threads around them. Always something to learn. :-) SC

Thanks, I looked at the Rydlime web site and it sounds like just the thing. Unfortunately, it looks like mail order is the only option. I couldn't find a dealer list. I sent them a message to find out though.
I'll let you know what they say and how it goes today.

I'm really hoping it's a hose, fitting or the t-stat. I'm on my way over today to dive in.

Cheers

[Play Actor]

If you haven't cleaned the heat exchanger, that's a likely candidate. I ran one of these engines for 22 years of it's 32 year life. Just replaced it last year because I couldn't get parts for trans rebuild. Seawater cicruit on mine was routed from seacock/strainer to trans to pump to heat exchanger to exhaust elbow. If you've replaced the elbow, and cleaned out the trans cooling passages, that leaves the heat exchanger. Mine was an old aftermarket Sendure unit, but most on that engine are similar.

If the coolant passage in the trans was blocked, most likely the heat exchanger is, too. It will also collect impeller blades and pieces of zinc, which will shut the flow down to a trickle. If it has an end cap that you can get to easily in place, take it off and see what's there. You may solve your problem. If not, don't mess with trying to clean it it place.

Just take it off and take it to a radiator shop. They'll clean it up for minimal cost. If that's not convenient, I cleaned mine in the back of beyond one time by removing the end cap, standing it up in a bucket, capping the seawater outlets, and filling the seawater side with a solution of 1/3 muriatic acid, 2/3 water. It foamed for about 20 minutes, and it was clean. If you do this, wear rubber gloves and be careful. Vinegar takes way too long. Muriatic acid is easy to find and cheap -- any paint store or hardware store will have it.

If the engine has always been freshwater cooled, there's not likely to be much scale in the block, unless somebody didn't bother with coolant for rust inhibitors. You can judge that by looking at the fresh water passages in the heat exchanger while you're cleaning it. If that's cruddy, once you put the heat exchanger back, run some caustic cooling system flush through the fresh water side. Get it from an auto parts store, and follow the directions.

The first time I did this job, I replumbed everthing so that the trans was freshwater cooled, as well, eliminating one source of rust.

Good luck. Loved that old engine, but I'm happy with my new Yanmar. Happy to provide more detail if it's useful.

[Sir Rondo Normal]

Thanks very much Bud, very informative post. It was the mechanic that told me there was still no water out the exhaust and I suspected that he might be lying to me because I was out of town so I told them not stop work and I took the day off work to look at it myself. There is about 3 gallons per minute coming out the exhaust.
I have to be out of this marina tomorrow and take her home so once I get there, I think I'll pump some of that ridlyme into the engine and let it sit and flush it out. Then I plan to convert to a fresh water system.

Thanks for the help guys. All is good... for now

[s/v Jedi]

I just convinced Marine Warehouse to sell me a "new" product called BarnacleBuster. It is apparently used by many professionals that clean cooling systems. It is not acid so safe to use without dissolving the engine etc.



I just received the product but didn't use it yet...

ciao!
Nick.

[donradcliffe]

Was the 3 gpm at idle or WOT??

From Jabsco:

What cooling water flow rate does an engine need?
On average, petrol engines and fast-running diesel engines with direct cooling require a raw water flow of about 36-39 litres (8 - 8.5 gallons) per minute for each 75kW (100 bhp) of engine power. Engines with indirect cooling require more flow: about 65-70 litres (14.5 - 15.5 gallons) per minute for each 75kW (100bhp) of engine power.

[Play Actor]

Capt. Wraun,

sorry I misread the original post -- I thought you had the version with a heat exchanger and fresh water cooling.

3 gpm sounds in the ball park. If you're running at the right temp, you're probably fine.

[Sir Rondo Normal]

Ya right on, that was at only around 800 rpm anyway so I think we're okay. Even if it is a little on the light side, we're in the north pacific so I'm pretty sure we won't have an overheating problem and ya, the temp stays just above 180*F.
I was hoping to maybe raise some sails tomorrow but the weather man isn't cooperating. Oh well I'm just very happy to be taking my girl to her new home.
Could be an interesting jaunt, 50 nm up the coast in heavy rain and (hopefully) the tail end of tonights gale force winds.