idler pulley snapped off doing a power slide u-turn

Mustangk · Feb 4, 2021

so there i am waiting for the red left light to turn green and i rev the rpms up and let go of clutch as the turn light turns green and all i hear is tink tink tink as apparently my ?idler pulley?{i think thats what its called} falls to the ground and bounces into the curb, KEY NOTE HERE: the engine still is running fine and i begin to question if i ran something over or if something fell off my engine, as i had recently done work to the motor mounts and a blowfish bracket, i pull over and get out of my car to check if something fell off the engine.,

Sure enough my idler pulley the one that is right above the tensioner and to the right and just SEEMS TO JUST SLIGHTLY PUSH ON THE BELT A BIT TO INCREASE THE TENSION ON IT is on the ground, i couldnt find the bolt.

CARS STILL SEEMS TO RUN FINE ALTHO THE BELT SEEMS TO BE A BIT LOOSE.

this happened because i put threadlock on it and it must of reacted adversely. The timing cover doesnt seem to be made out of metal, because where the pulley bolt seems to have pulled out{rather than snapped off} seems to be some sort of filler type material, almost like a bondo. anyways ill attach pic of the pulled out idler bolt and missing pulley.

engine still runs altho belt seems a bit loose, i drove 80 miles home. no overheating ?

question is: i wanna just thread a new bolt in there but as prior to this the idler pulley was loose and i couldnt get bolt to tighten i put a bit of threadlocker on it and this is what caused it to snap. Now do i just try to find the right size tap and tap the hole and put a new bolt in. Id rather not have to drill a size up and retap as i have no way to drill or even tap straight in or dont know how to do it straight. id just be doing it by eye if i retapped. What are my options for being a diyer but not a mechanic with measuring tools.

eighty6gt · Feb 4, 2021

Can't help without pictures, that should be easy?

Did you buy the car used? Every idler in the FEAD goes into aluminum. It's possible prior owner bodged the job, and put it all back with JB weld.

If that is the case, I'd replace the front cover.

Mustangk · Feb 4, 2021

well either way i may have overtightened the idler bolt and thats why i couldnt get it to tighten again. Well im sure i overtightened and crossthreaded it since i couldnt get it tight, so your saying normally blue threadlock shouldnt react with aluminum and cause the bolt to snap out so easily ? ive expereienced using threadlocker blue on screws in plastic where the plastic just snaps apart. but never any sort of metal. going downstairs to get a pic asap.

so retapping hole and new bolt is best choice maybe, or i guess im wondering if theres a longer bolt option i can use or shorter bolt etc...

also what is purpose of that idler pulley, cuss right nwo the engine runs fine without it, it seems the belt miught just not be as tight as it noramlly would be ? drove 100 miles yesterday

Midlife Crises · Feb 4, 2021

Really only a couple choices here. You can drill and tap for a heli-coil or thread-sert. Drill and tap for a larger diameter bolt or as eighty6gt suggested, replace the front cover. I see the degas tank, fan shroud and possibly the radiator coming out to have room to do the job right.

Flusher · Feb 4, 2021

Mustangk said:
so retapping hole and new bolt is best choice maybe, or i guess im wondering if theres a longer bolt option i can use or shorter bolt etc...

Probably the best would be to install a Time-Sert. Yes, it would require machining (drilling [maybe boring] and tapping) your cover.

RED09GT · Feb 4, 2021

Replace the timing cover, last thing you want is any misalignment of your belt. If the bolt pulled out of it, I'd junk it. A new cover should be able to be found for under $100.

Badd GT · Feb 4, 2021

https://www.ebay.com/itm/Ford-Musta...149437&hash=item26526a3fbf:g:4EwAAOSwhsVf3nFz

tbear853 · Feb 5, 2021

Mustangk said:
so there i am ... etc ...
some sort of filler type material, almost like a bondo.
... etc ...
question is: i wanna just thread a new bolt in there but as prior to this the idler pulley was loose and i couldnt get bolt to tighten i put a bit of threadlocker on it and this is what caused it to snap. ... etc ...

