hole in the thermostat question

[BigKriss]

I put a hole in the thermostat and placed the thermostat at 12 o'clock to help bleeding on the cooling system. Now the car runs between 1/3 and 1/2 way in the temperature range. I'm wondering if running at 1/3 operating temperature is okay?

The hole was 9/64" ~ 3.5mm in size.

I have a spare theromstat ready also.

[Rick L]

You should not put a hole in thermostat. Definitely NOT a good idea. It might take longer to reach operating temperature. As everyone knows, cold engine is just as bad as hot engine. If you look at the thermostat, there is an arrow. That arrow supposed to be either UP or DOWN. By putting in the thermostat correctly help bleeding the air from coolant.

I put a hole in the thermostat and placed the thermostat at 12 o'clock to help bleeding on the cooling system. Now the car runs between 1/3 and 1/2 way in the temperature range. I'm wondering if running at 1/3 operating temperature is okay?

The hole was 9/64" ~ 3.5mm in size.

I have a spare theromstat ready also.

[BigKriss]

okay thanks for your comments Rick.

[Tiger]

It will never reach operating temperature and burn more gas. Always a bad idea to drill a hole... if any, would be the smallest hole possible.

[BigKriss]

okay, thanks tiger

[Dave M]

3.5mm is a pretty big hole. I used the smallest bit I had (1+mm?) and the M50 runs just a hair left of center. It (drilling a hole) seemed to all the rage a few years ago, but its definitely possible to bleed these cars without.

Dave

[ss2115]

Hi BigKriss.

Nothing wrong with a very small hole in the themostat, but 3.5 is way too big.
Less than a 1mm used to be standard in most off the shelf thermostats.
Its for a bleed and also to allow just a small amount of water circulation so that water was moving around the engine and radiator and past the coolant sender.

At the very small size it made no difference to warm-up time or hot running. 3.5mm will certainly slow the warm-up time from a cold engine.

I'm not sure that it should have made a huge difference to the running temperature but obviously it has. Must be a very well sized radiator and cooling volume to find a 3.5mm passage over-riding the thermostats opening.

But as already stated, running too cool is detrimental as is running too hot. If the clearances haven't been taken up by expanding metals, you can burn more oil, have less performance, and the ECU may keep the mixture a bit richer than it should be as well (ie: increased fuel consumption). Engine wear will increase as some clearances meant to open won't, and the oil will be thicker and a bit more sluggish to pump around.
ie: Don't pull any 6 grand acceleration runs in this condition.

[whiskychaser]

I'm going to disagree. OK I've got an M50 not an M30 but my experience is quite different. When my stat was stuck wide open it would take 15 minutes for the car to reach full temp. With a new stat it took 10. I'm taking into consideration the fact yours might have the 'tropical' cooling pack. Mine has it too. I wouldnt drill a hole in a stat but its made my day you used a 9/64 drill. I've still got BSW spanners and sockets in the toolbox The question is how long does it take to warm up fully? Or does it?

[BigKriss]

Thanks for everyones comments. I will change the thermostat today. It took about the same time to warm up from dead cold then with a "normal" thermostat.

I did notice though the coolanty system was a lot easier to bleed than normal.

[632 Regal]

2mm MAX 1 or 1.5 is more ideal to help bleed the system. 3.5 is way too big and will mess up operation of heating it up and controlling the temperature. The BMW stats that I bought have a small orfice and a checkball to control direction of flow for whatever reason.