30. Disassembly of Engine and Receipt of 5-Speed Transmission

Article 30 Disassembly of Engine and Receipt of 5 Speed Transmission

Last month’s article addressed the installation of the independent rear suspension (IRS) unit. This month I will discuss dis-assembly of the engine and receipt of a 5-speed transmission.

I’ll cover the 5-speed transmission first, as that was the easy part. You may remember that last fall I worked for a while in Florida. During that time, I visited Paul Cangialosi at Medatronics. Paul has developed a very fine 5-speed transmission conversion based on the Tremec 5-speed box. I was very impressed with Paul’s development work. I also was looking forward to having new equipment in the transmission department. So a few months ago I placed my order for one of these transmissions. The transmission arrived recently but all that I could do for now was remove the packing material and admire the thing. I really didn’t have an engine to attach it to yet. A picture of the tranny is included here.

I had been thinking for quite a while about tearing down the engine. The time finally arrived after completing work on the IRS. I had high hopes that I might be able to get away with simply changing out the bearings, honing the bores, popping in a new set of rings, and lapping the valves. Unfortunately, that was not to be the case.

The engine had been removed from the car years ago and was ensconced in a corner of the garage. I moved it over underneath my overhead hoist and proceeded to remove the valve covers and the dome nuts that engage the head studs. I had read numerous stories on the Jag-Lover’s archives about heads that refused to release from the block without heroic efforts. One common problem is that the head studs, which are screwed into the block, also fuse to the head. Certainly, an application of PB Blaster or Kroil to the studs would be advised. A bottle jack can be placed at the front of the head and used to apply upward pressure. In my case, this was not necessary, as the head released from the block without much drama. I used my hoist to lift the head and move it over to the workbench. Place the head on wood blocks to support it off the surface of the bench and avoid bending any open valves.

My first step was to flip the head over in order to inspect the combustion chambers. I didn’t like what I saw. Several of the forward combustion chambers had obvious damage. It appeared that loose parts had been introduced and performed some destruction. I went ahead and pulled the cams, the cam followers, and the valves, which basically strips the head. I put the head in my bead blast cabinet. Since the head is fabricated out of aluminum, I loaded the cabinet with walnut shells and cleaned up the head. When I was done, the damage was still there, just easier to see! I did put a straight edge along the length of the head gasket surface and was happy to find no warpage, as might have occurred if the head had been overheated.

I moved on to the block. I had previously purchased an engine stand from Harbor Freight. I mounted the block on the stand, rotated it upside down, and proceeded to remove the oil pan and the front timing chain cover. This exposes the crank. After removing the oil pump components, the caps on the piston connecting rods can be removed. Once the rod caps are removed, a tap with a mallet will start the pistons out of the cylinders. To my dismay, each piston came out with their rings in several pieces. Upon closer inspection, 2 of the pistons were in very bad shape, with the ring grooves very battered. Next came an inspection of the cylinder bores. A cursory inspection revealed pretty deep scratches in 2 of the bores in the same area where I identified piston damage.

Things didn’t look good but I was interested in establishing an estimate of the true mileage of the engine. E-Type odometers don’t have a 6th digit so you’re never really sure of the total mileage. I checked for a ridge at the top of the cylinder bore. What ridge that was there was rather negligible. I had recently purchased a “bore gauge”, which is a precision instrument for measurement of the inside diameter of cylinders. To a great extent, the bores were very close to factory original specs. This is not too surprising, as the XK engine has a cast iron block with each cylinder “sleeved” with a thin layer of very high strength steel that has excellent wear characteristics. As we will see, the use of sleeves also simplifies the repair process.

I wasn’t sure what my next move should be. Repairing the damage that I had found was clearly beyond my level of expertise. I decided to contact Dick Maury at Coventry West. After describing the mayhem that I had found, Dick was very re-assuring. I gathered that he had seen much worse. We both agreed that it would be best to salvage my existing engine, as it was original to the car. Note that it is possible to basically drop in the engine from a late XJ-6. Well, it’s not quite that simple but it can be done. But again, Dick assured me he could salvage my original engine.

The main problem areas were the combustion chambers and the cylinders. The cylinders are actually quite easy. If the damage doesn’t “clean up” with an overbore (0.030″ is about the limit for overbores), then the old sleeves can be removed and replaced. Dick promised that one option or the other would work. The cylinder head damage was a little bit more of an issue but not a problem for Dick’s staff. The damaged areas would be supplemented with aluminum welding and then machined back to the original profile. The pistons and rings would of course be replaced with new components.

The rest of the rebuild would basically be the “standard” Coventry West engine rebuild, which I will describe in a subsequent article. So I put most of the parts back together and loaded the engine onto a pallet for truck shipment to Lithonia, GA.