Maintenance Maintenance
Car: Ford | Fiesta | CX (Mk3) | RS Turbo | Hatchback
Engine: CVH | 0 | Inline 4 | (EFI) | Turbocharged | Petrol

CVH Bottom end rebuild

The bottom end was drained of oil and stripped down. Heavy oil varnish is to be expected with the age of the car, but it's nothing that cannot be taken care of. What I was looking out for was sludge, going by the cars very comprehensive service history I really didn't expect to find any. As with any neglected engine, a CVH's will suffer from a have a pitch black coating over all internal coatings suggesting infrequent oil changes, and in extreme cases and the top end and crankshaft area will be covered in thick sludge and carbon deposits. None of those issues here, not that I expected them.

The CVH is an old engine, dating back to the early 80's. This is evident in some of it's construction, for instance the 2 main oil galleries are line bored from the rear of the engine and are sealed with threaded bungs. Modern engines use sand or lost foam casting to remove the need for additional machine work such as this.

Red Fiesta RS Turbo Restoration

The block was stripped of all components including the oil gallery bungs, and all gasket faces were scraped clean. I then sent the block to a machinists to be re-faced.

When re-facing was complete, I used a paraffin spray gun and air line to clean the block. Particular attention was given to the oil ways which were all were blown through with air after the paraffin.

When finally dry the block was sprayed in a coat of Silver Hammerite (right).

Red Fiesta RS Turbo Restoration

A comprehensive set of parts were purchased to rebuild the engine as a whole, including all new genuine Ford gaskets and seals, and new std size piston rings and bearings.

Main bearing and big end bearing caps bolts can be reused in the CVH, although I'd really only re-tighten them once following the original build.

The water pump and clutch had been recently replaced by the previous owner and were as new, the flywheel was also excellent which was a surprise. No re-face was required.

Red Fiesta RS Turbo Restoration

The pistons and rods were cleaned up, no scores present so the pistons were fine to be re-used. I cleaned the ring lands of any carbon deposits and fitted the new rings, paying careful attention to the orientation each of the 3 piece oil control rings. I tend to space the 2 compression ring gaps opposite each other for maximum compression - every little helps.

The original big end bearings showed slight signs of wear, so crankshaft measurements were taken. The crank was well within Ford std. tolerances so replacement with std. size bearings was fine, and this is what I wanted. I replaced both the big ends and mains with new bearings.

Red Fiesta RS Turbo Restoration

The final part of the bottom end to rebuild was the oil pump, and again this was stripped and cleaned with the paraffin. The casing itself is separate from the pump components and high pressure relief valve. The rotor recess showed no sign of wear or score marks which can be associated with contaminated oil.

In this case it is fine to rebuild the oil pump, and kits are available which comprise new rotors and a relief valve spring and seal. The pump was rebuilt and the cover torqued to spec.

Completed bottom end:

© Mark Stewart, Wednesday 15th June 2005
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