Oh No! Heater matrix leaking?

[NI_Volvo_Nut]

The side panels of the dash come away and allow plenty of access, havent done an air con model so I'd imagine there would be a bit more too it, but I would have thought straight forward enough got a DIY'er. No special tools needs just a bit of common sense and methodology

[wrinkles]

Mine started to leak and I put a tin of K seal in the cooling header tank and it worked fine still no leaks and that was 5 years ago.

[ericbeaumont]

Originally Posted by lnparry

I think I have found another reason for my heater feeling a little less hot (see recent post on temperature gauge. A slightly damp driver's carpet with a slick feel and sweet taste plus occasional topping up of coolant suggests my heater matrix is leaking.

Same here, Lee, with my 98 945 with ACC.

Noticed temp needle dropping slightly above 40; thought it may be a dodgy thermostat, but illness prevented investigation. Heavy window condensation appeared over Xmas after a run, and water dripped onto the front passenger from condensation on the sunroof. Discovered today that the flat areas of both front and rear passenger carpets are solid with water; no sign of passage of leakage anywhere in the carpets or up by the matrix, but water does odd things. Didn't smell sweet, but will taste it tomorrow (had to load and go to work today).

I'm hoping it's water and not antifreeze (the car was well-maintained by the previous owner at Braydon and latterly Sentinel, where Bernie and others still work) and that the FAQs suggestion turns out to be the problem:

If the only symptom is wet carpets and it’s not evident as anti-freeze then it’s more likely one of the following:
a) The drain for the AC evaporator core box may be plugged. Condensate can fill the lower half of the box until it eventually overflows, either into the intake air blower air box section or the air distribution box section, running onto the passenger floor area (more detail in FAQs).

The (b) possibility is a blocked air inlet in front of the windscreen under the wipers and backup of rain water.

Trouble is, the green in the header tank has been dropping slightly recently, and as the rad, head gasket and lots more was replaced a few thousand ago...

[lnparry]

Originally Posted by ericbeaumont

Same here, Lee, with my 98 945 with ACC.

Noticed temp needle dropping slightly above 40; thought it may be a dodgy thermostat, but illness prevented investigation. Heavy window condensation appeared over Xmas after a run, and water dripped onto the front passenger from condensation on the sunroof. Discovered today that the flat areas of both front and rear passenger carpets are solid with water; no sign of passage of leakage anywhere in the carpets or up by the matrix, but water does odd things. Didn't smell sweet, but will taste it tomorrow (had to load and go to work today).

I'm hoping it's water and not antifreeze (the car was well-maintained by the previous owner at Braydon and latterly Sentinel, where Bernie and others still work) and that the FAQs suggestion turns out to be the problem:

If the only symptom is wet carpets and it’s not evident as anti-freeze then it’s more likely one of the following:
a) The drain for the AC evaporator core box may be plugged. Condensate can fill the lower half of the box until it eventually overflows, either into the intake air blower air box section or the air distribution box section, running onto the passenger floor area (more detail in FAQs).

The (b) possibility is a blocked air inlet in front of the windscreen under the wipers and backup of rain water.

Trouble is, the green in the header tank has been dropping slightly recently, and as the rad, head gasket and lots more was replaced a few thousand ago...

Hi Eric,

Lets hope you just have a rain water leak somewhere but your symptoms sound similar to mine. I only have a small amount of antifreeze dampness in my front driver's carpet so I think my heater matrix leak is still fairly small.

Talking to a couple of classic car buffs (one a professional mechanic) in the pub last night they both recommend K-Seal as a fix for heater cores as wrinkles has mentioned in this thread.

There are some great guides on the forum if you want to see what is involved in changing the matrix:

https://www.volvoclub.org.uk/faq/Hea...eplacement.pdf

https://www.volvoclub.org.uk/faq/Hea...eplacement.htm

Good luck,
LeeP

[Laird Scooby]

Originally Posted by lnparry

Hi Eric,

Lets hope you just have a rain water leak somewhere but your symptoms sound similar to mine. I only have a small amount of antifreeze dampness in my front driver's carpet so I think my heater matrix leak is still fairly small.

