Alternator BOLTS sheared off!

geordi · **Posted:** Sat Mar 26, 2011 2:22 pm

Ok, this is a sad tale.

I was digging into my CRD to inspect / replace the timing belt (which I have determined to be in great physical shape, so I'm not changing it until another symptom presents)
More on that later.

What I did find while pulling the front cover off... Was that the alternator was being held in by ONLY the rear bolt and bracket! The two lower bolt heads were just completely GONE, and the back of the bolt holes (in the bracket) had the remaining part completely sheared off at the surface.

Has anyone else had this happen?

I had replaced the alternator myself last year, and in standard practice, re-used the bolts that I pulled out when putting the new unit in. I know for a fact that I did not over tighten the bolts, being that they were steel going into an aluminum bracket. So what the hell? Right now, even applying 1500* heat from my torch won't loosen the grip on these remnants to get them out of the holes. I can't back them out with an extractor, as nothing budges. I had tried slotting the back ends which do protrude slightly and trying to drive them forward and through the bracket completely... And have broken 2 screwdrivers in the attempt, with no result. There isn't enough to grab with pliers, but the most motion I had gotten with the heat was maybe 2-3 degrees rotation... Then the screwdriver snapped.

Tried drilling it out from the front, and before I have gotten one completely through... The drill bit broke off, at the same surface level as the sheared bolt. AAAARRRRRRGGGGHHHHH. (And other comments that cannot be reprinted here)

So... Anyone have any thoughts?

About the timing belt - I'm at 104k miles right now, and I'm not changing the belt yet. I have a new belt in hand (which is why I was digging into this now) but looking at the internals, everything is in perfect appearance. The old belt looks exactly like the new one. There aren't any noises during operation that would indicate a pulley failing, and the belt tensioner is in the right position, it doesn't seem to indicate any excessive stretching of the belt. Believe it or not, pulling the front cover wasn't that big an issue, and won't be any more b/c I'm not putting the fan back in. That shroud and fan were the biggest monstrosity of this job. I'm toying with the idea of cutting the front cover into 2 or 3 sections so that I don't need to remove the crankshaft pulley to inspect it (and I didn't pull the power steering pulley, just loosened the tensioner and worked the cover past it) and then I can remove a few screws from the dust cover and inspect the timing belt tension and appearance, and listen to it with the engine running. Until there are appearances of a weak belt OR noises from the pulleys... I don't think I'm going to dig into it.

I am not blind to the consequences of doing this, however I also have a unique perspective - I have already had a MECHANIC (gorilla) screw up the timing job by overtorquing the tensioner and strip the bolt, then try to "fix" it with a helicoil. That didn't work, and it destroyed every rocker arm, which IS the designed failure mode for this engine. The valves and pistons were all fine, thankfully. I still have a complete cylinder head from my original engine with all the rockers intact, so worst case... I can put that on without costing a penny. But I don't see that happening. These pulleys aren't special, but they are priced like they are. PaTracy on here already has found that the timing idler pulleys are the SAME as a $15 pulley he got for his other Dodge vehicles. Those types of pulleys run accessory belts forever, and don't get changed until they start screaming, which indicates a failure is imminent. I can accept that kind of warning system. Should I see the timing belt vibrating (indicating a weak spring) then I will get into changing everything at that time.

Sir Sam · **Posted:** Sat Mar 26, 2011 2:41 pm

In my experience with nissan T-belts they look perfect all over, except for the break in the belt. You wont notice any stretching or ANY other signs of failure, except for the nice clean break.

audiboy86 · **Posted:** Sat Mar 26, 2011 3:02 pm

Apply heat and use the extractor not at the same time of course. And i have never heard of such a thing on the CRD but since my timing belt is being done as we speak when i get it back i will double check my bolts.

geordi · **Posted:** Sat Mar 26, 2011 6:16 pm

Well, I managed to get one of the bolts out. Let me throw out a big THANK YOU to the designers of the Alden GRABBIT extractor that is sold at Home Depot. This thing is a helluva tool, it bit into the hole in the bolt (that it drilled) and with my 12v impact driver, pulled the wrecked bolt out of the hole in one smooth motion. This is the same bolt that I had been able to grab on the back end, and had heated, and had broken 2 screwdriver bits and bent a forged screwdriver tip.

