What's The Craziest Mechanical Problem You've Experienced?

Grove TMS 700E
Hangin iron over an American Airlines terminal at an airport shortly after 9/11..
Full permit ,red lights, security ... not much left in the permit we were hustling to get 80 lifts up ..Connector's cut me loose,cast my ball out ,turnned the crane loose looking for my groundman ..booming up and sinking the ball ...

All of a sudden ,,BEEP, BEEP.. lights flashed all over the console .. that crane ground to a stop faster than any operator would like with 110 main and 33 jib ,25 degree offset.. at a little better than 60degree's main boom angle.. full throttle ,full boom up ,full hoist down ,,and hauling on the swing to get the crane where it needs to go ..

Engine died ..Its the quietest I've ever heard an airport ..look back up theres the ball now a good 50 ft ahead of the crane and it comming back ..swings back and whale's into a beam web ..with a rather unsettling noise.. Iron workers have already scattered above and below..
Couldnt restart the crane ,no power ,dead stick ,flat line... called up the shop ,got a mechanic down ..the usual ,check fuse's ,batteries, power couplings,LMI and ECM for power at its source ..
nadda ,nothing ..
Pulled the cover of the electrical post ...spagetti,, every wire in there was either ripped out ,twisted ,or streched tight.. the set screw had backed of on the electrical post .. in effect it was the same thing as ripping the umbilical cord of a shovel..

no quick fix ..schematics, wire cutters ,crimpers ,and patience..

now the permit has expired ,and because were in the airport over an American based airlines terminal we are effectivly invading America's air space ,with more than a 100 feet of boom and what was deemed to be a potential projectile hanging off the end. ..the degenerates who ..i know have a job to do ,didnt need to get a tone and offer up what punishment I was in for if i didnt remove that crane right now, Immediatly, And i wouldnt have laughed that hard if it was in my power to get her down ..Broke is Broke gentilemen ..I'll get a torch and lay the boom down on that section right there ..
Thankfully ..the RCMP showed up along with Airport Authority and we were left alone long enough to limp the machine down ,in ,and out off the site

Good Times:Banghead

That is enough to ruin your day!

1999 Subaru Turbo station wagon. My friends had just gotten their car back from the dealer who had just put the 2nd new engine and turbo in their car, which was still under warrantee. They were still having the same problem with overheating and not wanting to mess around with the dealer. I said I’d look at it. For some reason I decided to check the radiator for something plugging the top inlet. I figured maybe a shop rag or whatever. I stuck my finger into the tube for a look see and it was sealed off. The radiator had been installed with a plastic knock out not knocked out. I knocked it out. Got a spaghetti dinner out of that one.
It’s still running ten years later. Dumb luck.

Now one I haven’t figured out yet. I had starter trouble with my 1985 Komatsu D20 dozer. New starter very expensive. Before it wouldn’t work at all, it would turn the engine once over then the bendix would kick out and the starter motor would race. I pulled it off and took it to a local guy to look at. A couple of days later I get it back. He says he can’t find anything wrong with it. I now take it somewhere else and that guy says sorry he can’t get parts. Everything is proprietary. I take the thing back to my shop, tear it down, turn the cummutator, deglaze the brushes, etc. I hook it back up to 24 volts and find the primary bendix solenoid works fine but the anti-restart relay gives nothing. So I figure how much for a new relay from Komatsu. $375. Ouch.

Plan B. A 25 dollar off the shelf 24 volt starter solenoid. Now it still turns the engine over once, then kicks out. I can live with that. It’s no worse than before. That worked fine to start the engine but now the hour meter doesn’t turn and the alternator light burns dimly. If I knew what to look for or test I could do a diagnostic on the relay but I don’t. If I knew what it did I’d make a work around but I don’t. Since all the machine has is idiot lights I feel like I are one.
Help

crazy

When i was still working on cars (before I moved to heavy stuff) had a pontiac sunfire come in that would die at one particular stop sign only in the mornings when the engine was cold and had lots of trouble restarting. Would run down the highway great. Checked all over the ignition system, etc. Finally found a bulletin.... Changed the oil pump and the problem went away. Seems the engine oil pressure relief was built into the pump and would go bad causing pressure to skyrocket and would pump the lifters up solid holding the valves open with no compression. Ran ok when warm I guess b/c the oil was thin enough not to pump the lifters up.....

