Water pump bolts

[owen]

The heads on my water pump bolts are becoming rounded. I can just get a socket on at the moment but would like to get some new ones.

It is a Yanmar 3gm30.

The bolts are 125mm long and 7mm metric thread..

Its clearly not a common bolt as i cannot seem to see them at the specialist suppliers.

I wonder if anyone else has been able to source these bolts??

 

[PeterBoater]

Have you tried a Yanmar dealer such as French Marine Motors or E P Barrus (not sure if the latter does retail)? Take out a second mortgage beforehand.

 

[Boater Sam]

Weld new nuts onto the heads? There are some odd sizes and thread pitches on Japanese bolts

 

[PetiteFleur]

How about an M7 stud with an M7 nut on the outboard end? You seem to get M7 x 125 studs on ebay.

 

[emmalina]

125mm long Wow thats a long bolt for M7 sure you don't mean 12.5mm ?

 

[ChromeDome]

Look it up in the parts catalog to at first identify the no, and dimension:

https://j109.org/docs/Yanmar-3GM30-parts-catalog.pdf

Fresh- and sea water pumps mentioned, could be on page 43

 

[ean_p]

Weld new nuts onto the heads? There are some odd sizes and thread pitches on Japanese bolts

Even for the Japanese M7 is an odd size.......

 

[Daverw]

I’m confused, the OP needs to confirm exactly which bolts he is talking about, I cannot remember any odd sizes on ours, just had a thought, is he referring to the long end over bolts that hold the bracket on, which can be removed to allow the pump to swivel and easier access, if this is the case it’s M8 x115

 

[CM74]

There are loads of sellers on ebay with various varieties of m7 bolts, though I'm not sure I've ever come across one! Do you have any pictures of the pump in question?

 

[vyv_cox]

Even for the Japanese M7 is an odd size.......

But not for Citroen! Lots of them on 2CV and Dyane, including manifold to head studs and bolts .

 

[penberth3]

But not for Citroen! Lots of them on 2CV and Dyane, including manifold to head studs and bolts .

Great idea having International Standards - every country can have its own!

Having said that, if I measured something as 7mm I'd check carefully it wasn't a skinny or worn M8.

 

[ChromeDome]

As per #6 it would be good to know the correct dimension (searching the manual doesn't return any M7 at all):

 

[ean_p]

But not for Citroen! Lots of them on 2CV and Dyane, including manifold to head studs and bolts .

yeah.....French....what would you expect..?

 

[vyv_cox]

yeah.....French....what would you expect..?

They most definitely like to use unusual sizes. Several of the bolt and nut sizes on my car require spanner sizes not contained in many tool kits, 11 mm and 14 mm amongst the favourites

 

[superheat6k]

Johnson on their US threads make their pump cover bolt heads cylindrical allowing them to be grasped with a pair of mole grips if they stick. The same thing can be achieved by finding the correct thread but ~ 4mm longer and adding a nut beneath the head, which then allows a suitable spanner to be used.

 

[Boater Sam]

They most definitely like to use unusual sizes. Several of the bolt and nut sizes on my car require spanner sizes not contained in many tool kits, 11 mm and 14 mm amongst the favourites

7/16" and 9/16" in my box.

 

[owen]

Thanks for the replies. Sorry I did not fully explain, it is the long bolts which attach the plate to the engine and allow the belt be tightened.
The exploded diagram shows an m8 x 12 but the bolt I have taken off is 7mm diameter( with a vernier) and screws into a m7 nut. ??
I guess I will just get the yanmar ones and try them in . thanks

 

[ChromeDome]

Bring the engine serial number- might be the key to get the right thing at the dealers

 

[jwfrary]

They are M8 bolts but with a 12mm head. Hex Head Flange bolt.

Had them out yesterday to double check for you!

 

[owen]

They are M8 bolts but with a 12mm head. Hex Head Flange bolt.

Had them out yesterday to double check for you!

thank you jon