940 heater matrix failure

[Ross 63]

Laney,

With the quick succession of blown hoses, leaking water pump, and now a leaky heater matrix, I think it's worth checking you don't have excessive coolant pressure. Hopefully all a coincidence but it's possible the head gasket is not perfectly healthy.

[Laney760]

Originally Posted by Ross 63

Laney,

With the quick succession of blown hoses, leaking water pump, and now a leaky heater matrix, I think it's worth checking you don't have excessive coolant pressure. Hopefully all a coincidence but it's possible the head gasket is not perfectly healthy.

Thanks, noted. This had occured to me and others. Although the head gasket was done in November 2021. Hot oil leaked onto the hoses and its probable the red coolant they put in rotted the brass solder in the matrix? Water pumps have been an issue long before the new head gasket went in to be honest.

[Laney760]

The new matrix with copper and brass which I have received is by Foursome Vehicle Heaters Ltd. It may be possible that they are actually cheaper directly from them than from the third party who I bought it from via Ebay:

http://vehicleheaters.co.uk/index.html

http://vehicleheaters.co.uk/Heater%2...Catalogue.html

Foursome Vehicle Heaters Ltd, Brockhill Works, Windsor Road, Redditch, Worcs B97 6DJ info@vehicleheaters.co.uk Tel : (01527) 64126

[Ross 63]

Originally Posted by Laney760

Thanks, noted. This had occured to me and others. Although the head gasket was done in November 2021. Hot oil leaked onto the hoses and its probable the red coolant they put in rotted the brass solder in the matrix? Water pumps have been an issue long before the new head gasket went in to be honest.

I don't think organic acids are so corrosive to brass that it would cause a leak after such brief use. I don't buy the hot oil bit either. Those hoses between the bulkhead and the No 4 end of the engine are pretty durable. The coolant hoses under the oil cooler plate get far more contaminated. I think it's unlikely that oil alone would cause them to let go. Oil combined with higher than rated pressure is more likely.

It would be worth seeing how much coolant pressure you have after a run. At operating pressure, you should be able to squeeze the top radiator hose so that the inner walls are touching without using undue effort. Noted that the garage replaced the head gasket a little over a year ago, but I guess this is the same place that used the wrong coolant.

[Laird Scooby]

Originally Posted by Ross 63

I don't think organic acids are so corrosive to brass that it would cause a leak after such brief use. I don't buy the hot oil bit either. Those hoses between the bulkhead and the No 4 end of the engine are pretty durable.

It's the solder the acid in the OAT coolant attacks.

Also given the previous HGF, it's possible those hoses were already weakened, presumably they were 20+ years old and original so the HGF would have caused undue stress to them, combine that with an oil leak and it probably wouldn't take long, even at normal running pressure for one of them to go pop.
The oil cooler hoses are made from a more resilient comopund than plain heater hoses for exactly this reason.

[Ross 63]

Originally Posted by Laird Scooby

It's the solder the acid in the OAT coolant attacks.

Also given the previous HGF, it's possible those hoses were already weakened, presumably they were 20+ years old and original so the HGF would have caused undue stress to them, combine that with an oil leak and it probably wouldn't take long, even at normal running pressure for one of them to go pop.
The oil cooler hoses are made from a more resilient comopund than plain heater hoses for exactly this reason.

All true Dave. Still, it takes 30 seconds to check the coolant pressure as belt and braces. Having experienced the results of an incorrectly repaired head gasket failure myself, it's worth remaining diligent and not writing off possibilities.

[Laird Scooby]

Originally Posted by Ross 63

All true Dave. Still, it takes 30 seconds to check the coolant pressure as belt and braces. Having experienced the results of an incorrectly repaired head gasket failure myself, it's worth remaining diligent and not writing off possibilities.

Indeed you're right Ross, however the expansion tank cap should take care of any excess pressure as it's desgined to vent at either 16psi or 23psi depending whether it's 1.1 or 1.5 bar - at one time Volvo caps were colour coded but sadly no longer. The pressure is only really there to raise the boiling point of the coolant in any case.

[baggy798]

When was the coolant cap replaced? Bit of a coincidence that all 3 things have started to leak in a short time, which could all be caused by over-pressurisation.

I wouldn't use a garage again if they used OAT coolant. They should know better! Although like Ross said, it's unlikely to cause damage if it was only in a short time.

[940volvoman]

I'm interested to know how the pressure relief part of the coolant cap works, if anybody know I would like to hear...

[940volvoman]

Dave(Mr Laird Scooby) what did you mean when you wrote the coolant caps used to be colour coded, but not any more. My new one was still green,like the original...