Quote:
Originally Posted by workingonit
I've not changed my X5's T-stat, yet, since the electric fan is keeping my M54 cool enough, but I've always changed my T-stats to lower opening temperatures, for added performance or trying to avoid head gasket problems (particularly on iron block/aluminum head combinations).
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I've not driven the X5 enough to see if it even needs a different T-stat or any performance boost as yet; with 10+ compression and 4:10 rear gear, it seems spry enough for a 4600-lb truck to be. I just don't need any overheating problems, and will address them if they crop up (Stewart pump, and perhaps modifying the T-stat with drilled holes would be my first set of solutions).....
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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.