Replaced water pump but still no flow

[keepingitsimple]

Hi - I'm having problems with a Honda 15hp 4 stroke 1999 model that I bought.
It starts and runs well be not pumping. I checked if the water pump/impeller needed replacing - which seems to be working - but still no flow around the engine - threatens to overheat. Any suggestions? Read some-where that the pipes may have not been flushed by previous owner after salt water. How do I check/clear this?
Cheers
Michael

 

[Sea Rider]

Re: Replaced water pump but still no flow

Welcome to Iboats,

That's a 14 year oldie, when checking impeller, have you correctly matched water pump grommet to lower water tube when assembling back ? It's impossible to know how much salt cloggs, obstructions, crusts you could have inside crankcase untill you tear all lids and head appart. Bought sometime ago a mint cond engine to find out weeks latter that engine peed with difficulty & overheated severely, discovered that last owner was not a big fan of rinsing engine after each boating excursion.- Remove thermostat, will give a good interior indication about it's salty/non salty condition.-

Happy Boating

 

[keepingitsimple]

Re: Replaced water pump but still no flow

Thanks Sea Rider,

Do you mean the small metal 'key' that holds the impeller onto the shaft? I thought I may need to check that it hasn't come loose. I removed the thermostat and cleaned that up today (it was a bit crusty) -it is working when heated but the water is still not circulating to cool the engine. I inserted a solution to break-down lime/salt where the thermostat goes - but still not circulating. The motor looks in really good condition - sat in a garage unused for 8 years according to previous owner. No obvious signs that the head gasket has gone (but could be?). Will recheck that the key is holding the impeller onto the shaft correctly. Is there somewhere I should be cleaning while the lower leg is off? All looked clean and new around impeller cover but blackened inside the casing (exhaust?) above this. Appreciate your suggestions. Thanks.

 

[Sea Rider]

Re: Replaced water pump but still no flow

Hi Keepingitsimple,

If you forgot to place impeller key, there's your problem, or probably water pump grommet is not connecting to lower water pipe accordingly, water is not being pumped to head. Impeller must be rotated clock wise when sitting upper WP housing. Was old impeller found with complete vanes, or with some missing ?

It's difficult to determine how much salt you have inside all water passages and head. if just thin salt layers as in arteriosclerosis (saltclerosis) engine will cool bit less than running with all water passages inmaculate clean, but will see water peeing. If iseverely clogged, probably not. Start cheking with what was mentioned at the beginning...

Happy Boating

 

[keepingitsimple]

Re: Replaced water pump but still no flow

Thanks Sea Rider!

All running beautifully now. I pulled it all apart again. I had the fins of the impeller pointing the wrong way. Also I found a problem with the impeller housing. It looks like it was an after-market cheapie - it had a malformed raised area that would have been inhibiting the impeller from spinning properly. It was also quite likely I did not have the impeller housing attached to the lower water pipe when I re-attached the lower unit. I have learned a lot through this process - and now have a good motor at last! Hope to be on the water for the first time in a few week. Thanks for your support. Cheers!