reboring + honing in situ service

This service is offered to those who wish to have their car/small commercial vehicle rebored while the engine is still 'in situ' in the vehicle. Not all cars/vans can be rebored with the engine still in place, but for those that can, this is a convenient and time saving service. However, there are certain conditions that must be met before an engine can be rebored in the chassis.

1. The cylinder head, head bolts/studs, sump, pistons and rods must be removed, and the big ends taped up

2. The top face of the engine block must be cleaned, deburred, and as horizontal as possible, or it becomes very difficult to centre the boring bar

3. There must be enough clearance around the top of the block for the boring bar to overhang the sides, as it's clamped on diagonally

4. There must be enough room for me to stand on the engine block in order to hone the cylinders after they've been rebored

5. There must be an electrical outlet (220v - 240v) within range of my extension lead (approx 50ft)

6. The weather must be dry, or the vehicle must be under cover in order to prevent possible electrocution

See photos below of a Lotus Elan engine that had to have no. 3 cylinder bored out and resleeved while still in the chassis.

(TIP: to see a larger version of any photo just click on it, then click on it again to return to the page)

the steps necessary to put a sleeve into an engine in situ

First bore out to try and clean the cylinder

The customer had a valve drop in his Lotus Elan in no. 3 cylinder. There was some damage to one area of the cylinder wall so I tried to bore it out to clean it up.

Still not cleaned at +.060"

As you can see from this photo, the cylinder still hadn't cleaned at +.060" which is the maximum oversize.

Bore out to fit a sleeve

So the customer bought a sleeve to fit into the block, and I bored it out to match the sleeve, but left it at the outside diameter of the sleeve -.002" so there'd be an interference fit.

To see a couple of short video clips of the boring bar in action please go to either of the following links;  

https://youtu.be/kzeWYh-gjSA  
to see the boring bar reboring the Elan engine. In the clip you can see that the Elan was parked on quite a slope, and the engine was at quite a difficult angle to work on.

https://youtu.be/LBX28eOEZHE 
to see the boring bar reboring a Toyota Supra engine. In this clip you can see that the Toyota engine was much more horizontal, and therefore easier to work on.

insert sleeve into block

With the block taken out to the outside diameter of the sleeve, -.002", the customer cut the sleeve to about 1/4" too long, then froze it in his freezer. After which we applied liberal amounts of Loctite 648 to glue the sleeve into position. 

I also deliberately left a small ledge at the bottom of the bore to prevent the sleeve from slipping downwards. 

We then set about fitting the sleeve without the aid of a 10 ton hydraulic press, which is what would normally be used in this situation. However, all we had was a 2lb lump hammer and a block of wood. So that had to suffice. 

I held the wood across the top of the sleeve and the customer hit it with the hammer many times, till the wood split. He then cut another block of wood, but that also split almost immediately, so then he found a flat steel bar, and we used that across the top of the sleeve to hammer it in. 

cutting the top off the sleeve with the bottom face of the boring cutter

As you can see in the previous picture, the metal bar did some damage to the top of the sleeve, but because the customer had deliberately cut it long, once inserted it was still above the level of the block, so I was able to cut it back using the boring bar cutter. 

NOTE: Needless to say, I don't recommend anyone fit a sleeve with the engine still in the chassis, and without the proper hydraulic press, but surprisingly we did manage to do just that, and it all went without a hitch.

I cut the excess height off the sleeve by setting the cutter to a size much larger than the sleeve, and carefully lowering the cutter till the flat bottom edge of the cutting tip cut the top off the sleeve. 

I left the sleeve a few thou above the surface of the block and then removed the bar so that the sleeve could be slowly and carefully filed back flush.

Bore and hone block to +.020" 

With the sleeve now safely in position and cut to length I bored it out to standard size, but  the customer had already purchased a set of pistons at +.020" oversize, so all four cylinders had to be bored out to that. 

The rest of the job went as per normal, with me boring out the four cylinders to +.019", then honing them the last .001" to the finished size. 

The picture above shows the four cylinders at their finished size and with their cross hatch finish. The customer then has to clean all the metal dust away (he used a small vacuum to do most of the work), lubricate everything, and reassemble.

Job Done! 

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