Thread locker didn't do it, didn't cause it to snap as it sounds like it just worked loose You were already having issues tightening the bolt you said, so you had pulled the threads out by over torqueing. That material is dried thread locker. Thread locker is not a glue substitute for sound threads, which you'r gonna need.

Might get a thread insert repair. Involves drilling the trash out with the right drill, then tapping for the insert, threading the insert in and it then provides new threads for a new bolt.

But ... thread locker did not cause this.

xeninworx · Feb 6, 2021

I’ve had the nut that holds the power steering pulley come off on my 2003 Civic. Never touched the thing. Just came off while driving. Very odd as the car was like 2 years old. Was not fun driving back home.

07 Boss · Feb 6, 2021

I snapped off the nub for one of my pulleys.

Just get a new cover. You have to pull the crank pulley but then you get to paint the cover and make it look cool. I used the black crinkle coat for that old school look. Went with new billet pulleys too.

xeninworx · Feb 7, 2021

07 Boss said:
I snapped off the nub for one of my pulleys.

Just get a new cover. You have to pull the crank pulley but then you get to paint the cover and make it look cool. I used the black crinkle coat for that old school look. Went with new billet pulleys too.

Oh wow. That’s messed up.

Iceman62 · Feb 7, 2021

OP; If you want to do it right, and last, @07 Boss has you covered.

Rugermack · Feb 7, 2021

I'd replace the cover

DieHarder · Feb 7, 2021

Mustangk said:
so there i am waiting for the red left light to turn green and i rev the rpms up and let go of clutch as the turn light turns green and all i hear is tink tink tink as apparently my ?idler pulley?{i think thats what its called} falls to the ground and bounces into the curb, KEY NOTE HERE: the engine still is running fine and i begin to question if i ran something over or if something fell off my engine, as i had recently done work to the motor mounts and a blowfish bracket, i pull over and get out of my car to check if something fell off the engine.,

Sure enough my idler pulley the one that is right above the tensioner and to the right and just SEEMS TO JUST SLIGHTLY PUSH ON THE BELT A BIT TO INCREASE THE TENSION ON IT is on the ground, i couldnt find the bolt.

CARS STILL SEEMS TO RUN FINE ALTHO THE BELT SEEMS TO BE A BIT LOOSE.

this happened because i put threadlock on it and it must of reacted adversely. The timing cover doesnt seem to be made out of metal, because where the pulley bolt seems to have pulled out{rather than snapped off} seems to be some sort of filler type material, almost like a bondo. anyways ill attach pic of the pulled out idler bolt and missing pulley.

engine still runs altho belt seems a bit loose, i drove 80 miles home. no overheating ?

question is: i wanna just thread a new bolt in there but as prior to this the idler pulley was loose and i couldnt get bolt to tighten i put a bit of threadlocker on it and this is what caused it to snap. Now do i just try to find the right size tap and tap the hole and put a new bolt in. Id rather not have to drill a size up and retap as i have no way to drill or even tap straight in or dont know how to do it straight. id just be doing it by eye if i retapped. What are my options for being a diyer but not a mechanic with measuring tools.

This is going to take some work/effort whether you replace the cover or not. If you don't have the tools/knowledge and you're not comfortable drilling/tapping and using bolt inserts for the cover recommend finding/paying someone who is. Drilling/re-tapping is the easiest/quickest/cheapest path but if you don't know what you're doing let or hire someone who does.

Replacing the cover is a good bit of work and involves removing the crankshaft pulley to get the cover off and well as removing several ancillary items and more to get enough room to work. If you're going to go that route you might as well get a new/used one along with all of the gaskets needed. Taking the cover off isn't impossible by yourself; just time consuming and requires the right tools but you'll learn quite a bit from the experience. Study the manual beforehand and ask questions if you're not sure.

Also, get yourself or borrow a torque wrench (5lb - 95lb) and assuming you have the proper sockets torque the bolts to spec (18 ft lbs) with a new cover (no tighter than spec, I might even go a pound or so lower just to be safe). You're working with steel bolts in an aluminum case. It's easy to pull the aluminum threads out if you're not careful.

