Coolant Flush

[BRETTMK]

I have mk8 idtec wondering what's best coolant flush to use for a blocked matrix, if that's my issue.

Always had heater issues. Luke warm passenger, aired drivers side. Never hot like mk7 cdti.

Changed drivers door blender, checked valve on bulk head. Had camera in it to check flaps open. New thermostat. Flushed once. Done another flush today and it's definitely a little warmer. Used liquidmoly flush.

Thinking got a blockage in matrix or water pump needs replacing.

Aircon works fine on all the vents.

When I bought the car Had the replace the radiator as it was leaking. Don't know what the previous owner was putting in it to top it up, not sure if he knew to use honda coolant.

Also had honda hds plugged in which doesn't bring up any faults

So want to try another flush first. Anyone had any luck with this or has anyone replaced water pump.

 

[BRETTMK]

Anyone had this issue.

 

[RedCloud]

I have not experienced your problem and own a petrol so this may not be relevant.

I had a successful flush using Holtz Speedflush.

Keep in mind that how flush is just as important as the cleaner you use.
For example, I had a empty my radiator 2 times before all of the original coolant was emptied.

Here's my method to do a full flush from cold engine (keep in mind that this is for a K20 engine):

1. Turn on engine
2. Turn on heater (to make water flow through pipes on Aircon system) to cold (to make engine get hotter quicker) with no fan (as you don't need it)
3. Wait until it goes to temperature (see image below to see temperature)
4. Raise engine revs to 2K (to make water flow through quicker) for 5 minutes (as this is how long it took to get coolant hot and get old coolant out (e.i. to cycle the 3L of coolant out of the engine))
5. Empty 4L of water
6. Repeat step 1 to 5 once (this will cycle 8L of water through the system)

Has it got better since Dec 2023?

 

[Channel Hopper]

Is the thermostat functional at the specified temperature ? It may be worth testing in a pan of hot water.

Bleeding the system after flushing /refilling is just as important on the Mk7 diesel. I have found that stuff always remains in the matrix, but letting off the radiator cap after the engine has reached temerature allows more of the trapped air to escape.

 

[BRETTMK]

its has a genuine honda thermostat - ive bled it on the side of the head with the bleed nipple - even bought a filler what you put on header tank to stop air going in - only other option is matrix blocked or it needs a water pump, when the bleed nipple is undone and i rev it it squirts it higher so would ***ume the water pump working - might try a white vinegar flush

 

[Channel Hopper]

its has a genuine honda thermostat - ive bled it on the side of the head with the bleed nipple - even bought a filler what you put on header tank to stop air going in - only other option is matrix blocked or it needs a water pump, when the bleed nipple is undone and i rev it it squirts it higher so would ***ume the water pump working - might try a white vinegar flush

I have the Mk7, the thermostat has no bleed on either side of the container (at least on the i-ctdi).

I've had to glue it shut anyway as one of the retaining bolts had sheared off.