Nice tool guys, and Made in the USA.

For the other one tho (also the harder one to get to, as its up against the cylinder head of course) the grabbit tip locked into place... Didn't rotate.... Then snapped off IN the bolt. Dammmit! The next idea is to try drilling it from the back end, hopefully weakening it enough to be able to break it free. Hopefully. I got a set of taps to re-cut the threads b/c I'm expecting to ruin the ones in the hole, but I'm also planning to put a safety-nut and lockwasher on the back side to prevent this happening again.

Interesting question for someone who has an intact alternator mount: Can you pull one of those bolts and see if it has metric or standard threads?
It looked like this was a 3/8x16 standard SAE threads... But the fragment that I got out threads in perfectly into an M10x1.5 bolt-checker at Home Depot, and will NOT thread into the 3/8x16. Is this correct, or did the gorilla who reassembled my engine use the wrong bolts and re-cut those threads, which is why these bound up so tight?

Turbo Tim · **Posted:** Sat Mar 26, 2011 7:45 pm

Sounds like "Someone" forced the wrong bolt into the hole.
What I have done in the past, and if you have just enough old bolt sticking out, find a nut that just fits over the old stud. Next break out your wire feed welder and weld the nut, from the inside, to the old remains of the bolt. Wait until it cools as hot bolts expand in cold holes.
Get your socket set out and twist away. All that can happen is the nut twist off and your back where you are now.
Good luck.

tjkj2002 · **Posted:** Sat Mar 26, 2011 9:15 pm

Sir Sam wrote:

In my experience with nissan T-belts they look perfect all over, except for the break in the belt. You wont notice any stretching or ANY other signs of failure, except for the nice clean break.

Very true since good timing belts are EPDM and some have kevlar in them also.

For the bolts and broken extractor you will want to buy a carbide bit,not a carbide coated bit but a actual drill bit with carbide welded on the end.Expensive but will cut through anything like it's butter.

I use the set in the link below at work,very well worth it.They are reverse bits also.

http://www.tooltopia.com/knkut-5kk9.aspx

geordi · **Posted:** Sat Mar 26, 2011 9:18 pm

Tim, I don't disagree. I also think that the gorilla who replaced my engine used a 2 foot breaking bar to install most of the bolts (the ones he bothered to tighten anyway) and probably shoved whatever he had into the alternator holes to make it fit. When I replaced the alternator last spring in Va, I know I didn't force anything wrong into the holes, they must have already been cut wrong.

A good bit of news however! Both holes are now clear, although the one that the tool steel broke off in was a monstrous pain to get past. I ended up carving out the entire depth and width of the bolt with successive drill bits. In the end, the last remaining piece of steel bolt was less than 1/16" thick and 1/4" long... It was just a little bit of thread. That hole has now been dug smooth at 1/2" while the other (driver's side) has the threads intact. I haven't decided yet whether I will re-cut those threads to 3/8-16 or use the metric bolt I got with a nut for safety. That really depends on if someone here can tell me if it was supposed to be metric threads all the time or not. Anyone?

More on the belt to come shortly - gotta get food, I'm starving.

tjkj2002 · **Posted:** Sat Mar 26, 2011 9:24 pm

geordi wrote:

Tim, I don't disagree. I also think that the gorrillawho replaced my engine used a 2 foot breaking bar to install most of the bolts (the ones he bothered to tighten anyway) and probably shoved whatever he had into the alternator holes to make it fit. When I replaced the alternator last spring in Va, I know I didn't force anything wrong into the holes, they must have already been cut wrong.

A good bit of news however! Both holes are now clear, although the one that the tool steel broke off in was a monstrous pain to get past. I ended up carving out the entire depth and width of the bolt with successive drill bits. In the end, the last remaining piece of steel bolt was less than 1/16" thick and 1/4" long... It was just a little bit of thread. That hole has now been dug smooth at 1/2" while the other (driver's side) has the threads intact. I haven't decided yet whether I will re-cut those threads to 3/8-16 or use the metric bolt I got with a nut for safety. That really depends on if someone here can tell me if it was supposed to be metric threads all the time or not. Anyone?

