Rear heater spewing coolant

[JonB]

...so that happened on the M6 this morning followed by a day at Stafford Service station with my wife and 2 young daughters (they had a great time).

Head gasket seems to have gone so the garage will be getting a phone call tomorrow to get that sorted but what's the likely cause of the leak in the heater? Pipes top and bottom were dry into the heater and the coolant definitely came through the heater grill, would this likely be a pipe connection onto the matrix or the matrix itself? Will it be obvious where the leak came from?

Also how corrosive is the coolant...is it a new wood floor / carpet job or bit of a wash with water and dry it out?

[Cecil]

Possibly The o ring joint between the flimsy plastic heater valve and the matrix .

[JonB]

Possibly answering my own question but looking through photo's on the internet and youtube, suggests that if it's dry around the outside of the heater box (pipes, valve and o-ring) then for the coolant to flow out of the plastic grill it kinda has to be the heater matrix that gave in under the pressure from the head gasket going.

Ultimately as the coolant pipes to the heater are blanked off by MR RAC I can just lift the heater out and strip down to see what I'm left with.

[Porkscratching]

Hi JonB, the coolent shouldn't be corrosive, it's meant to be a rust inhibitor.

I had a similar problem with my under bench heater when my JX head leaked. Whilst waiting to sauce a replacement heater matrix I bridged the two rubber pipes using scrap bits of 15mm copper tubing and jubilee clips. Removing the heater helped the van dry out that bit quicker.

Regards, Max.

[Cecil]

The valve is inside the plastic casing with the matrix so a leak at its joint to the matrix would result in coolant running out of the grille I believe . The matrix may have got wetted as well so not easy to determine source of leak! I found that putting sideways hand pressure on the pipe going to the valve caused coolant to leak from the o ring joint . Having said all of that a 30 year old matrix must have a high chance of being the culprit. I reckon the heater needs to come out of the van ( bed mechanism may be in the way) so you can dismantle it to inspect and / or test it under pressure in some way.

[multisi]

If you are going to replace the matrix you would be better off going for the more expensive type, I had problems getting a good fit of the pipes with the cheap version. Brickwerks do both types.

[JonB]

Thanks for the assistance people. We had a van free weeks at center parcs. I took the heater matrix out and there's a pretty big gash in the plastic which was a surprise...but would definitely explain the torrent that spewd out last week.

Van is getting picked up tomorrow for the garage to take a look at the head gasket...