Had a F250 ford service truck with a gas engine. The problem was intermittent. Engine would shut down when driving. Might go a month with no problems than do it every day. It would shut down you would coast to the shoulder, start it up and it would go for days and do it again. Tested every thing. And i mean everything three times for three years. Carb fuel pump fuel tank wires distr battery ..... on and on. Then on the third removal of the gas tank a two inch long piece of black electricians tape washed out of that tank. Truck never missed a lick again.

I in-framed a 451 Case in an 1150 dozer a number of years ago. Replaced pistons and liners, rods and mains and had the head redone. Screwed it all back together and it cranked over fine, oil pressure came right up- but it wouldn't start. It wasn't getting any fuel, so I figured it had dropped it's prime while the fuel lines were off. After a couple of frustrating hours trying every trick in the book to get it primed, I took the side plate off the pump and had my dad roll the engine over so I could see what was going on. There was nothing at all going on inside that pump- those plungers never moved a millimeter while the engine was cranking I'm thinking WTF, I drove this thing off the trailer to where it's sitting, never touched the injection system, and now the pump is broken?!? It was getting late, so I went home to ponder what I was going to tell my customer, who by now was clamoring good-naturedly for his dozer.
After a sleepless night pondering broken pump camshafts and other expensive maladies that I might somehow be mysteriously responsible for, I returned the next day and pulled the inspection cover off the pump drive gear. What I found was that sometime long ago- far before I had got hold of the machine- the bolt that retained the pump drive gear had fallen out. The thrust from the helical gears driving the pump had held it onto it's tapered and keyed shaft for who knows how long, but when I was rolling the main bearings in I had rolled the motor over backwards and wound that gear right off it's shaft! I retreived the bolt, reinstalled the gear, and the &^%#@! thing fired right up!
Sadly, the dozer later burned up- a can of ether fell on the battery, shorted and exploded, which burned thru the fuel line... it was one sad-looking thing once they finally got it out

Had a Ford Taunis back in the days with a v6 2 liter.
After a while i got charging problems , so I replaced the the alternator then it charged for 2 minutes and then no charge.. :bash
What the hell is going on?
Struggled with this for a few weeks changing out brush units, alts but every time it charged a little while and then nothing
Suddenly I spotted some coolant under the car , checked it and the pump was going bad leaking from the hole.
I also spotted the crankshaft front-seal was installed to far out and touching the pulley and leaking a bit .
So replaced the water-pump and installed a new front-seal and it started charging again!
My conclusion was that the water-pump was going bad for a while but didn't see it leaking because the droplets traveled via the v-belt up the the alternator and so did the motor oil (it had a fixed fan) and the alt would suck up the coolant oil mixture and stopped charging.
When the water-pump went really bad and was leaking substantially I then only noticed there was a problem with it
I cursed the car to hell and back again, but after the fix it never gave any problems.

crazy problems

CatManDoes said:

I had an engine with no power at full throttle. I could get full rpm but no power and a road speed of maybe 30 mph. After hours of testing and probing etc. I decided to check the exhaust system.

After removing the muffler I found the heat riser throttle plate blocking the inlet side! It had broken away and worked it's way down to the muffler inlet where it stopped for good and caused the power problem...And that's a true story!

Click to expand...

