Low Coolant Level

2007 Chevy Impala 1LT

Auto Transmission

17,000 miles

3.5L Flex Fuel engine – has only ever had 87 octane gas in it although all gas here in St. Louis has at least 10% ethanol by law

Since the car was new 2 1/2 years ago, the coolant level in the reservoir tank has always looked rather low to me but the dealership shop said it was normal when I had the car in there for another warranty issue and questioned the coolant level. They even made a mark on the coolant tank for where it should be.

Well, it has gradually gotten less and as of today is barely halfway up to that already low mark. No warning lights on the dash, temperature never running hot, no check engine light, no performance problems. No drips or stains on the garage floor to indicate a leak. Oil looks normal and not adulterated.

I’m due for an oil change anyway. Normally I would take it to the independent mechanic I’ve used in recent years but am thinking of going to the dealer this time to question the low coolant at the same time.

Any suggestions what to ask about, look for, whatever??? I can’t believe a car with this few miles on it would have any problem with coolant leaking into the engine somewhere.

Since I do mostly very short trip driving and have to make a point of regularly driving far/long enough to avoid excessive wear from unburned condensation, should I just have the cooling system serviced/flushed before the onset of really hot weather since it is 2 1/2 years old and watch the coolant level from there?

Perhaps have a coolant pressure test (with a dye in the coolant) done to see if there is a beginning of a possible gasket breach.

If you have to add a cupful per day to maintain the proper level, the coolant is definitely going somewhere.

I’m quite sure you know wheat happens when the coolant and oil mix.

You’re right though, you shouldn’t be having problems with any vehicle (let alone a GM) at 17k miles on it. Then again, it IS man made.

I suppose they’re like everything else, it could have faulty parts installed (or improperly installed) to begin with.

If the cooling system is working correctly, the coolant level in the reservoir (when COLD) should read at the FULL COLD indicator (NOT below or above). It also should show a level between the cold and hot marks (not over) when at operating temp.

Are you getting close to the end of your 3yrs 36K warranty, it looks like it. What I suggest is to be up front with the shop and tell them you suspect you are leaking coolant into the engine via a intake gasket. They will probably assure you all is well (unless they need the warranty work and these kind of claims are not getting someones attention). Make a deal that you want new gaskets or get a warranty extension on this (is your Dealer staying in business? get this extension in writing, I repeat no comprise with the in-writing demand).

Perhaps they just go ahead and do the gaskets. I don’t like my car being messed with unless there is a good reason, not just because I have near the end of warranty jitters or because it s free. Hate to see a hack get a hold of it and then you can get a new hobby of getting that straightened out.


Tell Me If I’ve Got This Right.

During the past 2 1/2 years and 17,000 miles you have noticed that coolant level in the resevoir/expansion tank has slowly gone down. It never was that full to begin with, now it’s lower and although the guys at the dealer put on a mark to show you where it’s supposed to be, it has gone below that.

First off, congratulations on being a concerned car owner/enthusiast. I recall that you have had other concerns with this vehicle in the past. It is terrific that you monitor for fluid levels, stains, leaks, etcetera. More people should learn these habits as car owners.

Now, as was explained to you previously, that tank isn’t supposed to be very full with coolant. When the engine is “cold” the coolant level needs to be low because when the engine heats up, particularly at shut-down, the normally expanding coolant volume in the engine and radiator needs somewhere to go. That’s why there is extra empty space left in the upper regions of tank. The level cycles up and down, cold and hot.

How much distance would you estimate there is between the mark the guys put on the tank (engine cold when marked?) and where it is now (engine cold?)? One inch, two . . . ?
Do you have a guess as to how much liquid it would take to get it back to its mark? A cup, quart, gallon?

Listen to the advice the others are giving you. Be concerned and vigilant. However, I think you’re doing too good a job. I really think you’re a little overly concerned, like I tend to get. With what you’re describing, I don’t think you’re overheating, going to get any warnings, performance problems, stains, and quite likely not leaking anything. That’s a long time since the original coolant fill and hoses have expanded and contracted and then staying a little expanded, pressurized by normal operation, and maybe the coolant is just seeking a normal 17,000 mile level.

I have had to put small amounts (cup or two) of coolant in vehicles with closed coolant systems that have never developed problems in a couple thousand miles.

I would follow Chevrolet’s schedule for replacing the coolant. Maybe you should get a bottle of the proper coolant, at the proper temperature mix and a little funnel and measuring cup. Only when the car is cold and the coolant level is a little low, give it a “sip” (“Sip” is poor choice of words here. The stuff is poisonous.) to get it back to the mark. (Or have the dealer do it at oil changes.) Keep a log and write down how much, elapsed miles, and elapsed time, between “sips”. Don’t overdo it. Wait til it drops a half inch or an inch (if it ever does). Make sure the cap goes on and turns all the way to the stop. Gloves will help.

