2007 Chevrolet Impala LT
3.5L FF engine, auto trans
11,225 miles
All book maintenance and oil changes every 3,000 miles been maintained since new 21 months ago.
Problem: low coolant level in reservoir tank
No warning lights, engine running at normal temps, no diagnostic codes
No leaks apparent on garage floor or what I can see under the hood.
Engine oil appears normal, not creamy
Okay folks, discovered barely an inch of coolant showing in the reservoir tank under the hood when doing a regular proactive check of the oil dipstick when filling the gas tank this evening. Car goes into shop first thing tomorrow morning to be looked at under warranty.
I’m aware of GM’s famous probs w/ coolant leaking into the engine oil (been there, done that, paid the bill on my old Olds!)
Am carefully NOT running the car through the car wash tonight so as to not wash off any possible evidence of a leak showing on the underside frame of the car. (Normally I try to always take a freshly clean car in when getting service.)
Anything in particular I need to ask the service tech/advisor or look for in explanations from them as to what the problem is? Any heads up advice?
I’m baffled how it could go from a proper level of coolant to such a low level in only about 350 miles without showing a drop of liquid on the garage floor or some sort of mess under the hood???
Marnet
(grumble grumble…it’s still a new car darn it!!!)
Well how full was it two weeks ago or when you last checked it? Remember that as the engine heats up and cools down that level will vary and that after a refill (maybe the first fill) some air may be in the system and as it works it's way out the level will go down.
Since you should have a factory warranty on this car, I suggest you let them take a look.
I might add that unless indicated in the car's owner's manual oil changes every 3,000 miles is really overkill. In fact there is even some evidence that changing oil too soon can INCEASE engine wear. (Note: that additional wear appears to be rather small. Modern oils and engines are far better than they were back in the mid 60's when I got my first car and 3,000 miles or even less was recommended.Any more info?
Good post. You really provided information and show that you care about your vehicle. sounds like you monitor underhood and under car on ground regularly. That’s smart. You seem pretty knowledgeable so I am sure you know that the coolant increases in volume when hot and and decreases when cold.
Therefore, it was hot when you checked 350 miles ago and most recently (based on the fact you were getting gas), right? You have to compare cold check to cold check or hot to hot.
Also, is this a skinny little reservoir? Can you guesstimate the volume of coolant difference you’re talking about?
Cars can consume coolant if there is a problem, without seeing any signs of a leak. I wouldn’t assume a problem, yet.
Some of the regular responders here are up on the newer vehicles. I don’t know if it is normal to have to top off coolant after everything breaks-in and trapped air can burp out out of the cooling system or not, but you should be receiving some advice shortly.
I would say that when you go in, definitely have the service people put in writing your complaint about dropping coolant level in reservoir in case it keeps going down after they bring it up to “full cold” or “full hot.”
A month ago the level was at the full mark on the coolant tank. Two weeks ago I thought it looked slightly lower but was preoccupied and didn’t follow through like I should. Today it is several inches lower, enough to really get my attention in a hurry.
As to oil changes, my driving rates as “severe” use due to low mileage trips, many rather short, although I make a point of taking good long drives a couple of times a month. And I did go 3,500 miles on the last oil change.
Come to think of it, all the coolant loss is since that recent engine oil change! Hmmmmm, any possible connection???
Thanks JEM.
Marnet
The engine was fully hot the last three times I’ve filled up after about 50 mile trips each time. I was even at the exact same gas pump with the same ground slope.
Yeah, the tank is one of those super skinny ones tucked up against the fire wall at the back under the hood and really hard to see any “full hot” or “add” markers on the tank.
It is quite low, only about one to two inches both when hot and now that the engine has cooled for a few hours.
As to knowledgeable, glory no, not in the least. I’ve just been reading this board for a couple of years and asking tons of questions, first about an old car and then when shopping for this new one.
Thanks for the info.
Marnet
One common place to slowly loose coolant that will not show up as a drip on the floor is the radiator/reservoir cap. If it leaks, it will blow a slow steady pinstream of steam all the time that the car is up to temperature. You will probably not be able to detect it, other than the water level keeps mysteriously going down. A failure mode on certain designs is that the O-ring swells such that it feels like it is screwed down tight when it is actually not screwed all the way down. Not expected on a 2007, though.