Im a pretty good at electrical work on my dump trucks, I had a issue a few months ago, the left had brake light wouldn't flash, when pressing the brakes. I checked wires, connections, etc:Banghead
Took it to a mechanic 3 times, every time, they said it was fixed. I finally decided to change the turn signal switch, which corrected the problem:Banghead


Another problem and costly
2000 Sterling, with a 8.3L Cummins ISC engine. Low power, engine lite comes on. Of course its a computer engine, so off to the dealer, $80 hr. First time they said fuel pump was loosing prime, replaced pump $700
Second time, same problem-2 sensors bad, $480. Shop said it was fixed, same problem next day. Back again, they said they could find anything wrong, but it cost me $350. I went in a raised h-ll with the owner and they finally put their top mechanic on the truck. Wiring harness, shorting out, As of a week ago its doing good, thats $1100 later. They replaced the engine, wiring harness.
Dont you just love those computer engines and those parts changers, that charge $80hr for nothing.

I had a wierd problem recently on my dump truck. The engine fan first started to come on intermittantly and then progressed to on all the time. It seemed like it might be the water temp sendor to the computer. I checked the wiring from the computer to the sender and the computer low voltage was present so I ended up replacing the temp sender. Still had the problem. Since I have air conditioning, I figured there also should be a signal to turn on the fan generated from the AC system. I found a solenoid in the AC system that had the computer low voltage present. I pulled off the rubber boot covering the connections on the solenoid and found some moisture and oily residue between the contacts. I cleaned and dried this area and haven't had the problem since.
It would have been a lot easier to find if I had a service manual. I have been looking for one for two years now - just don't want to pay the dealer prices. Electrical problems can be a real bear without a wiring diagram. Tracing wires is a pain.

I had a 69 F250 Camper Special, 300-6 with a C4 auto. It had a 40year old engine in it, so I pulled it and did bearings, seals, gaskets and rings. It had a pretty smooth bore, so I just honed it and figured I'd put in my spare engine when I got around to it. Get it all back together, and it runs great, great oil pressure, but it sounds like it has a rod knock at cruise. I drove it that way for a year or so, then got my replacement engine all prepped and installed. Same sound. Finally I understood- I damaged the stator in the torque converter when I yanked that 40year old engine the first time, it was a transmission noise. This was verified when I sold the engine, and installed it in a truck with a four speed three years later. That engine was the smoothest running 300-6 I had heard in a long time, not even a hint of lifter clatter.

The 2002 Sterling I drove one day suddenly had all the electrical gauges quit and the check engine lights come on really dim. Shut the truck down and waited a few minutes, started it back up and problem was gone. A few days later it did it again. I had everything under the dash apart and was looking for problems. My boss pulled every relay out while it was running until he pulled one out that replicated the problem. So we ordered a new one and stuffed it in there all proud of ourselves thinking we had the problem solved. Next day, same thing. The both of us were just about to check into an institution because it was just driving us insane. The problem started getting more frequent and after a while I noticed it would do it every time I shifted into Reverse... So Spitzair tears the whole backup light system apart but can't find anything obviously wrong... But the problem persisted... Finally I had the tail lights apart and was back there with my meter, boss in the cab and when he shifted into reverse I saw a small spark where the bulb plugged into the socket. It was one of those rectangular plastic base bulbs with fine little wires that plugged into a rectangular socket and it just barely touched the ground wire beside it. One new light bulb later the problem was fixed. Took us a few weeks to figure that one out.

More recently, Lama Helicopter, almost -40 outside... Pilot climbs in and starts the helicopter. Idles fine, goes to spool it up and engage the rotors when suddenly the engine accellerates very rapidly to full steam. Throttle does nothing, engine just screaming away at full RPM. Thank god for the governor that kept it from overspeeding... Got the engine shut down and proceeded to troubleshoot. Couldn't find anything obviously wrong so he starts it up again. Again it idles just fine but as soon as he goes to throttle it up it just spools up on its own. After about an hour or two of head scratching I found that we had heated the engine but not the fuel tank over night. On the fuel control unit is a bypass valve that's made up of a steel plunger in an aluminum alloy housing. When the fuel from the tank made it's way up to the engine the aluminum alloy shrunk because the fuel was now almost -40... The steel didn't shrink as fast so the plunger became stuck and it couldn't bypass the excess fuel back to the fuel pump so it went the only other way it could, and that was to the engine where luckily we still had a governor to keep things somewhat under control. Pre-heating the fuel tank and using Jet B instead of Jet A fuel fixed that problem...

