Poor heat, heater core?

[Mx3forever]

Since this car seemed to have poor heat for a while now, I decided to clean out the heater core before winter.
Got it cleaned out and the car does have some decent heat now. Not piping hot but warm.

However, one thing I have noticed is that when the car is at stop, idle, the heat coming out becomes luke warm.
Once I pull back off again the air coming out starts to heat up again.

Does this point to any particular issue? I've been wondering if it could be a thermostat problem.....
But, the engine temp gauge never alters, it's steady in the center.


Thanks
N

[SuperK]

some of those fail safe thermostats stick open. Some open at a colder temperature than others. I would get a thermostat that opens at a hotter temperature. some are like 160 vs 180/190.
but it's a cheap and easy solution to test.

[[LVPA]93GsSe]

Did you check coolant level?

[Mx3forever]

Did you check coolant level?

Yeah, I had to top the coolant off after flushing out the heater core. It lost some coolant when it was disconnected and blown out with compressed air and CLR.

Afterwards, I also left the radiator cap off for a bit to try to get any air out of the system.

It does seem like this car takes longer than normal to warm up in winter weather, I have to drive it for a few minutes before it gets to normal temperature.
I'm wondering if the thermostat is locked into some sort of open position.

[[LVPA]93GsSe]

Hmmm? I'm not sure, if I think of anything I'll post up. maybe cleaning the core fins? Sorry, I think about the more odd stuff first.

[SuperK]

My roommate had a aftermarket spectra radiator that didn't seem to perform as well as the OEM one as far as circulating coolant.
Beyond that, the thermostat is so easy to change out and is a good routine maintenance item, might as well go a head and take care of that anyways.

[kakarot135]

How old is your water pump. Sounds like what was happening before mine went out. Does your temp guage climb a little when stopped for an extended period of time.

[Frost881]

Thermostat would also be my first guess, also its important to note that the coolant temp. gauge isn't as representative of the actual temp. as one might think.

The stock gauge is really more of a rough estimate than a precision measurement. As long as the coolant temp is within a set operating range your probably not going to see it fluctuate very much if at all.

[Mx3forever]

Well, here we are again in freezing temps two years later and for anyone else having this issue, I never have figured it out yet!

Since my original post, I have replaced the thermostat with a 180 one. In the process, I cracked an original thermostat housing and had the fun expense of replacing it (not before trying unsuccessfully to repair the first with JB Weld). Having both thermostats out of the car, I went ahead and tested them both in a pot of boiling water. No issues evident with either thermostat, but I went ahead and left the new one in it.

My car still behaves as it did two years ago. When the engine temp reads halfway up, the heat blowing is only Luke Warm at Idle. When you drive and the RPMS increase, the heat blowing out becomes hotter. Back down to idle and the heat lowers again.

Even though I flushed out the entire cooling system including the heat core back in 2014, I'm wondering if I just need a new heater core or if there is something about the temperature controls. Although, I'm not sure if that would explain heat levels that go up and down with the RPM.

One thing that was odd this summer was that my engine went hot. I had to add 44 oz of coolant to the car, but haven't noticed it leaking/dripping. Could the heater core leak in such a way that you wouldn't even notice it?

[Tavman_1213]

Whats you coolant mixture?
Also my neighbor did CLR in his Mini and it made more of a mess than clearing it out because it left alot of sludge in his coolant system after flushing it straight with a hose for an hour. So your cooling system could still be just as clogged as before.

[4gotn]

Sounds like your water pump. Higher RPMs=More flow. The B6 series engine seems to be "overcooled"... I'm guessing because it was originally boosted and that caused excess heat. Maybe its time to do a water pump/timing belt replacement? New parts never hurt.