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View Full Version : Hydraulic starter on GM Detroit diesel?



Timleech
09-26-2012, 08:48 AM
I have to go & look at a pumping set tomorrow, which I think has a 3-cyl series 71 or similar 2-stroke diesel.
The starter is a hydraulic motor which fits in the place of an electric starter motor, run from a hand pump and reservoir, probably with a gas spring. Apparently this starter has jammed in some way, the system is pressurised but it won't work.
I'm not at all familiar with this type, anyone here ever met them & have any tips?

Thanks

Tim

BigJohnT
09-26-2012, 09:15 AM
I can remember pumping the hell out of them then tripping the start lever, which sometimes was pretty hard to do and if you pumped enough it would spin over. Does the start lever seem to work?

John

MrFluffy
09-26-2012, 09:20 AM
No experience, but I had a browse round at the mention of hydraulic starters wondering if it'd be a viable alternative for my dragbike (it wont, too heavy and extra fluids etc) and found this site, the layout at the bottom suggests the symptoms could be a result of a non functioning control valve :-

http://hydraulicspneumatics.com/other-technologies/hydraulic-starter-delivers-high-torque

Willy
09-26-2012, 12:35 PM
Sorry Tim no direct experience with hydraulic starters, lots with air air starters but that's no help here.

Here are some links though that may give you some insight into the system, one is a video.

http://constructioncranes.tpub.com/TM-5-3810-293-14-P-3/TM-5-3810-293-14-P-30045.htm

http://www.youtube.com/watch?v=jEo7ySCIjJ4

Can you relieve the system pressure in order to diagnose the "jam", in order to see if perhaps it is a physical blockage in the hydraulic system or the starter motor itself?

Black_Moons
09-26-2012, 12:38 PM
MrFluffy: Hmmm, Drag bike you say?
Well, a few thoughts come to mind.

First off, you got a nice pool of 'Not so hydraulic' OIL siting in your motor that might be usable.. probley ruin the seals though. Sure wouldn't hurt to have high oil pressure during startup though.

Other thoughts are if its a drag bike, can you have external systems? Two quick connects to an external powerpack... of course, then you might as well make a physical quick coupler and have the whole hydraulic starter removable.

J Harp
09-26-2012, 02:05 PM
I know from experience that pumping one up by hand will give you a sure enough workout. I used to help unload barges with that pumping system. Sometimes the pressure built by the engine pump would have leaked off, two or three of us would have to take turns on the hand pump to get enough pressure to start the engine.

Black_Moons
09-26-2012, 02:31 PM
J harp: Small (chainsaw? lawnmower?) motor + hydraulic pump = Easy starts? :)

Timleech
09-26-2012, 04:07 PM
I'm very familiar with the Berger 'Handraulic' starter which does the same job but rather differently. They use a pair of opposed cylinders with racks working on the end of the engine crankshaft.

http://www.atlanticdiesel.com/emergency-starting.htm

I've never dealt with a hydraulic motor starter though.

Tim

J Harp
09-26-2012, 11:49 PM
Black_Moons; Wouldn't want to use those on a barge load of gasoline, "kaboom" chance too high.

oldtiffie
09-27-2012, 02:40 AM
I have to go & look at a pumping set tomorrow, which I think has a 3-cyl series 71 or similar 2-stroke diesel.
The starter is a hydraulic motor which fits in the place of an electric starter motor, run from a hand pump and reservoir, probably with a gas spring. Apparently this starter has jammed in some way, the system is pressurised but it won't work.
I'm not at all familiar with this type, anyone here ever met them & have any tips?

Thanks

Tim

Tim,

the "air cylinder spring" will probably be a cylinder with pressurised air on one side of a/the diaphram and oil on the other - an "accumulator".

If the diaphram is not perished or holed and if the shraeder vavle is OK and if the hydraulics are OK, why not use a petrol-driven compressor to re-charge the accumulator and see how it goes.

Timleech
09-27-2012, 02:18 PM
Tim,

the "air cylinder spring" will probably be a cylinder with pressurised air on one side of a/the diaphram and oil on the other - an "accumulator".

If the diaphram is not perished or holed and if the shraeder vavle is OK and if the hydraulics are OK, why not use a petrol-driven compressor to re-charge the accumulator and see how it goes.

Tiff

My original post refers to the motor not functioning, not a lack of pressure.

