s50 conversion heater problem

[yetti24]

me again , with another problem
the heater works fine (blows hot air) on my s50 b30 e30 m3 when its parked or driving around locally , but as soon as i took it up the motorway or at any speed above about 50mph the heater starts to blow cold , then when i slow down it starts to come through hot again , i have had problems with a few 325s i have had which is the old air lock problem , but this is different ,
i think it might be the water pump as i am also getting a squeak from that region when the car is cold ,
anyone had this problem , any help is very welcome

[jmc330i]

Its possible that you have the heater matrix plumbed in backwards - Im sure I read someone having a similar problem with an M30 conversion ages ago.

At what revs does it start to blow cold?
Id try it with the car stationary - Get the car up to temp and blowing hot air, then hold the revs over the point where it would start to blow cold when on the move and see what happens.

If it starts to blow cold (or at least colder) with the car stationary as well as on the move, Im sure its the heater matrix plumbed in backwards.

[ian332isport]

As above. You've got the heater pipes the wrong way around. If you listen carefully, you can probably hear a dull thud from under the dash as the revs rise. This is the flow of water forcing the heater valve to close.

Ian.

[yetti24]

thanks guys i did wonder if i had done something silly like that , another problem solved by the zone , thanks , i will update got to take the carbon plenum off to do some more modifying in the next week

[dicko]

I have done this on the m50 it nearly drove me around the bend . pipe from head goes to the lower of the two pipes on bulkhead and the other one to the pipe that runs along the block to back of water pump

[jaistanley]

I can imagine it'd be easy to do.. On my S50 the pipes have to cross right over one another, and look like the 'wrong' way when they're right (if that makes any sense).

Jai

[yetti24]

thats exactly why i put them round the wrong way , they look like they should go one way but thats obviously wrong i will take some pictures of the correct way round and add them to the post for any future reference ,