Safety first - Can you cause a diesel to kick by turning over by hand.

Submitted: Monday, Oct 05, 2015 at 09:15
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Need to check the valve clearances on a 2.5 Courier. Easy enough to rotate the crank with a socket drive but I am now thinking I could cause the engine to kick during the operation. Petrol engines only need the plug leads off for safety. Are there any concerns with diesels? Just a thought but better safe than sorry.

Iza
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Reply By: Life Member TourBoy, Bundaberg - Monday, Oct 05, 2015 at 10:02

Monday, Oct 05, 2015 at 10:02
Hi, I seriously doubt that you would have the strength or speed to make the engine rotate fast enough for combustion to over power you. Maybe if you could go at 300 - 500 rpm. Diesels are harder to spin over compared to the same sized petrol anyway. If you are really concerned, pull the glow plugs out or crack the injector lines.
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Dave
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Follow Up By: Stu & "Bob" - Monday, Oct 05, 2015 at 10:29

Monday, Oct 05, 2015 at 10:29
Pull the glow plugs, it will make it easier to turn over by hand..


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Reply By: Member - tojofixa - Monday, Oct 05, 2015 at 10:30

Monday, Oct 05, 2015 at 10:30
These engines are fitted with an electronic fuel shutoff device that is activated by the ignition key. Therefore if the key is in the off position no fuel will get through the injector pump and it is quite safe to rotate the engine by hand without it firing. Hope this helps.
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Reply By: Ron N - Monday, Oct 05, 2015 at 10:38

Monday, Oct 05, 2015 at 10:38
Iza - No. You are comparing apples to oranges.
Yes, petrol engines will fire with just one pull over compression - as more than one aircraft owner who merely pulled a propellor over compression, when the magnetos were switched on, has found out.

Diesels rely on fast compression of the fuel-air charge to ignite the mixture - not a spark.
As a result, the engine must be rotating at speed to achieve this.

Diesels need a cranking speed of at least 150RPM to fire.
They MUST have substantial and adequate cranking speed to be able to start.
You can put a 12V battery on a 24V diesel, and crank it forever, and it sounds like it's going fast enough to start - but it never will. Substantial diesel experience (over 50 years) speaking here.

Cheers, Ron
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Follow Up By: Allan B (Member, SunCoast) - Monday, Oct 05, 2015 at 12:39

Monday, Oct 05, 2015 at 12:39
I totally agree Ron.

Having the need to hand-crank diesel alternators at Woomera I am painfully aware of the need for adequate cranking speed to fire-up.

However, removing the injectors would make it easier to rotate the crankshaft to check valve clearances.
Cheers
Allan

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Follow Up By: Ron N - Monday, Oct 05, 2015 at 12:52

Monday, Oct 05, 2015 at 12:52
Allan - Yes, agree on the injector removal angle.

However, be aware that injectors are often exceptionally tight to remove (usually involves the use of a very large rolling head prybar, if they have been in place for any length of time).

In addition, the injector lines and injectors MUST be totally clean before any removal attempt.
Failure to do so risks tiny particles of dirt or rust entering the injector, which will destroy them rapidly - or at the very least, damage the injector orifice and injection valve, so that the spray pattern is irretrievably damaged.

And finally - if injectors are removed, they normally have a copper sealing washer inside the head opening, that must be replaced if you don't want injector/compression leaks upon re-assembly.

Many fuel injection shops work on the basis that once you remove an injection line, they will not guarantee the performance of any injector that has been "tampered with" in this manner, due to the potential of tiny dirt/rust particles entering the injector.

Cheers, Ron.
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Follow Up By: Allan B (Member, SunCoast) - Monday, Oct 05, 2015 at 13:09

Monday, Oct 05, 2015 at 13:09
Geez, thanks Ron.
Iza.......don't touch the injectors!!!!
Cheers
Allan

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Follow Up By: Ron N - Monday, Oct 05, 2015 at 14:01

Monday, Oct 05, 2015 at 14:01
Allan, I think we can share our mutual old-diesel-hand-cranking experiences!
The old man had a 27HP, twin cylinder, CK model Ronaldson Bros & Tippett engine in the late 1950's, driving a 4" (100mm) centrifugal pump.

The engine probably dated to the late 1930's or early 1940's. It came from the Williams powerhouse.
That beast was hand-cranked - and I can tell you, you needed your Weeties to fire that thing up!

The crankhandle was massive, and I'm sure it was designed to be used by two men!
On top of that, the rotating mass of the engine components was enough to give any bloke a hernia.
The flywheel was about 800mm in diameter and probably 200mm thick.
It took an enormous amount of effort to just get the engine rotating - let alone get it up to starting speed.

