Leaking raw water pump advice please

M

mireland

Well-Known Member
Joined
26 Apr 2004
Messages
334
Location
Thames valley, UK
Visit site
I have a Johnson raw water pump on a Bukh 36 that is freshwater cooled. The raw water pump has been leaking as evidenced by rust all over the place beneath the pump! I checked it out while the engine was running today and found that no water was coming from the cover but instead appeared to be coming from the space between the impeller housing and the body of the the pump. It is the bit where you can see a shaft turning!

Can I repair this myself and if so does anyone have any simple advice on what I need and how to go about it. Have looked in the manual but it is not very clear to me.

Many thanks in advance
 
mireland said:
I have a Johnson raw water pump on a Bukh 36 that is freshwater cooled. The raw water pump has been leaking as evidenced by rust all over the place beneath the pump! I checked it out while the engine was running today and found that no water was coming from the cover but instead appeared to be coming from the space between the impeller housing and the body of the the pump. It is the bit where you can see a shaft turning!

Can I repair this myself and if so does anyone have any simple advice on what I need and how to go about it. Have looked in the manual but it is not very clear to me.

Many thanks in advance
Click to expand...
This link tells you how to do it.
 
I am not sure about that pump but all of the raw water pumps that I have seen have an O ring or a seal on the back which is easy to change and should in any case be changed every few seasons as the salt and grit in the water wears out the seal.
 
Your problem is that the lip seal behind the impeller has failed, allowing water to pass it and exit via the tell-tale drilling in the casing. It is important that you repair it soon, as water may be passing the inner seal and entering the sump, where it will cause considerable damage. The pump can be repaired easily. Kits are available containing all the parts and instructions. The link posted above has some good advice but differs considerably from the pump fitted to the Bukh I owned.

There is a drawing of the parts and some advice on my website under Engine>water pump. T Norris supply all the parts, as do many others.
 
Thank you very much for all your good advice. I have now ordered seals and subject to the houdini style contortions required to access the pump hope to fit them soon! I certainly will not be running the engine until I have fitted them. Vyv how do I know if water has got into the sump - is it just by looking at the oil on the dipstick or should I drain it to see?
 
It is usually obvious by looking at the dipstick but to be certain you could draw a little oil off with a Pela, making certain you push the tube to the lowest point of the sump.

You could use the old 'crackle test' as still used in refineries. Heat a steel plate on a gas stove or blow lamp, or use a hot plate if you have one. Let a drip of oil fall on the plate. If the water content is greater than 2% it will issue an audible crackle. In this case best to change the oil. Otherwise a good run, couple of hours or so, will usually dry it out if only traces of water are in it.
 
Check the shaft carefully

If the seal has failed it is possible the water passing has caused wear on the shaft... In with case you will not get it to steal again.. Look for any sign of ridges where the seal sits... If the engine is more than ten years old it is quite likely that you will need a new shaft as well. If you are not experienced with such things take the shaft to an engineer to ask for an opinion..

The shaft itself is not that expensive.. If you need one Johnson have a distribution centre in Dunstable, Beds and will take orders by phone..
 
vyv_cox said:
It is usually obvious by looking at the dipstick but to be certain you could draw a little oil off with a Pela, making certain you push the tube to the lowest point of the sump.

You could use the old 'crackle test' as still used in refineries. Heat a steel plate on a gas stove or blow lamp, or use a hot plate if you have one. Let a drip of oil fall on the plate. If the water content is greater than 2% it will issue an audible crackle. In this case best to change the oil. Otherwise a good run, couple of hours or so, will usually dry it out if only traces of water are in it.
Click to expand...

Never heard of the crackle test before - brilliant. I'll give it a try!
 
Tomahawk said:
If the seal has failed it is possible the water passing has caused wear on the shaft... In with case you will not get it to steal again.. Look for any sign of ridges where the seal sits... If the engine is more than ten years old it is quite likely that you will need a new shaft as well. If you are not experienced with such things take the shaft to an engineer to ask for an opinion..

The shaft itself is not that expensive.. If you need one Johnson have a distribution centre in Dunstable, Beds and will take orders by phone..
Click to expand...

I hope the seal has not been leaking long enough for this to have happened but thanks very much for the heads up.
 
Also check the bearings

I know this is starting to sound scary.. But it is likely that if the seal has been leaking then the bearings will probably be shot as well a they will have got wet and develop a bit of rust..

A pair only costs about £10 so they are really cheap... And it is silly to put new seals onto dodgy bearings as the movement in the bearing will wreck the seal in short order..

Send me a PM if you would like me to talk you through it..
C
 
I had the same problem on a Volvo 2010 with a Johnson pump, tried to get a replacement pump from a non Volvo dealer, but couldn't ascertain if it was an exact replacement, so bought a complete seal replacement kit, shaft and all from Volspec. Trickiest bit on a 2010 was unbolting the pump, two bolts from the front, two from the rear which involved a sawn off spanner and the mechanic lying on his back. Of course Canata has since told me that a flexible ratchet socket drive would have made things a lot simpler.
 
You must log in or register to reply here.

Other threads that may be of interest

D
No Raw Water Strainer - Trapper 500 Nanni 2.14
Replies
3
Views
210
Dulaman66
D
ianc1200
Sureseal shaft seal.
2
Replies
20
Views
539
ianc1200
ianc1200

Share this page

Top