I have a 1990 V8 with 115,000 miles. The timing belt snapped last year, damaging the valves, so I had the heads rebuilt. Ever since then, the car has been burning oil. The shop that did the work cannot identify the problem. The car does not smoke when the engine is cold, only when it is warm. It smokes the most when lifting off the throttle, and idling in traffic. At constant highway rpm, there is no visible smoke. I've pulled all the plugs and they all look identical. Good tan color on the electrode, and a clean, white insulation. ( i.e. I cannot identify a bad cylinder) Could I have a faulty crankcase breather? There is no loss of power, in fact, since the rebuild, the engine seems to run even stronger than ever. I burn about 1 quart of oil for every tank of gas while driving in town, and 1 quart for every 3 tanks of highway driving.
My 3.6 also smokes bad on overrun (lifted off throttle). This is typically due to head related problems - either worn valve guides, or worn / hardened valves seals, or both! If your engine didn't do this prior to the head rebuilds then unfortunately I would suspect that work to be the issue.
There are a heck of a lot of valves seals on a 32 valve engine.If your machine shop damaged any of the exhaust seals while putting [pound] them on then oil can run down the guide while running and the oil doesn't go into the combustion chamber but right into the hot exhaust header.So you look at plugs and they look fine because the oil wasn't burned in the combustion process.Engine runs fine because oil is not effecting combustion.The only thing is that when the car sits after it is hot I think it would smoke on start up.How bad where the valves bent when the belt tore?Did they replace the valve guides? Where any pistons damaged?I have seen some really screwed up valve jobs by people that are not used to working on stuff like the Audi V8.
The valves are damaged, the 3.6 V8 engine is the most reliable part of the car! Looks like you have a real engine problem, don't look anywhere else. You need a good, private Audi mechanic or/and a good second hand 3.6 engine (might be cheaper). The reason for recommending a second hand engine is becouse that is the least probable part to brake down, you'll find twice as many engines as transmissions for example. It all depends on how much you love this car. The 3.6 Audi engine is state of the art technology for 1988. Remember, Nissan got the same power out of the same displacement some 10 years after (sounds like Dumas the Father). This is a car that can be barely distinguished from an Audi 200. If you don't have the eye for it.... Cheers, Florin
Hello. I had the same problem on the v8 19913.6 After disassembly of the engine I have detected, that a layer NiSi on walls of cylinders has wear and actually rings work on aluminium. I have made pig-iron sleeves on one of our factories and have put rings the Shuttle. The problem with an oil consumption has decreased half. It is necessary to discriminate on color of a smoke that occurs in the engine. If the smoke black also is manifested on the big revolutions and at a sharp set of speed These are failures of a fuel system. Injectors , a lambda probe. Thus the fuel consumption under condition of quiet driving practically does not increase. But, because spray jets pour there is a dilution of oil, And its consumption considerably increases (1.5 litres for 1000 kilometres) If a smoke grey it is the fastest than a ring or seals of valves. For straightening preliminary treatment of this failure It is necessary to produce indication of a compression in the engine. After indication it is necessary to fill in the cylinder of 20-30 milliliters of a motor oil and to repeat indications If the compression increases, rings in the order, if is not present, repair of the engine is necessary. At replacement of seals of valves it is necessary to produce recovery of barrels of valves, Otherwise replacement of seals will not solve a problem of an oil consumption. I used for this purpose the tool of American firm NEWAY. The big role is played also with type of oil. This engine is not intended for work on synthetic oil when it designed such oil yet was not. I use to a semy synthetics Castrol 10w30/ After all 150 gramme listed an oil consumption on 1000 kilometres. Fuel consumption of 16 litres in city and 10 litres behind city at average speed of 140-160 k/h. That's all, that I would like to tell, it can to somebody will help. Dmitry
si tu v8 consume aceite debes mirar las juntas y los segmentos. No es normal la cantidad que gasta, Yo tengo un v8 3.6 de 1990 con 200.000 kms y apenas gasta aceite. unitilizo Esoo 10/40 semisintético. Saludos, Julio
