Ended the day with a bang.....

Started the day with two repair requests from a customer. I was able to complete one minor repair and sent that crew on their way back to the job. The second crew wasn't so lucky (or maybe they were) as they had to leave theirs for the weekend. Got all that situated and drove over to the next customers yard.

He had an old CAT loader with a 3304 suffering a top end knock. Listening to it it sounded like nothing more than a bad diesel knock. Given the noise and the exhaust smoke I did a pop tested on the injectors. Since they squirted halfway across the shop and didn't pop and atomize like they should I also did a compression check to insure no holes burnt in the pistons. All 4 checked good at 300 psi +/-. So I had put a new set of injector nozzels in Thursday but couldn't test run due to dead batteries. Went back today and after changing the NASTY fuel and air filters, getting the fuel line from the tank unstopped so it flowed, not trickled, changed the leaking hand primer pump, robbed an injector body off another machine to replace one that had been cross threaded when I removed them and then wouldn't seal back, took the muffler off another machine to put on this one, etc, etc, etc. All the while I had run the thing numerous times and except for not wanting to idle quite right it ran and sounded 99.999999999% better than it did before, and now there was no exhaust smoke.

I chalked the bad idle up to a sticky rack since the machine had been setting for awhile. So I put some injector cleaner in the fuel and got it ready to go to work, hoping the rack would free up and the idle problem would work itself out. With about 4 hours invested and all that finally done I got it to the point of going on a ride around the yard. Sooo, I hopped in the cab and fired it up.....for the last time. I let it set there for a minute at just above an idle then let her idle down and dropped it in gear. Within two seconds of hitting the throttle I heard a screaching, a kerclunk, and the engine STOPPED DEAD. As I hopped out of the cab I could see the oil on the inside of the left rear tire...not a good sign. Got down on the ground and moved to where I could see the side of the engine and I could now see inside the engine. Turns out #4 rod decided to let go and the rod bolt and part of the rod put a nice, fist sized hole in the side of the block. Funny thing between the new nozzels, removing the remnants of the old muffler, etc the knock had all but disapeared along with the smoke. Guess there was more than one thing causing the knock.....and the final weak link decided to show it's head....

Fortunately the customers outlook was that at least the machine had made him way more money than he had invested in it over the years, he now had alot of spare parts for the other loader....and now he didn't need to buy another muffler....

Today was a first for me, I've never spent that much time and money on a customers machine only to leave it more broke than it was when I got there......Now that takes real talent...LOL

Seriously it's rare to find a customer like this guy. He knows enough about equipment to know when even a serious problem is simply the next weak link in a severly worn chain, and further can face reality and find a positive view of even the worst kind of equipment failure. Hope everyone I get the chance to work for in the future can acieve that level of understanding....it'll sure make my work alot easier when I'm only expected to make chicken salad out of chicken $hit and not to work absolute miracles......

Hope ya'll have a great weekend...I know my week ended and my weekend started with a big bang.......so it can only get better from there...LOL

Wayne, you need to adopt a suitable motto for your "business"... "If it ain't broke, we'll fix it
until it is"!

Hey! Don't encourage him to steal from me; that's my motto.

Sure works well at my place!

I had about the same experience many years ago. There was a 560 Farmall diesel brought in with a slight engine knock. I started it and let it idle and it really didn't sound to bad. I decided to drive it into the shop at an idle to do more checking. I got about 50 feet and two rods and a piece of crankshaft decided to exit the block. That did not make for a very good day.

Owen,

A friend of mine had an even WORSE experience fresh out of mechanic's school in the early 80's.

A fellow had him look at a 930 Case diesel 'cause it knocked, and he ran it on a dyno 'til it knocked WORSE.

He dropped the pan and determined a rod bearing had spun.

The customer said he needed a few days to decide what to do/talk to his brother who lived out of the area.

When my wrench friend hadn't heard from him for a few days and couldn't catch him at his house in town he drove out to the fellow's farm and found he had blown his head off (several days before).

That was NOT a pleasant experience for my friend and he talked of having nightmares over it YEARS later.

(TRUE story.)

