How to start diesel engine after rolling

Itcheenut

New Member
Hi everyone,

If someone ends up on their side (or roof!) what needs to be done before cranking the engine? If I clean oil out of air intake and change air filter then remove glow plugs and blow the oil out of the cylinders is that all I need to do?

Cheers
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CTL

Well-Known Member
Umm, I think you will have a few more things to worry about if you roll other than oil in the engine
 

Itcheenut

New Member
Very true! But once it’s on its wheels it still has to be driven out of the bush which is easier if it can be started.
 

hulsty

Active Member
When I did it, checked the intake, used a socket to turn the motor over to make sure no oil in the cylinders then hit the key and off I went.
 

a1bert

Active Member
An ignorant question, if diesel can you still manually turn over the engine being high compression?
 

RBJET

Well-Known Member
Just to add to my post, I didn't use a socket to turn it over. I just did it with the key but didn't let it fire.
 

Lost1?

Active Member
Use a socket with a breaker bar is my recommendation. If it takes a while to get the vehicle back on its wheels you want to know if hydraulic lock is going to happen in slow time. Using the starter can break things. Trust someone who learnt the hard way when they took a shortcut one day.
 

SFA hilux

Active Member
That sucks man, sorry to see it.
You can turn a diesel Over with a socket, probably need a breaker bar from memory.
 

Petunia

Well-Known Member
High compression diesel ... or low compression diesel [ most small diesels ] ... same theory, depending on age any engine will have a minute gap in the compression rings and sealing of valves/rings may or may not be absolute perfect? Regardless of any variation, to wind an engine by hand is possible due to Einsteins Theory of R-Evolution, at low speed of revolution air/gas/or matter can escape through these minute gaps much faster than if a piston is at full warp speed.

All one needs do is try tightening a crank nut to the specifications of ''no one can achieve that without a rattle gun'' or even worse is trying to undo a crank nut from factory specs without a rattle gun. :cool:
 

Rusty Panels

Well-Known Member
High compression diesel ... or low compression diesel [ most small diesels ] ... same theory, depending on age any engine will have a minute gap in the compression rings and sealing of valves/rings may or may not be absolute perfect? Regardless of any variation, to wind an engine by hand is possible due to Einsteins Theory of R-Evolution, at low speed of revolution air/gas/or matter can escape through these minute gaps much faster than if a piston is at full warp speed.

All one needs do is try tightening a crank nut to the specifications of ''no one can achieve that without a rattle gun'' or even worse is trying to undo a crank nut from factory specs without a rattle gun. :cool:
I'm sorry Petunia but there really isn't such a thing as a low compression diesel. Even small Diesel engines run at over 200 psi compression. All diesels rely on high compression in order to ignite the fuel. If you have low compression good luck getting it to fire.

As far as tightening crankshaft bolts goes they should only be done with the use of a torque wrench. This should to be done with the flywheel locked. The manufacturers may have rattle guns on the production line to do the job but they would be calibrated to the correct torque setting.

There would be a risk of hydraulic lock to the engine if it you haven't checked for oil in the cylinders. I would be removing the glow plugs and using a breaker bar and socket to rotate the engine a few times to make sure the cylinders are clear before attempting to start it. You could crank it with the starter motor with the glow plugs removed if you can effectively disable the fuel system.

Good luck.
 

Petunia

Well-Known Member
Ok, sorry, I should have said ''lower compression in small diesels compared to big diesels'' 14 : 1 minimum to auto ignight diesel fuel up to 22 : 1 for serious big boys toys. Small diesels have glow plugs to pre heat, big diesels don't, small diesels rev to 4000rpm or a little better, big diesels don't, a truck will short circuit its pants at those revolutions, you should know from your history in the railway what a loco revs at full noise, 900 to 1000rpm. Why do little diesels rev better than big diesels?

My torque wrench maxes out at 150FtLb .... my crank nut from the guide states 123.17287893FtLb .... thats 9foot of one inch pipe as a leaver to get that done. so as always I did it up till it snapped then backed off quarter turn. tell me who drops a starter to jamb a screwdriver in the ring gear ? i sure as hell do !

No one has yet explained how oil gets in the cylinders? Everybody says it "might be" in there.
 

Chatty

Well-Known Member
No one has yet explained how oil gets in the cylinders? Everybody says it "might be" in there.
It can leak past the piston rings and valve guides. No matter how good an engine is, there has to be some form of clearance on these items as they need clearance (no matter how minute) to be able to slide past each other. Piston rings also have expansion gaps in them which can allow oil past.
The major thing with all these close tolerance items is that they are close tolerance at normal operating temperature - as the engine cools (like when it's upside down and stopped) the gaps open up a little bit, providing a path for the oil.
 
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