Bolts won't thread on water pump pully

[car noob]

I've taken out my engine driven fan several times over the past couple of weeks, and just a couple days ago I went to put it back on and the bolts refused to thread in easily. I've since taken the pulley off and tried to thread the bolts directly into the water pump and they will go in a few turns and then get really hard to tighten whereas it should just finger tighten easily... What could cause this? And more importantly how do I fix it?

 

[allcarfan]

sure sounds like you have the wrong bolts. However...try one bolt in each hole. Maybe the threads 'like' the bolt that was in them. Also, check for debris.

 

[car noob]

I'm using the old bolts, I'll check for debris before I leave for work in a few minutes

 

[allcarfan]

maybe get new bolts?

 

[usedtobe 67p51d]

H2o / fan bolts are FINE thread I think it's the only fine thread bolts on the motor!

 

[car noob]

right, have old and new bolts (different lengths for diff spacers) and neither of them would thread in properly

 

[brianj5600]

Is it a new water pump? Later w/p would have metric bolts.

 

[car noob]

the bolts are the correct size/thread count for the pump. Like I said I had installed them several times over the past month with no problems till Friday

 

[D.Hearne]

Sounds like you've stripped the threads.

 

[allcarfan]

I agree with D.

 

[car noob]

That's what I was afraid of, is there any way to fix this? The pump is a HO unit and only a couple years old so I'd really like to continue using it if at all possible

 

[allcarfan]

you could have the holes re-tapped. You can do it f you have the right tools or a machine shop could do it for you.

 

[Hack]

If the threads are stripped, consider helicoil inserts. Probably try chasing them with a tap and using new fasteners.. If that doesn't work go with helicoils. I've successfully replaced some threads with them, and I'm not the most mechanical guy around.

You just carefully drill a slightly larger hole, tap it, thread in the helicoil (looks like a spring), and use a punch to knock out the tang.

The helicoils will make new threads to replace the ones that are messed up.

I recommend replacing the fasteners as well, if the threads in the wp are bad, the fasteners probably aren't great either.

good luck.