peugeot 508 no heating

[BrayanLDZ]

it's strange but I have 70 degrees and the radiator is hot and the heater is not very strong, I can feel air on the heater hose.

[LedZep]

I filled the cooling system with demineralized water and added a product to clean radiators from scale, etc....the water pump seems to be working because when I rev the engine, the fluid disappears from the fluid reservoir, so something must be pushing it further.

The right way to check if the water pump is working properly is to take out the return line (the small one on the top.Watch out, is fragile) of Water Coolant Reservoir Tank with the engine running and see if coolant comes out with the engine warm because we want open thermostat.These water pumps are known to fail because of plastic impeller.By physics, if water pump barely works, coolant will choose the easy way with the least resistance.I don't remember the route of coolant hoses as we have same car, but maybe this is combined with some blockage due to old coolant of hoses. Watch video (in your language 13.38 min).



Another suspect is thermostat.If i remember it feeds the heater.

[BrayanLDZ]

I know the engine more than once, I've done the timing, I've never had a broken water pump impeller. I can always feel the heater hose that either has flow resistance or air. Maybe I'll go faster, the auxiliary will turn.

[BrayanLDZ]

if the thermostat is responsible for heating then it may be the culprit. after starting the car the large engine circuit heats up and not the small circuit. this may be the reason for the lack of heating and the engine overheating. sometimes it blows cold, sometimes hot. in addition, when it blows cold, the engine starts to get hot and you have to let off the gas to cool it down.

[BrayanLDZ]

I ordered a thermostat, it just arrived. Is it a small circuit, meaning a sensor, where is the output to the heater, why is there a 5-pin? Does it measure anything else besides temperature?

[LedZep]

It's electronic and electrically controlled by engine ECU and maybe combined signal temperature by MAF sensor.I think Peugeot calls it as an exotic scientific terminology "coolant system bypass". Before order "thermostat" did you manage a diagnostic search for any faults to make sure is faulty?

[BrayanLDZ]

I did diagnostics through diagbox. There were no errors from the thermostat. But as I mentioned earlier, the large coolant circuit should be closed and the small circuit open. And in my case it's the other way around and you can feel on the heater hose how the motor in the thermostat is trying to change the circuit and can't. I'll replace the thermostat after work today.

[BrayanLDZ]

I changed the thermostat but still no heating... but the pump? the pressure in the fluid reservoir is when it heats up.

[LedZep]

I suppose you bleed cooling circuit the right way through 2 bleeding screws on thermostat and over the heater pipes close to firewall.At least in mine it's like that.There must be a constant strong flow also through these two screws to understand if water pump works and not intermittent. Overflow pipe on expansion cooling tank is more difficult to understand if pump works.

[BrayanLDZ]

so after filling with liquid I first unscrew the bleeders on the lines only then I start the car and it heats up. however the heater does not heat up. apparently the faulty water pumps were disassembled and I will check the water pump drive.

[LedZep]

Bleeding cooling system the "hard way". AC heater and fan in full open position, engine running e.t.c. 18.23 min. Don't know if there is via diagbox a bleeding procedure as it was in 407 2.0. Have a mop next to you. You'll need it.

[BrayanLDZ]

problem solved. water pump drive broke. replaced pump with timing and everything works.

[LedZep]

problem solved. water pump drive broke. replaced pump with timing and everything works.

The solution.

[BrayanLDZ]

exactly as shown in the film, I had the same problem. I installed a new pump with timing and everything went back to normal. I still have the non-working seat heating but I guess no one knows anything about it...

[LedZep]

exactly as shown in the film, I had the same problem. I installed a new pump with timing and everything went back to normal. I still have the non-working seat heating but I guess no one knows anything about it...

It seems that you have to deal with 2 independent problems.One was the faulty water pump which you fixed it.The other is the heater core selector.I'm not an expert in this system because i didn't had to deal with.But in my opinion i would try this. There are two small hoses getting in to heater matrix. The right hose i suppose is the inlet of coolant. The other one is the outlet and has a bleeding screw. With engine running, AC on, fan and temperature in full and high position, see if coolant comes out like a "fountain" as saw in 18.48 in video.That means i suppose, that the electrically control selector of temperature can open in full position so hot coolant can pass through heater core with rush and reach the wanted temperature in cabin. If warm air blows only in one side or nothing at all even the blow motor is working, then it is matter of air vents or whatever in heater system under dash.Unfortunately in used cars there are secrets with service history and almost always there is a reason that someone wants to sell it.To tell the truth the look of old coolant that you change, was terrible and this is maybe the reason that cooling and heating system has failed. Just fix it and you will be o.k.