Thread: 2.25lt Aluminium Heater Plug

most people just remove the noc plate from the cab side of the firewall, drill a 2 inch hole and have at it.

Hi Stuart,

This aluminium plug will be a challenge. I've never had to replace one of these with the engine in place.

Over a few decades they tend, while slowly decomposing from the inside, to graft themselves very tightly to the engine block and become impossible to screw out. The only way I've found to remove them particularly with the engine in situ, is attrition.

You will need to break bits off and hopefully get most of it out of the hole, while at the same time preserving the thread.

Once that's done, you'll need to clean up the thread (no easy task as it's a very confined space) and screw in a new plug.

I've not tried to heat them, but I think if you did so, you might end up with more of a mess inside the water jacket.

Just another of Solihull's silly ideas.

Good luck.


Jack

Might be easier to lift out the passenger guard. That'll give you good access.

On a side note, my engine seems to be fitted with a 1" galv plug. I'm too scared to move it, just in case all the thread from the block comes with it.

Originally Posted by Blknight.aus

most people just remove the noc plate from the cab side of the firewall, drill a 2 inch hole and have at it.

Dave

I think you may be referring to the plug marked as #2 in the diagram. I had a look at a bulkhead today that has had this 2in hole cut to access the said plug.

The plug I am talking about is the one directly under the #4 cylinder exhaust outlet.

Stuart

Originally Posted by JackM

Hi Stuart,

This aluminium plug will be a challenge. I've never had to replace one of these with the engine in place.

Over a few decades they tend, while slowly decomposing from the inside, to graft themselves very tightly to the engine block and become impossible to screw out. The only way I've found to remove them particularly with the engine in situ, is attrition.

You will need to break bits off and hopefully get most of it out of the hole, while at the same time preserving the thread.

Once that's done, you'll need to clean up the thread (no easy task as it's a very confined space) and screw in a new plug.

I've not tried to heat them, but I think if you did so, you might end up with more of a mess inside the water jacket.

Just another of Solihull's silly ideas.

Good luck.


Jack

G'day Jack

The plug in my motor must be badly deteriorated as it has sprung a fairly large leak. I would like to try and remove as much of the plug as possible and then clean up the thread with the use of a tap.

As d@rk51d3 says, I may have to remove the lhs guard or I may be able to get at it by removing the inlet and exhaust manifolds.

I was also thinking of getting a stainless steel plug made instead of using the aluminium one. There has been talk about aluminium plugs being 'sacrificial'. Does this mean I will need to reinsert an aluminium plug?

Stuart

G'day Stuart,
If the plug has a hole in it then there will not be much chance of unscrewing it

I have just done two on my S1 engine; they came out in pieces with a few sharp taps of a cold chisel and hammer. The thread can be cleaned up quite easily with a thread file, which is much more versatile than one tap

I will replace mine with aluminium ones; as long as corrosion inhibitor is used in the cooling system they will not be a problem in the forseeable future. Use Loctite 515 on the threads,

Cheers Charlie

I tried to replace the one on the motor in Gus as a preventative measure, but in the end gave up - I couldn't budge it!

I agree that you will probably have to destroy it to remove it, and there is a risk of damage to the threads.

Stupid thing.

Old thread but the same problem. Mine is a series three and a couple of days ago she dropped the whole load of coolant on the road.
It was a small hole but I accidentally knocked the back out of the plug making a spanner for it.
I have now drilled a 50mm hole in the passenger foot well to have at it and I'm thinking of expanding it to a good size access panel so I can use power tools to get the old plug out.

Does anyone know what the thread is on this plug? I'll happily put a plumbing bung in there if it's BSP but I will put the original alloy one in if not.