legacycentral bbs

Ok so this is the second post... I finally realised which cap is the (water) header tank, and which is the (water) intercooler top-up, and which the (fluid!) PAS reservoir - and lastly that the weird little thing that looks like a washer-bottle filler over on the far right of the bay just between the battery and the headlight is another filler tank for the cooling system.

It's not pressurised, hence the dinky yellow press-on tank lid; in my car, it's not especially full either, because I can't see fluid in it. It has a hose & pipe combo going over to the pressurised tank, but (it seems) strictly as an overflow-catching system. Is that what it is? Should I fill it up, or does the engine do that when it's hot? This is a 1990 Legacy Turbo Estate, ex-Japan.

I ask mainly because the neck of this yellow-capped, unpressurised reservoir had an impressive, water-sculpted layer of greeny, crusty, slightly damp mud in it. Quite fine grained stuff, and possibly the result of years of growth of some kind of ultra-hardy algae in the hidden tank - I scraped out a half-handfull of the stuff, which doubtless by now has eaten all the biologics in the dumpster and is about to break out and start dissolving co-eds in an attempt to get a screen test with Paul Newman...

Any idea a) WTF the funny little unpressurised tank does or b) whether the algal sludge is a Bad Sign? Car runs great, and the temperature is rock solid...

If you mean this:


I do believe that's the overflow resevoir for the cooling system. The sludge which you indicate could be just dried up anti-freeze. You said yourself the car is old; it probably has never been flushed out and hence the sludge.

That tank -- the coolant overflow tank -- is an essential part of your cooling system.

When coolant gets hot, it expands. When it cools back down, it contracts again.

So, when your engine is cold, it holds more mass of coolant than when it's warm. When the engine warms up, this excess coolant flows into the overflow tank. When it cools back down, it's sucked back into the engine.

In the olden days, some cars didn't have this tank. Instead, they were just designed so that the upper portion of the cooling system would be filled with air instead of coolant much of the time. Ours isn't designed to work that way.

Under normal circumstances, the overflow tank is the proper top-off point. If you look on the side you should see lines labeled "MAX" and "MIN." When the engine is cold the coolant level in the overflow tank should be between these lines (it will be higher when the engine is hot). If there are air pockets in the rest of the cooling system, they eventually make their way up to the filler tank (the highest point in the system), and from there go to the overflow tank. When the system cools back down, coolant is drawn in to replace the void.

Yes, the sludge in there is probably dried-up antifreeze and whatnot. I've found it in every high mileage overflow tank I've cleaned out. Just clean it out periodically.

What does PAS mean?

vrg3 wrote:That tank -- the coolant overflow tank -- is an essential part of your cooling system.

What does PAS mean?

English abbreviation for Power Steering - Maybe Power Assisted Steering?

My sludge-filled filler would be off the bottom of the photo - and it's not a tank, it's just a neck whose bottom disappears into the very front of the left wing (fender). I assume there's a tank back in there, and I agree, it's likely the system has never been flushed. The car only did 20,000 miles from 1991 to 2002!

LondonThing wrote:English abbreviation for Power Steering - Maybe Power Assisted Steering?

Ah, I see.

My sludge-filled filler would be off the bottom of the photo - and it's not a tank, it's just a neck whose bottom disappears into the very front of the left wing (fender). I assume there's a tank back in there, and I agree, it's likely the system has never been flushed. The car only did 20,000 miles from 1991 to 2002!

Uhh... I was pretty sure even RHD Legacies had their coolant overflow tanks mounted on the left side of the radiator. It doesn't seem to make sense to hide an overflow tank, as you generally check its level by looking through the side of the tank.

Can you take some pictures for us?

vrg3 wrote:
Uhh... I was pretty sure even RHD Legacies had their coolant overflow tanks mounted on the left side of the radiator. It doesn't seem to make sense to hide an overflow tank, as you generally check its level by looking through the side of the tank.

Can you take some pictures for us?

here we have the "right means..." game to play. You can see some pix of the car at http://www.autolinkuk.co.uk/BF5-032148.htm - but of course the engine bay pic doesn't go far enough across to show the yellow cap on the filler neck! However, if you look at the top of the rad you can see a carefully shaped metal feeder tube which leads from the pressurised water tank (silver-edged filler with grip ears at about 8 o'clock in the picture) over to this odd thing.

There are marks on the elbow of the filler tube which look like they could be "high" and "low", but I can't see the point to them - there's no low-level return pipe I can see, and the difference between the marks (being on the neck) is about 30cc, which is hellish accurate for an "overflow" tank!

I'll try to get snaps later on today.

Right means right as viewed when sitting in the driver's seat.

I do see the tube on top of the radiator that you're talking about. This tube is used both for sending coolant into the overflow tank and sucking it out of the overflow tank.

So the proper coolant level in this tank rises up into the filler neck? Hm. I guess that's okay.

30cc seems like a pretty small range, yes. On my tank the difference between high and low is around thrice that.

Is the hose between the pipe and the overflow tank the same type of hose as is found between the filler tank and the pipe? Is the hole in the wing painted any differently or obviously cut after painting or anything like that? I'm wondering if maybe this is an aftermarket job.

Ok, some pictures. Zooming in from the bay we have:

http://www.photobox.co.uk/album/album_f ... o=30656229

And you can see the funny tank header tube in front of the battery. Looking directly at it from the driver's side we see:



and yo ucan just about make out the comedy "high/low" labelling. I think this neck goes into the wing but it's incredibly hard to either see or photograph. Looking into the tube there are some remnants of the layer of green gunge on the cap, and deep inside the tube:



And lastly, the cap is... uh... helpfully labelled, thus:



(those URLS work but clearly the image tag thing doesn't do what I'm expecting... ho hum)

Any chance you could be convinced to upload the pictures to THAWA's free hosting (see here) or to another host that doesn't require people to register to see the images?

Do you have bbCode enabled in your posts? If not, that would prevent the tags from working. Though in this case it's probably better not to include the pictures directly since (I'm guessing) they're large enough to interfere with the page.

Had a valuable day with a Subaru guy here (he might have been moonlighting from a dealership, it's hard to say...) he looked at the sludge and said "oh that's normal - so little comes in or out of the pressurised system that the antifireeze just gets deposited, especially in a hard water area. Just stick a hose in it and flush it out".

So I did.

Apparently on these early Legacys from Japan (the stamp on my space-saving spare says Oct '90) the coolant overflow tank hides in the nearside (left) front wing, but the cooling system doesn't often draw on that reserve.

wanna sell me your engine cover?

LaureltheQueen wrote:wanna sell me your engine cover?

What's it worth? It seems a tad loose anyway. I need some new wheels now (the current set are porous, it seems) and I'm hunting for a cleaner Momo wheel (leather rot on the current one...). Just did 750 miles in it in a week, some at 100 plus, some climbing in and out of West Country beaches up 1 in 3 slopes - stood up well!