Nissan Repair: Car Running a bit hot, radiator leaks, radiator leak

Question
QUESTION: I have a 1993 Nissan Sentra 5sd. 1.6 engine.  I noticed it running a bit warmer than usual. I also notice that when I come to a stop, the idle speed becomes higher than normal before resetting to normal.  I have to keep adding water and antifreeze to the radiator. When I do this, it runs at normal temperature but I have to keep adding it about once a week.  Is it possible that I have a radiator leak? I don't see any visible holes in the top or bottom hoses running from the radiator. Or could it be the radiator cap or water pump? What do you think  Please Help and Thanks in Advance

ANSWER: Hi Lynn -

Can you tell me how much water you refill each week? Is it a quart, or close to a gallon?

If it is the water pump, you would see drips coming from the engine where the belts are.

It could be the radiator, depending on your answer above. Because I am assuming you do not see any drips, it has to be a small leak, usually radiator leaks are along the seams of the radiator, so look for discolored, or greenish deposits on the radiator. That is a definitive sign of a leak.

Have you replaced the thermostat or flushed out the cooling system recently?

Please get back to me -
aloha
calvin

---------- FOLLOW-UP ----------

QUESTION: Hi Calvin

Thanks for your answer. I'd say I am adding close to a gallon a week to 10 days.  I looked but did not see any leaks from the hoses. Is there some type of test or something we can put in the radiator to make sure it is or is not the radiator (do you even recommend that).  Maybe we need to look under the car.

The cooling system was flushed about 3 years ago and I have never changed the Thermostat since I've had the car (since 2000)

I think I am going to put paper underneath the car tonight to see if small leaks are on the side of the belts to try and rule out the water pump.  I have a small oil leak so that makes it sort of hard to tell.

Thanks Calvin :-)

ANSWER: Hi Lynn -

There is a pressure tester that can be used to determine hard to find leaks. It attaches to the radiator. You pump it up to pressurize the radiator, and any leak will appear.

Have you inspected the radiator for telltale signs of leakage, as I described above?

Yes, paper under the vehicle is a good idea. Let me know how that goes.

aloha
calvin

---------- FOLLOW-UP ----------


Lynn   QUESTION: Hi Calvin

Yes.  I did look at the radiator for telltale signs of leakage and saw NO GREEN LEAKAGE AROUND OR ON THE RADIATOR.
Also, I saw no leaks on the paper from last night (I put the paper on the side where the belts are).

Thanks for all your help. I've attached a picture of me. Sometimes it's nice to put a face to an email.

Answer

Calvin and "Buddy"   Hi Lynn!

Thanks for your picture. I have answered thousands of questions on cars since I joined this site and you are the first to send a photo. I appreciate it. I am a visual guy, as I assume you are. That is the only challenge with attempting to fix cars this way. If I could somehow zap over in a New York minute and see each vehicle, I would love it. Here in Hawaii, tough to do that in the middle of the big pond.

Anyway, I will send you my pic as well. That is a nice picture!

Well, getting back to the situation at hand - If you are losing that much coolant, and not seeing it on the ground, the only other thing I can think of is you are burning it through the cylinders. Perhaps you have a small head gasket leak. A compression test would determine that. So, here is the next step you may want to do:
First, get a hold of that pressure tester. Pump it up to about 15psi and then inspect for leaks. If the pressure drops, then you have a leak somewhere.
Secondly, if the test above passes, then have the compression checked. You can also tell if your gasket is leaking if you see white smoke coming out of your exhaust. This is actually steam, so sometimes you cannot see it while you are driving, as it will dissipate quickly.

Let me know. BTW, after 5 correspondences, this site will not allow any more, you will have to start a new thread. To make it more comvenient - you may email me at cjiwash@yahoo.com.

Thanks Lynn -
aloha
calvin