Yanmar 1GM10 - Another Problem

[Wandering Star]

Am posting this thread as no one responded to the same request I tagged onto a 4 year old thread I reincarnated in order to save everyone having to repeat their advice and experiences in that thread for my benefit!

I have a leaking water pump on my Yanmar1GM10. The boat came to me with a brand new boxed Yanmar water pump So instead of stripping the old shaft & replacing the seals & bearing, I thought it would be a 3 minute job to just replace the entire pump with the new one.

Half a day later I’ve managed to remove 2 of the 3 bolts by hammering a 9mm ring spanner over the bolt heads. The third bolt also refuses to budge but is so inaccessible behind the belt pulley, that I can’t get the spaner on and I can’t use the hammer method. So my question is, how do I remove this third bolt? I’m loathe to remove the belt pulley (I’m not naturally mechanically minded) but I will if it’s my only option - if I do, is it relatively simple? Is there another simpler “trick of the trade” to remove the bolt? The 2 bolts already removed turned out to be reasonably solid and I suspect this third one will be too.

Any ideas from the usual suspects or others?

 

[Boater Sam]

A fine jet from a gas torch played on the bolt head will loosen it.
Or give it a good shocking using a brass drift and hammer.
Use a ring spanner rather than risk taking the corners off with an open ended spanner.


Why is it problematic to remove the pulley? I don't know that water pump but most are just 3 or 4 machine screws.

 

[jwfrary]

You might have a go with a flare nut spanner as these are 6 point rather than the standard 12 point. Might grip what remains of the head.

Worst case I'f its completely round is cut the head of the bolt off with a hacksaw and the extract the remains of the bolt afterwards.

 

[Dellquay13]

is it too late to put the bolts back, and just do what most people do and change the impellor and the 2 shaft seals? I've got spare impellors and a spare shaft with new seals ready to go on as needed, leaving the pump body in situ.

 

[oldharry]

If the seals are leaking the oil pipe directly below the pump will be rusting. If so, it too needs replacing. If it fails the engine will dump its oil in the bilge then seize. This will inevitably occur at the worst possible moment!

 

[andsarkit]

If the seals are leaking the oil pipe directly below the pump will be rusting. If so, it too needs replacing. If it fails the engine will dump its oil in the bilge then seize. This will inevitably occur at the worst possible moment!

If you do replace the pipe take the old one to a hydraulic shop. They will make up one for less than half the cost of the Yanmar part and it won't ever rust again.

 

[Bergamot]

I had a similar problem with my ancient 1GM10, although it was one of the two accessible bolts. I ended up removing the bolt head carefully with a hacksaw blade. After removing the pump the long remaining thread was easy to remove with a mole-grip. I would not be too worried about removing the crankshaft pulley to gain better access as you will not upset any timing etc.

 

[andsarkit]

Removing the pulley is easy if you have a 28mm or 1 1/16" socket.
I replaced the screws with stainless thinking I had solved the problem however the stainless steel and bronze pump body then caused corosion of the aluminium cover which then needed repair.
I think the best answer is to replace the screws every few years with zinc plated steel ones.

 

[penfold]

The best answer is to not have seawater leaking everywhere.

 

[Wandering Star]

Well, thanks for everyone’s input. Finally managed to unscrew the 3rd inaccessible bolt using penetrating oil and lot’s of expletives but with no real drama - it just suddenly decided to let go it’s grip. Have installed the new pump with new bolts and all seems well with no drips from the pump.