How about it?


Thank you Roadrunner, Oldschool, and CSA for your replies. I shall make good use of all your suggestions.

I confess I may be paranoid about this but as I went through having a gasket leak that leaked coolant into parts of the engine it shouldn’t have been in on my previous car, the 87 Olds, and didn’t catch the warning sign of rust stains on the garage floor back then, and knowing GM engines’ known tendency to this problem, I’m just being ultra vigilant and cautious this time around about seeing the coolant seem to slowly evaporate.

The cold volume is down about two inches from where it used to be and most of that decrease has been recent, so that’s why I’m concerned there may be a small leak. As to what actual liquid volume that equates to, I’ve no clue.

But I’ll check the resevoir for any stains around the seams, double check the hose and its connection on both ends, if I can get at it to do so. I’ll bring this to the attention of the shop when I go in for the oil change and point out the difference in what they marked there some months ago and what it is now, etc. And I’ll carefully monitor for any further changes.

I greatly appreciate the help folks. Due to physical limitations (as well as a utter novice’s lack of experience and knowledge) I don’t do my own mechanical work on the car but it is nice to have the help here for me to at least know what to look for, what to speak with the shop about, etc. You all are kind to spend the time and effort helping other folks here on the forum.


Car was serviced today (oil/lube/filter) by trusted indie mechanic shop. They thoroughly checked the coolant and found it is actually where it should be on this Impala model. My question about the difference in level being somewhat lower than previously is that ALL the Impalas of the past few years typically have the coolant in the reservoir tank look that low and that there seems over time to be very noticeable changes in the levels due to the size and shape of the tank and weather conditions. Apparently for all that it looks like a very noticeable difference to me over where it used to be it really isn’t much difference in volume.

Given that the warranty covering such issues runs out in November, they suggest that I check the level every few days for the next few months and if I notice any change then they’ll do a compression test to make sure there are no undetected pinhole leaks in the radiator. However, they don’t believe it is needed at this time and are trying not to cost me money.

So, I’m going to make a new mark on the plastic reservoir tank and check it obsessively and see where I go from there.

The shop is making a note to follow up on this with me well in advance of the warranty deadline so that if it appears there truly is a leak, I can get that checked and dealt with at the dealership while under warranty.

Seems the car’s manual vague mention of periodically needing to add coolant may be part of the Impala’s normal condition. However, the shop said none needs to be added at this time.

Thanks for all the feedback and info from all of you. I’ll closely monitor and follow through with a compression test on the cooling system if there is even a slight chance it is needed.

Marnet, This Sounds Like A Great Shop For You To Trust With Your Car Care Needs.

I love those Impalas! Enjoy your’s!

You worry about car problems that never materialize almost as much as I do. Do you see a pattern? Remember the “wrecked car rip-off” incident? Then the coolant problem. Keep being conscientious, but don’t worry yourself so much (easy for me to say).

This car is good hands, your’s and the shop’s. It should serve you well for a long time.


Thank you CSA.

Problem is, in years past with previous vehicles I didn’t do nearly as good a job of proactive maintenance as I should and failed to catch some developing problems early, such as coolant leaking. I’m trying to avoid that this time around. That said, there have been times when I’ve questioned things and taken answers at face value only to find the answers were wrong. Prime example, with the '87 Olds I thought there was a problem with the brakes getting worn. I specifically asked about the rear brakes. The dealership I went to at the time supposedly checked and said brakes were fine. A few weeks later I skidded out of control when I had to slam on the brakes on damp paving at only 20 mph. That’s when I first found this indie shop. Turns out the rear brakes were down to nothing. When I made a stop at the dealership afterwards to complain about this, turns out all they did was check one FRONT wheel for the brakes despite my concern about REAR brakes.

As to the “it might have been in a wreck” that turned out to be the rear end badly out of alignment, I’m still groused both at the dealership and at myself over that one. When I questioned excessive wear on the tires several times I was assured all was well and normal when it wasn’t! On the other hand, I initially flew off the handle and was ready to have everyone’s head on a platter before I calmed down and took the trouble to get a body shop to confirm whether or not the Impala was damaged and found out it merely had bad rear end alignment typical of almost all Impalas made the past three years.

Just more proof of why I go to the indie shop these days and will go to the dealership only for warranty work.

Don’t get me wrong, the folks at the dealership are nice and I know that the vast majority of mechanics working at dealerships are decent, honest, hardworking and not out to rip off the customer. The problem, from what I’ve gathered reading here over the past few years, is typically the service writers and/or the owner’s policy of how service work is treated.

Anyway, this car definitely better serve me well for many years as I can’t afford to swap out for something different for a long time!