Good afternoon, I need a little insight. During the removal of my water pump (5.3l) I snapped the heads off 2 bolts. I was able to get the water pump off and luckily there is enough of both bolts sticking out that I can get a pair of vice grips on them however, they aren't budging. Is it safe to heat up the aluminum around the bolts to try and brake them free?

Also should I use a thread sealer when putting them back in.

 

Have you tried Break Free, or some similar penetrating thread lube first?

Doug

 

The best penetrating oil I have for corroded screws is KROIL.
No DON'T USE THREAD SEALER OR LOCK TITE.
If anything you should use anti-sieze.

 

The best way is to heat the bolt stub. Get an induction coil type heater and hold it round the protruding bolt stub. The heat will crack the corrosion and any loctite in there. Let it cool and then it will come out. If not, repeat.

 

What ever you do, do not break the bolt off leaving the threaded part flush with the block! Ask me how I know!

 

Can you mig a nut on the stub? I did that on a ford and the heat also helped.

 

Nothing would get the broken bolt out, The bolt that was left just continued to snap until I finally had nothing left outside the block.
I finally decided to stop playing around and just drill it out. Drilling the bolt was not the hard part, getting it all out was the issue.
Nothing I tried after drilling it, including extractors would get it out. So I just gradually increased the drill bit size until there was just
a fraction of the bolt left in the block on one side. I used a carbide bit to slowly grind away as much of the remaining bolt without
damaging the threads. I then slowly worked a tap into the hole to clean up the threads.

I put the old water pump back on with a few bolts to ensure the hole was straight, would line up and would easily thread in, it did.
No Heli coil needed

2 questions -

1. the chamfer that was on the outside of the hole is now gone, it actually still has a piece of the old bolt still there but the new bolt
threads in with no issues. From a structural view point do I need to clean it up and put the chamfer back on or was it just there to allow
the bolt to thread a little easier. A few of the chamfers on the other bolts holes are also worn.

2. Since there is a potential I nicked the threads, even though I chased them and the bolts sees to go in and tighten up with no issues should
I use some Loctite (242 compatible with aluminum) or just stick with the anti seize?

 

No Chamfer needed, its just good machining practice to eliminate raised burrs.

No loctite, that won't help pull out strength, just anti-rotation.

If inside thread minor diameter is close to spec, you can check that with an un-buggered drill bit shank, you are probably OK with full torque. Its not the end of the world, though if something goes wrong, heli-coil or nutsert fixes lots of things

 

First of all well done! Gradually increasing the drill bit size is exactly the right thing to do. Did you use left hand drill bits? They are also a good plan.
Water pump bolts do tend to back out, there was a thread on this topic recently. I would recommend using a touch of Loctite to ensure this does not happen, it happened to me years ago and Loctite stops it happening.

 

Last question. From the factory there was a screw instead of a bolt in one the bottom holes of the water pump. Mine was replaced with a screw.
There doesn't appear to be any clearance issues, anybody know why they used a screw? I purchased new bolts including the screw wondering
if I should use it or the bolt the last person used.

 

I have forgotten exactly where and why, but when you replace something (maybe the coolant inlet spout or the power steering pump) you will see that unless a countersunk screw is used there is a clearance problem.

 

FWIW, my favorite thread stuff for external bolts is a couple wraps of white teflon tape (make sure you wrap it the correct way around the threads), or Permatex thread sealant,a white goop. They both seal against leaks if you have a penetrating into water bolt, keep things from corroding together,and are anti-vibration loosening, yet still allow removal without excessive force

Except exh manifold bolts, those need high temp antiseize.

Doug

 

After a lot of research I decided to go with a product called Blue Monster Nickel Anti Seize and thread sealer. Just waiting for the new bolts / studs. Based on everything I read this stuff should be perfect for the water pump bolts. Won't corrode, seize or leak and it's good for extreme temps. The down side is it's not cheap but you just need a very light smear on the threads.

 

Nickel anti-seize is great stuff, particularly good on earth points and spark plugs on the V12. It might be OK on studs in this application; but if you use it on the water pump bolts there is a good chance they will come loose.

 

Well the saga continues . I purchased an NOS water pump and installed it. As soon as I started adding coolant I had a leak around the bolt hole that I had to remove a broken stud from, so off came the water pump. I cleaned up the area around the bolt, added some Devcon and smoothed it out, let it cure and sanded it flat. I re-installed the water pump with a new gasket and continued to have a leak at the same bolt hole. It appeared to be coming out of the head of the bolt but it was difficult to see. This does not appear to be a bolt that goes into the water passage. I removed the water pump again and followed the same process, put it back and still had the leak. At this point I am starting to loose it. Off came the water again and I examined the area around the hole, while not perfect the gasket in combination with Permatex Aviation #3 should have sealed up any imperfection's if that is what issue was.

After I calmed down I started to check the water pump as I thought maybe I cracked the housing at the bolt hole. No cracks but I did find what appears to be a casting flaw directly underneath the offending hole. Kind of odd that the flaw would be at the same hole that I had the broken bolt on. While its to small to get anything into it including a very fine gauge needle and a single strand of copper wire it appears to be the cause.

Has anyone had a casting defect such as this on a NOS water pump?