Tuesday 11 December 2012

Epoxy repair of a Hillman Imp engine cylinder top edge

When the Imps top edge on a block fails its normally down to corrosion from lack of additives in the cooling water, the options are to scrap the block or skim it and add a thick shim. I have done the shim method and bonded a 1mm alloy shim in place with epoxy, it worked fine with a normal head gasket on top of the shim.


Click on the picture to enlarge it and see more of the problem.

I am not the first to try and repair this block!

Why bother you may ask? well we have discovered that this Mk1 block is a really early one, being 49 years old its worth reviving we think. The number stamped on the block is 501572, meaning this engine will be number 1572 made.


Here I have used a wood chisel to get down to new metal, then cleaned the surfaces with acetone as recomended by the epoxy makers.
I used the piston as a mould tool, wrapped with tape and a shim of thin white plastic to hold the epoxy in place.


I then packed the inside of the cooling jacket with more thin plastic, mixed the epoxy 50/50 as the instructions require and applied the mix.


The folded strips worked really well but will the epoxy?


I then bolted the cylinder head in place with a strip of  50mm sellotape where the epoxy would be, left the engine in the sun to aid cure time and checked it out around four hours later. Did it work, well time will tell but it looks good to me. 


Cleaned up when the epoxy was still uncured, the plastics came off with some effort but by the next morning the excess epoxy was bonded solid to the green plastic that was inside the water jacket, so early removal is advisable.

The shine on the surface will now be sanded lightly to help the head gasket grip better.


Roy