Unofficialbmw.com Forum Index Unofficialbmw.com
The UnofficialBMW BB, answers for your BMW questions.
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Broken bolt holding belt tensioner..Help!!!

 
Post new topic   Reply to topic    Unofficialbmw.com Forum Index -> 6/7/8 Series Forum

Support Unofficialbmw.com :: Download Free Healthy Habits iPhone app!

View previous topic :: View next topic  
Author Message
AllanGoFast



Joined: 06 Jul 2007
Posts: 8
Location: Poquoson Virginia

PostPosted: Wed Nov 14, 2007 7:42 pm    Post subject: Broken bolt holding belt tensioner..Help!!! Reply with quote

A few days ago while returning from the store, in my 93 740i a vibration developed in the car, I actually thought it might be a motor mount. Halfway home, my power steering went out, my battery light came on and a few other warning lights on the dash...by the time I hit the drive-way at home, it was climbing toward overheating. Opening the hood with the motor still running, I notice the serpentine belt was completely off the pullys. I shut the motor and on closer inspection found that the waterpump pulley was wobbling back and forth like it almost ready to fall off. I figured the shaft thru pulley must've worn out a bearing or something, it was also leaking coolent. Next day I pulled I went to work on the car and found that the pulley was cracked, the fan had a severe crack in two blades and the fan clutch was scrapped up on the fins. I removed the water pump, took out the shroud and radiator the shroud had a crack on the left corner where it connects over the radiator. I ordered a new water pump, new fan, fan clutch assembly,new waterpump pulley, new serpentine and ac belts and new shroud...(BIG BUCKS!!!) after installing the waterpump and while re-installing the serpentine belt was the first time I noticed that the belt tensioner was just flopping around...the bolt that passes thru the pulley and holds the assembly to the block and broken off flush with the block...apparently everything flailing around after it broke is what caused all the other damage...(thank goodness the radiator for some reason was not hit or damaged...) I tried several sources to get a new bolt, came up with nothing. But Thats not my main concern, how in the heck am I gonna get that broken bolt out of the block. Would I be safe trying to drill it out and re-threading for a different bolt, or try and easy-out. There's nothing of the bolt sticking out so I can grab it there's not enough room and its almost too small to try the chisel - hammer method, plus I don't want to mess it up anymore than it already is. I might be able to get a drill in there if I got a 90-degree chuck adapter....would like to get some ideas or suggestions before I proceed. thanks for taking time to read this and all responses will be very appreciated....I love this car.. Question Question It is in nearly pristine condition and has served me well.
_________________
Never do today, what you can put off til tomorrow.
Back to top
View user's profile Send private message

See all UnofficialBMW Ads
edjack



Joined: 04 Feb 2002
Posts: 3887
Location: San Jose, CA

PostPosted: Wed Nov 14, 2007 9:14 pm    Post subject: Reply with quote

First thing: cover the backside of the radiator (or condenser) so you don't slice your hands, and also damage the fins.

I would try a 90 deg drill (Makita makes one that may fit - try your local fully-equipped tool rental place) and an Easy-Out. Get a new drill bit of the proper size. I believe that titanium drills are good.

The bolt will be very tight, due to galvanic action between the bolt and block. Proceed with caution, lest you break the Easy-out off in the bolt.

May want to soak the bolt for a few days with some penetrating oil. How about some mechanism that will provide a pool of oil at the bolt face to keep it submerged.

The dealer is probably the only place to get a new bolt.

