Broken thermostat housing bolt in the block...?
 

Hello all,

I did something dumb, then I went and did something incredibly stupid and now I am praying for a hail mary. I have a 2010 Mini cooper s auto. I have been working on it and because I don't trust dealers and have been working on my trucks my whole life reckoned I could chase down a little coolant leak. Well during reassembly after replacing all kinds of little hoses, clamps, both water pumps, the coolant pipe I did the unthinkable and broke a bolt off in the engine block. It was one of the thermostat housing bolts. It had been off and back in before and so it had looked a little worse for the wear, so I should have known better and got a new bolt. But I was in a hurry because this was the end of my second day on the car and I was hoping to get it back together. Anyhow, the bolt is now broken off just as I got to the 11 ft-lb.

To accelerate from dumb to really dumb, I then drilled the bolt and placed an extractor and promptly broke the extractor off inside the bolt inside the block. I wasn't making any progress even trying to drill out the extractor with a titanium bit. I don't know what to do at this point.

I do have one of those small MAP torches I might be able to fit in there without melting everything else. I also have a Dremel and reckoned on picking up some diamond bits. Does anyone have another or better idea? If both of these options fail and I drill the whole thing out, what is the likelihood of being able to use one of those EZ coil thread dodads successfully? I ain't ever used one of these in a while and it wasn't in something as crucial as this. Thank you for any insight.

V/r,
Cowboy

If it was me, I would get a professional involved at this point.

Bummer! Had a similar story with a bolt that held the AC compressor clutch. Broke off, then broke off the extractor, tried drilling it, everything. Ended up having to throw away a working compressor and replace it. +1 above - I would think about towing it to a good machine shop because you may never get a leak-proof seal again unless that bolt is removed.

Soak the hole and treads with PB blaster overnight, go back with a small punch(long nose version and cut a notch in the one side and tap it out in a circle, I did this on a bolt once that would not come out when it broke off.

https://www.newtis.info/tisv2/a/en/r...-lines/5yRbE3Y

you over torqued it...it is 8Nm or about 6 ft.lb

OP - have you made any progress with this?

Thank you for the advice. It does appear that the book I was given gave me bad advice and I over torqued them, 11 vs 6.

I pulled the car over to a welder and he attempted to weld the nut on it. He didn't have much success, but pieces start breaking off so he made an attempt to drill the rest out and it started breaking off in more pieces. When he called and ask if I wanted him to proceed this all sounded like good news so I said yes before going to look at the car.

The whole is bigger than it should be now and I got nervous to attempt a re-thread since it's in the soft aluminum. I have experience mostly in big block GM motors. I took it to an independent BMW/Mini mechanic who initially said he could utilize a time-sert kit on it. A few days went by so I called him and now he says it's too messed up and he thinks I should start looking for a refurbished head. I am not ready to drop that much more cash in this car. Does anyone have any advice or know anyone in Northern Cali (Fairfield/Vacaville area) that's trustworthy that could render a second opinion? Or should I just consider it a loss and find another head...?

Thanks again.

V/r
Matthew

I think you could try one of these three options:
1- re-thread and use a bigger bolt.
2- re-thread and install a coil to match the oem bolt.
3- use a stud and a nut instead of a bolt.

with only 6ft.lb torque, there shouldn't be too much pressure to "knock" the new bolt or stud out!

what do you think?

I like the stud and a nut idea. I'm with you on the only 6 ft.lb, been thinking about that myself.

I ran into something similar on the engine block of a big block Chevy. Back then I utilized redneck ingenuity and drilled it out more, wasn't centered or anything and put a steel grade stud in and cut it off flush. I believe I put loctite in with the stud, but I honestly can't remember. Then I used a drill jig made from the gasket and drilled a hole in the stud tapped it for the eom bolt. It worked then. I don't know if it was a good idea or not and I honestly can't say how long it held. Would something similar be a good idea here or am I reaching for a solution that is going cause me more heartache than just searching for a salvage mini or refurbished head?

Reading through the forum here on how to swap the head it sounds like it gets complicated quick. I don't know if I want to even attempt it on my own.

Thank you all for your thoughts and time. I greatly appreciate this forum.

V/r,
Matthew

I guess going the stud route will not be as complicated as removing the head. At the end of the day, you do what's best for your skill set. Removing the head isn't that bad. It takes me about a day.

You could navigate newtis.info for how to

Just get a correctly sized Timesert and install it. It's not rocket science and shouldn't be that hard although you'll have to remove some things to be able to get a drill down into there. If the only other option is a new cylinder head I'd certainly give it a shot. You need to be careful to drill in the correct location though. If the hole is all messed up the "center" may not be correct and the thermostat won't bolt back up. However, I'd be concerned about drilling too big and breaking into a water jacket or something in the head. A timesert is one of the smaller OD options for a thread repair so it's probably your best option.

Update, I had to drill it out a little further than I had hoped to. After some struggling, I got the timesert kit in there and the housing back on. Everything seems to be okay for now. Thank you for your help everyone.

Matt

welcome, glad you got out.

That’s a good outcome. Congratulations.

Awesome glad you have a happy ending.