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#Post#: 98977--------------------------------------------------
bump starting 2.25d
By: spanner rash Date: September 18, 2015, 12:05 pm
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Hi all,
can anyone shed any light on as to why I can bump start a hot
engine easily- within a couple of yards- yet using the starter
motor doesn't work despite really good cranking speed...?
cheers
#Post#: 98979--------------------------------------------------
Re: bump starting 2.25d
By: Doug_T Date: September 18, 2015, 7:31 pm
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Possibly because you get an even better cranking speed by bump
starting? You're reversing your gear ratio so in second you've
got something like 1:4.7 (from the wheels driving the propshaft)
and 1:2(ish) in the gearbox.
#Post#: 98986--------------------------------------------------
Re: bump starting 2.25d
By: w3526602 Date: September 22, 2015, 2:40 am
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Hi,
I'd be reluctant to bump start a diesel in anything lower than
third gear, and even then I wouldn't just "drop" the clutch
pedal.
Your starter motor probably turns the engine over a one
revolution per second (OK ... guestimate). At 5mph in top gear,
it will probably be turning at 5 or 6 revolutions per second ...
less time for the compressed air to lose heat, and I would
expect a better spray from the injectors.
602
#Post#: 99175--------------------------------------------------
Re: bump starting 2.25d
By: spanner rash Date: October 7, 2015, 4:44 pm
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Thanks all- makes sense about the increased cranking speed... it
was just remarkable how slowly I would need to be rolling to
start in 3rd yet a fresh battery couldn't do the job!
#Post#: 99189--------------------------------------------------
Re: bump starting 2.25d
By: Serious Series Date: October 8, 2015, 1:14 pm
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Sounds like you got low compression how does it run when
started.
Head gasket failure on my 2.5 diesel made it very difficult to
start bu once running worked reasonably but erratic at tick
over.
#Post#: 99191--------------------------------------------------
Re: bump starting 2.25d
By: spanner rash Date: October 8, 2015, 2:13 pm
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spot on about lo compression Serious :( It used to run ok but
in the last few days I had to increase the idle speed ... then I
took the head off and found bores with a very pronounced step at
the top of the ring travel, and could even see the top ring on
one piston where something had been chewed up in there and made
nicks around the edges!! Still some hard shrapnel embedded in
the crown. Oddly enough the pre-combustion chamber was still
intact so maybe it had broken up in the past and the head
repaired but the bits left in the piston. Maybe one of these had
come loose and caused the terminal damage... Hey ho. I guess I
should have paid more attention to the warning signs- for the
last three years and 30000 miles oil has been blown out the
breathers as fast as I could pour it in :toothless:
#Post#: 99192--------------------------------------------------
Re: bump starting 2.25d
By: divie Date: October 8, 2015, 2:47 pm
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Get the block bored and start again ! Pistons are fairly cheap,
if you get them with a ring on the bottom (skirt) I would leave
it off. Pay attention to the ring gaps, I have used plus 0.040"
rings in plus 0.030" bores to get acceptable gaps on my last
build. Do the maths it is around 0.035" the pattern pistons gave
ring gaps over 0.050" !!!
#Post#: 99232--------------------------------------------------
Re: bump starting 2.25d
By: spanner rash Date: October 11, 2015, 3:22 pm
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Thanks divie, I'll pay close attention to that when I do the
rebuild...
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