nickwilliams Posted September 17, 2021 Share Posted September 17, 2021 I'm hatching a plan to adapt one of these to use as a compressor for onboard air on my 300TDi. This will involve making an interface plate to provide a mounting which matches the aircon compressor mounts on the top of the timing chest and and a shaft which links the belt driven electric clutch off a standard 300TDi aircon compressor to the splined socket on the compressor. The compressor requires a pressurised oil supply to lubricate the con-rod bearings and the piston. It has ports to allow it to be fed by the Merlin's oil system, and I suppose I could plumb it into the 300TDi oil circuit, but that would mean pushing diesel-filthy oil through it which I don't much like the thought of. Instead I plan to give it is own oil supply using a small pump driven by the shaft. I've looked at using the rotor parts out of a 300TDi oil pump - they are cheap, easy to get hold of and I kind-of like the symmetry of adapting 300TDi parts for this job. However, in practice the pump is far too big for this job, and a shaft to match its rather peculiar double internal keyway drive arrangement will be a bit of a PITA to make. Obviously I can do some looking about for something smaller but it would be a great deal quicker if someone here knew of a suitable alternative to the 300TDi pump. I think I'm looking for something with an outer diameter around 50mm and ideally with a single keyway round shaft drive about 20 - 25mm dia. Has anyone got any ideas where I might find a suitable sized pump rotor set which isn't too spendy? 1 Quote Link to comment Share on other sites More sharing options...
Maverik Posted September 17, 2021 Share Posted September 17, 2021 Before anyone else gets in, I'll point out that I presume this project is for pleasure i.e. fitting a merlin engine auxiliary compressor to a 300tdi wont be the most time/cost productive way of sorting out some onboard air... personally I love the idea I've looked a few times at fitting some vintage aircraft instrumentation. So a few thoughts - the Td5 uses engine oil to lubricate the vacuum pump i think so why not use engine oil? - you could take a tap off the blank port located on the oil filter housing. Alternatively - how about repurposing a PAS pump? 1 Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted September 17, 2021 Author Share Posted September 17, 2021 I've managed to knacker 4 aircon pumps using them for onboard air - and that's with mist oilers etc. I think the fact that my system runs at 15 bar may shorten the life. But yes, this is mostly about solving an interesting technical problem. Makes a change from sitting at a computer writing e-mails, which is mostly what I do in the day job. As I said in my OP, I don't really want to fill the compressor with black oil from the engine sump. An external pump is certainly a possibility but we have a rotating shaft and some space so having a crack at making a circulating pump sounds like an interesting possibility. Quote Link to comment Share on other sites More sharing options...
cackshifter Posted September 17, 2021 Share Posted September 17, 2021 A mini IE A Series pump might be about the right size, maybe still a bit big, but there are electric pumps too Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted September 22, 2021 Share Posted September 22, 2021 I like the idea and appreciate what's driving you. As Maverick mentioned the PAS pump, what about running a supply from that? It would need a suitable size-reduced line to limit flow/pressure, but since you're probably unlikely to need on-board air while travelling it should have no impact on the steering and the plumbing would be relatively simple. Mike Quote Link to comment Share on other sites More sharing options...
Nonimouse Posted September 22, 2021 Share Posted September 22, 2021 How about running a compressor unit from an old stationary engine? Quote Link to comment Share on other sites More sharing options...
Troll Hunter Posted October 14, 2021 Share Posted October 14, 2021 Did you ever get further than hatching a plan? Mike Quote Link to comment Share on other sites More sharing options...
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