Alternator adjustment arm attachment bolt broken off

[Colibri]

Today I was surprised to discover that the fastening screw for the alternator adjustment arm had broken off and the tension/adjustment screw with the metal square was just hanging around loosely. Unfortunately, the rest of the broken fastening screw is absolutely flat on both sides in the alternator adjustment arm. My questions:

- Is it normal for something like this to happen (wear, material fatigue, etc.)?

- Or does this indicate another problem? (We've had the Transit for 10 years and this is the first time. 4 years ago I changed this drive belt myself and everything has worked fine up until today.)

- I suspect I have to remove the alternator and try to drill out the rest of the broken screw from the thread in order to then use a new car screw. According to Heynes Repair Manual, removing/installing it shouldn't be too difficult. Do you have any tips on what to look out for?

- Is a car replacement screw in hardware store quality sufficient?

- Since I broke countless drill bits the last time I drilled out broken car screws, despite using drilling fluid, heating and bouncing: Any tips for drilling out quickly?

Thank you in advance for your quick responses.

[Chug]

Yes I've had one break and had to drill it out and on another van I had someone had previously done the same. Use new drill bits and start small, maybe 4mm and then work up through bigger size bits.

[Bruce e]

If it is the aluminum casting that the bolt has broken off in you can either put a helecoil thread restorer in it or a nut on the back. I have had several broken, you need a grade 8 high tensile bolt

Sent from my SM-A156E using Tapatalk

[MinorMatt]

Just undo the bolt holding it to the block, take it away to a bench and work on it in a nice easy location.

I have seen several brackets snap - but not the bolts.

They are a standard size - M8 (8.8 grade). If its the bolt I think it is, don't worry too much if you make a mess of the threads when drilling it out - you can use a (nyloc) nut.

[Colibri]

Replacing the tension screw worked:

I removed the alternator. I punched the broken screw in the middle. Then I worked with new drills: I deepened it a bit with a 2 grit drill. Then I drilled through with sizes 3, 4 and 5 one after the other. With size 6 I was able to unscrew the screw from the alternator on the other side of the thread. Two different screw removal sets proved to be completely useless because their thread was either destroyed by the harder screw or I ran the risk of breaking the unscrewing drill in the screw. The cleaned thread then had some play with the new 8.8 screw from the hardware store, so I chose a 60 instead of a 50 length to additionally secure it with a nylon nut.

Thanks again for your help!

Can you actually tighten the drive belt too much and cause damage?

According to the repair manual, the drive belt should be able to be pushed up/down by around 2mm. That's more or less the case. But now I'm in the adjustment range for clamping almost at the end of the slot, whereas before the clamping position was more in the middle of the slot.

[dumper]

Well done did a good job there shouldn’t have affected the ajustment much nobody likes drilling broken studs as for the belt being near the end of adjustment if it’s not squealing on normal running should be alright even if on startup you get a slight squeal for a second or so probably unless you saved the old belt maybe worth carrying a new one just in case

[Colibri]

Thank you, good idea.

The current tension of the belt is not too strong, is it?:

The belt can be twisted 45 to 90 degrees with two fingers in the middle of the longest section at the alternator.

At the same time, there are no squeaking noises when starting or driving.

Should this therefore not put excessive strain on various bearings?

Thanks again for your feedback in advance!

[dumper]

I always tighten mine just enough so when starting it didn’t squeal which would be the 2 mil movement up and down not tightening to rock hard. Nowadays transits have automatic adjusters or on front wheel drive a stretch belt never done one though cause mine have always been rear wheel drive so you don’t really till something goes wrong it’s a visual inspection on service.
If you have that bolt snap again as mentioned below you can drill it out and use a nut and bolt a lot of exchange alternators used to come with a nut and bolt back in the day

[MinorMatt]

The tension I use is to have enough slack to be able to rotate the longest length of the belt 90 degrees before the force required really starts ramping up.

Tbh its better to be a bit loose, than too tight. If its not squealing its tight enough

[Colibri]

Ok. Thank you again