As promised, here are a few shots of the heater core before I buttoned everything up. It mounts at a 45 degree angle upward from where the inflow and outflow tubes are (bottom right). Easy to see how air got trapped inside.

I think that is what we would call sub optimal design.

I think that is what we would call sub optimal design.

I don't know, it would be very easy to replace. I think it could be done in less than a half hour.

Just to give a bit of perspective - the actuator that I was bitching about is located just to the left of the fan in a very narrow cleft of the fan housing at the back and up.

Use a little imagination and you can see what a drag it was to get to.

UGH!

It's gone cold again!

UGH!

It's gone cold again!

Thinking water pressure could be part of the problem....which is why I wondered about the water pump.

I suppose that is a possibility.

But, I think that there was more air in the block itself that found its way into the heater core.

The heater core draws coolant from a high point on the manifold, so it makes sense.

I'm going to try to burp the core again.

PITA!

PITA for real....

You would think that a GM tech might have an answer for this. Your Tahoe can't be the only vehicle with this problem!

I have a thought about this.

I think it is connected to the loose manifold bolts.

The area of the manifold where the core draws water from is one of the spots I couldn't easily get to to tighten the bolts.

Air could be getting in when the engine is shut down and cools.

I'll burp the core and test the theory. If I'm right, it should work fine and then get cold after being shut down over night.

Edited October 25, 201014 yr by Camino LS6

That makes perfect, logical sense to me.

Pressure will equalize in a refrigeration system...I also used to keep aquariums, including Salt water fish...water will always try to equalize pressure with air....

Think you might be on to something!

Got to walk the dogs, then I'll put the theory to the test.

Got to get walked by the dogs, then I'll put the theory to the test.

Fixed it....Good luck bro!

LOL

Thanks, I'll report the conclusions.

Phase one complete, partial theory verification.

I dropped the core down to a flat position and ran an errand.

It got so hot I had to wait before putting it back in position.

Now, we'll see what tomorrow brings.

Confirmed.

Air is getting into the system, lodging in the core, and killing my heat.

Think you've got her licked....

Not sure.

All of the manifold bolts are now tight, but someone did a half-assed repair on the hose from the manifold to the core. It is supposed to be a screw-in fitting at the manifold, but someone cut the hose and forced it over a too large fitting and then clamped it.

I tightened the clamp, but I think it may be leaking around the threads of the fitting.

I'll price a new hose with the proper fitting from GM tomorrow.

Right now, the temp is lukewarm.

Edited October 26, 201014 yr by Camino LS6

Just think...by the time you get back to the Camino...you will have already done a nut and bolt restoration on the Tahoe, using all NOS GM parts!

With the level of practice your getting, the Camino ought to be a national show winner.

Just think...by the time you get back to the Camino...you will have already done a nut and bolt restoration on the Tahoe, using all NOS GM parts!

With the level of practice your getting, the Camino ought to be a national show winner.

That's one way to look at it!

My guess is that I'll complete both the wagon and the Mothertruck before I get to the Camino again.

After all of that, the damn thing had better win something!

...last non hybrid car operational on the planet?

I hope it doesn't take me that long!

Ordered the parts today - should have them tomorrow.

And get this...

I scored two virgin factory seats and a decent console for $200! One of the seats is still in the GM plastic.

A minor quibble is that my Tahoe has the 8-way driver's seat and the new one is just lumbar, but I should be able to add in the other feature. If not, so what?

You probably can make 2 into 1. The driver's seat motor assembly should be entirely contained on the track. As long as the two seats (specifically, the plastic trims) are the same color, you can probably swap over the button too.

That's what I was thinking, and yes, everything is the right color.

I wasn't looking for seats just now, but I couldn't ignore that deal!

Edited October 27, 201014 yr by Camino LS6

Here's the CL ad for the seats:

http://philadelphia.craigslist.org/cto/2023444155.html

I'm thinking the Tahoe just graduated to Project Car status - so I guess this thread ought to move.

