Member Since: 29 Apr 2019
Location: Perth
Posts: 118
Coolant flush / heater matrix
I was suffering from the "cold wife syndrome" and I noticed some grunge in the coolant bottle. I'd read a lot about attempting backflushing the matrix, and I'd done a "Cummins restore" flush which took a massive amount of stuff out of the system, but left the passenger side heater as-was.
I figured there might be a way to "blast" the grunge out of the heater, but it wasn't going to be gentle. I set up a "T" piece with 2 ball valves. One for the garden hose and one for unregulated compressed air. I put this on one hose, and on the other I just put a 1/2" clear drain :
Click image to enlarge
This let me gently flush, and finding this ineffective I played around until I found something that worked. The concept was to blow as much water out of the core and pipes, then release a "slug" of water into the pipe, then push it through using compressed air with "extreme prejudice". This worked and a pile of orange/pink snot came out (which was odd because I'd been using blue coolant). I repeated it until I was unable to release any grunge in one direction, reversed the connections and went at it again, and repeated the process until I got nothing out.
Magic. Now I have passenger side heat, just in time for summer. I also used the jig to pressure flush the block and radiator, then blow it almost dry before refilling. Given it took just over the rated capacity I must have managed to get it pretty "dry".
12th Sep 2021 11:12 am
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Why were you using blue coolant?
12th Sep 2021 11:20 am
BradC
Member Since: 29 Apr 2019
Location: Perth
Posts: 118
It's the local recommended coolant. It's a Penrite G30 recommended to replace the Havoline XLC which is relatively unobtanium here. It just happens to be blue.
12th Sep 2021 11:28 am
kajtzu
Member Since: 11 Aug 2017
Location: Helsinki
Posts: 6562
G30 (BASF naming) is equivalent to G12+ (VW spec naming) which is an OAT based coolant which is what the car needs. The important thing is, again, not to select by color but select based on spec.
12th Sep 2021 12:00 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
BradC wrote:
It's the local recommended coolant. It's a Penrite G30 recommended to replace the Havoline XLC which is relatively unobtanium here. It just happens to be blue.
No worries, I thought maybe you were using the old gear
12th Sep 2021 10:24 pm
altblech-schrauber.de
Member Since: 15 Feb 2021
Location: Lingen
Posts: 26
I removed my matrix from the car after i used the Hazet Tool without much improvement (which does the exact same thing as you are doing there).
I then made a litle snorkel out of a copper tube attached to my air gun and blew every channel clean, row by row, after soaking the schmoo in Diesel over night. Restored it to new.
Mine had black silocon like particles stuck in the matrix. Most of the channels where so blocked that while blowing it with air, trapped cooland came flying out
14th Sep 2021 10:15 am
BradC
Member Since: 29 Apr 2019
Location: Perth
Posts: 118
I like that idea. I'll file that way just in case it's required again.
The thing I found with all the air/water "blasters" I've seen is they tend to put a lot of water in very small bursts and not very controlled. Too much water in the core/pipes and it all just slows down.
The way I did it used the water as more of a hammer. Clean as much water out of the core and pipes as practical, then just one "slug" of water (about 4" long in the hose) and then 110PSI of air behind it. That seemed to slam the slug into the core with the inertia pushing it toward the back of the matrix.
I tried it many other ways, but once I settled on that one I had great results.
14th Sep 2021 10:32 am
Dreams3577
Member Since: 04 Mar 2019
Location: Aylesbury, Buckinghamshire
Posts: 3
ID of hoses
Morning all..
Have cold wife syndrome.. going to give “BradC’s” technique a try as drivers side is red hot and passenger’s side is cold..
My question is does anyone know the ID of the two rubber matrix hoses under the bonnet? so that i can make something up before try to get them off..
And secondly.. which hose is inlet and outlet? Top or bottom? Going to blast it both ways but think in reserve would be better to start with
06 Discovery 3 2.7 tdv6 SE 198K right hand drive UK
23rd Jan 2023 8:45 am
BradC
Member Since: 29 Apr 2019
Location: Perth
Posts: 118
On the pressure end I used a 3/4" black PVC reticulation hose nipple. ~19mm with a very pronounced single barb. That was probably a whisker too small, but it was big enough to do the job. On the waste end I used a 3/4-1/2" retic adapter and just used a 1/2" clear hose into the drain.
From memory the top hose on mine is the return from the core. I disconnected the top hose and the link between the coolant outlet in the Vee and the FBH and did all flushing between the FBH and the return hose from the matrix. I just alternated direction each time I eventually got it to flush clean, but I had the best results pushing into the return hose (so backflushing).
The trick was blowing it all clear with compressed air, then a little slug of water backed up by compressed air like a little water hammer. Too much water and the intertia just slowed everything down. Not enough water and the air just blew past it.
Remember this core and pipework are not rated for ~100PSI. I figured best case it worked and worst case I ruptured something. Either way if it failed I was up for a new core.
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