Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[MV6Driver]

I've got a 3.0 MV6, first registered 2000.

I've read quite a few of the posts regarding heater matrix flushing and disconnecting/replacing the heater bypass valve. I'm not too handy, so I'd like to get this fix right, first time.

Symptoms/observations as follows:

* the engine seems to work fine, with the temperature gauge reaching around 90°C after 5 minutes normal driving
* the coolant level in the expansion tank is up to the cold/kalt level - none is getting lost
* all the air con 'routes' work fine, i.e. air can be directed to the windscreen, footwells, dashboard, etc
* the auto/off air con manual reset causes clicks and buzzes for around 10 seconds
* there is no difference between the air temperatures for the driver and passenger sides
* the fan blows freely, both in auto and speeds 1 to 9
* the hose to, and the hose from, the passenger compartment bulkhead gets warm
* the heater used to work fine - I've no idea when it started to 'not work fine' - I've had no recent work done on the car
* the air from the heater is barely luke warm, at best
* the air from the heater does not seem to get any hotter/colder with changes to the fan speed
* none of the approx 2mm diameter vacuum tubes have any sign of damage/wear
* the heater bypass valve is between the engine and the passenger compartment bulkhead - I do not know how to tell if it is opened or closed

I'd be grateful for any advice on how to find out what's wrong with my car.

Ta.

[ffcgary1]

disconnect the small vac pipe on the top of the HBV and plug it, see if the heat inside the car improves, if it does HBV needs replacing.
Gary

[dbug]

Sounds like your heater matrix is blocked up mate - need to remove in/out pipes under bonnet and give it a good flushing with a hose pipe.  Worse case scenario - replace matrix

[MV6Driver]

Okay - tried the easy one first. I pulled the vacuum line off the HBV. It was a minor struggle for about 10 seconds, and it made a slight sucking sound for about 2 seconds as it came away.

I then took the car out for a hard drive to make sure the engine was fully hot.

No joy - the heater is still giving luke warm air.

Before I embark on the matrix flushing exercise, how can I tell if my HBV is stuck 'in the wrong position'?

If it was stuck in the wrong position, all the hassle of the flushing would be a waste of effort. And I might not get all the bits back the way I've found them!

[Bob G]

if you look at the most by ffcgary he explains what the HBV issue would be, seems as if yours is ok.  As for flushing, watched mine done the other day and apart from a bit of grunting the two pipes came off fairly easy, then the hose was attached and as descirbed in my posts a large glob of gunge came out, full flow of water then reversed, all put back together and result now have to turn temp down.

[ffcgary1]

You dont say if you plugged the vac pipe, did you? or the blend flaps will close.

[MV6Driver]

Yes, I used a countersunk-head chipboard screw. It wasn't so tight as to wreck the rubber L-shaped connector, but it also wouldn't pull straight out. The seal would have been made between the rubber connector and the countersunk head.

If I've to assume that all is well with the HBV, it looks like an attempt at matrix flushing will happen this weekend.

I've some questions regarding matrix flushing:

* should the wiper cowling be removed for access to the bulkhead connectors?
* the cooling system expansion tank is higher than the bulkhead connectors. Will it all drain out?
* how much of the cooling water will drain out of the matrix and the rest of the system before I connect the flushing hoses?

Thanks in advance.

[Kevin Wood]

If you look up inside the driver's side footwell, you should see the pipes from the bulkhead to heater matrix. Might have to remove the trim panel above the pedals - I can't remember. If these pipes are getting hot, then the HBV is flowing coolant to the matrix. The matrix can still be blocked, but at least you know coolant is getting to it.

Do you have cold air at both sides of the car? It's no unknown for one of the blending flaps to become disconnected from its' servo.

[Andy B]

.....
Here's the muck that was flushed out at the beginning of the first flush: ...

I wonder why you'd no heating ...... 

[Entwood]

Well done and a good write up .. another one for Jim to sort and move methinks 

[YZ250]

Nice touch with the hoses. 

[Andy B]

Just to add. After flushing through with the hose, you could leave the hoses as they are, dissolve a dish washer tablet in a pint -ish of water, pour into the heater matrix & leave it in there for a while/over night. Every little helps!