NC I have an excavator that the engine needs work. I can't decide whether to overhaul or replace. Sounds like You are a Man that could help with that decision.LOL
Ron

Customers like that, you want to hang onto.

When I was with Ford twenty years ago, we had a customer who would bring his car or pickup in and say, "I'm going to be gone for a couple of weeks. Here's a few things it needs. If you find anything else it needs, go ahead and do it".

When he got back, he'd pay the bill with a smile and a handshake, and be on his way.

Like I have always said about a repair person It is more important that you trust them than their being the cheapest around.
Ron

(quoted from post at 02:23:47 04/02/11) Hey! Don't encourage him to steal from me; that's my motto.

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aybe he can alter it a bit. Something like, 'If we can't fix it, we'll f@%* it up where no one else can!' My dad used to tell people that, but he had such a reputation that everyone knew that his statement meant that he was for sure going to fix whatever it might have been. But it would draw a curious look from an outsider.

If all 4 injectors tested even it should've been a "heads up"!for the knock.
in my experience only a stuck injector or valve mimmicks a rod knock
IMO you should've cracket the inj lines first.

But we all make mistakes at times,would hate to make a costly one like that.
More so on some one elses machine.

About like what happened to me once , went to a farm to check out a A/C 440 with a triple nickel Cummings with a bad miss and found two broken injector push tubes and two bad injectors . Replaced the parts and run the overhead and it ran great . The farmer had his hired man hook to a big wing disc and off they went to the field for a test run . I stood there and watched to see how it did and the farmed told me that it had never ran that well in all the time he had the tractor . Two weeks later she ventilated out both sides of the block . But not on the same two that i had replaced the injectors on . thank god.

Hello Vet. Hope all is well.

I believe that if a "mechanic" worked on a piece of my equipment for 4 hours and then blew it up, I'd expect him/her to fix it.

Just gave an estimate on a 3306 for a guy the other day. With all parts, labor, mileage, and other misc expenses rebuild typically works out to be around $2000 per cylinder on an your most common model engines. He also asked me to price a reman so I did. The remans I could find at reputable places were running anywhere from $12,000 to $15,000 plus a core charge, plus shipping both ways, plus labor to change over any machine specific parts, etc. In the end it's alot cheaper to rebuild than reman if you've got the time for the machine to be down that long. Like anything else with an off the shelf reman your paying for the convenience of not waiting on the machine shop, etc more than anything else.

If your interested give me a shout, I promise to leave yours running...without any additional ventilation....when I leave. LOL

I told the guy it took a really good mechanic to spend that much money and time on a customers machine just so it could kill itself. Your right though that is a great slogan. Problem is I've got to give it to the two guys that had replaced, and then rebuilt the new replacemnent transmission pump on his other loader. Those two repairs took him for a real ride money wise. All that was wrong with it was they had never bothered to clean out the suction screen....about a 30 minute job as stopped up as it was...Sometimes it's the simple things, sometimes it's something totally unexpected and you just have to follow the trail of weak links til the next one shows it's ugly head.

All 4 injectors tested differently. In other words none had the same cracking pressure. The only common thing between them was that none of them popped and fogged like they should have so any one, or all of, them would have cointributed to the knock and the smoke. Given that and the smoke present when running that lead me to believe that they were the cause of the diesel knock I was hearing on the TOP end. No one, not myself, not the customer, not any of any of his guys, heard anything coming out of the engine that sounded like a death rattle from a bad rod.

Like I said when I replaced the nozzles the knock subsided substantially, when I took the old piece of what was left of the muffler off even more of the knocking sound subsided as it had internal parts loose and rattling. With the new muffler in place she actually sounded pretty good except for not wanting to idle like it should....which is something I have never seen associated with anything like a bad rod bearing.

Needless to say it came as a huge suprise when I put it in gear and went to move, it came apart. In the end it all comes down to one thing...$hit happens....sometimes and there's nothing anyone can do about it but chase the next weak link til the flow of $hit stops....