The system works at up of 2000 psi,I'd be surprised if a Schrader valve would cope with that. The Berger type has a Nitrogen-filled gas spring, but they work at over 4000 psi. I don't know what the accumulator consists of in this case, it is substantially bigger than the Berger type but superficially similar external construction.

I spent some time playing with it this afternoon, my conclusion was that the motor assembly needs to be stripped & checked but that will have to wait for another day. It's GM's own product, unfortunately the engine manual goes into a lot of detail on overhauling the electric starter motors but no reference to the hydraulic type.

Tim

wtrueman
09-28-2012, 12:55 AM
Mr Fluffy: We have drag bikes that start by one inch, 12 volt impacts. This might be what you need. This impact provides the torque needed to remove 2400/24 ? tires off trucks, Wayne.

Willy
09-28-2012, 02:35 AM
Mr Fluffy: We have drag bikes that start by one inch, 12 volt impacts. This might be what you need. This impact provides the torque needed to remove 2400/24 ? tires off trucks, Wayne.

I can't say I've ever seen a 12 volt 1 inch drive impact for removing truck wheels, not saying they don't exist, just all of the ones I've seen were 1 inch air operated.
I wouldn't think you'd want an impact trying to turn the engine over. Would it not just hammer rather than turn?
Have you got a link to that? You've piqued my curiosity.:)

As far as drag bike starters goes all I've ever seen were the 12 or 24 volt cart mounted or hand held units with spine drives or 3/4" sq. drives and overrunning clutches. These usually connect directly to the engine's crank.

Like this 12 volt one:

http://i76.photobucket.com/albums/j31/250willy/Starter_zps83306d24.jpg

Timleech
11-23-2012, 02:33 PM
Well, I eventually got to sorting this job.

It turned out that there were two issues. The unit had not been run for four years, sitting on the dockside (salty atmosphere).
The starter is a pre-engaged device, with the same nose as the electric version. The pinion slides on splines on the main shaft, and is pulled into engagement with the ring gear by a lever which also operates the hydraulic control valve. The pinion was seized (rusted) onto the splines, so as well as not being able to engage it prevented the hydraulic motor from receiving any power.
The whole thing was duly stripped, cleaned, greased, reassembled.
Then came the next issue - pumping by hand, the accumulator went very quickly up to max pressure (3000 psi). The accumulator is a cylinder with Nitrogen at one end, and oil at the other, with a free piston between the two. It didn't take long to establish that there was no gas in the cylinder, in fact the charging valve was damaged.
Luckily it had a Schrader part number still visible, and I was able to find one, NOS, on US ebay.


http://i559.photobucket.com/albums/ss38/Timleech_2009/Workshop/GMStarter-1.jpg

Then I needed a way to couple a gas supply to this valve, luckily the adapter turns out to be one which is commonly used for charging struts on light aircraft. As private flying is a much bigger thing in the US than here, the simplest way to get one was by mail order from across the pond.
When these parts arrived, I had to make up some kit for charging the accumulator to 1250 psi from a Nitrogen cylinder:-

http://i559.photobucket.com/albums/ss38/Timleech_2009/Workshop/GMstarter-2.jpg

The regulator isn't in use as such, it's just a convenient way to connect the high-pressure control valve to the cylinder and provide a contents gauge.

That job done - there was just enough gas in the smallest size of cylinder to charge it - two of us spent a happy couple of hours pumping up the accumulator by hand - takes maybe 20 minutes and is hard going by the end - and discharging it again through the starter in a matter of moments. We charged it fully at least four times, probably five, the hand pump is set up so that it's a sideways movement across the body, my arms and shoulders will be sore in the morning. Eventually it fired up, and ran smoothly, after which I restarted it several times which it did really easily on only a fraction of a charge from the accumulator.

Edit - machining content - I had to make that gauge tee myself because I couldn't readily find anything ready-made to do the job and withstand the pressure. It's 1/4" NPT inlet and for the gauge, and 1/8" NPT out. I just went for major overkill on size to be sure it's adequate. The proportions are greater than those of the control valve, which is marked as suitable for 4000 psi.

Tim

Mcostello
11-23-2012, 11:00 PM
Some guys get all the cool jobs, well done.

wierdscience
11-24-2012, 12:38 AM
Good job Tim,I'm suprised the Droit didn't have at least one stuck injector after sitting that long,

Don't under estimate Schrader valves,I've seen them go to 10,000psi and heard they make higher pressure ones than that.