Rap 24 hp semidiesel, first start attempt in 20 years.

This engine was built in 1930 or earlier. Have been stored outdoors for the last 20 years. After spending hours getting all parts movable this is the first start attempt. Seems to be low start pressure (6.5 bar) and low capacity in start air hose that is the biggest problem.

Category:

Autos & Vehicles

Tags:

• Rap
• Rapp
• semidiesel
• semi-diesel
• semi
• diesel
• first
• start
• hotbulb
• hot-bulb

[schlusselmensch]

Some time ago you mentioned that the oil level in the crankcase was too high, causing the engine to run away. There is little information on Rapps here in North America, how is the combustion chamber isolated from the lubricating supply when the level is normal? It must be quite different from many 2 stroke hot bulb engines that almost universally had a scavenging pump or valve to evacuate excess oil from the crankcase. Any other Rapp experts know the answer?

[SveinHaDD]

@schlusselmensch There are a few different variations of the crank bearing lubrication on the different brands of semi-diesel engines. Some have direct lubrication of the crank bearing and the surplus in the sump blow back to the lubricating device. In Rap, oil is added in the crankcase and the level must be so high that a capture tube is picking up oil to the crank bearing. Excess oil follow the flushing air and is burned. This will normally hardly be noticed under normal operating conditions.

[schlusselmensch]

@SveinHaDD I see, so if the oil level is too high, the rod assembly will throw up enough that the engine will run on it instead of just injection oil? This capture tube supplies the main bearings or is it for the crankshaft big end bearing?

[SveinHaDD]

@schlusselmensch Yes. The capture tube supplies oil to the connecting rod bearing only. There are two channels on the lubricating device to supply oil to each main bearing. The excess oil from these bearings and also cylinder lubrication all ends up in the crankcase and will sooner or later be burnt, a drop or two every now and then...

[marcvie9]

For what is or was this engine used for please awnser i really like to know!

[SveinHaDD]

@marcvie9 These kind of engines were widely used for ship propulsion for many decades in the last century.

[SveinHaDD]

@Ghstwn Because there will always be some idiots watching it and make stupid comments :-(

[applecounty]

Do you know the history of this gem?

[EEguy85]

ya blew it.

[jack9102]

wow it reversed 37 times? nice engine :D

[dx80cruiser]

So boring, nothing actually happens

[SveinHaDD]

@MikeAdorff To get the engine turning, first the flywheel need to be set in a position where the piston is slightly past top dead centre (when the piston is at the highest point). Then compressed air is fed thru the startvalve into the cylinder pushing the piston down. To get the flywheel spinning as fast as possible, there have to be enough air at a high enough pressure. In this case, the pressure is too low. Normal start air pressure would be something like 12-30 bar.