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  1. #21
    Join Date
    Mar 2008
    Location
    near kingston upon thames, surrey
    Posts
    389

    Default Re: no water! - it isnt the impeller

    Got it all working!!
    The manifold was pretty gunked up so I put it in a bucket of brick cleaner for an hour. I still needed to be pretty firm with a screw driver and bit of wire but cleared the passages eventually. I'm just amazed any water was getting through last season.

    Refitting was OK, except the push on connector to the horizontal pipe didn't deal so the whole lot had to come off again. It sealed well the second time round. At least it seemed to. I'll keep an eye on it.

    Thanks for the tip with Rydlyme
    http://www.ricoservices.co.uk/environmentallyfr.htm
    I'll be doing this on an annual basis in the hope that I don't have to take the engine to bits again.

    Is it low speed running that caused this?

    From memory the water flow seemed OK last season.
    So I guess it is possible this got blocked up over a relatively short period of time.

    I did not winterise the engine either. Perhaps not flushing it out at then end of the season was a contributing factor

    Thanks for the help guys.

  2. #22
    Join Date
    Nov 2011
    Location
    Sydney, Australia.
    Posts
    4,493

    Default Re: no water! - it isnt the impeller

    From our experience with a similar blockage on a MD2020. The orifice closure in the exhaust elbow, primarily calcium carbonate but with carbon (so it looks like carbon) can reduce to a few mm before you will notice any loss of water flow - but below those few mm you will developed reduced engine revs - I never reached the point of no water flow. You can clean with acid, I guess that's what Rydlyme is? or brick cleaner - once - we never managed to do it twice as the acid is also attacking the steel - and we dissolved a neat hole in the exhaust elbow. Having 2 engines we have lots of time for practice.

    The blockage is commonly attributed to carbon - but carbon is inert to acid, whereas calcium carbonate readily dissolves. Calcium occurs in vary concentrations (around the world) in seawater - so its always going to be a problem.

    The blockage, with calcium carbonate, appears to be a reaction with the mixing of the, by now, hot cooling seawater and the exhaust gases - as that is the location it occurs. I don't quite see why running at low speed would make this worse - except the water flow would be faster at high speed (flushing the engine??). We do get calcium deposition in the water intake hose (note our water temperatures will be higher than yours, if its relevant), and I take it off occasional, crush the calcium inside and flush it out. I have never noticed deposition anywhere else. It does appear to be slightly more complex that simple hot seawater and exhaust gases as I detect that people who use stainless exhaust elbow claim better performance - but this might merit more investigation and may be false.

    This is a common problem, blockage of the exhaust elbow, it is a common cause of threads every 6 months or so (but is more common on Volvo than other engines??).

    Jonathan

  3. #23
    Join Date
    May 2016
    Location
    Suffolk
    Posts
    6,523

    Default Re: no water! - it isnt the impeller

    Quote Originally Posted by stu9000 View Post
    Got it all working!!
    Glad to hear it

    Thanks for the tip with Rydlyme
    http://www.ricoservices.co.uk/environmentallyfr.htm
    I'll be doing this on an annual basis in the hope that I don't have to take the engine to bits again.
    I'm doing mine this weekend, as a matter of course. I don't think it needs to be an annual job, although it certainly wouldn't do any harm.

    Is it low speed running that caused this?
    As with Jonathan, i can't see how engine speed is relevant.

    I did not winterise the engine either. Perhaps not flushing it out at then end of the season was a contributing factor
    Also doubtful. If the boat is out of the water for Winter i would nonetheless flush it, or you have pockets of saltwater sitting in the engine, causing corrosion.
    Rainbow Marine.
    www.rainbowmarine.co.uk

  4. #24
    Join Date
    Mar 2008
    Location
    near kingston upon thames, surrey
    Posts
    389

    Default Re: no water! - it isnt the impeller

    Lovely. Thanks for all of this.

  5. #25
    Join Date
    Jun 2016
    Location
    North West
    Posts
    507

    Default Re: no water! - it isnt the impeller

    Quote Originally Posted by PaulRainbow View Post
    Hook a small bilge pump, or pond pump up to the coolant system in such a way that the pump is submerged in a bucket of Rydlyme, pumping it through the raw water pump outlet pipe, through the engine and back to the bucket, from the pipe that goes to the exhaust, so it circulates the Rydlyme around and around the engine. Leave it running for 2 or 3 hours. As this won't do the elbow you will need to manually clean it, soak it in the bucket whilst it's pumping, or replace it.
    Do you have to do something with the thermostat when you do this?

  6. #26
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    42,359

    Default Re: no water! - it isnt the impeller

    Quote Originally Posted by JBJag27 View Post
    Do you have to do something with the thermostat when you do this?
    Yes. Remove it or you will only circulate the Rydlyme through the bypass.

    Also fully drain the engine cooling system before you start.

  7. #27
    Join Date
    Jan 2013
    Location
    Sevenoaks, Triola at MDL Chatham Marina
    Posts
    922

    Default Re: no water! - it isnt the impeller

    I wrote this up a while back - only just got this one on my website.

    http://www.albinballad.co.uk/how-tos...ngine-rydlyme/

    I daresay I missed some steps, but it worked pretty well.

  8. #28
    Join Date
    Nov 2007
    Location
    Boat Orwell - Me Norwich
    Posts
    6,437

    Default Re: no water! - it isnt the impeller

    Quote Originally Posted by MagicalArmchair View Post
    I wrote this up a while back - only just got this one on my website.

    http://www.albinballad.co.uk/how-tos...ngine-rydlyme/

    I daresay I missed some steps, but it worked pretty well.
    Very helpful.. Thanks.

  9. #29
    Join Date
    Mar 2013
    Posts
    20

    Default Re: no water! - it isnt the impeller

    I have a 35 year old Volvo 110 S drive and one problem I experienced was blockage in the water channels in the leg presumably from marine growth. This should be easy to check by taking the feed pipe to the strainer off the (closed) tap then open the tap. The tap should be well below the waterline and sea water should spurt out. My solution was to replace the hose insert a funnel and pour muriatic acid down into the leg interior and leave for an hour. This did the trick. I realise the potential for corrosion but we were in a remote area (Alaska) and you do what you have to in the circumstances. The only alternative involves removal and dissemble of the S drive to clean out the waterways. If this is not the problem then take a look at the exhaust bend where the sea water injection into the exhaust occurs and ensure that is not blocked. My engine was originally raw water cooled but after ten years in the tropics the engine interior waterways were completely blocked and the engine required complete stripping to clear the water ways in the heads and round the cylinder liners after pressing out the old liners. I then installed a Martec fresh water heat exchanger and all is well.

  10. #30
    Join Date
    Mar 2008
    Location
    near kingston upon thames, surrey
    Posts
    389

    Default Re: no water! - it isnt the impeller

    Interesting point. The engine is running but I'm drying out this weekend to change the oil. If I get time I'll try running a bit of brick cleaner through the water way.

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