Overheating Engine

[Naughty Cal]

Agree with above. If the blockage is definitely gone check the impeller.

[IndianChick]

 

 

Interesting.

 

Has the mud box blocked again perhaps? Is this the problem that has returned, or did you mean this time the mudbox filter remains unblocked but the overheating persists?

 

Where does the raw cooling water leave the boat? Via the exhaust or via a skin fitting? Look and see if there is a healthy flow of water. If not, and the mudbox filter is definitely still clear the new impeller you fitted probably got cooked/knackered by the previous blockage of the filter...

 

MtB

Hi Mike, I believe the mudbox filter remains unblocked and therefore the overheating problem persists. The raw water leaves via the exhaust and the water just dribbles out. I didn't think to check the impeller as I have just fitted a new one. I will check it at the very next opportunity. Thanks so much!

Agree with above. If the blockage is definitely gone check the impeller.

Thanks! Will do.

[J R ALSOP]

Make sure you get all the broken impeller blades out, as they will block the pipework.

[MtB]

Hi Mike, I believe the mudbox filter remains unblocked and therefore the overheating problem persists. The raw water leaves via the exhaust and the water just dribbles out. I didn't think to check the impeller as I have just fitted a new one. I will check it at the very next opportunity. Thanks so much!

Thanks! Will do.

 

 

I think the clue lies here. A sensible flow of water is needed to cool an engine.

 

One of my boats is raw water cooled and I happened to measure the flow from the output the other day. I can fill a pint glass from the raw water outlet in about 20 seconds with the engine speed control set to run at normal cruising speed.

 

I suggest you try this too and post the result....

 

MtB

[cuthound]

I think the clue lies here. A sensible flow of water is needed to cool an engine.

 

One of my boats is raw water cooled and I happened to measure the flow from the output the other day. I can fill a pint glass from the raw water outlet in about 20 seconds with the engine speed control set to run at normal cruising speed.

 

I suggest you try this too and post the result....

 

MtB

Blimey, you must have been desperate for a drink!

[Tony Brooks]

Hi Mike, I believe the mudbox filter remains unblocked and therefore the overheating problem persists. The raw water leaves via the exhaust and the water just dribbles out. I didn't think to check the impeller as I have just fitted a new one. I will check it at the very next opportunity. Thanks so much!

Thanks! Will do.

 

 

Have you checked the pipework, particularly on the engine side of the pump for blockages? As I said in an early post it is far from uncommon for broken impeller wings to get stuck across an elbow in a pipe or hose.

 

Do you have a heat exchanger (is there a cap to fill with fresh wtaer is another way of putting it)? If so have you checked the ends of the tube stack/core for blockages. Both will cause the problem but so will many, many other things. This needs either you to steadily work through what I wrote early on or a competent engineer. If your engineer did not check the heat exchanger and pipes then I would question his competence. Depending on where you are maybe you should contact Richard (Primrose Engineering). Otherwise give us a CLUE to the boat's location and a member may be willing to come and have a look for you.

[MtB]

Blimey, you must have been desperate for a drink!

 

It's only for guests....

 

 

MtB

[Timx]

IndianChick, on 24 Sept 2014 - 10:42 PM, said:

Thank you everyone for all your help. The filter coming out of the mud box was blocked. The problem has been temporarily fixed but I took her out on the cut at the weekend and the problem came back. So back to the drawing board so to speak and go through a process of elimination. Happy boating everyone!

where the water comes into the dirt box is probably blocked too, so poke a stick down there to make sure water is flowing in and not blocked

[MtB]

Thank you everyone for all your help. The filter coming out of the mud box was blocked. The problem has been temporarily fixed but I took her out on the cut at the weekend and the problem came back. So back to the drawing board so to speak and go through a process of elimination. Happy boating everyone!

 

On reflection, it's not 'back to the drawing board', it should be 'back to Tony Brooks' posts'.

 

Tony has given you everything you need to know to trace this fault, chapter and verse. There are very few people around with Tony's level of expertise. Pay close attention to his advice.

 

MtB

[IndianChick]

 

On reflection, it's not 'back to the drawing board', it should be 'back to Tony Brooks' posts'.

 

Tony has given you everything you need to know to trace this fault, chapter and verse. There are very few people around with Tony's level of expertise. Pay close attention to his advice.

I know. Will do. So glad I joined this forum.

[Philip]

I have a Volvo Penta in my cruiser which uses raw water cooling and had real problems last year with overheating. However it was nothing to do with the engine itself, it was in part due to broken impeller bits blocking the pipework as mentioned above. There was also some paint-like substance which somehow got in and this too caused a blockage in the cooling system. It's also best to check the coolant strainer to make sure it isn't clogged up with crud especially at this time of year because of leaf-fall.