Shredded Impeller on D2-55

[asteven221]

Hi folks.

On my new boat to me, my first outing didn't get me much beyond the marina entrance! I knew immediately what the problem was when the exhaust note changed, so I made the decision to "tickle" the boat back on the motor knowing that I am likely to face the prospect of a shredded impeller. Having never shredded an impeller before this is a first time fault for me to deal with!

I took the raw water pump plate off and retrieved what was left. Then I removed all the bits which trapped themselves in the void/cap prior to entering the heat exchanger tubes, which incidentally look to have very small bores which is maybe a good thing under the circumstances. I reckon I have got all (or the vast majority) of the old impeller out. I had "bright" idea to weigh all the debris and compare it to an identical new impeller. Also I am going to have at gathering all the bits and try and put the jigsaw back together to see what's missing. Initial attempts would suggest all all the obvious bits are accounted for.

Does that seem a good plan? Next I was going to use the marina hose to flush water through the heat exchanger hoping to see a nice flow appearing out the exhaust. Does that seem like workable?

Lastly the big questions!! After all that and assuming that I satisfy myself that all the big bits from the old impeller are found, do you reckon I am good to go after putting everything back together with a new impeller? Or am I being OTT thinking that there could be an outside chance of a fragment causing a blockage somewhere downstream of the heat exchanger? If so what on earth do I do then? Strip the whole engine apart?

As always, any advice is appreciated.

 

[Heckler]

Hi folks.

On my new boat to me, my first outing didn't get me much beyond the marina entrance! I knew immediately what the problem was when the exhaust note changed, so I made the decision to "tickle" the boat back on the motor knowing that I am likely to face the prospect of a shredded impeller. Having never shredded an impeller before this is a first time fault for me to deal with!

I took the raw water pump plate off and retrieved what was left. Then I removed all the bits which trapped themselves in the void/cap prior to entering the heat exchanger tubes, which incidentally look to have very small bores which is maybe a good thing under the circumstances. I reckon I have got all (or the vast majority) of the old impeller out. I had "bright" idea to weigh all the debris and compare it to an identical new impeller. Also I am going to have at gathering all the bits and try and put the jigsaw back together to see what's missing. Initial attempts would suggest all all the obvious bits are accounted for.

Does that seem a good plan? Next I was going to use the marina hose to flush water through the heat exchanger hoping to see a nice flow appearing out the exhaust. Does that seem like workable?

Lastly the big questions!! After all that and assuming that I satisfy myself that all the big bits from the old impeller are found, do you reckon I am good to go after putting everything back together with a new impeller? Or am I being OTT thinking that there could be an outside chance of a fragment causing a blockage somewhere downstream of the heat exchanger? If so what on earth do I do then? Strip the whole engine apart?

As always, any advice is appreciated.

The bits are usually caught on the inlet to the heat exchanger, any that go in usually come out and go to the exhaust. DONT put a pressurised supply to the engine without it running because it is the exhaust gases that pump the water out of the silencer and pipe! You will fill the exhaust up, it will then back up and fill your engine through the exhaust valves that are open!
Stu

 

[RichardS]

The bits are usually caught on the inlet to the heat exchanger, any that go in usually come out and go to the exhaust. DONT put a pressurised supply to the engine without it running because it is the exhaust gases that pump the water out of the silencer and pipe! You will fill the exhaust up, it will then back up and fill your engine through the exhaust valves that are open!
Stu

+1 to all that Stu says.

Did you forget to open the seacock or is there some other reason for the impeller shredding itself?

If you try and re-assemble all the impeller pieces and there isn't anything obvious missing then you'll be fine. The odd small bit isn't going to cause a problem and, as Stu says, will probably make a break for freedom of its own accord eventually.

Richard

 

[asteven221]

Thanks for the responses. I wish I had read them sooner................

I went through my plan last night and everything is working fine. The weight of the debris was about 2 grams difference to a new impeller. Did the jigsaw bit as well and no large bits or blades were missing.

