I am trying to catch a potential issue before it gets worse. This engine is in my CAT excavator. Twice in two days I have turned the key and got the grind. Flip key off and try again and she lit right up. Obviously every time there is a clash, damage is happening so I want to rectify this. Has anyone run into this? I realize starter issues are not uncommon. I was trying to formulate a plan. I am wondering if the starter is a bit fouled and not engaging all the way. Or I also suspect a minor power issue. A couple times I have turned the key and got nothing. I am wondering if the keyswitch, relay, or solenoid are not getting the full mamba. Basically acting lazy. What I have seen in other ventures is once power is pumped to the starter, voltage drop occurs and the relay or solenoid get flaky.
Check batteries then Replace your starter with a gear drive starter. Bob
Usually there is a little damage to the ring gear and a lot of damage to the starter gear, and you can go a long time it with a new starter. Take a look at the ring gear, you can clean up the teeth with a file if they're bad. When you get nothing could be a separate issue, run a test lead to the small signal wire on the solenoid, and see if you get voltage there when it does nothing. Then go from there. Or see if the new starter cures it.
I have not been in one of these. What is this gear drive starter? This is an upgrade? From what? yeah, I am trying to avoid flywheel damage here primarily. Once that is hammered, we got bigger problems.
A gear reduction starter is a smaller, lighter unit that will usually crank faster than the original direct drive starter. An excellent replacement for light duty starters on smaller engines. This one could probably be rebuilt, if it's OEM, and you can get the parts or still have a good rebuilder close by. If it was mine, I'd keep the original starter and put a new gear reduction on it, before I sent the original in for a core on a questionable rebuild, genuine rebuild would be fine too.
Cat had a issue with some starters on 3116 and 3126, Those that had the problem were MT 37 model which had a straight spline on the starter drive IIRC. Cat upgraded to a MT38 IIRC which had a helical spline. The ring gears IIRC are a shrink fit then drilled ,tapped and held emplace by the clutch bolts. I worked on two that I had to replace the ring gears and upgraded starters. That was in 2002.
Every Engine will develop over time bad patches on the ring gear at set locations, two on two cylinder three on six cylinder and so forth. But usually the starter is causing the most of the problem and if left not corrected really gets to munching the ring gear. The problem can be a worn bush on the armature, also a worn bush inside the Bendix, and the bendix spring and spline being dry and not moving freely. When power is applied to the starter motor the pinion is pressed against the ring gear with the bendix spring compressed and as it begins to turn the bendix is projected into mess by the spring. So if the end of the bendix gear is worn or the spring is not freely moving or the bushes are not presenting the pinion in the correct location you will get the pinion skid and not mess and chew away at your ring gear. If it was me i would be getting the starter out and check and service the drive end of the starter as a start. I would also rotate your engine by hand and inspect the worn patches on your ring gear as well when it was out. Cheers
Ah, the auto side calls them a "high torque" starter. I figured that was a standard item due to the age. machine is a 2006. I believe the starter has been replaced as it is black/silver and everything else being yellow. And it has a fairly fresh sticker on the top talking about the starter voltage. Actually warning against minimum voltage for the starter to avoid damage, which is something I was going to check and did. I found the battery voltage to be only 24.7V, which is not terrible, but not fully charged either. The starter is relatively small I would say, for what it is starting. I will snag some digits on it, but doesn't look CAT. I am very impressed with the cables though! DAMN, a pair of what appear to be at least 2/0 cables.
Delco.
Gotcha, never mind what I said about OEM and rebuilding. An undamaged ring gear will either have straight ends on the teeth, or the BACK side of the tooth ground at an angle to give the starter pinion gear more room to engage without bouncing off a tooth. As they wear the front side of the edge will get rounded off, and the starter gear will be much worse, so two rounded gears have a harder time catching than two gears with a square front and angled back. You can file either if you have to, but probably not worth it, or recomended.
Just add a little more if i may. The pinion rarely lines up with the ringgear and usually has tooth to tooth abutment when the starter is engaged. So when the solenoid brings the Bendix fork forward and compresses the bendix spring the bendix spring must slam the pinion into mess the moment the armature begins to turn. So if the Bendix spring becomes sad and does not push the pinion quick enough the grinding on teeth can occur as well. If the starter is non genuine i would carefully check that it is correct as have seen many times pinion gears that look ok but are different size when you measure them properly.
the numbers I see on the starter give me nothing. Is there an easy way to tell a 37 and 38 MT? The way I understand this design, power cannot even go to the starter motor until the solenoid is at a certain stroke? I am charging batteries now and doing some electrical reseat and inspection. But usually IMO, once a starter misses and grinds, it will probably continue. Hoping I am wrong.
