'02 Impala 3.4l: Odd coolant leak?

[Colt Hero]

'02 Impala 3.4l, ~83kmiles:

Just noticed a coolant leak right in front of the (top of the) engine. Doesn't look too bad - just a ring around the base of the 3" vertical black tube that comes out of the top of the engine and sends/receives coolant around the top of the block/head via a black metal tube to the right side and a 6" "elbow" hose directly into the center. I looked this part up in the shop manual and it's referred to as the "Thermostat bypass pipe hose". It sits just to the left of the left engine mount (or pivot). Can't tell if the coolant is leaking upward from the base of this metal "chimney" and striking the elbow hose above, or if the elbow hose is dripping coolant downward where it's collecting around the base. I carefully wiped the ring of coolant up with a paper towel and screwdriver head then ran the car at idle until the fans came on (~200 F) but I didn't see any coolant leaking out. A couple of days later, I re-checked and the (innocent-looking) green ring is back, but no other coolant elsewhere.

The question is, has anybody seen this on the Impala? The 6" elbow hose APPEARS to be OK, but it's only held on with those spring tension (factory) clamps. Should I just try replacing this short hose first? Might it be the "chimney"? This thing has a screw or bolt at the very top of it - like it's torqued down. Maybe there's a gasket underneath the bottom flange???

[tractorboy]

Whooaa , this is an 02 LA1 Impala ? you should NOT have the green stuff in it. You should have the red stuff, dex-cool. There is also a new blend that you can use in anything, i think it might be yellow. A mechanic told me , you can use the green stuff, although the green stuff may damage some plastic and aluminum parts. Also you do not get the extended service like you get with OAT type coolants like dex-cool. I have a 2003 3.4L LA1 also. Can not place what you are talking about, sounds like maybe a gasket, take your rad cap off ( when stone cold) make sure you have coolant in the rad. I will go out and look at mine.

[wafrederick]

Sounds like it is intake gaskets,a very common problem.Most auto parts stores stock the updated ones.

[57chevyragtop]

Well the first responder is right, your coolant should be the orange dexcool, but it may have been changed by previous owner. Not a great idea but others have done so with success when done right.
The screw at the top of the pipe is an air bleed device used to let air escape above the thermostat level. There another at the engine end of your top radiator hose on the right which this aluminum tube leads to the thermostat housing. These are used most often when refilling system and/or when air is suspected to be trapped in system creating an overheating situation. The flange at the bottom of this pipe at the water pump w/one bolt hold down may have a gasket or O-ring I am not sure, I haven't had a problem with mine (yet). The old 3.1 had a 2 bolt flange and a gasket which did fail once or twice over 140K.
Not sure by your statement where the water is puddling, on the ground? if so I would suspect it coming from the water pump weep hole first, indicating a failed bearing seal...this hole is on the back lower center of pump, in this case replace the water pump. If this is on top of pipe area the air bleed may not be tight..be careful these are brass but may be painted black, (soft metal) and is in two parts either could be the point of leak. Also the welds at the T and flange have sometimes failed. Also the clamps on the hose or hose itself may be the point of failure. Best way is to get the system pressure tested at a radiator shop, some guys charge for this, some don't, generally not more than 10 bucks. Hope this helps you some...dave

[phewop118]

That is not the intake gasket as someone mentioned. It probably is something to do with a hose by the thermostat. It's not too common, but I've heard people talk about it before. And don't use green coolant!

[tractorboy]

... also never mix coolant types like green with red. If you want to switch you have to drain and refill.

[richtazz]

Hopefully, someone flushed the system and re-filled with the newer greenish-yellow OAT type coolant, as Dex-cool (the orange/pink factory stuff) and the old formula green (ethylene glycol) coolants will gel when mixed. I would just replace the coolant bypass hose, and get rid of the spring tension clamps in favor of some stainless steel worm drive clamps. That is where it sounds like your leak is coming from. The intake gaskets leak along the seam between it and the cylinder heads, and wouldn't get anywhere near where you are describing. It's possible the black transfer pipe has corroded, or a weld let go, but try the simple cheap part first.

[tractorboy]

greenish-yellow OAT type coolant

I always thought the yellow was propylene glycol ?

[Colt Hero]

As far as the green coolant being in there ... I completely flushed the Dexcool out a year and a half ago (and 25,000 miles ago) when I noticed the plastic overflow tank looking slimy (along with the radiator cap - but NOT the engine oil cap). I wanted to clean all that crap out of there. I ended up putting in the "mixes with anything"-type coolant. Bought it from Wal-Mart. That's all that's in there right now - I flushed it repeatedly for a LONG time to make sure all the Dexcool was out of there.

Regarding the leak - which I STILL haven't done anything about - it's right at the base of that black tube that I mentioned earlier. It doesn't seem to be going anywhere and I haven't noticed a fluid drop in the plastic tank either. It really looks like it's just the 6" elbow hose that's very slowly leaking past the spring clamps and dripping or running down to the base of the short vertical black pipe. I'm going to try simply removing the spring clamps and replacing them with hose clamps. If that doesn't do it, I'll replace the hose next. If that doesn't do it, then maybe the short vertical pipe is leaking (upward?). Hope I can do this without having to drain the system. Don't feel like doing that...