stupid m42 cooling issues?

[e30sd]

a small story if you will. owned the car for almost 2 yrs. put close to 30k on it. PO replaced fluids/hoses/belts, etc. anyway coming on inspection time so among other things, i flushed the coolant and popped in a new thermostat. before the change, the car ran cool. never got above 1/2 mark, usually lived between quarter and half, in happy land.

now i put in the new thermo, same exact piece down to the PN (88 deg celsius). topped it up, bled it dow. drove it around, within 10 mins it's at half. doing my work commute (about 5-6 miles of freeway), it hits a needle's width above half. yeah it was 75 out today but similar weather yesterday, no issues. i let it cool down for a few hours, took it out for dinner, then bled it again. still same deal.

both hoses are to temp (lower is warmish hot, top is hot). heater is on full blast, loads of hot air.

what gives? i still have to test the old thermostat. maybe it was bad (however, just did pass smog last week with the old thermo). wtf.

[e30devo]

sounds like the old one was bad. thats what id go with. it was bad. for sure. the old one.. probably bad. hey you remember that one time when the old thermostat was bad? i do.

[e30sd]

you are teh funnies.

[Jand3rson]

Maybe a stupid question Pasha, but have you ever done the profile gasket?

[nando]

you probably had a lower temp thermostat in there before. there are like 3 different temperatures you can get, and 88c is probably the warmest one.

[e30sd]

according to the paperwork, it was done 4 years ago.

i'm gonna test the old thermostat tonight (ref it said 88 on it) and if it works, throw that back in.

yea nando etk shows a 75 and 88. whatevs.

[Jon325i]

you probably had a lower temp thermostat in there before. there are like 3 different temperatures you can get, and 88c is probably the warmest one.

That's what I was thinkin'. Of course, one can't rule out the pesky profile gasket on the M42. Too much of a storied past I'm affraid.

Jon

[e30sd]

most profile gaskets failed around 30-50k. im at 170k with a lot of hard driving the past 30k. big tell of profile gasket is steady coolant loss. it's never lost a drop.

my theories include a bum new thermostat, a possibly warmer new thermostat, or a functional new thermostat and some other problem in the system that wasn't appearant before if my old thermostat was opening early etc. i can't even understand myself.

[Jand3rson]

I'd say nando's theory is probably right on.

[e30sd]

just tested the old one, it was 88c, opened around 190-195f. hmm. so my old one is the same as the new one, and this one worked fine? wtf. stupid picky bleeding?

[Eurospec]

Bleed the system a couple more times. Refer to Brendan's write up, HERE

[MikesJo]

Is it really that big of a deal if it's a needle width over half?

[e30sd]

it's the most pressing matter in my life, probably in the past three weeks.

anyway, pulled the new one out this morning. tested both (both marked as 88c) side by side, the old one opened up at 190ish, the new one didnt open till 218. damn. so i have a bum new one. threw the old one in, bled it, bam, runs back in happy land. guess i'll take exchange it and test the new one before i put it in. damn you behr.

[DEV0 E30]

If it ain't broke...

Who sold you the bad thermostat?

[e30sd]

inter-auto parts.