i've got the cooling system blues...

After putting new rear brakes, new tires and some general maintenance on the car (and a couple hundred more miles) we headed off to the coast to enjoy time on the Oregon beaches. After a grand day, we were about 60 miles from home when the temp gauge went from happy to pegged with the overflow tank at the high mark. After getting towed home at dusk I started thinking about what happened.
So, morning arrives and I have a game plan. I was expecting a water pump replacement, but still wanted to check other things. So, I buy a cap and t-stat at the local autozoneout. I pulled the cap and the radiator is empty and the overflow immediately starts flowing back to the radiator, so I replaced the cap. I also pulled the t-stat and stuck it in boiling water. No change! Augh ha! Tossed the new one in the water and it functioned. SO, I toss it on the engine, button it all up and start bleeding the system of air. After all that, I go for a long test drive and all seems well. Up big long hills with the a/c on and the needle is happy.
Move on to this morning. The wife heads to the next town over, no issues. 3 hours later, she and the girls call me 5 minutes into the return trip. Pegged again! I get there with water on hand and send them on their way in my truck. When I pulled the cap off, there was NO, NOTHING, NADA, ZIP, ZILCH in the way of water in the system. This time nothing even in the overflow. I filled the system again and drove home without issue. Tonight I took it for a 5 mile drive and the needle started to climb rapidly. I opened up the heater and the needle settled in a bit higher, but stablized. Tonight after letting it all cool down, I added a little water and tried to bleed air again assuming it was still there from the last attempt.
Faster forward 45 minutes later and it is still burping... Am I wrong to assume I have a leak somewhere and it is pulling air into the system away from the radiator? Or, with the quick loss of water (even if there was air in the system) am I looking at a head/head gasket?

As you can see by my name, I'm a VW guy normally and radiators are foreign to me!

Thanks for looking!

See if you can get your hands on a coolant pressure tester (Either Advance or Autozone should have them to rent/use).

The one concern I have is the burping. (With a radiator/hose leak, I thought that the reservoir tank should empty out as well - at least mine did).

I posted on the ISSF, but have another item for you to check...your oil. Pull the dipstick and check the color. If it is normal...nothing to worry about. If it is tan foamy...you have a gasket issue.

What year is you wagon? 91-93? or 94-96? The cooling system is different between the two year ranges.

I would rent a cooling system pressure tester from the auto parts store and try that first. You might have a leak that isn't that noticeable by the naked eye. You stated that the rad and the reservoir were empty the next day, I assume that was with the new rad cap installed; so what cbshea13 was concerned about; "The one concern I have is the burping. (With a radiator/hose leak, I thought that the reservoir tank should empty out as well - at least mine did)." is indeed being emptied since you replaced the defective rad cap.

Have you noticed any blue smoke out the exhaust? With the radiator full of coolant, the rad cap off, and the car running at approx. 2000 rmps, do you see any bubbles/gurgling at the rad opening? if your confident you got all the air out of the system I would guess head gasket issue. You can get a test kit to check for exhaust gasses in the coolant, to verify that a head gasket is blown.

Good luck.

vwfye wrote:

I get there with water on hand

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ZILCH in the way of water in the system.

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I added a little water

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Or, with the quick loss of water

Water, or coolant? No offense meant, but:

Quote :

As you can see by my name, I'm a VW guy normally and radiators are foreign to me!

Coolant/anti-freeze has a higher boiling point than water, when mixed with water in the correct proportion. Water is better than nothing, of course, but does tend to boil off more readily and can boil in the block even with a good pressure cap on the system.

What car do you have -- the later (94-up) cars had the LT1 engine with a completely different cooling system than the earlier models. With the earlier ones, the reservoir is not under pressure. It draws coolant back into the radiator as the radiator cools down -- IF the system is sealed. The LT1 reservoir is under pressure and connected to the rest of the system at all times. Any air bubbles in the system are supposed to make their way here, lowering the coolant level in the reservoir proportionaly.