More on the belt to come shortly - gotta get food, I'm starving.

Well since you were the last one to touch the alternator your the gorrilla responsible for how tight those bolts were since you didn't complain about it back when you replaced the alternator.

geordi · **Posted:** Sat Mar 26, 2011 9:41 pm

Cute.

I don't recall pulling the alternator to be that big of a deal, but I guess you've never cross-threaded anything then? Its only hard to install while it is cutting the threads, once the bolt is in the first time, every time after feels like any other bolt. So my original theory still stands. I'm willing to admit when I've screwed up a bolt install and ripped up the threads, this isnt one of those times as far as I can tell.

On the belt:

I was going to go by the tensioner's little calibration window as a guide to the stretch of the belt, but I took another look at it and the "window" is very far to the left and completely clear of the spring arm. Most likely, the mechanic (since he didn't have either the FSM or GDE's directions) didn't use that window properly to calibrate the tensioner... So there is no way to know. Right now, since I'm already in there and getting there was so fast, I'm probably going to only change the belt itself and then check the tensioner every 5k or so for a while unless noises present themselves. I just can't afford the parts or downtime right now to do more.

Joe Romas · **Posted:** Sun Mar 27, 2011 8:13 am

I don't think you'll find any SAE bolts on any part of the engine :jester:

Expecially since you mentioned earlier you verified it was a M10x1.5 :BANANA:

I would clean up the holes with a M10x1.5 tap and replace both bolts.

Consider some never seize on them.
Your problem may have been caused by the current passing through the bolts as they are the ground path for the alternator :dizzy:

audiboy86 · **Posted:** Sun Mar 27, 2011 10:22 am

This is very true but there should be no excessive current unless he started his jeep with a jump box attached. But to weld those bolts in there like they were would take atleast a few times if it is even possible.

Sir Sam · **Posted:** Sun Mar 27, 2011 9:24 pm

Joe Romas wrote:

I don't think you'll find any SAE bolts on any part of the engine :jester:

IIRC the bellhousing bolts are SAE and not metric(at least mine where on my 02 engine)

geordi · **Posted:** Sun Mar 27, 2011 10:12 pm

I would believe that they would use whatever bolt happened to be in the bin when they were assembling everything, but in the factory they would have a bin of only the correct parts.

When a monkey is working on the motor for 3 months and finally goes to reassemble the motor... Who knows what he grabbed when he needed a bolt for that hole. He might have grabbed anything that roughly fit the hole. Based on what I've seen while working on this engine since I've gotten it back... I trust the shop's owner, but I don't want that individual mechanic working on my engine again.

The theory about the bolt electrically welding itself in the hole is an intriguing one. I can see how that might be possible, if I had connected a jumper box using the alternator as the grounding point. While I haven't used a jumper box on this vehicle (kills that theory!) I wouldn't connect through the alternator body anyway for a ground - I'd go direct to the battery for both. It would be interesting to know if the alternator itself could pass enough current to do something like that. The alternator is rated at like 120amps, which is 1400 watts or so. That is a decent amount of power, but does it really need to pass that much in ground as well, just to energize the field?

Squeeto · **Posted:** Sun Mar 27, 2011 11:08 pm

Maybe the alternator bolts were installed too loose. If the bracket was allowed to travel as the belt tensioned, the repetitive back and forth could have sheared the bolts off.

Joe Romas · **Posted:** Mon Mar 28, 2011 7:08 am

Look at the BIG picture :lol:

For current to flow there must be a complete path. On an alternator just having the positive lead connected won't do it, assuming it was hanging in the air. You need a ground path to complete the circuit and that starts with the alternator case, then into the mount, then to the engine, then the ground cable connected to the engine that is connected to the battery. That's a complete path necessary for current to flow.