If the rad is original, consider replacing it as well, along with the expansion tank.
_________________


Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.
Back to top
View user's profile Send private message Send e-mail
AllanGoFast



Joined: 06 Jul 2007
Posts: 8
Location: Poquoson Virginia

PostPosted: Wed Nov 14, 2007 10:31 pm    Post subject: Reply with quote

Thanks for the reply Ed, you've given me an idea about soaking the area of the broken bolt with penetrating oil. I think I can rig something up that should hold it in place while it soaks in...Do you recommend a drill bit about the same diameter of the bolt, or should I go a little smaller? How deep should I try to drill in order to set the easy out? ..It looks like the broke part of the bolt goes in about an inch. I've already taken the radiator out but the trans cooler is still in, thanks for advice on covering that up I had not thought of that and would hate to mess it up, let alone slice up my fingers. Only a few weeks ago I made a 1500-mile round trip in this car and she was a dream to drive and was absolutely flawless on the trip. I am very glad this didnt happen while I was 500 miles from home. I think you are right about the radiator and expansion tank...since i've got everything down this far, might as well replace everything with new and not have second thoughts about it later...or have to take it all apart again because I didnt do it. Anyway, thanks for reply and good tips on how to proceed with this. Allan.
Back to top
View user's profile Send private message
edjack



Joined: 04 Feb 2002
Posts: 3887
Location: San Jose, CA

PostPosted: Thu Nov 15, 2007 12:20 am    Post subject: Reply with quote

Select an Easy-out that needs a hole about 1/2 or less the diameter of the bolt. The bolt should be shorter than the threaded hole, so you should be able to drill at least to the bottom of the threads.

Try to center-punch the stub, so the drill doesn't wander. Perhaps drill a small pilot hole first.

Get the new bolt from the dealer before you start drilling, so you can see the length of the threads, and the root diameter of the bolt.

What a nasty break. Something I've not heard of. Must be a defect in the bolt, or the last person who tightened it damaged the bolt by twisting it ever so slightly.
_________________


Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.
Back to top
View user's profile Send private message Send e-mail
AllanGoFast



Joined: 06 Jul 2007
Posts: 8
Location: Poquoson Virginia

PostPosted: Thu Nov 15, 2007 8:06 am    Post subject: Reply with quote

Once again, thanks Ed. I'm going to do what you suggested. There are two BMW dealers near here. I guess I'll head out there shortly and see if the parts department has a new bolt. Looks like I'll have limited time to work on it today. My garage is full of Christmas stuff brought down from the attic, the car is outside and it's suppose to rain today...but in general we've had some nice weather here on the coast of Virginia...the forecast looks good after today and the weekend looks good. I'll post my successful operation as soon as its done...maybe I can even get some pictures on if anyone would be interested. Ed you don't know how much I appreciate your interest in helping me out on this.
_________________
Never do today, what you can put off til tomorrow.
Back to top
View user's profile Send private message
AllanGoFast



Joined: 06 Jul 2007
Posts: 8
Location: Poquoson Virginia

PostPosted: Mon Nov 19, 2007 10:04 am    Post subject: Reply with quote

Well...the bolt is out!!!! It was so easy I could not believe it. After all the fretting over getting the thing out. I used my Dremel tool with the smallest cutoff wheel and cut a slot in the top of the bolt, using a thin bladed screw driver the bolt turned out so easy I could not believe it!! I did soak it for a couple of days with BP blaster penetrating oil. I had to order a new bolt from the BMW dealer, its supposed to be here today so I can finally start putting it all back together.....I've had all the other parts on hand for about a week...just been waiting to get the bolt out and and a new bolt....''A HORSE, A HORSE...MY KINGDOM FOR A HORSE" Anyway thanks ED for your help and encouragement. I appreciate your replies and suggestions believe me just to have someone to comisserate with is what you need sometimes. Thanks again.
_________________
Never do today, what you can put off til tomorrow.
Back to top
View user's profile Send private message
edjack



Joined: 04 Feb 2002
Posts: 3887
Location: San Jose, CA

PostPosted: Mon Nov 19, 2007 10:32 am    Post subject: Reply with quote

Great! Glad I could help.
_________________


Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.
Back to top
View user's profile Send private message Send e-mail
Display posts from previous:   
Post new topic   Reply to topic    Unofficialbmw.com Forum Index -> 6/7/8 Series Forum All times are GMT - 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum



Powered by phpBB © 2001, 2005 phpBB Group