linderpat

okay, so not a great day. I previously broke off the top center short bolt when removing the water pump. The pump is off, bolt broke flush with the front of the block. After days of soaking with PB blaster etc, today I attacked it with reverse drill and extractors. Did not work so I had to drill the bolt out and prep for heli coil (which I have the right size on hand). So far so good, sort of.
Anyway, I ovaled the hole. Now what? Use a timesert insert? Make a stud instead? If I stud the hole, I will sink the block side of the stud into JB Weld. I am not sure a time sert will work. The bolt is 6mm X 1.0, 20mm long. I could go up to an 8mm? Also, I am now worried that the bolt won't line up properly with all the other 12 bolts when I go to put the new pump on.
Suggestions? Anybody else have this issue? TIA.

VegasGnome

I faced a similar problem when I replaced my water pump two years ago. A left hand drill bit broke off when trying to remove a busted bolt and the hole became oval in the effort to remove the broken drill bit. After extracting the broken drill bit I filled the hole with JB Weld. After it cured I put the pump in place and used the hole in the pump to center punch the JB Weld. After taking the pump off I had a perfectly centered spot to drill a hole for the TimeSert. It will work for a 6mm TimeSert if the oval is not too large. If the oval is too large an 8mm TimeSert should do the trick--which I have also done successfully. If you go with the 8mm TimeSert you will need to enlarge the corresponding hole in the water pump too. I have become very fond of the quality of the TimeSert product--and the messes it has gotten me out of. Good luck with your repair.

Lizard928

Agreed, use the old WP housing to center the drill bit.
They've come leaps and bounds with the epoxies. A little epoxy and a M6 timecert are the best way to go.
Btw, get the right size cobalt drill bit. It is worth the $$$ for it.

928wolf

I just did a Timesert repair yesterday on an M6 screw (I have a hard time calling that little thing a bolt) I stripped in my oil pan. A great product, following the instructions was like baking a cake with a great result. I'll post something later today.

James Bailey

There are stepped studs available (911s used them) so bigger on one end to fit a larger timesert and smaller to fit the water pump holes.

dr bob

There was a casual discussion at the great Anaheim 928 mind-meld a week or so ago. I was wondering why there hasn't been a discussion about using studs for the water pump instead of the bolts. Similar to the kit for oil pans, a water pump stud kit wold get studs plus flat washers plus either Nylok nuts or standard nuts. Nyloks won't vibrate loose, but it can be a bit tougher getting the bolt tension right based on a torque wrench setting.

Anybody have thoughts on this option?

linderpat

Dr Bob - the stud fix in my first post above was directly based on that conversation - I think this may be a case where the stud solution would at least be a fix to my present problem. I would not have thought of it otherwise. Not sure how to properly align it tho, since the hole is ovaled somewhat.

linderpat

Jim - where can one find these? Dealer?

James Bailey

Good nut bolt store , old VW parts place , dealers might have one even VW.
Metric Step Studs 6-8-9-10mm - Belmetric
www.belmetric.com › Metric Studs
M6x1.00x8x1.25x31, M6x8x31 Metric step stud. This stud measures 12mm left thread length, 6mm middle shank length, and 13mm right thread length.
click on the metric studs photo !

fraggle

I bookmarked this. I know I will need one someday.

linderpat

Is there an aluminum based epoxy that might be better than JB weld? Yesterday I filled a mold with JB Weld. After full cure, I will drill it and put a time sert into it and see what it taks to break it. I also counter sunk a screw in another gob, and the screw is very firmly in place. I will see what it takes to break it too. I think the JB Weld will be plenty strong, but the questions are:

1. how will it bond to the aluminum? and

2. how will it hold up over time to the engine heat?

RET

FWIW, you might want to use what is called a transfer punch instead of a center punch to mark the spot to drill. A transfer punch is a smooth cylinder with a raised point in the center of the business end; it fits snugly in the hole and precisely centers the mark.

http://www.mcmaster.com/#transfer-punches/=s18l8c

dr bob

Ed--

It should bond fine to the aluminum if it's clean. That apples to any epoxy of course. I keep a bucket of scroopels and small cage of hermit seals for projects like this. If you don't have those, brake cleaner will do an OK job flushing any stray coolant or grease film from the aluminum. As far as the heat, this shouldn't get much over maybe 225ºF, or you have other problems. I'd also look at embedding a stud or even a bolt in the epoxy, rather than trying to drill and tap. Consider that a little work with a file on a socket capscrew will net you a stud with a head on it, one that would be better held into the epoxy by the slightly larger head once it's all cured. You can use the water pump as a guide to hold the new 'stud' in place as the epoxy cures. Just don't glue the pump to the block...

123quattro

If you have access to a MIG welder I much prefer welding a nut onto the broken off stud. The heat generally loosens them up a bit as well. Not that this helps you now.

linderpat

The broken stud was flush with the block. I don't have a welder so it wouldn't have mattered much anyway, but that would not have been an option.