Outboard Chemical Flushing

[PaulJS]

Hi there,
My friend's (Honest! /forums/images/graemlins/smile.gif) 2000 four stroke mariner 25 outboard engine is running hot but has a cool telltale. Sounds as though the powerhead coolant passages are blocked with salt or corrosion. I've seen postings mentioning chemical cleaning which isn't too aggressive for small alloy engines, but for the life of me cannot remember what they were.
Can anybody give any advice?

 

[Pete7]

Have you thought about removing the termostat and giving it a good clean first. Also when was the impellor last changed. Might be giving some water but not enough.

Pete

 

[VicS]

After 7 years the pump impeller ought to be changed. it also makes sense to test the thermostat.

I dont know the Mariner but i know exactly what to look at on my Evinrude!

If it is scaling /corrosion build up you could try a sulphamic acid based central heating boiler descaler such as Fernox DS3 (I think that the right number) or Rydlyme which should be available from better chandlers. Google fot it, I think I have the spelling correct.

If it is scaling/ corrosion more than likely you'll have to take the head(s) off and dog it out.

 

[PaulJS]

Fernox!!!
Thanks very much, I'll pass that on to my pal, apparently he has changed the impeller and checked the thermostat already, so scaling up is definitely favourite. That will teach him to flush it out after the season. /forums/images/graemlins/grin.gif
Regards
Paul

 

[marilynch]

[ QUOTE ]
That will teach him to flush it out after the season.

[/ QUOTE ]

Does your 'Friend' /forums/images/graemlins/wink.gif only flush through at the end of the season?
I believe it may be a good idea for your friend to flush through with tap water after every use (or as frequently as possible) rather than once a year because, as I understand it, many problems that occur with these type of engines are caused by salt and all (I think) 'he' may require (that is; in the future once he has sorted this little problem!) is a bucket of water and, if needed, those 'suckey' things (sorry can't remember the name /forums/images/graemlins/blush.gif).

 

[VicS]

Fernox do a wide range of products. An acid descaler such as Fernox DS3 is what will be needed however it must be used on thin or corroded alminium with some caution

Rydlyme is said to be safe on aluminium

Because it is available in small quantities a kettle descaler might be worth considering.

Any chemical cleaning agent will only be effective if it can reach the scaled areas. If everything is totally blocked up it simply wont be able to get to where it is needed.

 

[PaulJS]

Honest Guv, it weren't me. I wouldn't do nuffink like that, on me honour.

To be fair to my pal, we both work offshore, and he has had very little time home during the last year. Also, just for the record my outboard is an ancient air cooled SeaBee... Mind you it doesn't run at all... at present!
/forums/images/graemlins/laugh.gif