Reader Question: I have a 1998 Nissan Sentra with 78,000 miles. A few months ago, I noticed that my coolant reservoir was empty and I filled it up. Three weeks later, it was back to empty position. Previous owner told me the car had overheated on them a few months back. I went to my mechanic who told me that my radiator cap was broken.
Three weeks later I found out it was not since I was still losing coolant. There are no signs of external leaking and this time my mechanic told me it was an internal leak and that the coolant is leaking but is being burned off.
Also, he mentioned that it would not be worth it to fix so I should just fill up the reservoir every few weeks. I bought Stop Leak powder and put half into my radiator without any success. A few weeks after I did that, I noticed that my coolant reservoir became very dirty and contained some oil and I was still losing coolant. Should I put the other half of the Stop Leak into the radiator?
Will I be fine continually refilling my coolant reservoir with coolant?
What will happen if I continue this pattern?
I would go to another reputable mechanic and ask them to pressure test the cooling system for leaks. This is the starting point, and it will rule out an internal or external coolant leak. It is simple and inexpensive to do, but do it FIRST.
If they still suspect an internal coolant leak like from a blown head gasket or something you might want to try this sealer I talk about here. Only use it if you are certain you have an internal leak.
Although you did not mention you had any of the common symptoms of an internal coolant leak, which are:
1. White smoke from the tailpipe
2. Coolant in engine oil – makes the engine oil look like a chocolate milkshake in color
3. Engine misfire and missing due to coolant getting on the spark plugs
Also, you should always check the coolant level inside the radiator itself, and not judge coolant level by the plastic overflow bottle. The coolant level in the plastic bottle will fluctuate and that is normal to do so.
The dirty stuff you now see in the bottle is probably from the stop leak stuff you added, or the coolant inside the radiator is rusty and needs to be flushed out.