Now instead of thinking about of a single large current flow, how about many miles of say 60 to 120 amps :JEEPIN:

Don't forget about the bolts and castings being different materials. Instead of "welding" how about long term corrosion :?:

boilermaker2 · **Posted:** Mon Mar 28, 2011 11:10 pm

Geordi,

If you are already at the timing belt, I would strongly recommend that you remove the water pump, reseal and remount (if you not going to buy a new one). Mine was just beginning to weep where it mounted against the engine at 118-119k mi when I had the service done. It leaked on the bottom side and the engine evaporated the evidence. All that was left was the residue on the mounting "plate".

In addition, my precious idler pulleys for the timing belt were going bad. One was OK (but worn). The other had bearings going bad and sounded like it had sand inside when you spun it. Probably would have lasted a few more thousand miles, but digging back in would have been much more expensive than replacing with new when I had them tear into.
Good luck.
Scott

geordi · **Posted:** Tue Mar 29, 2011 9:53 pm

Thanks for the info BM.

All the pulleys on mine were smooth, no play or grinding on the idlers or the water pump. I am not losing any coolant, so at this point... I have a running engine again with a new belt. I'm rolling the dice on replacing the water pump b/c I just don't have it available right now.

Without the cooling fan back on the engine, if I need to open it back up, it will take a lot less time. That fan was a cast iron pain in my arse. Compared to that... Now that I have opened it up completely and set the timing properly, that part is easy.

I was planning to loosen the cam bolts, but I was unable to do it. The nuts were on too tight, probably b/c the gorilla mechanic used an air gun on them. I wasn't sure which way they rotated, but I tried counter-clockwise (normal) first... And nada. Same for clockwise, not even a whisper of motion other than pulling against the pin in the cam AND the locking VM tool, more than I wanted to. Next time, I will try by using the 3-pin fuel pump sprocket holding tool to counter the wrench torque so that I'm not risking hurting the cam tools.

I'm going to have a loooooong talk with the owner of that shop the next time I am home, this guy has risked my entire engine with his over-torquing of all these bolts.

MACKJ · **Posted:** Tue Mar 29, 2011 10:36 pm

geordi wrote:

Thanks for the info BM.

All the pulleys on mine were smooth, no play or grinding on the idlers or the water pump. I am not losing any coolant, so at this point... I have a running engine again with a new belt. I'm rolling the dice on replacing the water pump b/c I just don't have it available right now.

Without the cooling fan back on the engine, if I need to open it back up, it will take a lot less time. That fan was a cast iron pain in my arse. Compared to that... Now that I have opened it up completely and set the timing properly, that part is easy.

I was planning to loosen the cam bolts, but I was unable to do it. The nuts were on too tight, probably b/c the gorilla mechanic used an air gun on them. I wasn't sure which way they rotated, but I tried counter-clockwise (normal) first... And nada. Same for clockwise, not even a whisper of motion other than pulling against the pin in the cam AND the locking VM tool, more than I wanted to. Next time, I will try by using the 3-pin fuel pump sprocket holding tool to counter the wrench torque so that I'm not risking hurting the cam tools.

I'm going to have a loooooong talk with the owner of that shop the next time I am home, this guy has risked my entire engine with his over-torquing of all these bolts.

Hi mate,
I am pretty confident you will find 99% of the bolts on the CRD are metric, certainly the engine and accessories.
I am also sure the alternator bolts are metric. One thing I did find a couple of weeks ago was that the two lower bolts (that you mentioned were sheared off) were tight to remove for me also. I found that there was some binding between the bolt and the casting so when I reinstalled I used some "never seez" (moly based anti sieze) lube on the threads and part of the bolt shaft.
PS. If you use a torque wrench and you lube the bolts you will need to decrease the torque setting somewhat as the suggested torque figures in workshop manuals are all based on dry threads, not lubed.
I can send you a torque chart for metric threads I use if you are interested. Some of the torque numbers in the FSM are crazy.

Edit: Here it is...http://www.cncexpo.com/MetricBoltTorqueNm.aspx
A lot of the bolts on the CRD are grade 10.9 but I prefer to err on the safe side and use closer to the grade 8.8 numbers. Besides we can always get into an argument whether we need to torque anything, just use the old mechanics "elbow click, feel" or "I know how tight these should be with my one foot lever arm" method. :lol:

Alternator BOLTS sheared off!

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