[Anonymous]

When I was in Spain in 2005 the exhaust outlet near the heat exchanger developed a hole and had to be replaced. The only replacement I could get was an exhaust riser which was a modification to my original, but all the fixing points were identical and all seemed fine. There is a drain point on it and although I have opened it on a few occasions nothing of any quantity has ever come out. However whilst out on the boat last weekend I became aware off a serious amount of seawater being forced out through the expansion pipe on the heat exchanger, which rapidly filled the bilges. After discussing the problem with Motortech I was advised to remove the exhaust riser and it then became apparent that it was nearly blocked, thus preventing large volumes of water passing through it, although OK at very low revs. Apparently it is reccomended that this particular riser which is fitted to 2030 & 2040 engines is flushed out at least twice a year to remove any build up which could evetually block it, and as the replacement cost me £324 plus VAT, it is something that i shall pay attention to. In order to flush it out it seems the best way is with the engine running, then attach a hose to the drain point and discharge it into a bucket etc, unless anybody has a better way. Ed Holmes Storm Dragon 🙁

[Anonymous]

Having contacted Volvo regarding the blocked exhaust riser, I was advised to contact a local dealer and having had no positive help from motortech in Gosport or Port Solent regarding measures of preventing the exhaust riser from blocking I contacted RK Marine in Southampton.
RK Marine also said they know of no preventative measures to stop the exhaust riser from blocking other than frequent rinsing and rodding. The rodding is done by removing the rubber exhaust pipe from the riser outlet and using something flexible to remove anything which may be forming inside the riser, and the rinsing can only be carried out by removing the exhaust riser. But RK Marine did say that some customers have had success in cleaning out the exhaust riser by immersing in a product called ‘Rydlyme’ which is available from Motortech at Port Solent for £11.63 per litre. Apparently the blockage is caused by a reaction of the temperature of the sea water and the cast iron. Ed Holmes Storm Dragon

[Anonymous]

Good Afternoon,
Having consulted our Service Manager we can advise that the success rate for completely clearing blocked exhaust risers is low however we recently immersed an exhaust in a product called Rydlyme for 48 hours and our customer was happy with the result. The blockage is caused by a number of factors including the temperature of sea water passing through a cast iron exhaust outlet. Unfortunately there is not a preventative measure that you could take other than to ensure the exhaust is cleared by rinsing and “rodding” on a regular basis. If the cleaning process does not work a new riser will be the answer.
Regards
Ian
RK Marine Parts.

Dear Sirs, the exhaust riser on my Volvo 2030 engine has become blocked after 1500 engine hours, can you advise any method of clearing it and what steps i could take to prevent it happening again.

Regards Mr E holmes
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Good afternoon.

You have hit the nail on the head. That is exactly right.

Kind Regards,

Martin Jerome

To: Parts – RK Marine
Subject: Re: Exhaust riser
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Dear Ian, by rodding do you mean to remove the exhaust pipe from the end of the riser and push something flexible up into the riser to remove anything that could lead to a potential blockage, and rinsing by removing the riser and flushing out with Rydlyme etc

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[Anonymous]

As the riser is a water jacket with seawater that has passed throught the coolant water jacket around the outside, and the exhaust from the motor mixing together and passing out of the wet exhaust.

I can’t decide from the post whether you are having trouble with the sea water or exhaust sections. Tanami’s exhaust section filled with carbon after about 900 hours. This stopped the engine (2020) breathing properly and it would only rev to 1800 rpm. Eventually the problem was found and the riser replaced as it could not be cleared.
This was a long story which I think I reported previously on this forum.

The end result was three recommendations:
1. replace the riser every 8 years when the rubber boot is replaced
2. Do not idle the engine excessively to recharge batteries etc.
3. Give the motor a chance to get nice and hot each time you use it and then run for a time at full revs to clear any carbon. i.e. do not just motor slowly to th estart line raise the sails and turn the motor off.

Greg

[Anonymous]

The problem was that the exhaust riser was partially blocked and although OK to run the engine at up to 1200 revs, but once past this point there as too much seawater trying to get through the exhaust riser, this then caused a build up of pressure on the rubber end cap at the rear of the heat exchanger and seawater was forced into the coolant area of the heat exchanger which in turn over filled and emptied via the expansion pipe which in turn filled the bilges. It was hard to believe that so much water could come out of such a small expansion pipe, but under such pressure it was coming out like a jet of water. The engine did not have this type of exhaust riser when new, but after the original exhaust elbow suffered from a hole blown into it whilst in Spain, the only replacement was this exhaust riser, and at over £400 to replace every 8yrs as you say makes expensive sailing, but i still have the one that was blocked and shall see what i can do to get it cleared as apart from being blocked there is nothing apparently wrong with it.

Ed Holmes Storm Dragon

[Author]

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