Our '03 3.4L Monte Carlo is at 230,000 miles and has been leaking coolant for almost a year. At first look the water pump was leaking, so we replaced it in January. A couple of months later the radiator developed a leak on the lower-left driver side. We kept coolant full every day until the leak became too much earlier this month. We took it to a mechanic who replaced the radiator. Upon receiving the car back we noticed that there was still a small leak while the car is at idle. We took it back to the mechanic and asked that they check it out. They then said that there may be a leak in one of the alternator bolt holes, the LIM Gasket or possibly the head gasket. We asked why they would return the car after replacing the radiator and not inform us that there was still another leak. They told us that the leak must have developed shortly after us picking up the car.
I told them that I wanted to take it somewhere else and get a second diagnosis. The second shop looked at it and said that there is a leak in the timing chain cover gasket. So we have two different diagnoses, Should we take it to a third shop for another diagnosis? Which one is most likely correct? Both shops pressure tested the system but each came away with different diagnoses. Shop #1 says the estimated cost would be $150-$200 to remove items in order to get a better view of where the leak may be coming from and if it was indeed the lower intake then that would be another $650. Shop #2 says that it will cost between $1,000 -$1,2000 to replace the Timing Chain Gasket.
Good advice would be appreciated. Thanks

 

Kinda hard to diagnose online. From how I read the story but could be wrong . You brought car to mechanic #1 and had him install a radiator. Did you ask them to find a leak or just say put in a radiator because it's been leaking for a while ? Now why I ask that is because you couldn't check for a leak because of the radiator leak. Not saying the shop was right for not pressure testing when done but most won't unless they diagnosed the problem. As for where you are now I would bring to a shop and have someone familiar with cars go with you. Not to call out a shop but to show you where the leak is and understand what you are looking at. A timing cover and a intake gasket are 2 completely different repairs and you should be able to see the leak and go from there. Sorry to be long winded but I hope some of this helps. Good luck

 

Told shop #1 to fix the coolant leak when they replaced the radiator. It was evident that is where the leak was because it was obvious that the leak was there because when parked there would be a big puddle. It seems that it is standard to pressure test the cooling system after making repairs to it or at least it should be.
I'm not saying that shop #1 is trying 'to get over' on me but I choose to get another opinion and the 2nd diagnosis came back different.

The current leak requires about a gallon in the past week and it shows no sign of leaking when the car is running at idle. Both shops said that is because there is not enough pressure built up to start the leak.

Just don't know which shop has the correct diagnosis One didn't mention the timing cover and the other noted a couple of causes.

I would tackle these jobs (timing cover and LIM) by myself but I'm afraid they may be beyond my capabilities.

 

Once again I'm not standing up for anyone, but if the mechanic was told to put in a radiator there really isn't a reason to pressure test when complete. Now if he was instructed to find a leak that's different. I'm guessing you didn't bring in the parts if you told them to find the leak even though it was obvious. Usually what happens when customers diagnosis own car. Normal practice would be remove and install new radiator. Connect hoses and transmission cooler lines fill system , purge air pockets by letting the engine get to operating temperature and look for a leak. Normally you wouldn't repressure th system because it would take longer, create a air which would have to be removed and have to be topped off again because when you release the pressure from the system it almost always leaks back on the ground. As for intake and timing gasket yes they both are bigger jobs . Another option is to borrow a pressure tester fron the parts store and find the leak yourself or with help from a friend if possible. If it's a bolt leaking from the timing cover the repair should be easy as it would require pulling a bolt re- sealing a bolt and torqueing back down. Not quite as easy if the timing cover or intake is leaking. $1000-$1200 seems high for that repair but probably close if it's the intake gaskets.

 

If it is the Timing Cover leaking, do you know of other things that should or could be replaced as a preventive measure, while they are doing that work? I have been researching, and I have heard it mentioned that the oil pan cover needs to come off to access the Timing Cover. If this is the case should I have a new gasket there, what about oil pump - oil level sensor (sometimes, I get a low oil light, but the oil is full).

 

If the oil pan needs to be loosened for this timing cover , yes a new gasket should be installed. As for the low it certainly can be a bad sensor. I would replace if it was mine. Only other thing to replace at that time would be the timing chain as you stated a lot of miles earlier. Good luck

 

I did not read this entire thread, I stopped at the point you mentioned . If this means it goes through close to a gallon a week, you have a pretty strong leak. This should not be overly difficult for a shop to find at that point. At your mileage, if the lower intake gaskets have not been changed at least once, it's possible they are part of the problem. BUT, at a gallon of coolant a week, if it is the lowers, there are some easy things you can do right now:
- After the car has sat for a while, check the oil dipstick. Is the oil level too high and/or the oil milky in color. If the lower gaskets fail on a 3400, typically (but not always), coolant dumps into the oil. Also, with the engine off, take the oil cap off, run you finger in the valve cover via the opening for the oil cap, inspect any fluid on your finger to see if it is milky in color.
- If it's the head gasket, odds are coolant is dumping into a cylinder. You should be able to tell by big white clouds of smoke coming from the exhaust and the performance of the car being really bad.
- If it's the timing chain cover (which I believe is more rare, but does happen), coolant will show around the passenger side under the car. My limited experience with this issue was the coolant port of the gasket blew towards the back.
- If the water pump is leaking, typically it leaves a nice wet line on your hood insulation (as the coolant gets on the belt and flung all around).

But don't forget old hoses. These too could be an issue.
If you want to do some other investigating on your own, you can get the radiator pressure testers as a "loan a tool" from most autoparts stores. This can pressurize the entire cooling system. With the engine off, car cool (so after it sat for a while), hook the tester up, pump it up to about 13psi (15 at most). Look, listen and smell for signs of anti-freeze. Bubbling, dribbling and/or hissing from somewhere (hose, gasket, whatever). Even if you are not familiar with what you are looking at, seeing where it leaks gives you a better idea of what is going on and hopefully better comfort to work with a shop.

If you don't want to mess with the pressure tester, then don't go to a random mechanic. If you don't have one you trust, ask for a referral from a friend who has one. This should be fairly easy to isolate the source of the leak.

 

Just an update. There were no signs of coolant in the oil. It was just losing coolant extremely fast, a gallon week. The timing chain gasket was replaced and the car has only lost a couple of ounces of coolant since it was repaired a couple of months ago and the heater is now working great.

While replacing the timing chain gasket they had to replace the oil pan gasket so the car is hardly using any oil now. I have only had to add about a quarter quart of oil in two months.

Replaced the brakes and rotors this past weekend so we are hoping for a few months of trouble-free operation.

 

Thanks for the update. This information will be very useful to others who are experiencing the same issue.

 

I just replaced the timing cover gasket for a customer when I diagnosed it I had a pressure testing tool so I could pressurize the system I could see the coolant spraying out but it was hard to tell where it was coming from so the customer okd me to start tearing the motor down after I took the tensioner off I could see that the leak was coming from the timing cover gasket area. I replaced the gasket,water pump& gasket,crankshaft seal,and all the other gaskets that were timing cover related and that fixed the problem it took me approximately 4 hours and I charged him $260 for my labor. Now I do these kind of repairs every day I have a mobile mechanic business in Kennewick WA. I love to help people out and do free diagnostics and only charge $45 an hour and am buisier than I want to be most the time but I love to meet people and hear their story I am 52 years old and I am raking it in doing what I love to do