Project Barndoor it is.

Glad to see it making progress.

I think I'm going to pick-up that factory stereo too.

I kind of like what your doing here, kind of like what Dodgefan is doing. Building a factory version of what you could have ordered back in the day...but paid for and on your own schedule.

Well, almost.

The one I ordered was a 5spd. manual and had a tailgate.

...and was supposed to be black with a grey interior.

But other than that, yeah.

I often wonder what happened to that truck.

The twilight zone?

Maybe.

I saw it the day it came in, and then one time after it was sold.

It's a rare truck if it still exists.

I used to have the VIN #.

New line, fitting, and sensor installed - we'll see what happens.

Keep us posted.

No joy yet.

Same old thing - drop the core down flat, and it gets so hot you can't touch it. Re-install it in the proper position, and it goes cold.

No new ideas on the heat, but I picked up the factory stereo today.

Getting more than a little chilly...

Just $12.99

Just $12.99

Thats just wrong. Have you ever actually used one of these? He'll get more heat from the non-functional HVAC through the floorboards.

Ha, more heat is available from two big dogs, methinks. Just gotta be the Gorton's Fisherman and wear a big yellow raincoat to guard against the heavy mist.

If I had both of them in the car it would be red mist.

Installed the stereo - works like a charm (have to chase down some speaker wires and test the CD player).

And, I just finished an extensive "burping" session on the cooling system. I'm going to leave the heater core in the "down" position for a while as I drive around.

We'll see what happens.

CD player works like a charm.

I'm thinking about installing the new seats today ( I'll deal with the 8-way thing later}.

Heater core is still not getting hot like it should - at least not as quickly as it should (even in the "down" position).

Once the seats go in, Arkus is banned from the Tahoe.

Maybe I can find one of those pet barriers people used to use in wagons.

Is there still and issue with the intake manifold bolts?

Nope.

All of them are tight and it no longer makes a cloud of vapor when running.

However, I am wondering if a small leak is allowing air into the system when the engine cools.

I am going to cycle it a few more miles to see what happens.

Wouldn't that small leak allow coolant out as well?

Wouldn't that small leak allow coolant out as well?

This small leak may not even exist when the engine is hot due to expansion of the metals.

When the engine cools, it is possible that a minute gap opens. If so, since it is at a high point (manifold), any air in the system could settle there and not allow for a coolant leak. I don't know, maybe I'm just clutching at straws here. Never had so much trouble with bleeding a cooling system before.

At any rate, no coolant is leaking anywhere, and the core seems to be heating up as it should now. I still don't want to put it back in the "up" position yet, as I want to be reasonably sure the problem is solved.

On another note, I installed the new driver's seat - and WOW!

The brackets it sits on are pickup-spec and sit much higher - so much nicer than the old seat. I may never re-install the lower, 8-way adjustable, Tahoe version. I now have "command seating" and I like it!

I can feel the temperature dropping, even here inside the house. So, I think I'll go install the other new seat and console before it gets too chilly.

With the new interior parts, dash controls, and stereo, this thing is really starting to get pretty nice.

That doesn't mean that I don't still have a long list of things to do to get it "right".

It sure does help to make it worth it, however.

Have you done a pressure test on the cooling system with the engine cold? If there's a less-than-perfect seal anywhere, that might force some coolant out, and you'll find where the air is getting in.

I don't have the equiptment to do a pressure test, but it might be a good idea to get that done. It heated up just now, but I'm not sure it will repeat (I re-installed the core again).

The seats are both in now and man, what a difference! The interior is starting to look really good now.

The console doesn't fit - who'd have guessed that the trucks have a different floor than a Tahoe? Mine is in just as good of a condition, so I just cleaned and re-installed it. Guess I'll CL the other one.

My father has one of those things. It looks like a bicycle pump with an end that fits over the neck of your radiator, and it has a little pressure gage on it.

Kind of like this