Need help please

[Peggy207]

Evening all,I need a little advice,so basically my Peugeot 207 is having a little issue I recently had a new water pump pulley and thermostat fitted mechanic said that once engine gets to 90c it drops down to 0 then slowly creeps up to 70c and drops again,he said it could be down to a faulty ECU as he said there is a little water ingress on the harness,BUT before he did all this work I had a compression test done by him and this is when all the problems started (before water pump pulley and thermostat replacement) Basically told him that temperature was struggling to reach temperature and that's when he said I needed the above parts replaced,so my question is is it really the ECU or could it be something else please help as I don't believe the ECU is the issue as I never had the problems before the compression test.
Many thanks.

[Steve Walsh]

Possibly not filled the cooling system properly, might need burping.

[GiveMeABreak]

Hard to help here without knowing what he has done and whether he drained the coolant system and more importantly refilled it and bled it correctly as there are different methods to do this depending on the Euro standard of the vehicle (Pre Euro 6 and Euro 6 on).

[Rp0thejester]

Possibly not filled the cooling system properly, might need burping.

Is that also the problem with babies??

[Peggy207]

Hard to help here without knowing what he has done and whether he drained the coolant system and more importantly refilled it and bled it correctly as there are different methods to do this depending on the Euro standard of the vehicle (Pre Euro 6 and Euro 6 on).

Thank you for replying he did put fresh coolant in it as it was a different color to the last coolant I had in it if it needs to be bled how do I do it is it fairly straightforward?

[GiveMeABreak]

I'll need your VIN to determine the engine Euro standards.

[Peggy207]

VF3**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

Ok so you have a Euro 5 engine so as part of the coolant refilling and bleeding / degassing:

Fit the charging cylinder, closer and adaptor assembly on the expansion bottle, in the case of draining using the tool for filling by vacuum.

• Open the rod on the filling cylinder.
• Start the engine.
• Keep the engine speed at 1500 - 2000 rpm, up to the second cooling cycle (cooling fan(s) cutting in and out).

N.B.: The air conditioning control should not operate during this phase.

Degassing and checking the cooling system (continued)

CAUTION: Check that the level of coolant in the filling cylinder is sufficient.

• Stop the engine.
  ESSENTIAL: Do not remove the filling cylinder while the engine is hot.
• Leave the engine to cool.
• Blank the filling cylinder using the blocking rod .
• Remove the filling cylinder , plug and adapter assembly.
• Check the coolant level when cold.
• Top up the coolant to the "max" level (Cold).

[Peggy207]

Thank you for helping me