I didn't personally blow it up... I just put in new injector nozzles that empowered it enough to blow itself up....Thats what they call new age mechanicing, you empower the machine and give it a choice to either fix itself or not...LOL

Forgot to mention, a stuck or bent valve, or something along that line would have also been indicated by the compression test I did. Instead all 4 cylinders tested good which told me none of the valves were stuck or bent in an open position where the piston would hit them and cause a knock, nor had the injectors squirting fuel directly on top of the pistons caused them to get a hole burned in them as commonly happens with bad injectors that squirt like these did.
The strange thing about this whole deal is that #4, which is the one that ventilated the block, tested about 15 psi better than the lowest one and 5 psi better than the next in line. With a rod that has spun enough to be sloppy and create a knock like we were hearing it should have sounded like it was on the bottom end for one, but also, you'd expect that cylinder to have a little lower compression than the others. In other words the crank wouldn't be pushing it quite as far up as the other pistons due to the lost bearing material in the top half of the bearing, therefore compression would be lower. In this case it was actually higher, go figure. Now if #2 had let go I wouldn't have been quite as suprised since it had the lowest compression of the bunch at just under 300.
In the end all you can do is locate the apparent problems that would cause the symptoms your seeing, repair them, and go from there.

I tell them all the time if I can't fix it I can sure f-it up......right after I tell them that even if I can't baffel them with brillance I'll do my best to blind them with BS...

Honestly though this is the first time I ever left a customer with a machine not running and as much as I joke about it it really bothers me that it happened like it did. Still I also realize that in the end there's nothing me or anyone else could ave done about it, it was just it's time to let go. Heck Dad has been in the business for nearly 40 years and even built engines for CAT for a number of years and when I ran the scenario past him, before telling him what happened, he said he'd have done the same things I did......and given the situation ended with the same results......

hey wayne ,, just thinking , not that it really matters now .. , could it be that the missing bearing material allowed the piston to sling up a little more increased travel ,thus increase compression and cause such a reading ,, personaly i doubt it since the compression would not allow such slap ,, but i agrre with you that seems strange and would like to understand the reason . so i present that theory ? does that make any sense to you guys ?

when i worked for a tractor dealer several one of our good customers brought in his oliver 1850 gas tractor.
tractor had a problem of some kind wich one of the mechanics checked it over and didn't find anything major.
so the farmer took it home about half there the engine locked up on him as it spin a main bearing.
didn't make for a happy customer. ended up welding and turning the crank so machince shop could find bearing that would work
the customer had been told engine had a recent
rebuild before he bought tractor

I see what your saying, the centrifugal force created by the crank would basically be allowed to throw the piston up higher due to the lack of bearing material on the bottom half of the rod. The piston going higher would then cause a higher compression. It makes sense that this could happen when the engine was actually running and that would acount for the slapping sound if/as the piston was hitting the bottom of the head due to the extra travel allowed by the loss of bearing material. The problem with the higher compression caused by that in this instance is that I checked compression by just turning it over with the starter. I guess anything is possible but I don't understand how the crank would have developed enough force to throw the piston like that at such a slow speed.

Taking that idea one step further, when I got the nozzels changed and the cylinders all firing like they should be there would have been more force on the top half of the rod from a better burning fuel/air mix. It's possible that the better, quicker burning charge would have allowed the downward motion of the piston to keep up with the cranks movement thereby reducing the severity of the knock just like I saw happen.

What really happened inside the engine I guess I'll never know. This particular machine also had other issues such as a worn out center pin, worn rear axel trunions, etc that the customer wanted me to eventually repair after it was running. Given that and the fact he has three others he can also use it's just not economically feasible to spend money getting the engine rebuilt on a machine with so many other costly problems. Ultimatly all I can do is chalk it up to a learning experience where $hit really did happen.

I have found on diesel engines that they can spin a rod bearing to the point where the bearing inserts will double up. When they are on the cap end of the rod the engine will run with no noticeable rod knock. If they slip around so that they are on the top side they will force the piston up enough to hit the head and really hammer. It can be rather frustrating when a customer calls you out to look at a tractor that he says is knocking so loud he is afraid it will fly apart and when you get there it runs perfectly quiet.