Talking to a couple of classic car buffs (one a professional mechanic) in the pub last night they both recommend K-Seal as a fix for heater cores as wrinkles has mentioned in this thread.

There are some great guides on the forum if you want to see what is involved in changing the matrix:

https://www.volvoclub.org.uk/faq/Hea...eplacement.pdf

https://www.volvoclub.org.uk/faq/Hea...eplacement.htm

Good luck,
LeeP

I'd try Radweld first before K-Seal, much less likely to cause problems with other blockages.
I'm not suggesting K-Seal is a bad product, it's good at what it does but it has a tendency to block slow moving channels that don't leak.
With any form of sealant, you want the minimum that will do the job, for me that would be Radweld. If i was using it in something big (big like you need a forklift to crane each of the 16 cylinder heads into position) then K-Seal would probably be a better option - horses for courses.

[ericbeaumont]

Lee,

Drove forty miles at speed last night with the temp needle dropping to 11 o'clock above 40 and heater output reduced, but this morning the header tank was green to max.

Matrix theory
Sampled the carpet water in both front and rear and it tasted of not very much - a very slight salt flavour, but after all the carpets (though clean and only 105k) are 22 years old. The header tank was a different matter, and I had to go rapidly indoors and wash out my mouth numerous times (since then a glass of good sherry has cleared the rest). The green mix tasted of very acrid, not very sweet medicine and was strong. However, the fact that it tasted significantly different from the carpet water doesn't convince me that the two are unconnected: the strong header mix could stay in there for a long time without moving through the system (this is a guess).

Vent theory
Came across this link http://www.forums.turbobricks.com/sh...d.php?t=341184 which explains how a vent in front of the nearside door hinge and behind the kick panel can fail and flood carpets, so that's worth exploring.

Sunroof theory
Poured water down the front exit holes in the sunroof gutter. Nearside came out of a drain hole two feet from the front nearside door hinge; offside came out of a drain hole one foot from the door hinge. Seemed to come out alright. Couldn't see the rear sunroof drain holes, but apparently pipes lead to the rear of the car.

Current optimism leads me to hope that the vent hole is flooding the carpets and that the temp gauge drop is the result of a dodgy thermostat or gauge temp sensor.
Have you summoned the courage to replace your matrix?

[ericbeaumont]

Originally Posted by Laird Scooby

I'd try Radweld first before K-Seal, much less likely to cause problems with other blockages.
I'm not suggesting K-Seal is a bad product, it's good at what it does but it has a tendency to block slow moving channels that don't leak.
With any form of sealant, you want the minimum that will do the job, for me that would be Radweld. If i was using it in something big (big like you need a forklift to crane each of the 16 cylinder heads into position) then K-Seal would probably be a better option - horses for courses.

I have an unused bottle of Steel Seal, Dave. Tried K-Seal as a temporary fix for a failing HG on my previous 940, but all it did was block all the small pipes (especially the turbo cooling pipes) which I found when stripping the entire water system when I did the HG. To be accurate, the previous two owners had done the same, which didn't help.

[Laird Scooby]

Originally Posted by ericbeaumont

Lee,

Drove forty miles at speed last night with the temp needle dropping to 11 o'clock above 40 and heater output reduced, but this morning the header tank was green to max.

Matrix theory
Sampled the carpet water in both front and rear and it tasted of not very much - a very slight salt flavour, but after all the carpets (though clean and only 105k) are 22 years old. The header tank was a different matter, and I had to go rapidly indoors and wash out my mouth numerous times (since then a glass of good sherry has cleared the rest). The green mix tasted of very acrid, not very sweet medicine and was strong. However, the fact that it tasted significantly different from the carpet water doesn't convince me that the two are unconnected: the strong header mix could stay in there for a long time without moving through the system (this is a guess).