Load test your batteries only way to be sure. Pull starter and check contact plate in magnetic switch inside of solenoid. Bad starters don't heal themselves . Bob
You can get a very rare grind but yes typically when they start doing it repeatedly it only gets worse. The way they typically work is the solenoid plunger has pulled the bendix fork out, (May or maynot be compressing bendix spring) and then at the very end of the stroke the plunger closes the contacts to apply power to the armature. So as i said earlier that if the bendix does not mess and compresses the spring, the bendix has to get pushed into mess by the bendix spring lightning fast as the armature begins to turn the pinion when the power is applied. So any stiffness there as in dry splines slows the bendix travel down. Bendix springs can be hard to test and often the spring is ok but one loop of spring wire has shifted and will just not sit correct in the cradle. Usually you would just put a new bendix in as the labor in removing starter is not worth messing around and having to revisit it. I have come across other bizarre reasons causing this issue but you should check the typical things first. The Starter just clicking and grinding on the ring gear are two separate issues.
So I inspected the terminals and start relay in the big box with the master switch. All appeared reasonable but I decided to pull all red cables on the main terminal to inspect and clean as well as ones on the start relay. I didn't see anything that gave me huge concern but I wanted to strike some fresh surfaces. I also charged the batteries and gave them many hours to normalize. All tests I have done so far would indicate batteries are far from fresh but are likely not the core issue here. 1. Battery voltage returned to 12.6V on one of them. That is not considered full charge, but it's reasonable. 12.65-12.75 is what I want to see. 2. Under load the battery bank (tested at the batteries) pulled down to 20V. 3. Batteries recovered to reasonable voltage. 4. Start current showed about 170A. However, during my testing, I actually got nothing but clickage for about 5 consecutive attempts! It is NOT the key. I can hear the hard make at the back of the machine. I intend to test the start relay more but sometimes those are hard to diagnose unless I can slam it and verify higher resistance. I suspect it is not giving me full voltage to that start solenoid. But could be the start solenoid too. But right now I am just going to plug my disgust with my Fluke meter right now! FLUKE, pay attention! I swapped out my very trusty 337 meter to get into the 376 so I could bluetooth with my phone just for testing like this....no help. Not only was I wasting time to get all connected up, it would not stay connected and I missed critical data when I got a dead key situation. I could have thrown a fuU&*ng POS in the field! What is the use of BT if it can't stay connected at 6ft away!!!!!!!!!! Great job Fluke! You now have me to circulate the pool and bash your equipment. First it was the pathetic backlight that turns itself off right in the middle of a critical reading, to this. Fluke is slipping. I am now looking for alternatives.
Pull the starter off and take the end plate off the solenoid and check the burned up plate and contacts in the switch. Bob
Forget your blue tooth. Find some wire and put a couple of alligator clips on end. attach them between the main +terminal on the starter and the small solenoid terminal. Sit up in the cab with the other ends of the wires and try to start machine. If it just clicks keep the key in the start position don't relax it and connect the wires together. If if suddenly starts you do not have enough power at the solenoid to pull it in. Your problems are not the starter but elsewhere in the machine. If it does nothing its probably what Bob said and a burnt up solenoid cap.
First test was on the start relay. It failed.... Just the meter across the poles with 3 different contact methods revealed 20-40 ohms with lazy response. Coil voltage was verified at near battery voltage. Only one key turn of many showed acceptable resistance. I can only hope I caught this in time, before real starter damage. relay was tested with solenoid cable removed. I will try to open it just so I can visually verify the issues. Props too Cat though, for doing a pro job on wiring! Not only shrink wrapped terminals, but glue/sealer shrink. Proper! I cannot yet confirm this is the only issue, but I don't see reason to continue until that is replaced and verified as fixed. Because I don't have my back probes, I was unable to confirm coil voltage with load. Might have to see what I can rig up.
Grr, I cracked up the relay and not entirely fuzzy about replacement. Contact surfaces looked nice. Again, super impressed with build quality. Very robust contacts, but they are copper on copper unless they are using different alloys. In any case, I did not find the smoking gun but I have to replace it just because of the failed tests. I guess we will know soon enough. If there is so much as a sniffle after this, the starter is coming out.