yabbadoo4

iTrader: (8)

right i,m at my wits end with my bug and need some advice! i did a coolant change a few weeks ago using the back fill method from the turbo water feed hose like i,ve done many times before. this time tho its overheating badly and i,m guessing i,ve got an airlock but its more than that i think. the heaters started blowing cold and i started fearing the worst as it would drive for around 20 mins then the gauge would start heading north to the 3/4 mark! so i switched off and let it cool enough to slowly drive home. so i drop the coolant again and remove the thermostat. quick check in a pan of boiling water and its opening ok. also to say that the bottom water hose was staying cold the whole time. as you can imagine im fearing head gasket and read somewhere that drilling a few holes in the thermostat lets it open easier if there,s exhaust gases in with the coolant stopping the stat from opening. so i drilled a few holes and refitted the stat and refilled the coolant again using the back fill method. went for a drive and all seemed fine for around 25 mins of driving, heaters were blowing hot and all seemed well but suddenly there was a big puff of steam/coolant in the cabin from under the glove box area and the gauge heads towards 3/4 mark again! damn! so i pull over let it cool and trundle slowly home. the heaters are now blowing cold again as well! so next day i refill the system and drive to work which is only about 2 miles away and it overheats before i even get there! heaters are still stone cold as well. so i get it back home again today and drop the coolant again and this time i just fill it the old fashioned way from the header tank and go for a drive and it seemed fine again for a good 40 mins of driving. heaters are now blowing very hot and again i,m thinking i might have cracked it but i stopped at the garage to check the air in my tyres and have a quick nosey underneath and there,s coolant dripping from a drain hole under the rear door area wtf! i feel the floor carpet and its soaking wet so i lift the carpet in front in the passenger side footwell and its sailing with coolant! so i,m thinking now that either there,s a blockage in the heater matrix or its leaking? i,m starting to think that backfilling on an older impreza might not be such a good idea as my radiator is rusty as hell (got a replacement to fit) and im thinking if you fill the radiator from the bottom then all the rust and crud at the bottom of the radiator will be lifted up and then sink back down and may cause a blockage? is doing the heater matrix a big job on these cars? any advice much appreciated lads before i end up pulling out all my hair. thanks.

Hustlersalvage

Definatly sounds like it’s heater matrix that’s popped. Don’t think iv ever bottom fed on a Impreza.
You can bypass heater matrix quite easily with a piece of pipe could try that and run it up to temp make sure it’s just that.
No idea on a heater matrix on a Impreza never done one.
Best thing about everything you’ve said is you haven’t put any miracle bottles through it!
Try not running it any where till it’s fixed imprezas aren’t strongest when it comes to head gasket!

Don Clark

The heater works on a bypass system so whether on or off has water flowing through the matrix - no shut off valves, temp control done by air flaps - so driving around will always empty your coolant/pull air into the system.
Only way to isolate the matrix is as said above pull the inlet/outlet water pipes off in the engine bay and connect together or plug both.




Download this section of the MY01 workshop manual to see how to remove the matrix

imp01 body section1 pdf

yabbadoo4

iTrader: (8)

some great info there lads thanks very much, this is the reason why i still come here instead of crappy facefook. ok so i can get some sort of plastic joiner and remove both hoses to the matrix at the bulkhead and join them and see how it runs without the heater in the loop? good idea will def try that. don thats a good diagram and simple enough for me to understand lol thanks as always for taking the time to help. huntersalvage i was tempted at one point but resisted as i know that stuff will just make a mess and wouldnt be good if the gaskets did need done. i know what i,ll be doing this weekend now lol thanks again guys.

yabbadoo4

iTrader: (8)

Does any one know the diameter or thickness of the hoses that go into the bullhead to the heater core? The engineer in my work has some joiners I can use to fljoin the hoses and bypass the heater matrix. Thanks

Henrik

iTrader: (5)

16mm internal diameter on a new-age at least, afaik

yabbadoo4

iTrader: (8)

Top man Henri thanks

Henrik

iTrader: (5)

Just been out to measure to make sure I wasn't giving duff info, and the hoses are indeed 16mm, at least on a 2003 WRX

yabbadoo4

iTrader: (8)

Henrik thanks for doing that. Got a 16mm join pipe. From the engineer in my work so will be trying to bypass the heater matrix tom. Will post up how I get.on. thanks again for all your advice lads much appreciated! ☺

yabbadoo4

iTrader: (8)

update time: so i bypassed the heater matrix and the car is running spot on with rock solid temps! next step tom is to back flush the heater matrix and try and flush out the crap that must be in there. hopefully it works as its a dash out job to replace it! im still convinced that the back fill method might have contributed to this and maybe it isnt such a good idea on a scoob with an old or original radiator which might have settled rust in the bottom of it. i refilled it the old way from the header tank and just burped it and its been spot on.

Hustlersalvage

If your carpets are wet mate the matrix has a hole in it some where and wants changing, they won’t be mega dear new and your do it in less then a day.
Patience and cups of tea/coffee will get you through.
as said don’t be tempted at all to run it and don’t be tempted to put any miracle bottles through it, k seal liquid steal .. eggs etc lol

Don Clark

As above
Back flushing the heater matrix now would seem pointless as you have already had wet carpets. It may only leak when under pressure so flushing will prove nothing more than you already know.

yabbadoo4

iTrader: (8)

yeah i guess so. had a local guy offering to do it so will see what sort of price he wants. about 4-5 hours labour in it or more?

yabbadoo4

iTrader: (8)

Don if your still about do you know the part number for a replacement heater core/ matrix or who sells them? had a search but not having much luck i thought ICP might sell them but couldn,t see it. thanks for any help.

stamina_daddy

iTrader: (3)

A quick ebay search bought this up?

https://rover.ebay.com/rover/0/0/0?m...2F303194973177

stamina_daddy

iTrader: (3)

https://rover.ebay.com/rover/0/0/0?m...2F122560678824

yabbadoo4

iTrader: (8)

thanks for the links stamina daddy, i did see the first one but its an aftermarket one and doesnt seem too sure on fitment? was wondering where to get a genuine one (apart from a subaru dealer). i wouldnt want to fit a 2nd hand one after going to all the bother of removing the dash etc

Don Clark

Have been busy attending Rally Day ....

Heater core for pre Hawk GD Impreza 72130FE000

http://opposedforces.com/parts/impre...llustration_2/

The complete heater unit 72110FE001 as shown in 2nd ebay link supplied by stamina_daddy above, is a match

yabbadoo4

iTrader: (8)

cheers for the input Don, hope rally day was good! i saw the links from stamina daddy but the unit in the 2nd link is 2nd hand and i didnt think that would be a good idea as i could go to all the bother of having it fitted (a big job by all accounts) to find its also leaking? or do i take a punt on a 2nd hand one being ok?

Don Clark

That I'm afraid is up to you.

Have you priced up a new core from Subaru UK??
Cost if purchased from a genuine parts supplier in Germany is €570.00 (includes VAT but not postage)...........................

At least if you purchased the complete heater, you could remove the core and pressure test it before fitting, and repair if necessary £60 ???

yabbadoo4

iTrader: (8)

yeah some good sense there Don. especially after seeing the price you quoted ! might just have to take a punt. thanks as always for your input always appreciated