Water pump damage.

Steve509926 · 27 July 2022, 22:34

Firstly, this isn't about my OB! Mine is running as good as ever.

If an OB is run with either a damaged impeller or run "dry" with no water for a short period of time ie: before overheat mode kicks in - what damage other than a knackered impeller and/or knackered pump can or is likely to happen?

Jon Tallis · 28 July 2022, 11:08

Probably depends how the engine is running at the time.
If at idle and shut down quickly, damage likely limited to impeller, pump housing, bonding of housing liner to housing, local o-rings etc.
If under load / high rpm might be less lucky if overheat warning is missed or engine doesn't go into "self protect" mode, possible head gaskets and a host of other increasingly expensive problems right through to seizure and cracked heads / block.
Glad it's not yours [emoji846]

Steve509926 · 28 July 2022, 11:23

Thanks John, taking a look at a friends OB next weekend. He had a hole in his water bin when he was flushing out and didn't notice the water loss.
Fired it up, went to the loo, made a coffee, came back and noticed it wasn't peeing water and could smell burning plastic.
He shut it down straight away but us now sh1t scared to fire it up again.
I've advised not to even try, until "we" at least take a look at the impeller and pump housing.

spartacus · 28 July 2022, 12:50

The impeller will be toast. At the very least get a new impeller, water pump liner and any gaskets. I'm sure it will be fine as it was probably started from cold if a few minutes. Longer than that who knows? Always worth keeping an eye on the engine when running it on land.

Harry Dwyer managed to set fire to his!

Jon Tallis · 28 July 2022, 16:09

Quote:

Originally Posted by Steve509926

Thanks John, taking a look at a friends OB next weekend. He had a hole in his water bin when he was flushing out and didn't notice the water loss.
Fired it up, went to the loo, made a coffee, came back and noticed it wasn't peeing water and could smell burning plastic.
He shut it down straight away but us now sh1t scared to fire it up again.
I've advised not to even try, until "we" at least take a look at the impeller and pump housing.

I assume your mate stopped the motor and it didn't sieze?
Definitely don't run it until you've rebuilt the waterpump as @spartacus says. Check the fit of the new liner into the pump housing which is likely plastic, as the housing may have melted / distorted - if in doubt replace it.
Assuming it didn't sieze, your mate has probably escaped any power head damage but to be sure check it is turning over freely and do a compression check.
If that all checks out, your mate got lucky. Give it a good long test run before using in anger - and buy a new wheely-bin [emoji1787]

And I'm with Spartacus - avoid if at all possible leaving engines on "flush" (especially on muffs) running unattended

Steve509926 · 28 July 2022, 16:50

I was astounded when he told me he left it running! Saying that, he is the type of person to leave his car running when he nips into the corner shop!
Thanks both for the advice, hopefully it will be OK. Any suggestions as to where to get the parts, 9.9 Merc 4 stroke 2006

jeffstevens763@g · 28 July 2022, 19:40

If the impeller has broken up bits could be a pain to remove from the water ways

Steve509926 · 28 July 2022, 21:24

Quote:

Originally Posted by jeffstevens763@g

If the impeller has broken up bits could be a pain to remove from the water ways

Is there anyway to backflush an OB to dislodge any bits that may be stuck?

jeffstevens763@g · 29 July 2022, 07:23

If it’s worn slowly it will be ok if it’s torn up there might be some big bits lodged you can flush from the thermostat housing to a degree the tell tale will be a bugger if it’s got that far good luck

Steve509926 · 08 October 2022, 12:51

We finally had a chance this morning to take a look at, and replace the impeller and the housing. Good job we did as I don't think it would have lasted any longer.

Pikey Dave · 08 October 2022, 13:06

Quote:

Originally Posted by Steve509926

We finally had a chance this morning to take a look at, and replace the impeller and the housing. Good job we did as I don't think it would have lasted any longer.

I think the technical term for that is “f***ed”…

Steve509926 · 08 October 2022, 13:13

Quote:

Originally Posted by Pikey Dave

I think the technical term for that is “f***ed”…

Yep, it was well and truly fragmented

jeffstevens763@g · 08 October 2022, 15:49

Been run dry by the looks just read the first post da