Engine Component Design
Engine Sludge has ruined thousands of automobile engines, often surprising car owners who thought they had done proper maintenance.
Automakers responded poorly, leaving thousands of customers in the lurch.
Sludge prone engines in some cars from Chrysler, Dodge, Toyota, Saab, Volkswagen, Audi, and Lexus from 1998-2004 await unwary buyers.
But any engine can develop sludge if maintenance is delayed.
Class action lawsuits have resulted in settlements, but no manufacturer has issued a recall.
News reports still trickle in, offering a continuing picture of used car buyers whose bargain dream car turned into a sludge monster. Sludge is gelled oil, with its additive package depleted by heat and contaminant accumulation. Oil galleries, small passages in the engine block and cylinder head, can build up deposits. These block delivery and starve engine components of life giving oil.
Once the oil galleries are blocked, reverting to manufacturer’s recommended oil change intervals generally fails to reverse the sludging.
Engine failure due to oil gelling is expensive, and in sludge-prone engines, can be repetitive.
Among cars that sludged, mean engine failure occurred at 63k miles.
A few poorly maintained engines locked up with as little as 15k.
Many still had warranty coverage, but numerous claims were denied.
Rental fleet cast-offs and lease returns, which often are poorly maintained by first owners, composed the majority of sludged engines.
Oiling problems are not a new issue.
In the early days of the auto business, motors were routinely disassembled and scrubbed with kerosene.
My father was the third owner of a 1956 Plymouth V-8 that sludged up in 1961, despite his regular maintenance. I went to the dealership and watched it being steam cleaned. Oil change intervals had been getting longer for a couple decades without incident when the sludge problem reappeared. An engineering crisis in the mid-1990’s brought the sludge monster back.
Evolving emissions standards and fuel mileage targets added new complexity to drive train engineering, putting pressure on overworked design teams.
Here is a very brief overview of a few of these issues.
Aluminum engines with new heat transfer rates combined with hotter internal temperatures for emissions compliance, often overheating oil.
Finer internal tolerances and friction reduction called for lower viscosity motor oils.
These thinner lubricants allowed smaller pores on oil pan uptake screens which tended to clog easily. Front wheel drive compacted entire drive trains in crowded engine bays, where heat from tack-on turbochargers and catalytic converters built up. Cylinder heads evolved with three and four valves per cylinder, variable valve timing, and overhead cams with their associated chains and gears.
This new head complexity and crowding gave engineers few alternatives but to downsize valve guides, oil passages, spark plug threads, and coolant galleys.
Long life antifreeze and radiator maintenance intervals up to 100,000 miles allowed some cooling systems to deteriorate.
This guide is intended to aid the owner-mechanic in understanding and diagnosing Alfa Romeo SPICA fuel supply system malfunctions. It is not a substitute for the official factory repair publications. No claim to absolute accuracy or utility is expressed or implied. The reader uses this guide at his own risk. As an early caveat, keep in mind that Alfa Romeo did not necessarily change the specifications and equipment design in strict accordance with model years. It is possible to have cars of the same model year with components from different manufacturers or systems that are slightly different from one another. In the following descriptions, references are made to model years, but you must look at your particular car to determine the exact system design and component installed. In addition, previous owners (PO’s) may have substituted components from other model years. Something else to consider is your own ability and knowledge. This guide assumes the reader has a basic knowledge of automotive systems, experience in mechanical repairs, and safety practices. The fuel supply of the SPICA Fuel Injection System has traditionally proven to be the most troublesome part of the system. Specifically, the most common failures are: 1) Clogging of the rear in-line fuel filter. 2) Weak or failed fuel supply pumps. 3) Rusted, leaky, and dirty fuel tanks (that clog rear fuel filters) . The fuel supply system for the SPICA (say “speek-a”) injection system is a medium pressure (10-20 psi) closed loop recirculating system. See Appendix 8 for schematics of the fuel system. On ‘69 thru ‘74 models, fuel gravity exits the fuel tank, goes through a in- line filter, then to the fuel supply pump where it is put under 10-20 (ideally 15-18) psi and pumped forward to the canister type main fuel filter on the right side of the engine compartment. The canister has several functions. It filters the fuel again, has an inline pressure-sending unit that detects pressure below 7 psi, and may have a pressure relief valve (‘69-’74) . The pressure regulator is inside the big cap screw that secures the brass fitting that the fuel return line passes through. If the pressure is above 17 psi, the relief valve opens and vents fuel back into the fuel return line to the tank. If below 7 psi, the top left red light on the center instrument panel illuminates. After the front fuel filter canister, the fuel enters the SPICA Injection Pump through the rear fuel inlet fitting where it is used for engine and cooling/lubrication purposes. Unused fuel exits the pump through the front fuel outlet fitting. This fitting has a restrictor orifice (3/32″) that allows the supply pump to maintain adequate pressure in the injection pump fuel galleries. If, for some reason, you remove both fuel fittings and inadvertently reverse them (putting the restrictor in the rear) , you will have “apparent” good pressure (fuel low pressure warning light OUT) , but have very little pressure in the injection pump fuel galleries and the engine will probably not run well, if at all. After passing through the restrictor, the fuel passes though the segregated top section of the main fuel filter (containing the PRV) and then back to the fuel tank. A healthy pump will emit a medium frequency audible “hum” into the passenger compartment and produce about 10 psi under battery-only power, and about 15 psi with the alternator running and a charging voltage of 13-14V…
Download Alfa Romeo FUEL SUPPLY SYSTEM DIAGNOSTIC GUIDE.Pdf
