Hi folks, In my haste, I stupidly cracked open the drain on the water separator while the machine was idling before leaving the shed. She started drawing air into the filter and by the time I had the bung closed and reached the cab, she was stuttering before cutting out. I didn't think to much of it as we often have to prime our crushing plant so I took off the water separator filter, topped it up with diesel and did the same with the secondary filter (which was only half full). I unscrewed the hand primer and pumped until I felt resistance. However I've turned and turned and turned the engine but she won't fire. I've disconnected the return to the tank and while there is return, it's only a light flow. I've cracked open the bleed screw on the secondary filter and have diesel at the thread but she still won't fire. That's the limit of my knowledge. My fear is she drew some of the gunge or water that was in the water separator up into the pump or as far as the injectors. However I'm not even sure where the diesel pump is on her or how to access the injectors to crack the feed! Any advice I can try before requesting a call out? Is there a procedure somewhere for priming / bleeding these engines?
Firstly, never fill a fuel filter before installing, especially a 2 micron final filter. When operating the hand pump, you should feel resistance AND hear fuel returning to the tank. Pump until you don't hear any more bubbles returning to the tank. I remember mine being a bear sometimes. I've lightly fogged it with starting fluid to get it go. There is no "crack the injection lines" procedure that I'm aware of.
Noted on not filling the filter. I was a little thrown when I unscrewed the secondary filter as I was expecting to see a paper filter inside a canister but it's a similar style filter to the water separators I see on our machines and while I didn't spend long studying it, it didn't see a paper element inside it... which had me wondering was the right filter on it at all! There was no gunge in the secondary filter thankfully so perhaps there didn't go too much up the line from the water separator. When I prime with the hand pump, I have a small trickle of fuel returning through the tank return line.. no more or less than I'm seeing when I crank her. I was expecting the return flow to be a bit higher - especially when cranking - but at least there's something getting back for now I suppose. I'll try a spray of easy start tomorrow. We see a similar fault in our A30D Volvo from time to time (first engine variant had a poor shut-off plunger design) and easy start is literally the only thing that will bring her to life!
Try clamping a pair of mole grips on the fuel return line until it's shut tight and give the engine a crank. If it fires up you’ll need to get the grips off within less than 10 seconds or so, so probably better done as a 2-man job.
Thanks for the tips folks.. got sorted here just now. I used a suction bottle to draw diesel through the return to the tank until there were no air bubbles to be seen. I hand primed her again after this. It still took a good 20+ seconds turning before she finally fired and that's with my batteries recharged last night and a booster pack connected! I get the feeling the starter might not be cranking with the force she's meant to after all these years as while I could tell from the smoke that she was passing diesel but she really struggled to get her to to fire. She's starting grand on the key now thankfully. Lesson learned and a few new things learned about this old girl along the way!
I sure don't like using ether, but give her a little puff and see if that doesn't solve your problem. As far as pre-filling your filters goes it's the best way I know of to prevent air locking in the first place. The only caution I offer to pre-filling is to make sure you use filtered fuel. It is possible to dump grunge into your filter and send it directly to the injector pump and that's not good. When somebody speaks against pre-filling, think Pennzoil VS Quaker State (Ford vs Chevy, Hot tea vs Cold) everybody has their opinion as to whether to or not to.
Anyone remember when Caterpillar went so far as to discourage pre-filling their high efficiency fuel filters, they installed that plastic valve in the center? The AFCi plant made those for what? Maybe two months before Cat recognized the error of their ways. Guys were jamming screwdrivers into the valves or tying to break the valves out to pre-fill them. Lol. I saved one because I knew in 20 years nobody would believe.
I agree, no disrespect to those that swear against pre-filling. There is a sound logic to avoiding the practice, that logic is: "don't introduce unfiltered fuel to your injector pump". I have heard of folks carrying a quart of tranny fluid to use as a pre fill. Their logic is that the transmission fluid in the bottle is 'clean'. Either way - I have been to re-start a 3126 in an RV that was built with only ONE fuel filter. It was a combo water sep filter for cat. The owners manual (2002 Fleetwood Discovery) clearly stated NOT to prefill the filter. Well, the owner did exactly as the instructions said and you got it..... Fired up the main, it ran for about 30 seconds and shut down. To make matters worse....this machine had no lift pump and no way to hand prime from the factory. I cobbled together a primer set up to get it rolling. It worked so well I left it with the RV in case he ever needed to prime it again.
The silly fuel filter arrangement Freightliner & GM speced on the 3126B powered units was nothing but heartbreak. Wasn’t hard to install the Cat standard primer pump, but that was a hard sell to the motor home crowd. And the ridiculous thermoplastic air brake hose they used on the suction side. Created many suction leaks on the supply side at the QD fittings. Plus, Freightliner often did install a primary filter with was a cheeesy inline screen that belonged on a lawn mower. Which, they hid very well. Oh’ well. Troubleshooting the suction leaks & re- plumbing all those Cat powered FLD and M2 Freightliners paid the mortgage on my single-wide. Still does. Fixed a Cat C7 in a aircraft refueler earlier in the year with leaking thermoplastic fuel hoses.