Lopez

Well... I knew it had to happen sooner or later

After driving 1300 miles with the car being flawless, the FIRST TIME I take my wife (and 2 kids) for a ride in the new car I ran into the first problem. Not a major one I don't think - lost all coolant on the freeway, although fortunately I was already exiting, and as soon as the temperature spiked I had it off and parked on the side of the road within 30 seconds or so.

The coolant loss was fast - way faster than a blown head gasket or anything like that. It was was cascading down from what looked like where the filler tank is, about 1/2 way up the passenger side fender. It was hard to see (dark, water was coming from somewhere down the side, under the intake tube). Also, the oil stayed totally clean. and it really seemed not to be coming from the engine itself.

Any ideas where to start? The car has new rubber between the engine and radiator, but probably has old heater hoses and any other coolant lines are probably brittle. Just wondering if there's a common culprit for this...

Thanks!

Chris

NickT

The over flow tanks do crack over time.. I would not be surprised if that was the problem. Not a big item to fix, $120 if I remember right when I did mine and about 30-45 mins of work. It's not the easiest of things to get out, bit of a fiddle but doable.

NickT

In that area you also have the lines going to and from the heater core and obviously the lines going to and from the coolant thank. Not sure about the 79 but my '88 also has a metal "Y" tube that I found to be perforated, just rusted over time. While your there you might also want to check out the heater control valve. It's plastic and also wears over time and allows the flow of hot water when it shouldn't. NAPA has an all metal replacement for it and much cheaper than the OEM version.

Good luck.

Mrmerlin

if you can find out whats leaking then it will be easier to give proper instruction, but. look at the resivour tank having cracks, if its yellow looking then its time to replace it as well as the cap and level sensor, even if they work,
When you remove the tank disconnect the hose that connects to the metal lines not the bottom of the tank, when you put the new tank in then connect the hose to the bottom of the tank first making sure to orient the clamps so they can be snugged at a later time from under the car.
Also pay careful attention to the rear of the passenger cylinder head (after you remove the aircleaner lower housing)there is a heater hose connection that has a small 2 in. hose this usually breaks or the rib on the heater control vave cracks and then the valve slips out of the small hose. Either way i would replace the heater control valve and the small hose at this time, this is the usual fail point.
The other thing to look at is the top of the pass side radiator this is where your radiator will usually start leaking, and lastly look just under the crank damper (The big Orange pulley)on the top of the oil pan make sure its dry , if its wet then it could indicate that you have leaking waterpump

Lopez

Thanks everyone - seems like it is probably in the tank / heater hose / core area. TB/WP are new and the radiator is in good shape and does not leak. I'll start pulling it apart later today.

Bill Ball

Most people only replace the upper and lower radiator hoses, but all the coolant and heater hoses in a 79 are long, long overdue. The overflow tank can crack, but with an abrupt dump like you had, the likeliest cause by far is a blown hose.

Nicole

That was my first thought when I read that the coolant comes from near the filler tank.

I've done the preventive coolant hose replacement last year, and it was a "fun" project that required a few unexpected WYAITs. You can search for threads I started on Coolant Hoses in the last year and follow the drama before you tackle the project on your own car.

Best of luck!

Cliff Ruckstuhl

I had this happen 2 blocks from home I started to smell coolant and then the steam. On my car where the heater hose comes out of the block to feed the heater coor in the dash the metal nipple just poped out. I took some JB weld for metal and glued it back and it has been fine. WHen it let go it pumped out all the coolant very fast.

Cliff 87 $ 4 Murf # 44

Lopez

Well, interesting problem this is turning out to be. So I pulled out the expansion tank just to get a look at everything in there and see if I can see the source of the leak. The tank itself looks fine and doesn't seem to be wet at all on the bottom, and all the hoses seem OK. In fact, I can't see any source of last night's coolant leak at all (save for the spot on the driveway where it was starting to leak before setting out - I noticed that after we got back with the car on a flatbed). Also, this morning, it also seems that there is still water in the radiator (can feel/hear it in the main radiator hoses).

So, I got about 3 feet of radiator hose and hooked it up to the main connection on the bottom of the expansion tank so I could re-fill the system with it on top of the spider and watch what happens. After checking the hoses everywhere, I topped it up and started the motor to let it warm up, hopefully to see the source of any leaks when the system pressurized. So far, it's not leaking at all that I can see, but the temps are running up above normal (toward the red line at the top of the gauge - which never happened before yesterday) and it also seems like the water isn't flowing. The hose that runs from the bottom of the radiator up to the motor is staying cold - as is the radiator itself.

