Scaling and deposits in the hoses

[Sundancer]

I have an 89 300 DA with twin 350's. This week I decided it was time to winterize (It's kept in an insulated building and rarely freezes!) and I captured all of the water that drained out of the blocks when I pulled the hoses and the freeze plugs. I get a lot of "black" water with a lot of flakes in it. It's 26 seasons old and not getting any younger. At what point do you start worrying about all that stuff coming out? I also noticed there was an orange/white buildup in the hoses. Again, at what point should I be concerned? It runs great but I just want to be proactive instead of being towed in. I've never opened up the risers, but plan to do that this winter as well. It runs cool, I'll be putting new impellers in the Alpha's this season.

It's primarily been run in freshwater, but I spend two weeks in the San Juans every years. I don't have heat exchanges so I'm sucking saltwater all the way through the block. I use salt away before and after and usually come out of the saltwater and put it back in freshwater within 8 hours and run it overnight or longer to eliminate as much of the salt as possible. When I get home after that, I run the salt away through it one more time.

Am I just paranoid???

 

[fwebster]

I think you begin to worry when you remove the plugs in the block skirt and no water comes out or it drips out a drop at a time. That indicates the block is filling up with rust particles which cannot be fully cleaned. Other engine parts like risers, manifolds thermostat housings, water pumps, timing covers, hoses and hose clamps are all replaceable. Generally a block filling with rust cannot be fixed since even vatting won't get it out and when water won't circulate in the block, you cannot cool the engine. Other parts can be replaced and then it becomes a financial decision about which is the most cost effective, a reposer or replacing the needed parts.

If the engine runs cool now, I'd be inclined to so some basic maintenance like flushing the cooling system, replacing impellers or water pump as well as any suspect hoses, checking the exhaust castings and see how long you can get out of it.

 

[Sundancer]

Frank,

Thanks for the reply! I feel honored to hear from someone I've watched on this board for a long time. I trust your judgement.

As far as flushing the block, just start it up and run it with the plugs out or flush it by running it normally with a specific solution? Just curious. I wondered if running it without the plugs would help flush some of that stuff out. I figured a minute or less probably wouldn't hurt it. The water would be flowing, just exiting quickly. I usually have something in my hand when I pull the manifold plugs to push the stuff out of the way to help improve the water flow. Once I do that, I naturally catch all of that stuff the first come out in my hand. That's what caused me to start this thread.

Sounds like I need to start setting aside some engine money!

 

[fwebster]

I would use a normal automotive radiator flushing kit. Whgat you are seeing in t he hose is calcium related deposits formed over a long time. I think you need to get the engine up to operating temperature and keep it there for a while with the flushing chemical circulating in the system. You method will get some of it but you need the chemical action at operating temperature to clean the internals. Follow the instructions and you will flush a couple of times with freshwater after the chemical cleaning before you are done.

risers fail differently than most people think. They usually rust from the exhaust passage into the cooling jacket, not from the part carrying the salt water into the engine. The reason is that your exhaust system is open to the atmosphere while the boat is sitting idle on the trailer, lift or slip. I think that should be a priority for you when you get the cooling system clean. Get some gaskets and pull the risers off and check the interior for rust and flaking then decide if they need replacement and go from there.

Don't throw in the towel until you lose compression or oil pressure or when the engine no longer cools when you have a healthy cooling system.

 

[JVM225]

I'll second the advice on the risers. If you haven't checked them out yet, you should.
In the entire scheme of things, they aren't all that expensive (in boating dollars), are super easy to remove, and just as easy to replace.
If I were you, and I was pulling them off after they've been on there for who knows how long, I would just replace with new ones since you can't always tell how good they are from looking inside.
The only other thing I'd advise doing is going with Mercruiser brand risers, and get the E coated ones. The aftermarket brands don't seem to be as good as the OEM, and the E coating will make them last a little longer.

 

[Sundancer]

Great advice Frank! I knew it would be straightforward! I'll flush it and then probably replace all of the hoses anyway. They are old enough and are probably ripe for replacement.

I figure if I'm pulling the risers, they've served their purpose and I'd feel better putting new ones on. I had heard the Merc last longer, but hadn't heard about the e coating. I'll go that route!

Thanks!

 

[SCORPIO]

I had to replace one of my raw water cooled 260's last spring due to water ingestion/hydrolock. I installed a half system of FWC on that engine and like it a lot. My other engine is an original raw water cooled Merc 260 from 1989. The boat was in brackish and salt water all its life and I get about what you mentioned out of the block every fall. I have a Superflusher back flush kit on that engine and use it after every outing and follow up with SaltAway. I do replace my manifolds and risers every five years as a maint. item due to the salt water issue. You will likely get many years out of that block using it as you do. I think I would replace the risers and examine the manifolds carefully if I were you. You can loose and engine to hydrolock all to easily if one of those components rusts through. They are not all that expensive compared to a new engine and are easy to change.

BTW, I installed a new Vortek 350 with 325HP on my port side and it runs like a champ. Up to 3800 rpms, both engines are in sync. but I think if I pushed it to WOT, the old 260 would fall on its face way before the 5500 rpm redline of the new engine. In a few years, I plan to change the starboard engine over to a Vortek as well.

 

[Sundancer]

Scorpio,

I don't think I could replace just ONE engine! Vortek and EFI would be a great combination! I'll file that away for when the time comes. I'd HAVE to do both at the same time. The power increase would be way more noticeable that way. A different set of props might be in order too!

I'll get on the e coated risers and get them ordered so I can replace mine. Mine have served a great life and deserve to be retired before they fail!

 

[SCORPIO]

My Vortek has the Edlebrock four barrel carb. I would have done both at the same time, but my wallet said otherwise.

 

[h_gerry]

My Vortek has the Edlebrock four barrel carb. I would have done both at the same time, but my wallet said otherwise.

I had the same issue when one engine on my 1989 280 Sundancer went. I was only able to replace one due to financial constraints, so I replaced the bad engine with a remanufactured engine: the 5.7 TKS. The following year the other engine went, but Merc stopped building the 5.7TKS remanufactured engine! I had to use their “new” 357 remanufactured motor. So one side had a 350 cu. In., 4 bbl carb’d motor while the other side had a 357 cu. in., 2 bbl carb’d motor. I can’t remember the full differences now, but there was enough of a difference that I could not just swap out the 2 bbl for a 4 bbl manifold and carb, so I had to leave them be. In the end, they worked fine together. Slightly different pitches on the props, but I was able to match the rpms and she ran fine. It was a little weird seeing the throttles at different positions, but I think that just bothered me.
Moral of the story, don’t wait too long between engine swaps…..