Thank you.
Just checked and the radiator cap is tightly screwed on. Found no sign on the underside of the hood of any steam or other stains of any kind on the hood liner. Whatever the problem is, it doesn’t show any stains or mess visible on the top area of the engine or on the floor under the car.
Marnet
Hello again Marnet. New car eh? good for you.
Look closely for the FULL COLD mark and when you do see it, mark it with a felt pen to make it easier to find.
Only, and I mean ONLY fill to that FULL COLD mark. When the coolant is hot it will show above that mark until the engine and coolant cools and is drawn back into the engine and rad down to the COLD mark.
It is IMPERATIVE the engine be COLD when checking the coolant level in the coolant reservoir.
We’ve long since gone over the ifs, ands or buts concerning the likes of the past leaking intake manifold gaskets, etc.
You’re exaggerating when you say the level was down ‘several’ inches. The reservoir isn’t that deep.
Taking the vehicle back to the dealer and saying it’s losing coolant and they keep it overnight and don’t do any tests isn’t going to solve the problem.
The dealer has to do a leak-down and coolant pressure test to find anything sans any visible leaks.
Hi Roadrunner.
Actually, the coolant tank is very tall and skinny. The down by a couple of inches is per measurement with a ruler held up against the tank.
Thanks for the idea about marking the FULL COLD mark with a felt pen. Hadn’t thought of that one. Duh…and it is soooo obvious and simple. LOL So much for my thinking straight!
Also, appreciate the reminder about a leak-down and coolant pressure test.
Hopefully, it is nothing more than a pin hole leak in a hose or my having simply mis-read and mis-remembered exact levels between fill ups. I’ll be sure to have the FULL COLD mark shown to me so I can mark it and not have any question about relative level in the future. Like I said, the placement of the tank makes it impossible for me to see the FULL COLD or ADD marks on the plastic tank so I’m going by relative levels from past to present.
Y’all are so helpful here. Not the first time I’ve gotten good help here.
Marnet
P.S. Well, I’ve had the car 21 months, so it is still “new” as far as I’m concerned. But then I drove my previous cars 14 and 20 years respectively. G
The heads up I can give you is be prepared for "no trouble found"I think the dealer wont invest any time in this concern until more symptons develope.Now if you could report that the “low coolant” light comes on that could get things moving.
Oldschool, that’s quite possible. I’m well aware that the real problem is most likely “owner error.”
But I can at least make sure that the coolant level is where it should be, the tank more clearly marked so I can easily keep track of the level, there is no apparent leak, and that the concern is documented just in case a true leak is found to exist farther on.
Trust me, I have no fun waiting around while a car is serviced nor do I wish to waste a mechanic’s time even if it is paid for under warranty.
I’m not expecting anything serious and assume either I’m in error or that it is a quite simple, minor prob. I’ll be downright stunned if it is otherwise. I’m just trying to be sure I understand things BEFORE I take up the shop’s time.
Thank you.
Marnet
Marnet
You wondered about a connection between an oil change and coolant loss. There isn’t one, barring someone damaging your cooling system by hitting something, etc. But then you would no doubt see a leak and you don’t.
Okay. Like I said, I assume the most likely scenario is “owner error” in my reading of the level and recalling where it was last time. But as the coolant tank is a skinny silly thing stuffed back where it’s impossible for me to see the marks in the plastic showing proper FULL HOT, FULL COLD, and ADD levels like my previous cars had I’m basically clueless despite reading the car manual.
If it turns out it is an error of my ignorance, I’ll sincerely offer to pay the dealership for the time and effort, warranty or not.
Thanks for the input.
Marnet
UPDATE: Oldschool called it; “no problem found.” No signs whatsoever of a leak anywhere. However, the level was just slightly lower than ideal so a tiny bit was added. And the tech marked boldly with a felt pen where the AVERAGE level line should be so I’ll know better in the future if it drops significantly low. So I’ll keep an eye on it and find out if it was simply my ignorance and brain freeze or if there actually is a tiny slow leak somewhere.
Thanks again everyone for all the feedback and help!
Marnet
Well! Good to hear there’s nothing serious wrong.
Happy motoring and drive safe.