Yikes, I also put fresh water through the input to the heat exchanger for about 40 seconds and the flow was excellent out the exhaust. It wasn't being forced through at a massive pressure i.e. the tap was only opened enough for a decent stream to pass through. But I now realise that it was not a good idea and worried I might have caused a significant problem! Hopefully got away with it, although (coincidence? hmmm not so sure now) the engine seemed to turnover a little longer before firing than I would have expected. Once started it ran fine and restarted perfectly ok. No strange noises and I had it running for about 10 mins.

Thinking about it now, I can see why there could be a big problem created by water getting into the engine via the exhaust valves. Never thought of that at the time. Interestingly the hose I used was a nice tight (ish) fit to the pipe on the heat exchanger making it an easy affair to get water in without splashing it leaking out the sides. Anyway I mention that because when I finished and the tap was switched off, when I started to remove the pipe I could sense a rush of air coming out of the heat exchanger inlet enough to spray water. I didn't think much of it and thought it was water built up and coming back out. Thinking back now it was more like air that was under some pressure.

Now I am a bit worried. Should I just leave it and consider that I have been lucky. Should I do some checking e.g. remove the rocker cover and have a look for water evidence. Would water get into the sump oil? Any advice would be appreciated.

Thanks.

 

[Moonbeam]

Now I am a bit worried. Should I just leave it and consider that I have been lucky. Should I do some checking e.g. remove the rocker cover and have a look for water evidence. Would water get into the sump oil? Any advice would be appreciated.

Yes, I would remove the rocker cover and also check your oil (dipstick). If the oil is milky/creamy, then water is in there. Hopefully you got away with it, but the good news if you did not, is because it's fresh water, you should be OK as long as you change the oil several times over (running to hot each time after the oil change), there should be no lasting damage. Once there is no sign of water in the oil, then re-check the rocker cover for moisture hiding there.

If it had been salt water, you'd be looking to sell the boat or get your self a new engine.

 

[asteven221]

Thanks Telstarr.

Yes I will do as you say. Since posting I have been researching manuals etc... for the engine stressing over whether I have made a relatively simple issue into a big screwup. The fact the engine seemed to run ok is a good sign. The fact I wasn't hosing the water in with the tap full open and not for too long is lucky. Looking at the design of the exhaust set up there is from what I can tell a bias towards the seawater running downhill away from the exhaust manifold into the exhaust itself which if that's saved me then that's lucky too. Geezo if I have got lucky this time I will take that as a lesson to think things through better before leaping in with my big stupid feet!!!

Thanks again for you reassuring reply. Except selling the boat of course - as I only got it two weeks ago!!!

 

[zoidberg]

The fact the engine seemed to run ok is a good sign. The fact I wasn't hosing the water in with the tap full open and not for too long is lucky. Looking at the design of the exhaust set up there is from what I can tell a bias towards the seawater running downhill away from the exhaust manifold into the exhaust itself

Among the manuals you've researched you may have come across this set of guidance-principles from Beta Marine - https://betamarine.co.uk/wp-content/uploads/downloads/operators_manuals/B10-25-HE-OM-221-02887-REV-01-0118.pdf - specifically pages 12-16.

I'm far from expert on these or others' engines, but you may find it informative to slip a suitably-small diameter plastic tube down your oil dipstick hole, place your finger over the end, and draw a decent sample. This sample ( or a couple ) dribbled into a clear jar should show whetehr your engine oil is contaminated - or not. You'll need this sort of tube anyway, attached to a Pela or some other manual/12V powered pump, to drain your old engine oil when the servicing time comes. Force 4 and other chandlers have options.

Best of luck!

 

[RichardS]

Thanks Telstarr.

Yes I will do as you say. Since posting I have been researching manuals etc... for the engine stressing over whether I have made a relatively simple issue into a big screwup. The fact the engine seemed to run ok is a good sign. The fact I wasn't hosing the water in with the tap full open and not for too long is lucky. Looking at the design of the exhaust set up there is from what I can tell a bias towards the seawater running downhill away from the exhaust manifold into the exhaust itself which if that's saved me then that's lucky too. Geezo if I have got lucky this time I will take that as a lesson to think things through better before leaping in with my big stupid feet!!!