Vent theory
Came across this link http://www.forums.turbobricks.com/sh...d.php?t=341184 which explains how a vent in front of the nearside door hinge and behind the kick panel can fail and flood carpets, so that's worth exploring.

Sunroof theory
Poured water down the front exit holes in the sunroof gutter. Nearside came out of a drain hole two feet from the front nearside door hinge; offside came out of a drain hole one foot from the door hinge. Seemed to come out alright. Couldn't see the rear sunroof drain holes, but apparently pipes lead to the rear of the car.

Current optimism leads me to hope that the vent hole is flooding the carpets and that the temp gauge drop is the result of a dodgy thermostat or gauge temp sensor.
Have you summoned the courage to replace your matrix?

Firstly Eric, you need a new 'stat.

Secondly, your heater matrix isn't leaking. If it was, your carpet water would taste the same as the expansion tank coolant which is circulated round the system.

I would suspect the floorpan. It's a known rust spot on the chassis rail that runs under the passenger footwell, similar on the drivers side but the passenger side seems to go first then water gets into the drivers footwell by capiliarry action.



From underneath, that hole was invisible almost, held together by underseal. That was after removing the sill trim, kick panel trim and folding the carpet back.

After cleaning up the hole and getting back to good metal :



Note the cardboard template for the repair panel that went in. All cleaned up with weld-through primer and repair panel ready to weld in :



Worth taking the 5 minutes or so to remove the bits of trim described and lifting the carpets. Might save a lot of time chasing your tail trying to find an alternative cause and if it doesn't, it will hopefully eliminate that as a cause.

As for your 940 turbo coolant pipes, they have a habit of furring up inside by themslves, combination of the heat and everything else in the area. Definitely worth using a flushing agent every 2 years when you do your normal antifreeze change.

[ericbeaumont]

Thanks for your insight, Dave.

Thermostat: yes, a new 92 will go in when I get back to London.
Leak taste: that's good to hear!
I'll check first from underneath and if necessary, take the carpets up.
You don't think that vent behind the passenger kick panel is likely?

Re. the turbo coolant pipes blocked with ancient K-Seal: took a few hours to soak and clean them out but was very satisfying. Car ran really well after the refit, but last September it was written off in Kennington Lane by two idiots in a stolen van, who decided in stationary traffic to do a rapid u-turn without looking. Within a minute they'd scarpered, leaving the Elephant & Castle traffic backed up for miles. Lucky I was only doing 25 at the time; 30% of the front offside was caved in, but the front of the van turned into a pile of plastic.

[Laird Scooby]

Originally Posted by ericbeaumont

Thanks for your insight, Dave.

Thermostat: yes, a new 92 will go in when I get back to London.
Leak taste: that's good to hear!
I'll check first from underneath and if necessary, take the carpets up.
You don't think that vent behind the passenger kick panel is likely?

Re. the turbo coolant pipes blocked with ancient K-Seal: took a few hours to soak and clean them out but was very satisfying. Car ran really well after the refit, but last September it was written off in Kennington Lane by two idiots in a stolen van, who decided in stationary traffic to do a rapid u-turn without looking. Within a minute they'd scarpered, leaving the Elephant & Castle traffic backed up for miles. Lucky I was only doing 25 at the time; 30% of the front offside was caved in, but the front of the van turned into a pile of plastic.

There's a fairly simple reason i'm dubious about the vent in the kick panel Eric - i've never seen one do that in the UK. While you are lifting the carpet, you can check it though as you need to remove the kick panel trim, it's only one or two screws and then a tongue in a slot to slide out. You'll see evidence of the water coming in if that's where it's getting in.

That pair in the van certainly picked their spot to do a decamp after causing an accident! Wondered why i recognised the road name, just looked it up on Gaggle Mops and found it was just off a road i used to use regularly.