Hello,
I hope everyone is fine and safe. I decided to make use of the time and got to the thermostat housing. However, when putting everything back together. I dropped a bolt somewhere in the engine bay. Looked for 3 hours and blowed air, yet it just vanished. I was thinking of just buying a new bolt. Do I need the original bolt? Or will a normal m10 bolt do? Will leaving the bolt in oblivion cause problems? I am somewhat still getting into doing my own work so excuse me if the question is very obvious. Also, what is the H S M inscribed on the bolt?

 

The lost bolt should be okay. That's not to say it won't resurface down the road as the cause to some issue, but it's not likely. Be certain the match the thread pitch on that m10 bolt. I'm not sure what it should be.

 

I would think you'd be fine using one of your existing OEM bolts to find a match of width and thread pitch for your replacement. Most home improvement or hardware stores should have something in inventory that will work. I've also used Amazon from time to time for specialty fasteners, if you know the specs your needing.

 

could you please help with the specs? I have measured it. Its 30mm long and 6mm in diameter.

 

I suggest you learn to use this site --- https://www.realoem.com/bmw/enUS/select it has all the part numbers you need. Most bolts are also described so they can be ordered from a hardware store. Note that bolt measurements don't usually include the head, only the shank.

 

Yes, I am an engineer so I’m familiar with the standard. I just cant figure the HSM annotation. I believe it is related to the material. Do you know anything about that? Will a stainless steel bolt work?

 

Just spent an hour or so looking up bolt head markings, etc. Best I could come up with was mfg ID marking, altho neither "HSM" or "WSH" was included on the old (2008) list I found. Considering the purpose of this bolt, it isn't critical compared to a head-bolt, so just finding an 8.8 grade metal bolt with the same length and pitch should be sufficient. A purist would order the RealOEM part number from a dealer, or 2nd choice, one of the NAM suppliers.

 

Im both sorry and thankful you did that for a whole hour. I cant believe this slipped but it is W S H. Its a supplier in germany called WÜRTH. I looked it up and its normal galvanized steel. Thank you so much you’ve been a great help

 

https://www.ecstuning.com/Mini-2011-...ng/Thermostat/


11537565526

as you see on the bottom we will list the size of the bolts from realoem. I am not at home and working remote otherwise i would pull one and help you out.

 

I know where your bolt is :-) It will be hiding towards the front of the engine, under the oil filter housing. Use a length of wire, like a bare copper electrical wire with a bent end on it and flick where you cannot see, it will drop out onto the floor, done this twice!

 

Actually thats the exact spot where it went missing!! I cant believe you said that!
Ive searched for 3 hours. I even jacked the car and tried from beneath it.
Ill try now, fingers crossed

 

needs to be about a foot long, hard wire/copper type, bend the end into a 90 deg angle, just keep flicking away at it from the top.

 

Which way do i flick towards the expansion tank? Or the fan?

 

from the left to right, towards the expansion tank

 

Ive been at it since you've told me, but to no avail. The part you are describing is exactly where it slipped. Ill try again tomorrow. Thank you so much. I am really amazed how you managed to know that.

 

Hey Ahmed, I'm like you, I'm an amateur. However, I just spent my isolation down time replacing the entire engine on my R56. I've lost like a thousand bolts in my life (that's how good I am). Just take one of the other two thermostat bolts down to Lowes, Home Depot, Wilco, Henry Hardware, etc. and they have little gauges that you can thread your bolt into. It's a sure fire way to know exactly what diameter and pitch the bolt is. Then buy a grade 10.9 bolt to replace it. Those little markings on the head are just labeling it per some "standard" system but there are lots of standards and you don't necessarily need the exact one. The thermostat bolts really aren't as critical as say a cam bolt or a head bolt, so whatever the hardware store has should be sufficient. But I'd still go for at least a grade 10.9 if available, which it should be. I just bought a subframe bolt replacement from Wilco last week and it was the exact same shape as the one you're missing. But if you can't find the exact same shape with the built in washer, just make sure you buy a washer. Never bolt without a washer. If you've spent all that time looking for the missing bolt, just give up, not worth it as easy as it is to find a new bolt. Hopefully that helps, and good luck!