Perkins MC42 - Core plugs size???

[Toad555]

Hi

 

Does anyone know the size of the core plugs for a Perkins MC42.

Its the one behind the starter motor which is leaking and needs replacement.

 

I'd really like to get a replacement before I dismantle it to remove the failed one.

 

Thanks

Julian.

 

[Toad555]

Morning

I didn't get any replies to this post so I went ahead anyway and removed my failed core plug, I managed to measure it at 40mm and ordered a replacement.

Unfortunately it didn't go so well. I fitted the new 40mm plug and it went in very easily which was a concern, sadly its still leaking so I'm guessing its not 40mm.

Does anyone know if Perkins engines are imperial measurements meaning I should have ordered an imperial core plug.

The nearest imperial measurement seems to be 1" 9/16ths, does this sound right???

 

[Chewbacka]

49 minutes ago, Toad555 said:

Morning

I didn't get any replies to this post so I went ahead anyway and removed my failed core plug, I managed to measure it at 40mm and ordered a replacement.

Unfortunately it didn't go so well. I fitted the new 40mm plug and it went in very easily which was a concern, sadly its still leaking so I'm guessing its not 40mm.

Does anyone know if Perkins engines are imperial measurements meaning I should have ordered an imperial core plug.

The nearest imperial measurement seems to be 1" 9/16ths, does this sound right???

 

25.4mm per inch, so 25.4/16=1.588  then x9=14.29 then plus the extra inch so 14.29+25.4=39.69mm  which is close but smaller than 40mm.  As you said it was a loose fit, then the imperial plug will be even looser (using 1 & 9/16"), so it sounds wrong to me.

Added -

Here is the spec for a 1&5/8" core plug, it is worth noting the suggested interference is about 2mm ( I trust this does not trigger an argument about mixing units in a sloppy manner)

Nominal ø 1.5/8" (1.6250" or 41.275mm)

Actual ø 1.6204" (41.16mm)

Thickness 0.0704" (1.79mm)

Interference 0.0820" (2.085mm)

Total ø when absolute flat 1.7025" (43.245mm) ~1.45/64"

http://www.coreplugs.co.uk/index.php?route=product/product&path=62&product_id=90

and they cost less than a quid each, so even with p&p shouldn't break the bank :-)

Edited June 18, 2017 by Chewbacka

[Toad555]

Ah, very valuable info, thanks for that.

It's beginning to seem like the engine is a mismatch of metric and imperial anyway according to several PDF's.

I think the answer has to be a 40mm plug, the one I bought had a shallower shoulder than the original so that has to contribute to a poor fit too.

I'm going to get another 40mm plug from a different supplier with the correct shoulder height and give that a try.

I sealed it with blue hylomar, does this sound appropriate to you? or should I use something else or nothing at all?

 

[Chewbacka]

14 minutes ago, Toad555 said:

Ah, very valuable info, thanks for that.

It's beginning to seem like the engine is a mismatch of metric and imperial anyway according to several PDF's.

I think the answer has to be a 40mm plug, the one I bought had a shallower shoulder than the original so that has to contribute to a poor fit too.

I'm going to get another 40mm plug from a different supplier with the correct shoulder height and give that a try.

I sealed it with blue hylomar, does this sound appropriate to you? or should I use something else or nothing at all?

 

Why not buy a couple of different sized plugs as they are quite cheap and use the one that is a good tight push fit, as without any interference you will be relying solely on the sealer to bond the plug in place.

[bizzard]

If a flanged plug they need to be quite a strong interferance fit, needing quite strong but gentle and careful square knocking in. If its the contact lens type, convex, concave, which ever side you look at it, they push in by hand up against a ridge and then you thump the centre of them to expand them. Hylomar is fine.

[croftie]

Make sure the core plug hole in the block is cleaned up of any rust etc. which type of core plug is it?

Edited June 18, 2017 by croftie

[Toad555]

Yeah I did do, it was clean and dry, I installed the new plug with Hylomar and it still leaks.

I've been learning as much as I can but I'm still a little in the dark about why it leaks and why it was so easy to install.

The next size up definitely won't fit and the nearest imperial size is smaller than 40mm so that won't do either.

Maybe the 40mm plug I installed wasn't actually 40mm, going to do a little ringing around in the morning before ordering another new plug.

Its not too bad to get to but I really don't want to make this a habit, the starter motor has to come off each time too so not ideal afternoon entertainment.

 

[Chewbacka]

9 hours ago, Toad555 said:

Yeah I did do, it was clean and dry, I installed the new plug with Hylomar and it still leaks.

I've been learning as much as I can but I'm still a little in the dark about why it leaks and why it was so easy to install.

The next size up definitely won't fit and the nearest imperial size is smaller than 40mm so that won't do either.

Maybe the 40mm plug I installed wasn't actually 40mm, going to do a little ringing around in the morning before ordering another new plug.

Its not too bad to get to but I really don't want to make this a habit, the starter motor has to come off each time too so not ideal afternoon entertainment.

 

It was so easy to install because it is too small.  It needs to be a tight fit because if the core plug is not an interference fit then with a bit of temp cycling etc it will leak.

[WotEver]

19 hours ago, Toad555 said:

The next size up definitely won't fit

1 5/8" convex won't fit?  It's only 1mm bigger than the one you have. 

http://www.enginecoreplugs.co.uk/product/engine-block-cylinder-head-core-freeze-plug-dish-type-1-5-8

[croftie]

Thing is we don't know if its a dish or cup type. Cup needs a good interference fit to seal and a dish expands on fitting to give a good seal. Did ask earlier which one but was not told.

[Toad555]

Ah sorry I forgot to mention, there cup ones. 

Quite a deep cup too at 12mm.

I've been in touch with Perkins this morning and they confirmed 40mm is the correct size, I assume the interference clearance on the one the third party one I have tried is incorrect.

Going to order directly from DiPerk now I think to ensure they're correct  

 

[croftie]

36 minutes ago, Toad555 said:

Going to order directly from DiPerk now I think to ensure they're correct  

 

The OE ones should certainly be correct. Good luck and personally I would use a thin film of blue hylomar on both the cup and block