Cylinder liners - honing and replacement

Well dear reader, having decided that the liners in this motor were serviceable but not perfect I set about commencing the rebuild. First was to hone the liners prior to fitting new rings. This gives the new rings something to break in against and the (ideal) 45 deg cross-hatching that honing produces, allows oil to cling to the bore.

For honing I used 3-in-one-oil or ATF- whichever I have to hand to lube the bore. I used a Draper engine hone 56246 covering the range 51-177mm. This comes fitted with 180 grit stones and I bought a set of 240 for a second pass.

Honing unit fitted in cordless handheld drill

Honing in progress, avoid the clamps at the top and avoid pulling the
hone out of the cylinder while running!

To get a 45 degree hone the tool needs to be moved up and down in the bore at the same speed as it rotates. I found this was achieved by using the slow speed setting on the drill and depressing the trigger about halfway. Plunging could then keep up with the spin and 45 degrees hatching resulted. although to be truthful this wasn't as good as I had hoped.
A couple of the cylinders came out I thought rather well.

But others wouldn't clean up properly, some marks remained on the walls and no 4 had some evidence of very slight pitting where I assume that some water had rested on to of the piston during storage. I decided it would undoubtedly be best to fit at least two new liners and if I'm doing 2....

... yes, you guessed it and the inevitable mission creep set in- I ordered 4 new iron liners from QED motorsport and a whole load of bits (shells, rings, gaskets etc.) from SJS.

Christmas comes early in Surrey! Two packets from SJS and another from QED- partly unpacked!

I bought a puller to remove the old liners from eBay- £50. It looked rather puny when it came but in fact it worked very well.

Liner puller- threaded studding looked puny to me but it worked well. I'm sure with a little ingenuity this could easily be replaced cheaply with a couple of bars and some studding.

puller in use...

once the seal of the liners was broken they slid out easily by hand.

The sockets into which the liners had been fitted were a bit mucky but looked OK. However once the liners were out it was possible to see that the lower side of the motor had silted around their bases with sediment from the water jacket. Lots of it! This was highly satisfying to remove and clean out.

Note crud surrounding the base of the liner sockets

It was easily scraped out and rinsed away

Clean block sockets

Hopefully removal of this muck will help cooling.

The new Liners arrived but- as you might guess they just wouldn't fit! The old sockets once cleaned and lubed slipped back in easily, but the new ones - no way!... and I was unwilling to force them.

I cleaned the sockets with a drill-mounted wire brush.
This did the trick and liners 4-2 slid in with silky smoothness with
hand pressure alone

Sockets cleaned and ready

I would also say that it helps if you rotate the block to ensure that the cylinders are vertical so that gravity helps them slide in square, they can jam if they don't get dropped in vertically. The only fly in the ointment was the last liner- in cylinder 1. This just wouldn't fit. The other 3 liners would go into any socket and were completely interchangeable, but this liner would go into none of them. It seems to be an oversize- perhaps a quality control issue for QEDmotorsport to think about? I therefore resorted to the hone and after a several burst with frequent checking I did manage to get this liner into the no-1 cylinder position. It was still tighter than the others though.
At this point I checked nip- you will remember that the old liners were on the low side of acceptable at around 1-1.5 thou in nip. Nip is actually only adjustable one-way. You can remove material from the liner step which will lower the cylinder and decrease nip but there seems to be no way of increasing it. Lotus could presumably sell ring shims to go round the liners but they don't. Thus the nip is simply what it turns out to be... and in this case I was lucky in that the new liners sat slightly higher at 2-2.5 thou. All were the same so all was in order to go ahead and use the sealant to fix them in place.

This is the liner sealant I got from SJSsportscars- its Permabond A1044. Seems to be a thread and pipe sealant and  general engineering adhesive I suspect there are satisfactory cheaper alternatives out there- some of which were probably already in my stock!
Anyway it didn't come with any instructions but a search on the web found them. Degrease thoroughly, abrade surfaces with emery paper, clean and degrease again before applying sealant. Obviously the sockets were already roughened from my brushing, so that left only the liners themselves. The use of methylated spirits wasn't recommended as it might leave a residue (presumably the dye?). Anyway I used meths for an initial degrease, scuffed with 240 grit paper and degreased both liner and sockets again with meths followed by cellulose thinners. Then I applied the sealant.

... before fitting the liners. Now degreased and roughened, all liners proved stubborn to fit. No more silky slide in, all of them needed persuasion with a rubber mallet!  I supported the block from underneath whilst I did this as the block is only mounted at one end on the engine stand. I'm not at all happy with this procedure as the silky fit was more satisfying. I suspect there is something I could have done to ensure that this assembly process went more smoothly and if anybody knows what that is please let me know. Maybe sealant around the base of the liner could have acted as a lubricant? I also think that some appropriate 2-4 thou shim washers would have been a great idea. If positioned under the liner clamps then I could have used the clamps to push all liners down to a specified, matched and accurate nip.

All 4 liners in place

Liner clamps refitted- I tightened then to finger tight and then one flat
more on the nut as I didn't want to risk driving the nip lower.

Finally I left all liners to sit undisturbed for 24 hours before I recommenced the rebuild.  I see on the forum that Loctite 567 is recommended for this sealing job and used as a ring around the shoulder...  Ooops! I - hadn't seen that in time. Well I guess my sealant will have pushed up around the shoulder anyway as the liner went in, but to be at least a little more confident  I think I will test the block by filling it with water to ensure that the liners are actually sealed- even at normal atmospheric pressure as I do NOT want my fluids mixing! Actually at this point I decided that I had scratched the crank with the micrometer in my passion to measure it, so I've now decided to get it checked and polished before refitting- I don't want to endanger my lovely new shells! That will be my next task and hopefully I'll get the crank back before I go on holiday.