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cjboring (Agricultural) (OP)
27 Jan 11 11:22
I have recently replaced the wet liner sleeve in my Clark 667 skidder. This is a 4-53 naturally aspirated engine with low hours. Problem I am having is that now that it is all back in the skidder I can't get enough fuel through system. I filled new filters with fuel and went through system from tank to manifold. I am not a diesel mechanic but I am mechanically able to repair almost anything with enough info. My Detroit service manuals say to prime system. I assumed it meant filling filters with fuel. Is there something I'm missing? When I remove the outlet line on pump when cranking it is pumping fuel. Just seems to have air in line and not much pressure.  
Helpful Member!  dgallup (Automotive)
27 Jan 11 11:55
I don't know anything about Detroit Diesel injection systems, but on most mechanical injection systems, you have to crack the high pressure lines at the injectors and crank until you get all the air out.  If the quantity of air in the injectors & lines is greater than the injection quantity, the air just compresses and you never build enough pressure to open the injectors and pump any fuel.
cjboring (Agricultural) (OP)
27 Jan 11 12:03
Thx for your response. After thinking about it, the engine was receiving some fuel since there was white smoke bellowing out of exhaust. When I took engine out to replace cylinder sleeve, I was so cautious not to screw with injectors or rack. Hopefully didnt mess something up there. I have had a buddy tell me about cracking the lines on injectors. Will let you know.
rmw (Mechanical)
27 Jan 11 22:11
Do you have 2 filters?  If so one filter is on the suction side of the transfer pump and the other is on the pressure side.  If you let air into the side on the suction side of the pump, you will have an air lock there.  Priming the system means installing a priming pump (Detroit Diesel has a discreet device, but I have rigged up barrel pumps to do the job and it worked) and pump up from your tank through the filters until you get all the air worked out.  You have to have a functioning check valve, foot valve, or isolation valve between the tank and the first filter in order to take the priming pump off and not lose prime when swapping over.

If you have a way of pressuring your tank - can't put much pressure; warning - you can prime by pushing it up from the tank.  I've done that too.  But be careful.  

I've primed a few (most were sixes and eights) and it isn't much fun.  Makes you very careful when changing filters or opening the system to make sure you don't lose the prime.  Also makes you very careful never to run one out of fuel.

rmw
cjboring (Agricultural) (OP)
28 Jan 11 2:26
Well  I cracked the lines on the injector to no avail. Will try to prime system tomorrow. Still confused as to the white smoke since I know that is unburnt fuel. Would I have to time injectors?
TheBlacksmith (Mechanical)
28 Jan 11 11:00
White smoke could be slobber/left over unburnt fuel/lube oil.
rmw (Mechanical)
28 Jan 11 21:08
Could be a blown blower seal too.

What else did you do besides replace a liner or liners?  Did you monkey in any way with the injector linkage?  Was any of the governor linkage changed?  Did you take any injectors out?  Is the return line to the tank flowing anything?

If you are pumping enough fuel for it to run at all, (unless you have an air leak on the pump suction somewhere,) you should clear out the air in the fuel lines and begin to run OK.

rmw
rmw (Mechanical)
28 Jan 11 22:13
And, to dgallup's advice above, while what he said is true about high pressure injection systems, Detroits aren't high pressure systems.  The fuel is pumped to the injector at fairly low pressure by the transfer pump and the injection pressure is put up by the injector stroke.  The plunger on each injector is a metering device and the "rack" moves those levers in respone to governor commands to meter the fuel.

rmw
cjboring (Agricultural) (OP)
29 Jan 11 0:46
Bled all the lines. Still not firing. To give some info on the entire process. I removed the air box, blower, water pump, governor assy with fuel pump. Didnt adjust or move anything on the rack, but i did have to remove spring and rod from governor to remove head. We replaced 1 cylinder sleeve and cleaned out the block and went through oil pan. Placed new seal kit on head and put it all back together. Installed engine and put blower, governor and fuel pump assy back together. Went through all fuel fittings and bled system. Receiving fuel through all injectors and out return line. Starting to think its in the blower. Going to go through that in the morning. Thx for all response.
rmw (Mechanical)
29 Jan 11 17:52
OK, your problem is priming and bleeding the lines won't cut it.

With a priming pump, you pull fuel up from the tank, push it through the filters, push it through the head (yours leaked out when you had the head off) and, of course, out the return line.  But in the process, you get a good air free hydraulic lock.

As it is now, you have air at some or possibly various points along the fuel train, and you will never have success until you prime it and get the air out.

As I stated in an earlier post, Detriot had a dedicated piece of equipment that all Detroit mechanics kept around but I made one by adapting a hand cranked barrel pump, so I never bought one.  I seem to remember that there were electric (vehicle voltage - 12 V in our world) models too.

I toyed with the idea of putting fuel (didn't have an exact plan as how to do that - vacuum it in maybe) in a small Freon cannister and then pressurizing it with air and turn it up side down letting the pressure push the fuel through the system.  As long as I had that old ridiculous looking barrel pump rig I never needed to move forward with that plan.

I only had to prime a couple of times over 25 years of messing with Detroits, so the barrel pump was all I needed.  But when I did need to prime, nothing else would do.  The pump you need has to be the type that will pull up from the tank without itself needing to be primed initially.

rmw
HRHtex (Aeronautics)
4 Feb 11 7:43
I meant to mention before - you haven't got the fuel shut-off/engine stop in the wrong position, have you? I have seen this happen quite a few times - especially on old engines where the on/off markings have worn off.
bcs5274 (Industrial)
5 Feb 11 20:11
see if the rack is in max fuel or fuel off postion, make sure it is not hanging up , if you get to max fuel it must move in and out freely
MiketheEngineer (Structural)
11 Feb 11 16:52
I have been following this thread from afar.

Did you ever get the damn thing started???
rmw (Mechanical)
16 Mar 11 21:21
This thread has gone cold so I guess the OP got it started.

However, I just found this in a bus enthusiasts forum and thought I'd paste it here for the record.

Paste follows:

Install a Schrader valve at the fuel filters, go get a new air tank at WalMart,
partially fill it with diesel and pressurize it with air. If you run the engine
out of fuel, attach the hose with the clamp on chuck, turn the tank up on end
and open the valve on the tank. Cheap and easy way to get the system primed. I
keep mine onboard and have had to use it twice. Mainly keep fuel in the tank. I
had to run mine out of fuel to kill it when I could not get the air flap to
close.

Enjoy,

rmw

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