Blocked water flow through inboard - what to backflush with?

[Trevelyan]

With no water pumping, I pulled the impeller to bits - which was fine.
After trying to blow into the pipe to the engine block (from the impeller), I found no airflow - i.e. blockage in engine!
I then blew into the pipe from the engine to the exhaust elbow, with no luck.
I put a foot pump on it, and after a few good pumps got some flow.
I have used an old outboard fuel line/primer to pump hot water through the block ("backwards"), does anyone have any advice on any chemicals I can add to help clear out salt deposits and other crud? Obviously I have cleared one path through the engine, but concerned other waterways could be blocked.

The engine is a Vire 7 - the cooling water goes through part of the engine which is ALUMINIUM, so I need to be careful?

Cheers for any tips,

Trev

 

[RobF]

Personally, I would try Rydlyme. It's designed to clear deposits and is safe on Aluminium.

 

[VicS]

With no water pumping, I pulled the impeller to bits - which was fine.
After trying to blow into the pipe to the engine block (from the impeller), I found no airflow - i.e. blockage in engine!
I then blew into the pipe from the engine to the exhaust elbow, with no luck.
I put a foot pump on it, and after a few good pumps got some flow.
I have used an old outboard fuel line/primer to pump hot water through the block ("backwards"), does anyone have any advice on any chemicals I can add to help clear out salt deposits and other crud? Obviously I have cleared one path through the engine, but concerned other waterways could be blocked.

The engine is a Vire 7 - the cooling water goes through part of the engine which is ALUMINIUM, so I need to be careful?

Cheers for any tips,

Trev

Salt is soluble in water so a warm water flush should remove it. There are proprietary salt removers eg "Salt-Away" and "Salt-X" but I have no idea how effective they are.

If the cooling passages are blocked with limescale I'd consider a sulfamic acid based descaler such as Fernox DS-3 . Because you don't know the condition of the aluminium parts ( exhaust silencer and cooler ???) I would avoid strong acid based cleaners including Rydlyme and very definitely brick cleaner etc

 

[Neeves]

I know nothing about this - but it never stopped anyone else contributing to a thread - but if you had no airflow then its difficult to believe its salt or a chemical deposit (unless the engine has sat idle for a very long time) If its something that will not dissolve in acid, like rubber, adding acid is simply going to make the problem, much, worse.

When you cleared 'some' passage you must have produced something that might be the problem - what deposit did you find?

I'd drop whatever you 'cleared' into a jam jar and try weak acid on it - before soaking the engine in acid.

Jonathan

 

[Trevelyan]

Have backflushed with HOT water, all sorts of interesting white deposits, which when manipulated with the fingers disappear to bits. Also some other slightly more robust deposits, which I guess are aluminium oxide out of the silencer/exhaust...

 

[Neeves]

I might try to soak as long as possible with the hot water - though I suspect its not easy. But hot water is going to be more gentle than anything else.

At the end of the day I do not know how you will know you have cleared everywhere, no matter how you do it, without taking the engine apart. But maybe the coolant water run is very simple?

Jonathan

 

[Trevelyan]

I'm slightly tempted to run the engine (to generate heat) whilst pumping the cooling water through backwards, but have no idea what the implication of that would be.... perhaps I'll assume that what I've done so far using a tank of hot water is enough (and find out when I take it for a test run!). Trev

 

[Mistroma]

I might try to soak as long as possible with the hot water - though I suspect its not easy. But hot water is going to be more gentle than anything else.

At the end of the day I do not know how you will know you have cleared everywhere, no matter how you do it, without taking the engine apart. But maybe the coolant water run is very simple?

Jonathan

Probably a wise initial step. VicS used to be a chemist so worth accepting his suggestion to avoid acid even if others think it's a good idea. One person mentioned using weak acid but I suspect that he was talking about dilute hydrochloric and not a "weak acid". I'd also suggest avoiding strong alkaline cleaners on Aluminium (a bit obvious I suppose).

I also worked as a chemist but it was a very long time ago and it was research work with organic compounds, so memory of inorganic chemistry is even fainter.

I owned a boat with a Vire 7 many years ago, probably 35 years. I seem to recall that it had plugs on one side of the engine and they were designed to pop out before frost damage caused problems. It might be possible to remove these as a last resort to get access deep inside the waterjacket. Pretty much a last resort and I don't know if you could get replacement plugs.

You could check this link below for information on possible source of blockage.

http://gofree.indigo.ie/~vire7/tips2.htm#water

 

[Trevelyan]

Thanks - I do indeed have the dreaded bango fitting. It is also fitted with o-rings - I will try to source some replacements and have a go at taking that to bits too. Although the flow is ok-ish at the moment and the engine is giving me plenty of grief (see other threads), so I might hold off for the moment and give her a test run first...

 

[homa]

I second Rydlyme
I flush my outboard and inboard diesel at the end of every season.
Recommended by my outboard service center
definitely works in removing calcium deposits