Machine: 2011 Cat 256C skid steer S/N CAT0256CLDWS01755. I appreciate your input and ideas on two items described below: 1) the replacement engine turns over but will not start and 2) no voltage at the glow plug bus bar. Background: The machine was purchased used last year with roughly 4,000 hours. The engine started easily but when warmed up, it would lose power. I changed oil, oil filter, air filter, fuel filter, coolant, and hydraulic fluid & filter. Twice, the oil filter seal failed blowing out a lot of oil. Then, the engine seized due to two spun rod bearings (#2 and #3). Rather than rebuild the original 4,000 hour engine, I decided to purchase the zero-time surplus engine. I finished replacing the original C3.4T engine with a zero-time surplus engine. The surplus engine was an attractive option because it included a new turbocharger, new fuel meter & injectors, new starter, alternator, water pump, and glow plugs. I don't know if the surplus engine was test run prior to delivery. The new engine installation went well. When attempting to start, it turns over normally and puts out black smoke, but will not start. With the ignition in the on position, the fuel pump pressurizes then stops, the glow plug light comes on for several seconds then goes out, and there are no informational messages displayed. When attempting to start, the engine turns over normally and puffs black smoke. I verified all electrical connectors are re-installed as labelled, fuel lines routed as removed, and the air intake system is clear. Due to clearance issues between the old and new engines, I do not have the muffler currently installed (I plan to fabricate an exhaust once running). I have not performed a compression check or verify camshaft & fuel injection pump timing. The diesel fuel is probably a year old but a fuel sample is clear with no abnormal odor. During troubleshooting, I discovered that I am not getting voltage to the glow plug bus bar. I removed the "cold start relay" part number 115-1615 and bench tested the relay. There is an audible click when I energize terminals 85 & 86 and the switch closes between terminals 30 & 87. With the ignition off, I have battery voltage at terminal 30. With the ignition on, I get 0.02 volts at terminal 86 (I think I was expecting 12v for 2 to 8 seconds) and no voltage at terminal 85. With the relay reconnected and the ignition in the on position, I do not get any voltage where the wire terminal connects to the #4 glow plug. I verified engine ground at the base of each glow plug and verified wire continuity between the bus bar connection and relay terminal 87. I also verified the 10a fuse labeled with the glow plug symbol has continuity and performed the same relay bench test on the electronic relay in the fuse panel which is also labeled with the glow plug symbol. I don't know if the glow plug issue existed prior to the swap.
Good job on posting serial number, some of the smart folk on here will be along shortly to give you good advice
Black smoke doesn't sound good something blocking air intake? turbo turning?
Based on your description, 85 is your ground, therefore when your key is on or in crank, you definitely should have 12v at 86. Check your 85 terminal, to start with, and verify its grounded. You already verified continuity between 87 and bus bar. You have lost the 12v for terminal 86, somewhere. You could temporarily jump ter. 30 to 87, with a 10 amp fused wire, and see if your glow plugs light up, and try starting. Have you got an electrical diagram, that might help.
I would really appreciate a better electrical diagram, thanks. I have a partial but it’s not complete, is cut off on the ends, and not specific for this machine. After my first starting attempt, I removed the air cleaner assembly and looked for any blockages. It’s squeaky clean. I can see the turbo vanes on both the intake and exhaust sides. I did not check to see if the turbo turned. Good suggestion which I’ll try tomorrow when I have a helper. I’ll also do more electrical tests with the help of a correct electrical diagram. Thanks all!
I can help you with an electrical schematic. Check your message inbox.