will my engine be damaged

[mbay]

my engine was running with no cooling water going through it for at a guess 15 mins, i say guess because i only realised this was happening when i smelt burning and there were exhaust fumes in the cabin. I immediately stopped the engine removed the strainer but found nothing wrong so can only dedeuce that something was blocking the intake. did a few more visual checks and restarted it, there was a large cloud of steam coming from the exhaust and could see the usual trickle so thought water must be flowing through the engine, however the engine was still very hot so i left it to cool. Once it had cooled i again restarted and now seems to run as well as it always has, so should i be concerned?? the oil levels are all fine

 

[Sultans_Kapitein]

I'm sure there many things to check but first check the state of and/or replace the impeller in yourwater pump. A friend (truely !) ran his engine for a little while after clearing the raw water filter but had forgotten to OPEN the sea cocks ! Similar symptoms to you and one 'shattered' impeller. Good luck.
Mal

 

[mbay]

its not an impeller its a diaphram on my engine and have checked this also, thankfully it seems fine.

 

[elton]

Cold water flowing through an overheated cooling jacket is bad news. You should have stopped the engine and waited for it to cool before restarting it with the sea water cocks open. If you had exhaust fumes in the cabin it sounds like the exhaust or the exhaust manifold is cracked. Apart from that, check for water in the engine oil, which would indicate a cracked cylinder block.

 

[Richard10002]

For the cost of an impeller against a major engine repair, you should change the impeller. If it's been run dry, it is probably damaged, even if you cant see the damage. Maybe one of the blades came off, blocked the pipe, then unblocked when you switched off. If any part of the impeller is missing when you change it, you need to find the missing bit/s.

I wonder if there was something blocking the intake, which fell off when you stopped the engine... or something was squashing the exhaust pipes, which you removed during your checks?

Cheers

Richard

 

[chriscallender]

I once managed to start the engine and get 15 minutes or so with the seacock closed /forums/images/graemlins/blush.gif. I had to replace the rubber exhaust hose and the plastic muffler which had been melted, and as a precaution I changed the impeller (which still worked) and gave the engine an oil change.

But otherwise 2 years on no problems, although its impossible to say that it did no damage at all.

So you might want to think about changing the oil (I think it can get degraded when it gets cooked) but otherwise I'd say you will be fine).

Chris

 

[[10753]]

Definately suggest an oil change as boiled oil apparently loses its full lubrication properties.

 

[Guest]

All sorts of causes ......

Plastic bag picked up and blocking intake ..... as another boat I know off..........

Stopping engine allowed the bag to fall away .... that owner has run his engine without trouble since.

 

[mbay]

yes agree, seems to have been something blocking the intake which fell off when i stopped the engine, will change the oil re: other suggestions, a guy in my club had a small see through plastic pipe attached some how to the cooling system on his engine, this drained into cockpit so you could tell at a glance if the water was getting through maybe another job to add to the ....to do list

 

[Talbot]

IIRC ASAP have a water flow alarm.

 

[steve28]

What make is your engine ?

 

[duncan]

ran my (biggish) Yanmar 15 minutes at idle with the seacock closed..........didn't overheat but it didn't damage the impellor either (it was 3 years ago and I only changed the thing last month with the old one 'imaculate'.............

absolutely agree it's worthy of inspection - if of course you have an impellor which here he doesn't.

 

[mbay]

18hp sabb 2hg diesel

 

[Anonymous]

A lot depends on whether the engine is raw water cooled or fresh water cooled via a heat exchanger. From your description is sounds likely that the smell was from the exhaust hose that would have got very hot without cooling water. These can delaminate inside if subjected to great heat and you should inspect it before relying on the engine for passage making. If you are fresh water cooled there is a good chance that no other damage was done.

 

[Oldhand]

I would replace the exhaust hose completely and possibly any silencer unit. 15 minutes of diesel exhaust in a rubber hose with no cooling is too long for it to be trustworthy.

 

[smeaks]

exhaust in the cabin.... may not be fatal im sure if the engine overheated there must be oil (and some surface gunge - or is that just my engime!!!) may have cooked along with it causing a fume that would be apparent in the cabin. i would think if the exhaust had damaged the fume would continue to be apparent even now.

 

[Anonymous]

[ QUOTE ]
i would think if the exhaust had damaged the fume would continue to be apparent even now.

[/ QUOTE ]No, the damage is insidious. The exhaust hose could fail without warning and should be inspected internally at the very least or replaced. It will be obvious on internal inspection, not external. If the exhaust fails in service the engine will have to be shut down immediately.

 

[smeaks]

oops scary stuff!!! I suppose if you buy a secondhand boat you just dont know! to be sure you would need to replace a massive amount of kit! Iam going to get a bigger bailing bucket - one I can fit in and paddle!

 

[Blueboatman]

Mbay,my first old boat had a Sabb.the main thing is that you noticed it before it seized!
It is a very very tough cast iron unit-alloy engines can warp their cylinder heads when overheated(though I am not an expert).

Roller bearings and grease nipples abound on the Sabb and the diaphragm water pump will not have disintegrated...It is slow reving and theres lots of cast iron to help remove heat...so if it starts easily it should still be fine..
Because it is a raw water cooled unit and the standard muffler/water injection point for the exhaust is cast iron,there are plenty of known instances where this item gets bunged up with crud/rust/salt deposits-making it more difficult to pass cooling water and restricts gas flow and thus power output.Would be worth checking the gasket joint between this component and the cylinder head..If you want to remove it to have a look,dont sheer the studs!
hope this helps a bit.

 

[awyatybw]

Re: will my engine be damaged (fit a flow switch)

From a peace-of-mine point of view, one of the best bits we added to our engine system was a flow-switch and horn for the raw-water inlet.

You can buy a shiny, expensive, ready-made "product" for this these days (advertised regularly in the mags). We just bought a flow-switch from RS Components. It has a plastic body so we epoxied short pieces of tube in each end and clamped the raw water hose to these tubes. See RS Stock no. 257-082: N/O liquid flow switch,22mm dia 3.5 l/m. They do three variations for different flow rates, so you need the right one for your engine.

The other piece is a vehicle reversing alarm from any auto factors. Get the 3-cable variety (the third wire is intended to be attached to the lighting circuit to silence the thing at night) and then no fancy electronics etc. are required (to reverse the normally-on/normally-off sense of the flow switch).

I admit that you get a really horrible noise for a couple of seconds when you start the engine (it is not a subtle horn).

Alan.