Heater slow to heat up in 1991 W126 500SE

[Roygarth]

Takes about 15 minutes to get lukewarm and about 30 mins to get hot? So not much use!
Any ideas on what is wrong?

Thanks in advance.

 

[Sp!ke]

Could be a failing thermostat.
(cheap and easy)
What temperature does the car run at when cruising?

 

[219]

Mine has always been the same - never gets REALLY hot . I've had the duovalve apart and checked it is operating and not choked , the electric circulation pump next to it is also working , drained , flushed every which way and re-filled the cooling system : result - an absolute INFERNO of heat from the heater like I had never experienced before when running with the halfords two-part flushing agent and afterwards with just water , but as soon as I put anti-freeze in it went back to being lukewarm ??? I've done everything but change the thermostat and will try this but was reluctant to throw £30 of anti-freeze down the drain so left it as it was . I know it can't be much that's wrong though .

Engine always does and always has run at normal temp .

 

[219]

Sorry , double post as I got ' flood control' message first time then discovered post had gone anyway !