So now I am wondering if what really happened was the thermostat is sticking shut and the leak yesterday was the cap venting from too much pressure. It seemed like a TON of coolant was coming off yesterday, but it was totally dark and I wonder if the steam was making it seem like more volume than it really was... For now I am going to keep it shut down until I can pull the thermostat. Unless someone here has a better idea...

thanks again everyone.

dr bob

Chris--

On my car (S4 so may be different...) there are some smaller coolant hoses to the reservoir from forward. Two have steel sections where they pass along the shock tower, two smaller vent lines pass above the shock tower. For the steel lines, there are connecting rubber sections between the reservoir and the pipes in the rear, and between the engine and the pipes in front.

In the rear of the pass side head there's a short section of hose between the nippel on the head and the heater control valve. The valve itself is notorious leaker, while that short hose is a commpn failure point due to the higher heat it sees at the rear of the head. From that heater valve, a hose reaches across to the nipples on the heater core on the driver's side at the base of the windscreen. The return from the heater passes back across to the pass side and the reservoir area.

IMHO, a baseline service would include ALL of those hoses, just to be sure you don't get stranded by something stupid again. This is of course especially important for when the family is riding along. They will forever carry a paranoia about that cursed car.



The overheating problem is likely caused by air stuck in the top of the water manifold where the thermostat lives. There's a vent line on mine that's supposed to allo air in that area to bleed back to the reservoir, but the line doesn't (can't really...) slope correctly for the air to 'rise' up to the reservoir. More than a few folks have chased your symptom, and replaced the thermostat and the sealing ring behind it, stuff like that. While it may in fact be a thermostat, it's much more likely just the air in there. Pull the ends of the vent hoses off at the water manifold and the top of the radiator shell as you fill, and only replace the hoses when you have a solid stream of coolant coming out of the nozzles there. That should get you going OK. After the car has been run a bit, the remaining air will bubble out at the reservoir.

When you order all those hoses from Jim, get a new thermostat and the two seals, a new reservoir cap, and a couple aluminum 'sealing' washers for the two galley drain bolts on the sides of the block at the rear.


There was a nice discussion on coolants lately that you can look for. Best is likely what's in there now if you know what it is. Otherwise, flush completely with those galley drains and the radiator plug open, and fill with some coolant and distilled water. I've been using the G-05 stuff for a while with no gripes, along with a bottle of Redline Water Wetter additive. This is Pep Boyz stuff, BTW.


Let me know if you need help on any of this. You have my phone number.

Ron_H

Always carry a spare section of heater hose in the car. This is how I know: on the road to Boise, Idaho, that passes through Rome, Oregon, (a literal spot in the road) and miles from anywhere civilized, in an instant, I see huge steam clouds coming out the back of the car and see the temp guage fly up. I wait for an hour. No one comes by. I load my shotgun expecting a long night. Finally, a car stops and he has a CB radio. He calls a tow truck back in Rome. The car is towed 100 miles to Boise. I couldn't figure out why no bears were roaming around the roadway. Then I heard that during that period of time, they were all out in the desert searching for a convicted murderer who had escaped from a prison in the area. Comforting thought for the evening I almost spent on the side of the road. Keep a section of heater hose in the car; It is an easy fix. And carry extra water if you cross the desert.

Lopez

Hmmm....

So, following Dr. Bob's advice, I made sure there is no air behind the thermostat - I can squeeze either of the two main radiator hoses and water will shoot out through the air vent line into the overflow tank. So that would seem to indicate to me that the thermostat is open? Would this be correct?

The car still is getting too hot, however. No leaks anywhere I can find, but if I let it sit the temperature is creeping up too high. I guess I'll do a search for "overheating" and see what I can find.

Lopez

Okay - I have a theory. Please tell me if it makes sense:

Car runs absolutely perfect for just over 1000 miles (driving cross country), suddenly starts to overheat after several short trips locally. I can't find anything but lovely, supple rubber hoses and no leaks when pressurized.

Car has NEW TB/WP, installed just before I picked it up in. Job was done by someone who is NOT a 928 specialist.

My theory: The TB wasn't properly tensioned when it was installed. Even if it was close, it may have stretched after being driven and now needs to be re-tensioned (and is loose enough to not be turning the water pump pulley). Does this make sense?

Ron_H

How many miles have elapsed since it was installed? It should be re-tensioned at +/- 1500 miles.

Lopez

It's been about 1300 miles altogether.