I did an in-frame rebuild on a 6-71 in an IH truck back in the 70's. I fired it up and within a few minutes it was blowing white smoke. I spent days checking and changing everything from the injectors to the head, to pulling the flywheel housing and checking the gear train. Finally I pulled the engine out of the truck and put it on a stand for someone else to put fresh eyes on it. I was getting grief from the other mechanics for screwing up the rebuild. It turned out that after pulling the head and pan the guy found a pin hole in a new factory piston by filling the pistons with solvent and checking for leaks. The hole looked like a speck and was not really noticeable until it showed the dampness of the solvent.

Bought a brandy new 91 F-250 .. 4x4 .. 300-6 .. 5 sp OD .. Drum Brakes on the rear.
Fought with FORD the first couple years ... fought myself for the next 14 .
Ford said "It's a common problem .. live with it".
Never had any rear brakes .. every time I'd get ready to pull a trailer .. I had to get under it & adjust the rear brakes .. then a few days later .. no rear brakes again.
After 16 years , I finally got pist off enough that I decided I was gonna just remove the auto-adjusters & maybe that would help. Took the brakes apart for the umpteenth time ... & just fiddled with the threaded adjuster a little while looking at how the auto-adjuster worked. Low & behold I figgerd out that Ford had put the threaded adjuster spools on the wrong side of the truck. SO ... instead of them adjusting out any freeplay when backing up & hitting the brakes ... the dam thing was LOOSENING the adjuster .

Another 300-6 story.
I had worked in my buddy's NAPA Machine shop a couple of years prior to him asking me to go back in the shop & listen to this 300-6 they had just completely overhauled & installed in a 5 ton truck. (yeh .. really .. 300 in a 5 ton ???)
It had a pretty good knock in it .. they had been hunting for .. for a week.
They had already pulled the pan & checked the rods & mains .. but everything looked fine. Knock was coming from front part of the engine .. so they had also changed out another new fuel pump.
I told them it sounded like it was coming from the timing gears ..to pull off the front of the engine & I would stop back tomorrow.
Got there & they said they couldn't see anything so I crawled underneath & poked my head up in there & looked for about 5 minutes till I spotted it.
The hot-shot kid machinist had pecked the crank gear on with a hammer & had dented the front face of one tooth .. ever so slightly. New timing set & no more knock. I felt like putting a ball peen dent in the kid machinist's forehead.

Long time ago (40 years) I was working for a forklift company that had multiple branches across the state. One particular branch sold a reman engine to national account in an adjacent state and we were the closest service for them. So customer calls, the engine is installed... but it has a knock. Not a minor tick tick tick but a real metallic knock. Boss says you'll have to go check it out, way behind on calls and now another day or more if I have to do an engine install.

The next morning I leave and of course being 4 hours away one has all the time in the world to diagnose a problem, one of the things that I hate to do is second guess everything before I even get there. But you know how it is, customer forgot to add oil before starting or something attached to to the engine is bad or.... well. Anyway the plant crew was just firing up the furnaces (die casting plant) when I arrived. Takes a few minutes to get to the area where the lift truck is and get set up. The mechanic that installed the engine came by and says "I just can't imagine how a new engine could have a knock like this" and he fires it up.

To me it sounded like a cam bearing was left out or an under size wrist pin, it was that loud. Well I checked everything that I could without starting a tear down and nothing was out of sorts. I was just getting ready to get authorization to pull the engine and started picking up the area a little. I pulled my trouble light from underneath the truck and as I did I noticed something. The engine was running and I saw a reflection..... but it was flashing. This is a propane truck and when an engine is run on propane the pad for the mechanical fuel pump is either not finish machined or a plate is bolted over it. Well when a machine shop paints them they just tape over and paint. It's expected that the installer will do the proper thing.

