Cooling system/ damaged water pump threads m42 1990

[BHadley]

Hi all
Just changed thermostat, water pump and done a full coolant flush on my 318is m42 engine

Top and bottom hose were hot, top hose hotter than bottom hose on drivers side.
Left the heater on max to aid bleeding and started to check for leaks.

I'm pretty sure that the water pump is leaking from a mounting bolt hole area as once cooled down I checked the bolt tightness. Three where tight as I torqued them to (10nm) however one continues to spin freely. Once the bolt was removed alloy parts are in the threads!!!

My question is what are my options? Is helli coiling an idea

Also was the bleeding process I explained above in the correct order as I put 8 pints of coolant in to start left to run and the gauge slowly climbed into the red ideling on the driveway

Thanks in advance.....

[Speedtouch]

You may be lucky and be able to get away with using a tap and die set to re-cut the thread.

Otherwise, you may need to drill it out and use the next largest tap, or as you say, helicoil it.

You could also 'bodge' it in using Chemical metal, Araldite or similar.

[BHadley]

You may be lucky and be able to get away with using a tap and die set to re-cut the thread.

Otherwise, you may need to drill it out and use the next largest tap, or as you say, helicoil it.

You could also 'bodge' it in using Chemical metal.

Hi,
thanks for your reply, what I don't get that is that winding it back in is fine and then it just spins!
So just a good quality m6 tap to start if that fails then helicoil, just a bit panicky about drilling into an engine block!

I shall leave chemical metal.... I want to keep this one nice....

[Speedtouch]

Yes, try the standard sized thread tap first.

[BHadley]

Thanks, shall do in the next few days think I have some knocking around...

[broadie]

What size thread is it?
I got some hellicoils kicking around.

[BHadley]

Hey broadie;
It's m6 thread.... Il have a go at speed touches idea of re cutting thread first if that don't work il give you a shout to see if there available....

Get good progress one min then slowed down by a small puddle of coolant!

[broadie]

Also try a bit of PTFE tape on the thread as well.
Let me know if you want the m6 kit.

[BHadley]

Ok, I guess that's on the m6 tap thread yeah?
Thanks for the offer il PM if its needed....

[Brianmoooore]

When you've cleaned up the thread with a tap, you could try screwing a length of M6 studding into the hole as far as it will screw, then fitting a nut onto the studding to secure the pump, before cutting the excess off. There's always some unused , intact thread at the bottom of the hole that a bolt never reaches, and with luck, this'll be sufficient to hold the stud.

[BHadley]

Thanks Brian,

prob going to give that a go today, didnt know the threads go that deep, would it go straight through to the block?

Is it worth locktite on the threaded bar?

The one I took out had "89"stamped on it, so was well due a change at 200k and near on 25 years old so hardly surprising there is a issue or two on the way....

[Speedtouch]

Yes, Loctite would be a good idea. A long M6 bolt would suffice if you don't have a length of M6 stud - just cut off the excess as mentioned by Brian.

[BHadley]

Brilliant, thanks all

Had a rummage and found the parts and tools for the job.

Didn't want to do something as a repair that's not strong enough hence the daft questions

Ta....

[BHadley]

I think its fixed....... Can't see any leaks and is evenly right as it needs to be.

Thanks all

Now I can't get the darn thing to bleed see next post......

[Speedtouch]

Good to hear that, fella. I commented on your other thread.