I've had a brief look over my cooling system on my blobeye wrx, and the header tank is leaking slightly from the seal between the lid and the bottom half. It isn't a big leak, but there are pink residue marks down the side of the tank, so perhaps it is only doing this when very hot and it evaporates off quite quickly.

Looking at the top and bottom hose, I also have pink residue on the metal fittings as if coolant can slightly seep out the ends of the pipes. The pipes look original and so do the clamps so rather than attempting to tighten these and reseat hoses I'm going to replace them. These leaks are small as my coolant doesn't appear to have dropped in level at all over the last year or two.

My current plan is to get an updated plastic header tank new, and a new top and bottom radiator hose (either silicone or genuine new). I also have a thermostat I bought from ICP a couple of years ago I didn't use so I'll replace that as well. The radiator was replaced by a garage for the previous owners shortly before I bought the vehicle in 2018 so that's fine. I'll leave the waterpump for now and will probably change it next time I do the cambelt in a couple of years.

I plan to do a more thorough inspection soon, I have done some searching and there are a few other places than can leak like the crossover pipe, but the header tank seems to be the main part that goes on most of them eventually. Are there any other particular weak points that are worth just replacing with new parts while I have the whole system drained or is the rest generally robust enough that I should just check for leaks and replace whatever is leaking and leave the rest?

I am also aware of the correct method for refilling so no need to repost that here.

Thank you!

 

I recently had a slow but sure coolant leak. We pressurised the coolant system to about 18 PSI via the header tank, and lost a few PSI in about 5 minutes.
It started dripping from underneath every 5 or 10 seconds. I'd already had the main top and bottom hoses and radiator recently.

The leak was coming from the hose the feeds the turbo. Awkward to get to, but may be worth at least checking, mine just wasn't fully clipped on properly...hopefully, but I've heard these hoses can go home sometimes :

https://www.importcarparts.co.uk/par...se&searchPart=

What made this leak hard to find for me in the driveway was that any leaking coolant was just evaporating with the heat of the turbo. It was probably just a mist of coolant whilst driving. So no residue to see.
At some point, for the price, I may just get the above replaced, but far easier if you're draining the system anyway.

The turbo heat shield and TMIC were removed to gain easier access to the top of this hose where the leak was coming from, and maybe the bottom of this hose needs access from underneath to get it off.

 

I’ve been updating my hoses as I’ve gone along on my 2003 wrx too.

none of the hoses I’ve replaced have been leaking as such, but definitely at least the top rad hose used to balloon slightly, which I didn’t feel comfy with.

I’ve gone with genuine subaru ones from ICP where the hose is kinked or has any particular weird shape (eg the rad hoses and the turbo feed as per above). For the non bendy bits, I’ve gone for normal coolant hoses (I think most of it is Mocal or Goodridge).

I went with genuine hoses over silicone for three reasons:
1. The originals lasted between 15 and 20 years.
2. I have in my mind that they don’t split in the same way. On other cars with OEM hoses, I got weeping around the clips and ballooning rather than outright leak immediately (or big splits).
3. The price for the silicone kits (at least the good quality ones) is astronomical. I don’t believe for a second that they will last 2-3 times longer than the OEM equipment.


There’s a bunch of hoses at the bottom of the engine as well. Don’t forget about these if you are renewing.

 

That's all good information, thank you.

Once lockdown eases I'll be swapping on another turbo and getting it mapped in so that might be a good time to replace the turbo's coolant feed hose.

I'm fortunate in that I think I'm getting a very slight egress of coolant under high temp as my levels don't drop and the vehicle is my daily so it's not like it sits unused- it is just that the header tank and pipe ends have pink witness marks in the form of some pink residue. The actual top and bottom hose look completely fine, so I could probably get away with new clips and tightening them, but it seems sensible to replace them. Genuine top & bottom with 4x clips is just under £40, black silicone with clips from fuji racing is just under £70. I need a header tank and header tank cap as well, and of course coolant so it does add up quickly!

I don't really want to go around changing absolutely every hose with genuine replacements as that would get expensive very quickly, but you're right in that if there are a few connecting hoses with the same diameter that aren't complex shapes a reel of new, generic hose could replace a fair few. I'll keep that in mind. Henrik, did you need to buy lots of individual straight bits or did you find that a fair bit of it was replaceable with a larger amount of a single size cut down to length?

In the coming weeks I'll get it on a lift and inspect as many as I can to get an idea of the condition of everything.

 

i agree with the top and bottom rad hose being changed , if yours was leaking your level would be going down which it does not sound like it is , i change the cross over pipes as a matter of course , they are easily forgotten about till they fail , paint gets burnt off by the exhaust then rust starts , i heat wrapped my last one i did , i did one pipe on one car took an hour tops , different car same model took me four hours to do 😒😒 water pumps are generally very reliable i do not change them as a matter of course , last one i had did 198000 miles and was still working , i do always do the tensioner with cam belt change , and keep an eye on the pulley in front of the cam belt cover that the ac belt goes round , that fails and can take out the cam belt , on a separate note , i cut away some of the intact ducting in the offside front wing , a great way of increasing turbo intake noise and more than likely helps air flow , but cut it out in stages not in one go and if you do it gets a bit too much intake noise 👍

 

Impreza Turbo Oil Cooler Modine Cross over Pipe & Hoses & Clips (importcarparts.co.uk)

This is the part you mean? I'll inspect mine soon but you might be right, if I'm draining everything down I may as well- I'll see in case it happens to be in perfect condition!

I did the cambelt with a full kit about 2 years ago, the tensioner had a slight leak so I'm glad I did.

 

i had a brand new subaru original part tensioner fail in about 500 miles , luckily no damaged caused , and yes that is the part , as above it’s not a lot of £ , it’s either a quick change which two of mine were or a bit of a b..l ache to do , but i was surprised how bad they had got even on a rust free car so i did both of them