Technical Engine warm-up

[fiat500]

Having just watched a new video by Ian Tyrell, I now realise that one of the frequently complained about starting issues with an unmodified 500 is actually a blessing. When we leave it for a few days, it's normal for the engine to need quite a few turns before the fuel is pumped to the carburettor. That cranking also makes sure that oil is pumped around the galleries and bearings. As a result, when the engine fires, it's already got lubrication. As Ian Tyrell explains, if it fires first time when cold, in its initial moments, on choke, an engine might be running quite fast with minimal oil at the bearings.

Car manufacturers are aware of the importance of a time lag before the engine fires and in modern cars, the computer deliberately adds a slight pause before allowing the the engine to fire.

 

[bugsymike]

Having just watched a new video by Ian Tyrell, I now realise that one of the frequently complained about starting issues with an unmodified 500 is actually a blessing. When we leave it for a few days, it's normal for the engine to need quite a few turns before the fuel is pumped to the carburettor. That cranking also makes sure that oil is pumped around the galleries and bearings. As a result, when the engine fires, it's already got lubrication. As Ian Tyrell explains, if it fires first time when cold, in its initial moments, on choke, an engine might be running quite fast with minimal oil at the bearings.

Car manufacturers are aware of the importance of a time lag before the engine fires and in modern cars, the computer deliberately adds a slight pause before allowing the the engine to fire.

I enjoyed watching the classic start procedure and how it relates to modern vehicles. It reminded me of two things, one in the 1970s working for a Mazda dealership with some of the brand new 626 and 929 models on starting you could hear the bearings rattle before the oil got round due to high revving choke fast idle settings so during the pre delivery inspection we used to set the fast idle to to nearer 1200 to 1500 rpm which would cure the issue as some were nearer to 2500rpm! The second thing I recalled was something that relates to some modern cars such as my daughters VW Tiguan, to start it is necessary to hold the clutch down as a safety feature. So what I hear you say, but many years ago I went to go and start a customers car supposedly due to a flat battery, it quickly became apparent it was much more serious, the engine was seized solid. On stripping the engine down we found the crankshaft thrust bearings worn away and the crank seized to the the engine block which had to be scrapped. The job of the thrust bearings is to take the load when depressing the clutch. It turned out the driver was of the old school when gear oils were thick and by depressing the clutch the engine could spin faster on the starter on cold days, but as Ian Tyrell's video shows the worst thing to do is load an engine from cold before oil gets around. I suppose when they get problems due to that the will have a recall and fit auxillary electric oil pumps that allows the starter to only operate after full oil pressure is achieved, they already have auxillary electric water pumps for circulation hot spot issues after switching off hot engines?

 

[giardini]

Just another instance of the superior design features of our 500s, as you're able to happily crank the engine and circulate the oil forever provided
you omit (Forget ? Never !!) to turn on the ignition.

 

[Ant Knox]

Just another instance of the superior design features of our 500s, as you're able to happily crank the engine and circulate the oil forever provided
you omit (Forget ? Never !!) to turn on the ignition.

Yep, it's embarrasing wondering why the engine is turning over so enthusiastically but not firing, only to realise you've left the ignition off! Don't ask me how I know!

 

[Ant Knox]

Ian has done some great videos on the channel, and can teach a thing or two about 'mechanical sympathy'- the look on his face when Harry Metcalfe was ragging his Countach with a knackered gearbox was priceless!