Heater is only pushing kinda warm air

[b-rad]

No Heat at high speeds

Similar issues here...

High speeds it's cold cold.
Thermostat has been replaced by previous owner.
This is a 1987 325is with M3-95' S50 Swap... think I am saying that right.

Heat is ok when neighborhood driving.
Probably going to take it to shop... but would like to give them direction to look.

[Das Delfin]

1 - top off oil

2 - check that t-stat is installed correctly. Look up a diagram. Often times the o-ring is installed on the opposite side of where it should be

3 - make sure coolant hoses are hooked up correctly and bleed the system

[b-rad]

This mention of a blend door.
To me this makes more sense than the valve?
This is a question to the forum...

Meaning we replaced the t-stat.. now the heat is better but at above 40-50 it starts to blow cold.

Anymore info on the blend door, exploded view would be welcome

[b-rad]

Hose Flip

Ended up being the hoses were flipped
The replacement of the Stat along with heater core flush... helped as well.