Back to the knock. The tape, multiple layers, and finely trimmed around the pad along with the paint had set up and dried to a consistency almost like a tin can. Well when the engine was running the pressure pulses in the crankcase would make it pop in and out. If someone told me that masking tape and paint could sound like that I would look cross eyed at them. When I pointed it out to the customer he thought I was nuts until I took a screwdriver and punctured the tape and voila the noise was gone. Even after all these years it still amazed me, all that noise from tape and paint and I suppose a little amplification from the crankcase. I sure wish i could have claimed excellence in troubleshooting, but it was just luck.

Looked at a 20V149 that was in a Komatsu 830E. It was intermittently revving up by itself. This was a DDEC (electronic injector) engine. Had me absolutely stuffed as to why it would do it, looking at the DDEC reader it would go to 100% load when it went to high idle by itself. While troubleshooting, I noticed a leak from the engine oil dipstick, pulled dipstick and a nice mixture of fuel and oil comes pouring out. So now we got fuel dilution as well... Anyway rocker covers come off and found my problem immediately. One of the front RH bank rocker shaft bolts had come loose, the other then broke. The rocker shaft and rockers arms would sit up in the holder ok then every now and then the cam would knock the whole establishment down, where it would then short on the injector harness terminal. Didn't know it before then, but if that injector harness goes to ground, the engine goes to "Full Givit". Fuel dilution came about because the rocker arm hit one of the fuel lines and put a hole in it.

Subscribed, when I have some time I'll post up a few I've experienced in my short years. Just scanning through these is hilarious!

I'm sure I posted this around here on other forums but seems to fit this one too so if I'm repeating myself sorry! This one hunted me for almost a year as they would not shut down the machine to let me work on it only could do a quick check while doing service work and when shut down for winter they laid me off, that's another story!

This was a couple years back at the quarry the operator pulled in the shop near the end of day with the 988H. This indicator was lit up on dash:
View attachment 141995

OK, easy problem. Needs new filter, but first thought to check the differential pressure switch. Normally closed switch so if it is seeing too much pressure differential while running I should be able to test continuity and see an open circuit. Thing is I could not find it to be open. So I knew it was not seeing a differential pressure, but boss overrode my opinion and said if dealer had one he would pick it up so I could install it. Well had to wait till morning to get switch. Installed it and actually seemed to solve problem. As I said seemed. Over the next several days this warning would flash on again. It also would sound the warning buzzer that was driving the operator crazy, short trip but I'll leave it there. Among things I did to try to figure this out I installed two pressure gauges on on inlet other on outlet to read the differential pressure. As I had expected readings were way below the limits for the switch. Another test to prove it was not the switch was to disconnect the wire to switch and ground it solid. I tried checking wiring as best could be done but it is very tight under cab but did not see any spots that looked questionable. Trying to rule out wiring I located the terminal in the monitor plug that the wire from the differential switch is connected to and removed the wire from the plug and made up a short jumper to run straight to ground there by completely eliminating machines wiring. Well that worked for about 3.5 hours then alarm went off again! So now decided it was time to see if Dealer's special tech person had any ideas. He came back with the idea that the monitor itself must be faulty and suggested we try to locate a good used one to install as a test as reman ones are about $800.00. Well as we were sure this was a problem with anything other than a warning device it was put on the way back burner. I had also asked him about checking with Cat ET and he did not think it would show anything more than number of times and the dates it happened. Then finally I was lucky enough to have access to Cat ET and laptop, another long story, hooked it up expecting it to show many indications of plugged filter and to my surprise it showed none for filter but did show a number for trans. temperature. That was odd as I was not aware of ever being told that that indicator had come on, and operator confirmed that. Anyhow I looked at the converter and found a temp. switch on it and it was nasty looking from a leak that I had not been allowed to fix over layoff. So I spent some time cleaning the area very good along with the switch and the plug connector. The next day loader was still in the shop and with things cleaned up I was able to get colors numbers off the wires at this sensor. Tried checking the wiring diagram to see how this switch was hooked in to monitor and found them to be wrong for Tran. Temp circuit??? After studying wiring diagram more found that there was 'another' temp. switch this one on the left rear corner of the valve body on top of the range transmission. Once access panels were removed so I could see and touch the wiring to sensor I had a person sit in cab watching the "plugged filter" light and guess what touching the wires at the temp. switch turned that light on and off. New temp. switch.

