Heat Exchanger

[Guest Sword]

Hi all, whilst driving home from work today, car started to get hot. So hot that the warning light on the water temp gauge started to flash. I was under so much pressure to get home, I had to run the risk of not stopping. Anyway, about 1/4 mile from home, it happened. A HUGE explosion in behind the dash board. IT WAS SOOOOOO LOUD, hurt my ears. After the bang, complete inside the car was filled with steam and coolant started "squirting" into the footwell of the drivers side.

 

Not nice as I couldnt see where I was going, approaching a traffic light and a left turn, cars infront and behind me. Anyway, I managed to scald my left foot, the water was obviously above boiling.

 

Right, my instant guess was the heat exchanger (matrix). What do you all reckon?

 

I have got the dash almost off, just got to get better torx for the airbag removal on the steering wheel. If it is the exchanger, does anyone know of a good shop?

Below is a ss of the part and number

 

http://img142.imageshack.us/img142/2755/matrix9pm.jpg

 

Once the dash is off, is a difficult task to remove/replace?

[johnb80]

Sounds favourite, never done it on a Gal but I have done many other cars. Once the dash is out of the way it should be easy.

 

Regards - John

[Masked Marauder]

More like the head gasket has gone and that has pressurised the coolant causing the overheat. If it has been going for a while the oil suspended in the coolant will have been rotting away the rubber water pipes.

 

Then the rotted pipes and the pressure..... BOOM. A matrix would not have gone with a bang, it would have split. It has to be a hose.

 

Then again, I don't think there are any hoses inside the car....

[Guest Sword]

ok, I understand that the HG could possibly be at fault, as the car seems to have been running on the hot side alot lately, but why the waterfall of coolant in the driver footwell??

I checked inside the oil cap, no gunge, any other way of testing with home DIY tools? I have noticed alot of what looks like corrosion from the joints on the coolant pipes behind the engine tho.

[johnb80]

Head gasket failure doesn't always give oil & water mix, it can fail between cylinders, to the outside world, into the water jacket or into the oil galleries. My sierra had a heater matrix that did exactly whats happened here, the plastic header simply let go, no warning, no water leaks just a dull thud followed by lots of steam and loads of hot water.

After replacing the matrix, everything was fine i.e. no head gasket problems.

 

Regards - John

[Guest Sword]

I got another question....

Is the Heater Matrix for the Sharan2.8 VR6 the same as for the Galaxy2.8 V6?

Volkswagen want near enough

[Masked Marauder]

I think the heat exchanger is common across the range, all makes, all models.

 

Will check in a bit though!

[Guest Sword]

so, I got the dash out and wow, what a hole

 

http://img50.imageshack.us/img50/4128/matrix16ni.jpg

 

OK, so I have found the cause of the bang and the flooding. My concern is now, just getting another replacement unit and popping it all back together again. Has and CAN the matrix unit fail? Or does it need another factor to fail. Heater matrix problems are really common, but if the unit was failing or completely failed, could this have been a cause for the car to be running at higher temperatures than normal over the last few months???

[Masked Marauder]

Nah, thats not the cause of the overheat, but must have been failing for it to blow.

 

How quick was the car overheating? Was it when there was load on the engine the gauge soared or was it a gradual climb?

[Guest Sword]

It was more of a gradual climb, worsened by stop and go traffic. When in stop and go traffic it climbed up to above three quarters and then the fan kicked in. Normally it would drop to below three quarters after the fan comes on.

 

My father has just told me to bypass the heater matrix by cutting the pipes that go through the bulk head and connecting them. Has anybody done that before? He told me that it was a common thing in his earlier haulage days on foden trucks. He told me that i won't have heating but should complete the cooling circulation.

[johnb80]

Yep that works, no problem.

 

Regards - JB

[Masked Marauder]

I would be inclined to fix it properly whilst the dash is out.

[Guest Sword]

that is very true MM, I would if I could and I can, but I am reluctant. I have put more than

[Ivor_E_Tower]

Why didn't the header tank pressure cap blow first and reduce the pressure in the system?

[Guest Sword]

not sure. Possibly the flow on the circulation was stronger on the entry point to matrix than the exit. The matrix was faulty obviously, if the pressure was higher on the return hose then possibly the valve could have blown. MM would know better though.

[Masked Marauder]

I don't know what he pipe is made from, is it aluminium, if so most likely it has corroded internally and the pressure is enough to have burst it.

 

But I am confused as anyone else as to why the pressure cap did not blow, it does not take much on this car.

[johnb80]

not sure. Possibly the flow on the circulation was stronger on the entry point to matrix than the exit. The matrix was faulty obviously, if the pressure was higher on the return hose then possibly the valve could have blown. MM would know better though.

The pressure in the cooling system is the same throughout (there is a tiny isignificant difference that causes the water to flow but to all intents and purposes it's all the same).

Regards - JB

[El Dingo]

Is the pressure cap faulty or tampered with? Any other evidence of over-pressure, like bulging hoses? I get the feeling that whatever caused this blow could cause another...

 

:D

[Guest Sword]

there are no obvious pipe bulging to be seen. I do know though that there was no coolant in the car, just water and antifreeze. So i know that the over heating was bound to happen now. I have just bought 5 litres of coolant. Whilst I was fixing the pipes together that go to the matrix (bypassing matrix) another T connection piece snapped away. The entire cooant system has been corroding away. So I am going to get a T piece connection, renew that, flush the system then put the coolant in and see what happens.

 

I have spent 2 hours today putting the dash back in, all works, thank god.

 

There was ALOT of scaling on the outside of the matrix. Also, I remeber when I bought the car, a VW mechanic told me back then that there was a sweet smell in the car, probable cause, coolant leaking from the matrix. Now 4 weeks ago, my Rad was also leaking, I put some radweld in, now probably, the rad weld has found its way to the matrix and also caused the leak there to solidfy, causes a blockage, just a guess, but I imagine that is what has happened.

[arnie]

good day i'm nu to all this, but very inresting read i've go galaxy v6 n whilest kicking the back side off it the pipe out the top of the head to the heater went bang and now what i can only assume is the heater matrix leaking cause i have a coolant smell and very wet steamy passanger side front window, why didn't the pressure cap let go?? think i'll invest in a new one but still don't understand how or why it happened..