Strangely, I have never seen a Ronaldson Bros & Tippett engine that size again, anywhere, in any antique machinery show I have been to.
Maybe the old machinery blokes haven't got the strength left to start one!

Cheers, Ron.
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Follow Up By: Frank P (NSW) - Monday, Oct 05, 2015 at 14:54

Monday, Oct 05, 2015 at 14:54
We had a 5HP vertical single cylinder Ronaldson Tippet diesel to run our 32V lighting plant on our farm.

It had auto load-sensitive starting, using the generator as a starter motor. But at one time we were in a rural depression (read poor), the batteries were too weak to crank the thing in the mornings, we couldn't afford to replace them so we had to hand crank it. That became my job.

It had two massive spoked flywheels about 4 inches wide, and about a metre or 3 ft diameter or so. Plus the generator which was about the size of a 10 gallon drum. So, Ron, I go with the rotational mass :-)

As a 12 to 14 year old I was able to get it turning fast enough to start - just. On a cold morning I'd bust a gut to get it turning. Sometimes I'd have to stand on the crank handle to get the initial movement - it became a point of honour. On dropping the compression release it would wheeze and blow blue smoke every couple of seconds as it fired while I continued to help it with the crank handle until it became self-sustaining.

Don't know if I could do it now.

FrankP

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Follow Up By: Allan B (Member, SunCoast) - Monday, Oct 05, 2015 at 15:02

Monday, Oct 05, 2015 at 15:02
Ah yes Ron.... memories!
Too long ago (late 1950's) to remember details but 'Lister' was one I think, plus others.
Typically 3-cylinder with huge flywheels and a crank handle designed for two men, but I was usually alone! The technique was to wind the crank up to 'sufficient' speed then whack the decompression lever to allow compression and hopefully ignition. Problem was that if you skimped a bit on the windup then it did not fire and you had to have a second go....... however you now did not have the energy for 10 minute or so! As I said... "Ah, memories"!!!
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Allan

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Follow Up By: Member - Scott M (NSW) - Monday, Oct 05, 2015 at 16:08

Monday, Oct 05, 2015 at 16:08
One other way to turn the crank around is to jack up the rear end (both tyres) engage 2wd and turn the motor using the rear tyres .... last stop if the socket drive doeswn't work...

Remember a rather large bull-dozer in my youth that was turned over by a small B&S petrol engine - saved the need for large batteries.

Or the one in the tractor museum that's started with a blank shotgun cartridge.....
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Follow Up By: mike39 - Tuesday, Oct 06, 2015 at 19:56

Tuesday, Oct 06, 2015 at 19:56
Spent too much time cranking a Lister twin cylinder 7kva genset to forget it.

The endearing aspect of those engines was that the crank handle fitted an extension of the camshaft so the blanky thing had to be cranked backwards.
Couple this to the revs/crank handle location with dropping the decompression release made for very precise timing of the whole operation.

With alternating piston strokes the initial firing was "ba bum...ba bum......" never a smooth sounding engine.
Starting a much later 3cyl. Kubota genset was simply the turning on of a light in the house or a push button on the genset.

Now we live in town, still with blackouts.... do things really change?
mike
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Follow Up By: Phil 23 - Wednesday, Oct 07, 2015 at 08:01

Wednesday, Oct 07, 2015 at 08:01
Remind me of the 2 Southern Cross engines my grandfather had on his mine.
Both 4 cylinder & stood about 5 feet high. A 38 & 40 hp from memory.

Also recall him setting their RPM with a hand held Tacho dial, that counted the revolutions with a worm drive.

It was considered a very precious instrument.

Cheers.
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Reply By: Iza B - Monday, Oct 05, 2015 at 14:11

Monday, Oct 05, 2015 at 14:11
Thanks for the reassurance, all. Just wanted to check.

Iza
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Reply By: Member - Phil G (SA) - Monday, Oct 05, 2015 at 16:49

Monday, Oct 05, 2015 at 16:49
I've always used a 32mm socket on a ratchet to turn the Toyota motors I'd had to adjust valve clearances and usually takes a bit of effort. Make sure you turn in the correct rotation. I'm usually lying underneath the vehicle to do this but the marks are above the crank pulley, so I usually make some white paint marks underneath to tell me when the crank is at TDC.
AnswerID: 591217

Reply By: member - mazcan - Monday, Oct 05, 2015 at 18:15

Monday, Oct 05, 2015 at 18:15
hi Iza B
when i have adjusted the valve clearances on my mazda bravo same engine as your courier
i remove the glow plugs they are very easy to get at and you can test and clean the ends of them while out with the g/plugs out the the motor rolls over easily no straining required do it the easy way
cheers
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