Did some research on Dou valve and I will look to pull them, clean & lube them.
Do they control the heat to each side of interior ?

If so what is the chances both would pass same time ?

__________________
Gary
Experience is something you get, Just after you needed it....
'99 E300 295K, '83 300D 220K, '75 240D 185K sold
'80 MCI Bus Conv DD 6V92TA, w/4 cyl. Kubota diesel GenSet 12.5KW