Crank pulley bolt size

[1979C20]

Need some help guys, my crank pulley decided it didn't want to be a part of my engine anymore and jumped into my fan shroud. I started hearing a strange noise while I was driving, but it was late and I went home and went to bed. Well, this afternoon I got up and went to take my girlfriend to work and the noise was more noticeable. She only works 1/4 mile from home so I figured id take her so she isn't late, then come home and diagnose the problem. Well, I pulled into her parking lot, the noise got louder and then I heard a gut wrenching noise. I though my clutch just exploded, but that was still working, but then I realized I had no power steering, so I thought maybe the box I just put back in went south. I pulled over and popped my hood and saw that all my belts weren't on, then saw my crank pulley resting in my fan shroud. All of the bolts were M.I.A. So, I limped my truck home with no power steering, and it started to get hot when I parked it. I tried putting 3 new bolts in, I figured they were probably 3/8th x 16 and I was able to get 2 in, but the third one wouldn't thread. I started it up, the pulley wobbled a bit so I took it for a test drive to see if it would get my by till tomorrow. Well, it fell off again. The bolts are pretty loose in the holes, so I'm wondering if I have the wrong size bolts, or if the holes are destroyed. I'm probably going to pick up a new balancer on Friday when I get money, but for now to get me by I used a trail-fix technique. I put a plastic zip-tie in the 2 holes that the bolt would thread and I cranked the bolt in next to it, the zip-tie takes up the extra space and acts as a nylon lock nut. So, what size are the 3 crank pulley bolts?

[1979C20]

Also, if I'm not mistaken, the balancer removing tool has 3 bolts that thread into the balancer, but since the holes are being less than cooperative, how can I get the balancer off? Is there a different type of tool I can use that doesn't thread into the holes?

[DustyRusty]

Kyle -

I had the same problem as you a few years ago.  Mine was caused by a seized air pump.  However, instead of the belt being thrown off it broke the crank pulley bolts.  Like you, I thought the bolts were 3/8".  If they came loose before they backed out/broke they likely wallowed out the holes and it's doubtful you can get anything to work properly.  You might have to wait until you get the new harmonic dampener.

When you get your new dampener make sure you get the correct bolts to attach the pulley to the dampener.  I don't know if Grade 8 or Grade 5 bolts are necessary.  Installation may require a shear bolt.  A competent auto parts store or the dealership should have the correct bolts.  I can't remember if I used LocTite on the threads to keep them from backing out.  It probably wouldn't hurt.

I may have used a steering wheel puller to get the dampener off but my memory is a little fuzzy.  IDK if you can use a slide hammer w/o removing a lot of 'stuff' to get a straight pull.  I'm sure others have more recent experience to respond better with. 

Rusty

[Donut]

IIRC, they're 3/8". 
How much room do you have?  If you can't get the bolts in, or drill+tap for the next size larger, try going smaller with a nut on it.

[jdl71]

If you do decide to remove the balancer, you will need a puller. Steering wheel puller or similar "Y" shaped puller should work. I would not use a slide hammer or any other hammer for that matter when removing or installing the balancer unless you want to see your thrust bearings go bye bye.

[1979C20]

they are 3/8ths x 20. I bought a new balancer today, but took it back. I decided to tap the holes out to a 7/16's x 14. I saved myself 60 bucks. Im going to finish it up tonight. I was on my way home after buying the new balancer and the pulley fell off again. This time it broke my fan shroud, the pulley fell and rolled onto the sidewalk, and when I limped my truck home it started getting hot and I ended up getting a pin hole in my lower radiator hose. So, I bought a new hose, took the new balancer back, picked up some bolts and lock washers and borrowed a tap kit from my friends parents. I might have to buy a new crank pulley since mine got a little road rashed, and its 60 bucks too. So I figured ill make the old balancer work in case I have to buy a new pulley. Can anybody recommend how I can flush my coolant system? The coolant is all rusty from the freeze plugs that rotted out.

[Donut]

Road rash on pulley may not be that bad.  Unless it's all bent up, I'd just use a file and clean up sharp edges.  If it's more damage than that (holes wallowed out, big dents, not straight, etc) I'd hit a junkyard.  Last one I hit had a stack of old pulleys in the misc scrap pile.

Cooling system.  IIRC Prestone had a flush kit that worked for me in the past.  You cut a "T" into a heater hose, attach a garden hose, nasties out the top of the rad.  Or drain, fill, run, repeat, until clear.  Don't be afraid to pull the lower hose on the rad when draining.  Heavy rust may collect in the bottom of the rad.

[VileZambonie]

They should be 3/8" x 24 not 20 by 1"

[1979C20]

The holes were wallowed out, so I didnt need to drill it. Im under my truck right now tapping out the three holes to 7/16 x 14 and I have 1" bolts with lock washers for it. I need to drill the holes in the crank pulley out a little bit. I should be done in about an hour. Ill let you all know how it works out. Thanks for the help, its much appreciated.

[gwgdog66]

The center crank bolt came out on mine today and sheared off the three bolts on the harmonic balancer. I guess I'll be doing the same thing this weekend.

[1979C20]

Man, it sucks. Well, I got 2 holes tapped out to 7/16, didnt even need to drill it. Then I learned that the reason the 3rd bolt wont go in is because the old one is sheared off inside the hole. So I didnt want to take the time to remove it, so I just put the 2 in. I was able to torque them down enough to turn the crank and they havent back off at all. The pulley barely wobbles, but after the holidays ill fix it the right way. I was able to take it to 65 with no issues, so I think ill be alright for a little while. But I think I may have damaged my fan clutch because my truck wont go hotter than 150 and the enigine is louuuddd.