jeffreyalman

while checking the overflow bottle this weekend, I was alarmed to see that it was near empty and the coolant was dirty / rusty / nasty.

I flushed it out real good with a hose and left it about 3/4 full of water, while cold.

I checked the radiator the next day and was alarmed to see the coolant (good and green and clean) was about 3 inches low (from the top)

I did not top it off.

I just drove to work (about 20 miles) and checked the overflow bottle, looks about 1/4 full after the ride (too hot to open rad cap)

I am trying to figure out what is going on.

When I got the car a month or so ago, I had the rad replaced (well, re-rodded) and the cooling system flushed.

My mechanic says that he did the entire cooling system, i.e. block and all and added a conditioner and that may be why there is crap in the bottle, crap coming loose from the flush and conditioner approx 1,000 miles ago.

I buy that but I am puzzled as to why the level is low in both the bottle and the rad itself, with no apparant leaks.

Car runs fine, no steamy exhaust, and the coolant looks fine (not oily) albeit low in the rad.

Any ideas?

rocketraider

Although it's unnerving, I think you're chasing a problem that doesn't exist. An understanding of how the closed system works is in order.

A closed cooling system's pressure cap relieves pressure to the overflow tank instead of to atmosphere. It also self-vents the cooling system to overflow to purge any air out of it.

When the system cools, a vacuum is created in the radiator tanks. After a cooldown cycle, pressure cap then opens against vacuum to siphon coolant from the reservoir back into the radiator to keep it full at all times.

I expect the radiator wasn't completely purged of air after the work was done. It sometimes takes several heat/cool cycles to purge out all air and establish the system's optimal level. If you will look at the "cold" and "hot" marks on the overflow tank, you'll see that "fill cold" is roughly the same level as the radiator cap.

If you don't see any external leaks, or signs of internal leaks, you should be OK though pressure testing the system may give you some peace of mind. With the system cold, fill the radiator tank to just below the filler neck. Then fill the overflow jug to "fill hot" with 50/50 coolant mixture and drive the car over a few days, allowing it to go thru several heat/cool cycles or until you no longer see the level in the overflow dropping.

At that time, I think you'll see the radiator tank level has established at just below the filler neck and the overflow should be stabilized at "fill cold" when you check the levels cold.

If not, then you need to pressure test it and see if there are leaks.

If this is on the wagon, I'm guessing the car also has "low coolant level" warning. Most 70s Toronados and Custom Cruisers I've seen have had it. See if there's a probe and wire on the radiator cold side tank (same side as pressure cap). My 76 CC used to flash that warning lamp for no good reason, with the system full and no air pockets. The Ninety Eight has done it a couple of times on very hot days after a high-speed run.


The closed system w/overflow has fooled a lot of people on cars with open systems (overflow tube that vents to atmosphere), because they will try to fill the radiator up to the bottom of the filler neck same as they would a closed system. Then the car will puke antifreeze until it establishes the coolant level it wants. Most of those radiator tanks are embossed "full cold"- about 3" below the filler neck.

Fill it and let it go thru a few heat/cool cycles, establish its overflow tank level, and I think you'll be fine.

jeffreyalman

thanks a bunch, yes, it is on the Custom Cruiser. Makes a lot of sense. Do you think I would be ok in filling the overflow bottle and letting the system find it's happy level via driving / cool down, then just keep an eye on it? It's usually too hot to open the radiator when I am ready to check it.

jeffreyalman

Well the problem existed all right. Whilst driving home a couple of weeks ago (S Fla rush hour, 90 degrees out, A/C on, bumper to bumper traffic --- is that considered severe duty???) I noticed steam on the outside of the windshield at a red light. Hmmm. That didn't seem right. Got home, looked around, all seemed dry. Next morning, 6am, on the way to work, same thing. Just summer humidity??? Got to work and popped the hood. Saw a little seepage around the water pump but no biggie. Later that day, got home, popped the hood with the engine still running and just stood and waitied. As soon as the A/C kicked on (I have eliminated the VIR but that's another story) the extra port on the water pump (with the rubber cap) started spraying a fountain. $6 later it was fixed. Replaced hoses and bypassed heater core, along with another flush.

Where there's smoke, there's fire (or a coolant leak)

"Trust your instincts"

rocketraider

The car's had the water pump replaced if it has an "extra port" that you had to cap off. The correct one should have either a pressed-in cap plug or a blank casting boss at the extra heater hose fitting location.

The 1976 car routes the heater return hose to the top of the radiator cold side tank rather than the water pump. It was a permanent engineering fix for a heater moan and gurgle condition they were getting complaints about in 1971-73.

I'm waiting for someone to ask about the weird heater hose going back to a brass tee in the lower radiator hose setup on their car. That was the temporary fix released in mid 73.

jeffreyalman

For sure it was replaced, and that's fine (one less thing I have to do)

Same replacement as the other 2 girls have had done, and none of them by me.

Now that the heater core is bypassed (I suspect that was starting to leak as well, and I do not need heat in S Florida) I no longer get steaming on the inside of the windshield after I park (although the r/f carpet was dry) I suspect it was only a matter of time and I do not need nor want heat or the possibility of coolant inside the passenger compartment.