nymart

I was sitting in the line at the car wash yesterday (I think I'm going to stop washing the car because this is the second time in a month something has happened while sitting in that line...I guess our cars really do just want to be driven and not washed!! ) and I noticed that I was putting out a lot of exhaust. It was white and seemed to dissipate quickly so I wasn't sure if it was really anything or just steam (it was in the low 40s outside). I decided to drive the car straight home and when I was about 2 miles away, the temperature gauge shot up and the light came on saying engine too hot. I got ready to pull over and the temperature went back down as quickly as it went up, but then the coolant light started blinking and a message said low coolant. I got home and let the engine cool off. When I checked the level in the tank, it was really low. I added a gallon of coolant with a gallon of distilled water and that brought everything back up to right around the max line.
I started it up a couple of times in the process and let it run for a few minutes. No indicator lights came on and temperature remained as it should. Then I would let it cool and add more coolant mix. No leaks showing anywhere but occasionally, I still saw white exhaust that smelled of coolant.
Today I took the car out to run an errand. Coolant level was near max when I left and I let the car warm up as I always do until the rpms settled down. About 3 minutes into the trip, the coolant light started flashing again and the low coolant message came up. Engine temp wasn't even up to normal by then. I drove back home and looked at the coolant level and it was way low again. I eased off the reservoir cap allowing the pressure to escape and glug, glug, glug, the expansion tank begins to fill back up from the lines. But it never got back to even the MIN mark on the fill tank. Seems like it is down about a quart or so if I had to guess.

Any thoughts or suggestions? I have no leaks showing under the car and everything seems to run fine. I didn't notice any excessive exhaust today either.

BTW...AOS was done back in March so I doubt I have an issue there.

fpb111

What year, how many miles?
Did you check around the front rads and plumbing down the center of the car? What part # is on the cap, end in 04? Under the water pump completely dry? Thermostat sticking?

BAD.TAG

Its going somewhere, I would check the oil before driving any further.

nymart

fpb111...2004 C4S 48K...checked around front rads, completely under car to back, blue cap on reservoir says 447.01 on the end, water pump looks dry...no crusting around reservoir cap, thermostat could be sticking I guess, but it moves fine from cold to normal operating temp just left of the zero in "180"...

nymart

Bad.Tag...first thing I checked...with the dipstick...oil is clean and clear...I read that it would look like a milkshake if I had intermix...

BAD.TAG

Ok good. Didnt see that mentioned initially and wanted to verify.

I did have a case on mine where a leaking radiator was losing coolant but not dripping. Instead it was crusting up on the fins and I would get a strong coolant smell when spraying them in a self service bay. It was not something that was immediately noticable.

Have you ever had the rads cleaned or replaced?

Macster

Reads like the coolant got exceptionally low -- probably due to the cap leaking -- and low enough that adding the gallon of coolant probably trapped a bit of air in the system.

The subsequent behavior was from this air bubble working its way out of the coolant system.

You have done all the right things, checking for intermix (and check the oil level too to be sure it is not suddenly "too high") and for leaks.

With no leaks then the cap becomes suspect #1 and I would replace it pronto. Be sure the coolant level is correct and keep a close eye on it. If it goes down again there's a leak. If there is my WAG (I like to get mine in early to beat the rush) is the coolant tank has a crack/split in it that only really opens up when the coolant is hot.

So one pressure test you can do is to drive the car around until it is good and warm, fully up to temperature and has been for some time. Be sure the A/C is off.

At home raise engine RPMs to say 1500 and hold until you hear the radiator fans come on. Then shut off the engine. The coolant is hot, based on my info 212F. With the engine off the coolant will get hotter as the heat load of the engine permeates the engine and its coolant. This raises the pressure. Hot coolant under pressure can often make a leak known that remains hidden under less demanding conditions.

fpb111

+1 with getting a new cap first ~$20. Original caps, part # ending in 01, were weak and have a bad rep for partial/full failures. I think the latest part # ends in -04.

2nd look at the "frame rail" under the tank for stains that would indicate expansion tank crack. If your tank is original there is a pretty good chance that it has a crack that opens when the engine gets hot and makes pressure. Use Macster's method to check the tank.

Also not the problem now, but could cause it in the future. Clean the rads so they don't corrode!

nymart

Thanks for all the input...I was planning on cleaning the rads over the winter...will be first time since I've owned the car (2 years)...I'll order a new cap immediately and see if that helps

It's raining here today so it's a little hard to check for leaks anywhere since the whole bottom of the car is wet. I'll let it sit til the roads are dry and then try Macster's tests to see if I can pinpoint any leaks anywhere. Has me pretty scared to drive it around right now as I don't want to overheat and do some real damage. Read up today on water pump replacement and although it doesn't seem to be an issue, I may go ahead and replace it as preventive maintenance.

fpb111

get a UVeiw 550000 to make filling very easy

Sneaky Pete

That is pretty neat gizmo. Amazon has it for about $120.

wwest

You have a head gasket leak....

kromdom

+996 to having a PRESSURE test done soonest...help you pinpoint/locate the source of the leak.

nymart

wwest...that's what I'm afraid of...but since I don't have visible intermix right now, it would have to be fairly small...and then that leads me to the next question...is there a way to test for this? Wouldn't a pressure test on a car with a cracked head gasket force coolant into the heads thereby causing more harm?

Macster

I reread your initial post and I do have to say a head gasket leak is a possibility. I would therefore advise you to not run the engine.

With a head gasket leak there could be oil in the coolant or coolant in the oil.

Usual sign of oil in the coolant is globules of oil floating on top of the coolant in the tank.

For oil you can drain the oil and look for coolant in the oil. If you don't want to drain the entire amount of oil just remove the oil filter housing and dump the oil out into a *clean* pan. You can pour some into a sample bottle and send it out for analysis. Among other things the analysis looks for anti-freeze compounds in the oil.

Another way is to remove the plugs and check them. If there is coolant leaking into the cylinder this will clean the plug tip and electrodes and the plug from the cylinder with the leaking gasket will stand out from the other plugs.

Or just take the car to a proper shop and have the system pressure tested.

Oh, it might seem odd but I'd do this with the system drained of coolant.

The issue with coolant leaks is if the leak is under water so to speak and the system cold even pressure may not be enough to cause enough fluid to leak out to lower the pressure that much. Really, a pressure test with the system full of coolant just tests those areas of the cooling system that are above water.

By draining the coolant all areas of the cooling system are above water, are exposed to air directly, and experience air pressure directly. Even the smallest leak will let air out and you will see this as a pressure drop.

But of course the above is my thinking. I'm sure your trusted tech will advise you of what he believes is appropriate.