W124 Heater Pump Problems

[Noddywithout Bigears]

New to the forum, so sorry if I appear rather thick.

Mercedes 230TE 1992

I have a problem with my heater (stone cold), after reading the posts regarding the duovalves I've been trying to identify exactly where the problem is. The small separate pump which is directly before the duovalves (located inside engine bay on N/S wheel arch) appears not to be working, as the hose into the pump from the water pump is warm, but the hose out of the pump into the duovalves is cold. But the rear of the pump housing is warm (I hope everybody is following this ) so my question are these;

How do I confirm that the pump has actually failed? new one £136 excluding VAT.

Is there a cheaper alternative?

P.S All fuses have been checked and replaced.

 

[Bolide]

I think you've answered your own question, but...

Why not whip the pipes off the pump, remove it and see if it works with 12 volts across it? If it doesn't work, bin it & replace it. If it does, look for an electrical fault

Or start with a voltmeter at the feed to the pump, then remove the pump, test it and bin it...

Nick Froome
www.w124.co.uk

 

[Noddywithout Bigears]

Thx for the info Bolide

I'll whip it off and test with 12v, cheers :grin:

 

[mattkh]

Hi

Cant the noise of the pump be picked up with a stethescope. This would avoid all of the antifreeze handling issues.

Also, would a direct 12v connection be a good test.

 

[television]

Hi

Cant the noise of the pump be picked up with a stethescope. This would avoid all of the antifreeze handling issues.

Also, would a direct 12v connection be a good test.

You must disconnet the plug first to avoid sending 12v back into the system,not a good idea where semiconductors are involved

Malcolm