https://www.mishimoto.com/bmw-m52-m5...mostat-v2.html

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Guys, I have the V8.

We know. Just curious on performance thermostat replacements.

Thanks workingonit! I'll add it to my replacement parts lists.

I bought my thermostat from an indie manufacturer called BAVlogic, the guy is very knowledgeable and can be caught on his business phone number for a chat to ask/answer questions. He buys an OEM bmw thermostat, takes it apart and re-calibrates it, then re-assembles it - what ever special process that is. So yes I have one in my N62 and it works as advertised. The actual temperature that reported is higher and that's what expected in the computer programming. But measuring the temperature of the output hoses with a temperature gun shows running at 90 degrees.
His website also offers a great deal of tips and knowledge.
https://www.bavlogic.com/?p=4035

Well said. This is a rabbit hole to be sure.

M62 runs at 221 deg at the engine outlet so yours is working as intended. Mine is plus or minus a few degrees of that always. Except of course when it sheds a belt or blows a hose that I’ve installed incorrectly. Then it gets very hot, very fast.

I’d read everything you can find about cooler thermostats on the M62 family on this site and bimmerforums to be sure, before doing it. The 540 guys over there beat the crap out of each other over this mod.

The radiator outlet on my car can be anywhere from 120 or so, up to 180 or higher depending on how hard I’m driving, outside temp and if the AC is on. I’ve worried about the higher temps. Hot for sure, but I’m currently of the mind that BMW knows best in this case of this system. Frankly I think better money and results could be spent on a custom high efficiency radiator set up to enable more cooling capability than the crappy plastic sided OE piece. Unfortunately none exist it seems.

I’ve thought about installing a full electric puller fan to replace the clutch version, but can’t come up with a compelling reason aside from the fact that it would be a fun project. Plenty of guys do this mod with good results. Maybe when I’m done with other more pressing needs on the car.

Great lead on that - I read the whole rant on that page :thumbup: :rofl:, and found almost everything matching my current understanding of things.

Do you have any idea about what is done to modify the thermostat?

I've seen drilling holes in it (example pic below), but would prefer a mechanical modification to the opening temperature setpoint, rather than a simple always-on bypass.

So for example, did you see holes in the plate?

Attachment 82274

After my previous statement, I reviewed what I wrote, and also referred to "Stewart Components" (the supplier of various performance water pumps I've used on Chevy engines, both small and big blocks, street and drag racing applications, and the supplier of the hi-po BMW water pump I'll no doubt get when needed). They also have custom thermostats (not, unfortunately for BMW's), and have a tip sheet about flow restrictors and drilling holes in thermostats. https://www.stewartcomponents.com/in...ormation_id=11

I have used holes drilled into my T-stats before, when I wanted to eliminate hot pockets in the water jackets, or to allow the engine more time to fully warm up; both worked OK on various set-ups I had, where many non-factory components were used, and nothing worked the same as factory, so experimentation has to be done. I'm not prepared to experiment on my M54, since I want to keep it as-designed for the most part.

I also used flow-restrictors, when I was using a vertical-flow 1966 Chevelle original Harrison copper/brass radiator, after I added the hi-flow electric water pump (55gpm, full-time), which actually helped to a certain extent, but wasn't needed after I changed to a horizontal-flow aluminum racing radiator. No T-stat was ever installed on that system, purely meant for drag-racing.

Back to drilled T-stats: I've read that the BMW radiator/expansion tank system needs burping (as do the coolant lines on both of my Chevrolet Ecotec 4-cylinder engines), or there may be problems (I failed to do so once, and had my HHR Panel overheat, throwing a P0128 code...The most common causes of P0128 include: Low coolant level (an air pocket trapped at the engine coolant sensor) ). Having a small opening on the "closed" T-stat would help eliminate the need for manually burping the system on the small 4-cyl cars, or even on the BMW. If I ever need to replace the T-stats on those vehicles, I'm going to either get a modified T-stat, or do it myself (I've always used three 3/16" holes). The N.Texas climate makes the loss of a quick warm-up not so critical, so it's not a factor.

I don't really know why, but I looked further into this, and found the following source, which seems pretty good

https://electrorefit.com/product/col...ol-engine-bmw/

About 80% of the way down that page, they even go through a few different home brew attempts (which of course they try to convince you that you'll still wish you just bought their product). Very interesting.

It seems as if the cleanest mod would be to change the wax to one with a lower temp phase change. But that's easy to say and not so easy to do. But that's what you'd want - a simple offset in thermostat opening, leaving the DME-controlled functionality the same. No extra electrical activity to wear out or trigger codes. Just like a wax thermostat from the 20th century. :rofl:

If I had a 105*C V-8 I'd definitely get some solution, but with my M54, it is a less pressing issue.

This guy has all the credibility of the wacko conspiracy theorist who inhabits the comments section on my local channel 7 news website. Yikes



Source: am also mechanical engineer who is not completely insane.

For 3.0i part number 11 53 7 509 227 $80.00
When I do a coolant system upgrade later this year, I'll have one of these modified thermostats to install. Plus a Stewart metal impeller pump too.