Thanks again for you reassuring reply. Except selling the boat of course - as I only got it two weeks ago!!!

It's certainly worth checking the oil level and looking for any milkiness indicating water but that is not usually the main problem. The main problem is the the water runs back into the exhaust manifold and past the exhaust valve into the cylinder. It could, indeed, get from there past the rings down into the sump but the immediate issue is that when you try to start the engine the water in the cylinder compresses .... and water doesn't compress .... so something has to give.

If there is only a bit of water in a cylinder, and you are lucky, the engine will be a bit reluctant to start but it will then expel the water out through the exhaust valve and clear itself up. You won't be aware of this because the water just mixes with the normal cooling water and comes out of the exhaust. The only symptom you will experience is a tardy start until it clears.

Chalk that one up to experience.

Richard

 

[asteven221]

Hi Richard. Appreciate your response.

Yeah I understand that water cant compress and bits breaking because if that. A pal wrote of a van engine driving through a deep puddle. I am guessing my engine got away with that guven it ran for 15 mins. Down at the boat now. You are right about the first time I tried to start the engine. It took a about three attempts and then started and seemed fine. Ran it for about 10 to 15 mins at about 1200 rpm. Then a few blips at 2000rpm and all fine. Switched off and it restarted instantly.

Had a look on the diostick five mins ago. All lools ok and no sudden rise in level. I also looked down the filler cap and I think I can see some evidence of water. A very small amount of course and no more than I would expect if it was oil after the engine lying for 24 hours. Some if it will be oil I guess.

I will start it again and run it for 5 mins and check the oil for milky appearance. Right now its very clear.

Fingers crossed!!!!!

 

[asteven221]

Added a small oil top up to get some oil to the valve spring area. Just started it. Started instantly. Ran it for 5 mins at idle then in gear on pontoon at idle for 5 mins. All ok. Switched off and no sign of milky oil. Opened filler cap and all seems as expected. No obvous signs of water thank goodness. Restarted and currnently running un gear at 800rpm and all seems ok. Severe lesson learned.

When the penny dropped in what I had done I thought oh no I might have trashed my engine. Or at the very least given myself a lot of work and expense. A very luck man?. Cheers everyone for your help. This forum is brilliant when one is stuck or in my case totally balls it up Thanks.

 

[dunedin]

Excuse my ignorance but where exactly is the inlet to the heat exchanger, and is it normal / best practice to check it if have to change impeller?
Have heard of quite a few people having to change impellers at sea, and can’t imagine wanting to strip heat exchanger at the same time

 

[RichardS]

Excuse my ignorance but where exactly is the inlet to the heat exchanger, and is it normal / best practice to check it if have to change impeller?
Have heard of quite a few people having to change impellers at sea, and can’t imagine wanting to strip heat exchanger at the same time

It's normally the end of the H/E which is furthest away from the wet exhaust hose that leads to the water trap.

Richard

 

[asteven221]

On my D2-55 install (Bavaria) and on my last sailing boat with a D2-55 (Beneteau) changing an impeller on the D2-55 is a doddle normally and doesn't require touching the heat exchanger, assuming the old impeller is fully intact when it is removed. If it's shredded like mine was, then the first place you will find the missing bits will be at the inlet to the heat exchanger. Undo the jubilee clip, pull the hose and start fishing out all the impeller bits. I made up L shaped tools from a wire coathanger and fished around carefully to get every bit out.

Given my extreme balls up with my "bright idea" (big mistake) of flushing water through the heat exchanger, I perhaps don't have the authority to offer advice to anyone!!!

 

[Tranona]

Changing impellers is made so much easier if you fit a Speedseal front cover to the water pump. particularly true for the Volvo pump which although very easy to access is held on with 6 little screws which seem to prefer life in the bilges if given the chance when you remove them!