Why are these caps off? Kubota engine

[NFG]

Hi

 

Nice to see some core plugs that have worked!

 

N

[GardenKit]

I certainly would never refit a core plug that had blown out. New ones are slightly domed so the sides splay a little, which gives them a sharp sealing edge and a good interference fit.

As said above, they are dirt cheap, just do not take the chance with the old ones.

[SteveA]

When I worked in garages we used to use blue Hylomar, clean off the rust and pop a thin smear around the edge... Hylomar – Non-Setting Compounds

cheers, steve

[aspenarb]

I would be concerned as to why the core plugs popped out, with the rad needing repair as well I wondered if the thing was pressurising. It may be an idea to run it up with the cap off and see what sort of commotion is going on in the water system, the last thing you want to do is blow up your new rad.

 

 

Bob

[Suffolk-Matt]

When I worked in garages we used to use blue Hylomar, clean off the rust and pop a thin smear around the edge... Hylomar – Non-Setting Compounds

cheers, steve

 

I have reused them using Hylomar a couple of hours ago, i must of predicted your post

 

Ill run the machine with the side case off for the next few days to keep an eye on them both and the coolant level.

[Suffolk-Matt]

I would be concerned as to why the core plugs popped out, with the rad needing repair as well I wondered if the thing was pressurising. It may be an idea to run it up with the cap off and see what sort of commotion is going on in the water system, the last thing you want to do is blow up your new rad.

 

 

Bob

 

I did consider that, and will be mindful when running for the first hour. Rad cap seems in good order.

 

The leak in the rad was towards the top, it was up to 13 years old if original. The block would still of been at least 90% full of pure water ( :blushing:yes i know)

 

That and the caps must of come off at the yard as if they had of popped while the machine was running (on site) they wouldnt of made the trip home on the bumpy roads being where they were in the bay. They would be been lost.

 

Sharp frost and the plugs seemed to have worked.

[SteveA]

I have reused them using Hylomar a couple of hours ago, i must of predicted your post

 

Ill run the machine with the side case off for the next few days to keep an eye on them both and the coolant level.

 

Good man.

After the initial start and topping up levels (oil & water), removing air locks, squeezing pipes, etc I run an engine until the cooling fan cuts in and out (pick the revs up high / but not flat out revs).... if there's something wrong it's most likely to show itself at full heat & pressure.

You probably already know that.

cheers, steve

[rustcutter]

The core plugs are not there as a frost protection; they are to fill the core holes left in the block as a part of the casting process. It just happens that they are a weak link and will pop out if an engine is lightly frozen, they wont protect an engine which is full of neat water in a heavy freeze. remember ice does not start to expand until it is -4deg. C.

However these which are the cap shaped ones with straight sides will tap back in with a bit of sealant; quite often they are rotten and not really fit to reuse. We used to replace them as routine on a ford tractor whenever we split them (i.e.for a clutch) in the places which you cant get at normally.

The slightly dome shaped ones have an edge which bites the hole when you tap them into their seat but I have in the past used a shilling coin filed to size and hammered to a dish shape and bashed in as an emergency expedient which worked fine and never gave any trouble. I probably would find an older coin to use not one of the modern steel cored shrapnel.

[openspaceman]

The core plugs are not there as a frost protection; they are to fill the core holes left in the block as a part of the casting process. It just happens that they are a weak link and will pop out if an engine is lightly frozen, they wont protect an engine which is full of neat water in a heavy freeze. remember ice does not start to expand until it is -4deg. C.

 

Yes right about the core plugs and I've repaired an MF35 engine which cracked out the block at the pedestal that is the pedestal for the injector clamp.

 

In fact liquid water is at its most dense at 4C, so it sinks to the bottom, the lighter, colder water rises and turns to ice which is less dense so the volume increase exerts the pressure which bursts the block.

[cornish wood burner]

I would never reuse a core plug unless it was a "get you home" measure. If they popped out in use it would be a rapid coolant loss and probably cook the engine very shortly after.