Backhoe Flipped Excavator Won't start

shironbo · Jan 18, 2014

While building a retaining wall for my mini farm in Japan, I accidentally rolled my 3-ton backhoe upside-down. I luckily got away with just some scrapes and bruises and a dislocated finger, but after getting the excavator (a Caterpillar MX-W30 wheel excavator) back upright with a crane and letting it sit for about a week it will not start. It was upside down for about 3-4 hours, but the fuel pump was running for about 30 minutes while it was upside down. The engine stopped turning off after about 5 seconds of being upside down.

It seems to have lost both oil and fuel while it was upside down, so I initially filled both (the oil not full in case some returns when the engine starts up). The engine rolls for about a half-cycle when I turn the key, and the fuel pump makes a small continuous clicking noise. I've heard that I should try to remove the injector pins and manually crank the engine a few cycles as a first measure. I haven't done any serious work on this engine yet so I'll have to start by finding them in the first place. After that I plan to try to jump start in case the battery is just too weak.

Any advice would be greatly appreciated. It is difficult and expensive to hire repairmen to come on-site for these things in rural Japan.

- doug

groundcover · Jan 18, 2014

Sounds hydro locked. Oil is in the compression side of the pistons. Pull the fuel injectors and crank the engine over till the oil is pumped free then repace and bleed the injectors. Might be wise to change the oil and check all fluids. Glad you didn't get hurt !

MHarryE · Jan 19, 2014

Not sure which engine your excavator uses but if it has glow plugs they are usually much easier to pull than injectors to blow out the oil. Also if you can find a way to do it turn the engine over by hand. The starter can develop enough torque to bend a rod or crack a piston when it comes against a hydraulic lock. If you ever watch old documentaries you might notice air crews walking the prop through before starting the big radials. They tended to have leaky cylinders so oil collected at the bottom cylinders so they walked them through to clean the cylinders to avoid broken cranks, rods, etc.

radioman · Jan 19, 2014

Sound advice from these guys already. I just hope the crank is not bent from trying to start from being hydrolocked. With any diesel, if it flipped, its time to pull plugs/injectors and hand crank it over with wrench. Then drain oil and refill.

shironbo · Jan 19, 2014

Great advice everyone. Many thanks. Now I just need to do some reading and figure out which are the injectors to remove and whether or not the engine has glow rods. Unfortunately I've been unable to locate a manual for the machine anywhere...

Tx Jim · Jan 19, 2014

The only Mitsubishi engine I've worked on had glow-plugs which is what I'd remove.

arrow · Jan 19, 2014

shironbo said:
Great advice everyone. Many thanks. Now I just need to do some reading and figure out which are the injectors to remove and whether or not the engine has glow rods. Unfortunately I've been unable to locate a manual for the machine anywhere...

Remove the glow plugs if you have em. You'll know if you do if when you turn the key on but not enough to start the engine, a little light will come on the dash and then go out after a few seconds. Japan can get cold so I'm thinking you have them. They are on top of the engine and look like small pencil like protuberances. Sometimes there is a top nut to remove otherwise just pull up the wires then fit a socket on the plugs and yank them. You can turn the engine over (safer by hand) and where there is the hydro lock will show which cylinder/s were locked with oil squirting out which in your case doesn't mean a wit as you are just trying to start the thing and not hunt down a chronic cylinder problem. That is an interesting machine. Never saw one but I'm thinking you have around a 30-40 hp Mitsu motor which could be the same as what they put in their compacts.