M42 Coolant Leak - Aluminum connection gash

[HorayshE30]

I had a coolant leak so I took everything apart to find out where. Turns out I have a gash in the aluminum where a hose connects. Any idea on how to fix this without dismantling the engine?

[82eye]

its non replaceable. maybe jb weld or something similar but it's likely only temporary.
looks like it had the wrong coolant.

[roguetoaster]

Steelstik is ideal, wire brush it, fill the voids lightly, sand, reassemble. You can also just RTV it if you must, or even move the hose clamp to the very far end of the hose.

[econti]

I think that's the one I did. Many years ago. I cut it flush, then tapped it out to be the right thread for a brass barb fitting. Couldn't tell you what size it ended up being, but it worked as a last resort. I'd JB weld it first, though. Make sure you're running correct coolant to stop corrosion.

[HorayshE30]

Thanks for the replys. I've sanded it down to a point where pits were smaller. Now going to JB it to fill the small pits left and then sand down to get as much metal surface as possible. Then hose clamp as close to the block as possible, flush coolant a couple times then replace with OEM BMW coolant.

The idea of cutting it off and threading in a barb fitting is a good one if this doesn't work.

Just got the car last July, now trying to sort out all the minor issues.

[82eye]

I think that's the one I did. Many years ago. I cut it flush, then tapped it out to be the right thread for a brass barb fitting.

that's the pro fix. good job.

[82eye]

Just got the car last July, now trying to sort out all the minor issues.

nice looking car.

[HorayshE30]

How do I keep debris/mess from falling into the hole if I was to cut it off and tap a new barb in? If something gets in there, how do I clean it out?

[roguetoaster]

Clay, rag, vacuum, ball of tape, whatever you have. If some shavings get in, NBD.

[econti]

When drilling it, run a vacuum just underneath and it'll suck the majority out. When you're tapping it, stick some grease on the tap and all the shavings will stay on the tap

[HorayshE30]

Thanks for the help, all back together after Sanding aluminum down pretty smooth and jb weld just a tiny bit to fill pits. So far no leaks and proper coolant! Pics for fun

[Jordan]

I always just use a punch to collapse what is left of it on itself and pull the crumpled mess out. Tap the head for 1/2 NPT and thread in the nipple with loctite thread sealant. I've done at least a half dozen M42 heads this way. Works perfect and it'll never fail again.

The factory nipple is thin sheet metal, and coupled with time and peoples poor coolant maintenance habits... this failure is inevitable.

The exact fitting I last used seems to be unavailable right now, but the Parker 68HB-12-8 looks to be the same if not slightly longer.

[HorayshE30]

This is awesome information. In the next few years I want to do a rebuild and clean everything up so this is going to be on the list.

I would have loved to do this now but I was too concerned about getting bits in the head and also being able to make it as clean as yours with the slightly awkward positioning in the engine bay. I was also afraid of messing up and then not being able to drive it. It just came out of hibernation.