[Mk2] [Turbo] Airlocked heater matrix? Coolant system woes.

[Lee H]

Due to my recent overheating issues I have just changed the radiator and thermostat and at the same time decided to flush all the old coolant out.

Last night I refilled the system and tried bleeding it. Got loads of air out of the radiator and that all seems fine (warm all over), however the heater matrix is causing me some issues. I can get the coolant level in the bleed hose fine but as soon as I start the car with the valve open it takes the coolant in and the level won't return even though its still full at the back of the car.

The hose into the heater matrix is getting red hot, however the return hose is cold even by the time the thermostat has opened. Heaters are cold in the car.

Have coolant all over the floor from trying to bleed it as the cap at the rear is leaking constantly when the car is up to temp due to only being on one click as advised in the bleeding procedure.

Any ideas anyone as I'm getting close to breaking this money pit?

[ashley]

Might be worth reverse flushing the heater matrix- could be a blockage?

[calum4492]

I agree try and flush the matrix
if uv got an out side tap, take both the heater pipes off and try sticking it over or inside the matrix pipe and see what comes out, if it come p1$$ing out then u know ur matrix is okay and the problem lies else where

this is a common fault with the rover k-series engines

[Lee H]

I have already flushed the matrix both ways with a hose and it seems to flow absolutely fine. The coolant I drained out was in really good shape tbh with no rust in the system at all when I flushed it.

Seriously getting fed up with this car now.

[Driftlimits Performance]

Try only open the heater matrix and give it a good rev.

[Lee H]

Try only open the heater matrix and give it a good rev.

With the expansion cap on fully in the engine bay?

Just noticed revving with the lid on one click results in more coolant all over the drive.

[Marf]

Get a water bottle and cut the bottom off.

Take the filler cap off, and place the bottle into the filler neck, top end down.

Fill the bottle up half way with coolant, connect the bleed pipes to the rad and heater matrix and start the car, let it warm up, then once warm give it a damn good revving.

Having the water bottle in the coolant filler neck stops you losing coolant after you stop revving, and allows the system to take up more coolant as the air bleeds from the matrix/radiator.

Oh and ensure your heater is on full heat and blowing.

This method never failed me when bleeding my MR2, took a while but worked a treat.

I think you can actually buy funnels which fit the coolant neck perfectly, the bottle I used sat in the filler neck just right and barely anything leaked at the union.

[Lee H]

Cheers Marf, will give that a go tomorrow.

Other thing I have noticed is my radiator bleed drips constantly when the valve is open. Both the old and new radiators do this, guess this is normal due to the angle of the valve and water coming up the threads?

[Marf]

Yeah mine did that too.

[RyanRs]

You don't need the rad cap on 1 click, just do it up properly. As the car hits operating temp the air will be pushed out of the overflow pipe into the bottle, make sure the bottle is 3/4 full. Leave the matrix bleed valve open with the hose connected and pinned up high, make sure the car is facing uphill, Jackup the front end if you have to. Then fire it up, let it run for a good 20min, keep squeezing the coolant pipes in the engine bay to shift the air bubbles. Once it cools down it will drink in coolant from the expansion bottle to replace the void where air used to be. Once it's down to warm (40min later ish) remove the rad cap and top up if nesecarry, squeeze the pipes as u do this also. You might need to cycle this procedure a couple of times to get all the air out.