Two things that caused me to have such a problem with this problem. First was why does a temp. switch actuate a restricted filter warning light? Next is if I had had easy access to Cat ET and laptop I may have hooked it up the first day this problem showed it's head and started questioning why there was no logged codes for plugged filters but some for temperature switch activation? It was like I spent months working on the taillights when the problem was in fact a problem with the windshield wiper switch!

Well I am no mechanic, and the following little story will seem like childs play to most of you, but:

I was driving truck, a 1980 Freightliner COE, on my weekly run from Idaho to California, Utah, Wyoming, Montana, and back to Idaho (not that the location has anything to do with the problem), when I began to have problems with the marker lights. Sometimes you would turn the switch on, and no lights would come on for a bit, and then mysteriously they would all of a sudden come on. Same thing with turning them off, I would turn the switch off, and sometimes they would go right off, other times they would stay on for anywhere from a few seconds to several minutes before they would go off.

By now all you mechanics no doubt have the problem diagnosed, but anyway, I was going through Nevada one night and began having the problem more frequently. Afraid that when I went through the new inspection station at Truckee, CA. later that night that I would be put out of service, I decided to delve into the situation. I pulled the switch panel off and started testing wires (the marker lights were stuck on at the moment). I finally disconnected all of the wires from the marker light switch, and yet the marker lights were still on. I was literally scratching my head, when I heard a faint click from the other side of the dash, and the lights went out.. AHA, says I, there must be something over there that is causing the problem. I switched sides of the doghouse and began tearing panels apart to see what I could see. I found a series of little black boxes about 1" square, with wires going to the back side. After hooking the wires back up to the switch and playing with it, I could here the click coming from one of the boxes.

Well, by now I am sure that you all know what the problem was, but that was the beginning of my education in regard to relays. I destroyed one of the little boxes to gain access to the inside, and low and behold, there are little contacts in there. I swapped black boxes around and got the marker lights working, went into the truckstop and bought a few spares, replaced the bad one, and wala, no more marker light problems!

We had a stick shift Cat 955 that would run great then just stop, fuel filters were empty, refilled the filter cans, it would start and run fine for 10 mins up to days on end, then would shut down with no fuel in filters. WTF, I screwed with it for weeks. One day I was fueling it up with the tank strainer out for some reason and saw something float by, I drained the tank, pulled it off and turned it upside down and blew air in it, after a little time and much swearing out pops a cellophane cigarette overwrap, all I could figure it would sometimes get sucked over the fuel feed, stop the engine, then float on its merry way after the engine quit til it got sucked to the inlet again!! Back then almost everyone at the company smoked so we never did find out whose it was, sure drove us nuts for the better part of a summer. No great mechanical sleuthing just dumb luck solved this one

Here's another one with the same 988H.

When I changed the fuel filters for the first time on this then new loader figured it would be a simple job what with the electric priming pump. Well after installing new filters activated the priming pump. It ran for a long time but was not getting any fuel. Checked to be sure I had turned fuel valve back on, that right but still no fuel? Pulled check valves out of filter head, all looked fine? Okay removed the priming pump and submerged it in a bucket of fuel and hooked up wires. NO fuel coming out of outlet, but bubbles coming out of the suction port. Checked wiring diagram and wiring to pump appeared to be correct but I reversed the connections to test and now it pumped just fine! AS the wiring to the plug on pump were right per the wiring diagram decided to swap the internal wires on the pump motor. Nine years latter it is still working just fine! The only other thing I can think is that the magnets in the motor were put in backwards when it was built causing it to run backwards.