jav

Good guess on the bleeder screw, but it's bone dry around there. I also did the bleed trick on the hose on top of the heater core just like you said. I loosened it up and squirted coolant all over the place. Then I actually flushed the heater core with water, hooked it back up and tried to bleed it again.

This is when I noticed something really weird (and I'll probably start a new thread on this shortly) - I warmed the car up and the lower heater core hose got nice and hot. The upper hose....cold. The aluminum coupling....cold. COLD!! WTF!!! How is this even possible? I flushed the freaking core out 10 minutes before that and the coolant (and then water) flowed right on through. Now, one hose hot, one hose cold - this just doesn't seem possible!

What am I missing???

fjasper

Sounds like the heater core is plugged.

You might try a cooling system flush. There are different methods, I used wood bleach and washing soda because my cooling system was in really bad shape. Makes a big mess and takes a lot of time, but it worked. Probably worth it to start with gentler chemicals or have a pro do it.

http://www.bobistheoilguy.com/forums...Number=1682519

jav

I was able to run water into the upper inlet and it came out of the lower with no discernible resistance. Just coolant came out with no rust, gunk or other goo.

But thanks for the suggestion.

5v/cyl

Still clogged or you have a air bubble caught in there.

My heat was weak so I flushed the core with Limeaway (or CLR) in a 50/50 mix with water. Left it in there 15-20min a time and did it twice. Flushed it out really good with water afterward.

To get all the air out I elevated the reservoir and filled until coolant with no air bubbles came out of the top hose bleeder spot(engine off). Slid hoes all the way on and started the engine with reservoir still elevated and cap off. Ran for 10 minutes and revved it up a bit. Recapped + remounted the reservoir and test drove. Heat was nice and hot.

fjasper

In the original post you mentioned the water pump. Have you done any checking on that? At idle the flow is pretty weak, but it should increase noticeably when you rev it up. The heater core bleed hole is a good place to check this, if you have someone rev it up while it's bleeding.

If it doesn't, maybe the water pump is damaged somehow? I think some of the early pumps had plastic impellers that could lose effectiveness without catastrophic failure, but I could be thinking of a different motor.

I don't think the 2.7 has an electric coolant pump other than the after-run pump. ??

As for mystery water loss, if it's leaking around one of the coolant temp sensors on the cross-pipe at the back of the heads, the coolant will drip on the hot manifolds and evaporate, leaving no visible liquid, but a strong coolant smell.

Maybe take a look at the whole heater circuit and see if there's a blockage outside of the heater core.

Good luck.

swamper8

Yes there’s only one electric pump and that’s the after run pump. The main pump is engine driven. I have read a few threads indicating that some water pumps have plastic impellers. I’ve also read that if these impellers do fail, not only will you see decreased flow/volume, but the little plastic pieces can get stuck in all sorts of places (radiator, small diameter coolant tubes etc) which could cause restrictions in flow throughout the system. The “clog” wouldn’t necessarily need to be in the heater core, it could be ANYWHERE in the system. Once the flow is restricted, it’s restricted. I’d exhaust the “burping” methods described here before you tear into your cooling system to check on the water pump impeller. That would require labor similar to that needed for a timing belt job (removal of the front bumper, swing out the radiator support, partially strip down front of engine) so that’s a lot of work to do if it’s only air stuck in the system somewhere.

jav

I tried a method similar to this but didn't have anyone rev up the system while I was bleeding it. I would agree that at idle, the flow is pretty weak. Might help explain why things are the way they are.


Hmmmm.....now THIS sounds like you might be on to something. I can hear a little something right after the engine is turned off coming from the back of the motor area (it quits before I can track it down) and after looking at my new Bentleys last night, it might just be the passenger side temp sensor. I'm going to have to find a way to get a good look at it tonight. Good call. A temp sensor leaking would sure be a whole lot simpler than the water pump falling apart.

jav

If I'm digging into it that far, I'm replacing everything along the way anyway so whether or not it's toast wouldn't be relevant at that point. Way too much labor to not replace all that stuff while I'm in there.

The flip side of that situation is now there are plastic pieces all over in the cooling system and god only knows where they all are and what sort of damage they'd be doing. I'd hope that the temp gauge would actually register a high temp if this were the case, but I've been working on cars way to long to just assume that the temp gauge is giving me the real info and not what I want to see.

I'm going to try to burp it again and check that water leak. The good news is that I'm slowly learning a lot about the car. So I suppose that's good.

fjasper

Ha, ha, ha. Be careful. Next thing you know, you're in a long-term relationship that you can't get out of...you'll know so much about this car you won't want to switch to a different one.

You (I, at least) get this little burst of endorphins when it's all working right, and you'll do or spend anything to get that feeling back again. Drugs would probably be cheaper and easier...

brider

Let's hear "the rest of the story"!!

Just discovered I have NO heat, so I'm curious how this turned out...