That said, both are closed systems and you should not be going through that much coolant in such a short period of time. There's really only 4 places it can go:

1. boils over out the cap/reservoir bottle as you drive. Usually obvious by clouds of steam escaping from under the hood. Most likely causes are plugged radiator, bad thermostat or use of water instead of coolant, particularly under load.

2. leaking out through a hole in the radiator, hose, crack, heater core, etc. Usually detectable by stream of coolant or steam visible from hole, puddle under the car. Small leaks may evaporate as fast as they leak, making detection difficult. Look for damp areas or small puffs of steam. Yours does not sound like a small leak though.

3. internal leak into engine. Detectable by checking the oil, as mentioned above. Cause is usually blown head gasket (usually associated with warped head), may also be cracked block or head.

4. internal leak into combustion chamber. Usually obvious by white clouds of sweet smelling exhaust. May also hydro-lock engine when shut down, preventing cranking. Causes similar to #3.

Sorry guys, I forget how different these cars could be under the skin. Mine is a 92 with the 305.

I'm currently awaiting a pressure test and a hydrocarbon test at a shop. I think it is the rear left soft plug. I'm waiting to find out how wrong I am.

Sorry for missing that "overflow" being empty earlier - I blame the lack of coffee in my system. Hopefully it's nothing too drastic, good luck!

Diagnosis complete at a shop. The leak is from the intake manifold seal. Also, while functioning, the output of the water pump is low (probably from when it was running dry). The lower radiator hose was also the original... yikes! The shop found no hydrocarbons in the system (head gaskets okay). They wanted almost $800 to replace everything. We can't do that, so $110 into parts and I am tackling it myself.
My only confusion right now (due to vision issues) is how much at the rear behind the TB has to come off.

You can take the TBI and manifold off as one piece. You will need to pull the air cleaner box, coil, cap, dizzy. Disconnect the coolant hoses, fuel lines, vacuum hoses; I know I'm missing something. but that should get you started. If you have an factory service manual there's a pretty straight forward process all written down for easy reference. Oh be careful with the brittle vacuum lines.

scoffman wrote:

You can take the TBI and manifold off as one piece. You will need to pull the air cleaner box, coil, cap, dizzy. Disconnect the coolant hoses, fuel lines, vacuum hoses; I know I'm missing something. but that should get you started. If you have an factory service manual there's a pretty straight forward process all written down for easy reference. Oh be careful with the brittle vacuum lines.

I picked up a Haynes manual for mine, and it's pretty straight forward. Though in there it says to remove the alternator brace as well, and recommends to label all the wires/cables for reassembly, then it's just the manifold bolts.

Intake manifold is easy. You can leave everything on the intake and just remove it. Mark distributor, remove, pull the intake.

Distributor comes out by pulling up, leaning toward the driver's side, and pulling it. You have to pull the rotor off to get it to clear the cowl.

Been there, done that. lol

Water pump is cake, too. Pull 4 nuts for the fan, remove fan/clutch. Undo serpentine belt with 1/2 drive ratchet, disconnect lower radiator hose (and throw that old one out... way out), then it's just 4 bolts that are (I think, if I remember right), 9/16".

I have the pump replaced!  I'm working on the back 1/3 of the intake manifold.  The coil pack bracket and distributor specifically.  I can't get the coil pack bracket bolt without getting the distributor out, but with my crappy eye site, I can't see where the distributor lock down is.

I also know now why it leaked... The entire old "gasket" is a silicone home brew job :-(

I'm still fighting the manifold removal at the moment. Didn't realize I needed a special wrench to get to that silly dizzy bolt or a 5.5mm socket to remove the dizzy cap. That corner of the manifold is a pain in the butt! I can't remove the shackle eyelet because the heater core hose is in the way. I can't remove the hose because the electrical connector on the shackle is in the way and I can't get anything else removed because the dizzy is in the way. Doh!

I'll pick those up in the morning when I go pick up the ordered parts. Hopefully it will all be buttoned up tomorrow.