If you're not comfortable tackling this job alone get a friend who knows cars and has hopefully done it before to help.

Here's an online manual: http://iihs.net/fsm/?d=159&f=Engine.pdf&p=17
Here's a one-pager for torque specs: https://lmr.com/products/2005-2010-mustang-46-3v-torque-specs

Good luck.

DieHarder · Feb 7, 2021

07 Boss said:
I snapped off the nub for one of my pulleys.

Just get a new cover. You have to pull the crank pulley but then you get to paint the cover and make it look cool. I used the black crinkle coat for that old school look. Went with new billet pulleys too.

Really like the work. Where did you get the pulleys?

07 Boss · Feb 7, 2021

DieHarder said:
This is going to take some work/effort whether you replace the cover or not. If you don't have the tools/knowledge and you're not comfortable drilling/tapping and using bolt inserts for the cover recommend finding/paying someone who is. Drilling/re-tapping is the easiest/quickest/cheapest path but if you don't know what you're doing let or hire someone who does.

Replacing the cover is a good bit of work and involves removing the crankshaft pulley to get the cover off and well as removing several ancillary items and more to get enough room to work. If you're going to go that route you might as well get a new/used one along with all of the gaskets needed. Taking the cover off isn't impossible by yourself; just time consuming and requires the right tools but you'll learn quite a bit from the experience. Study the manual beforehand and ask questions if you're not sure.

Also, get yourself or borrow a torque wrench (5lb - 95lb) and assuming you have the proper sockets torque the bolts to spec (18 ft lbs) with a new cover (no tighter than spec, I might even go a pound or so lower just to be safe). You're working with steel bolts in an aluminum case. It's easy to pull the aluminum threads out if you're not careful.

If you're not comfortable tackling this job alone get a friend who knows cars and has hopefully done it before to help.

Here's an online manual: http://iihs.net/fsm/?d=159&f=Engine.pdf&p=17
Here's a one-pager for torque specs: https://lmr.com/products/2005-2010-mustang-46-3v-torque-specs

Good luck.

And I might add I went ahead and replaced phasers and timing set with tensioners as I think I was nearing 90K miles at the time. Figured I only wanted to pull the cover once so I might as welll take care of that stuff while it was off.

07 Boss · Feb 7, 2021

DieHarder said:
Really like the work. Where did you get the pulleys?

I think they were Metco. It was a set but I had them swap put one for my whipple set up. I think one of my 90mm is 100 mm or something like that.

Flusher · Feb 7, 2021

With the price and availability of replacement parts, clearly that's the direction to go. At $100 for a replacement cover, if you took your cover to a machine shop, the price would be very comparable, if not more.

I would definitely not try to drill/tap by hand. The drill bit will try to follow the original damaged hole and "wander," drilling the new oversize and out of round. When I perform a repair like yours, I would bore the new hole in a mill. Boring is a machining operation that has the ability to shift the centerline of a hole. That way, I could indicate a good portion of the existing hole and ensure that the location is exactly where it needs to be.

Tap drills are sized to produce 75% thread engagement. There is a tolerance for the hole size or minor diameter. Erroring oversized reduces thread engagement and thread strength. This is particularly a problem in castings and soft materials, like aluminum. I would make the hole size on the small side of the tolerance.

Here is a video briefly explaining the very basic difference between the grain structures of castings, extrusions, and forgings:

Tapping by hand is almost impossible to make the tapped hole perpendicular. When I am forced to tap by hand, meaning that I have no way to hold the work piece in a machine, I make a tapping fixture to ensure the tap starts and remains perpendicular during the tapping operation. As was previously mentioned, pulley alignment is critical to belt life and function. Here is a video briefly describing pulley alignment:

Re omitting the ideler pulley: If Ford didn't deem it necessary, it wouldn't be there. I would bet that you don't have proper tension on your belt. I'm suprised that it is working, even in the short term.

idler pulley snapped off doing a power slide u-turn

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