The Fordson Tractor Pages Forum

Five years ago my super d had he engine overhauld with new liners and pistons by a workshop. Three weeks later the liner in sylinder two loosend and ended up in the sump in pieces. I then took over and made a groove in the blockand changed the liner with a lip on the top. Now it has went again. Can anyone tell me what I'm doing vrong?
Cincerly

Liners in Dexta engines have always been a concern of mine. The proper Dexta liner is no longer available and so the only replacement is an M-F or Perkins one.

The original liners were press in with a hydraulic press and were a really tight fit. They then had to be bored to size. A dropped liner was a very rare occurrence even when pistons seized and dragged.

Then we started to here that Dexta liners could be pushed in without any special tools and did not need boring to size. Then blocks were machined to take the stepped liner being used by M-F.

I am still of the opinion that the liners need to be a very tight fit in the block. I think that this is the answer to your problem. I would suspect that the liner is a slightly loose fit in the parent bore. It is not gripping the liner enough so that the originals dropped and the ridged one could move and broke at the retaining ridge.

I wonder if your machine shop bored the original liners out rather than pressed them and in doing so increased the size of the parent bore.

New liners with a coat of "Loctite" may be the answer.

Thank you Brian.
I'll try to do that. Now I understand why the liners are too loose.

i was told there are 3 types of liners for 3 cylinder perkins diesels
1 is push fif ,with pre finiished bores
2 a press fit, with unfinished bores ( these need to be a press fit to stop them turning while been bored out)
3 oversized, with a larger outside diameter which requires your block to be bored out
i dont know if this is the same in the dexta version

yes there are several types. there are also liners made of chrome and others made of cast iron, both with or without lip on the top. My Roadless has those with increased outer diameter, and they are a really tight fit