anti freeze leak

I have a 95 chevy corsica that has 60000 miles on it. I have a anti freeze leak that my mechanic can't seem to find. Sounds a little strange since I have had 4 pressure checks on it. The anit freeze seems to be leaking after the car has sat overnight. I don't understand this. There is no anti freeze in the oil because I checked that myself. Any suggestions?

 

Small amounts of antifreeze could indicate a leak from the weep hole on the water pump. You could drive it up on a piece of clean cardboard and let it sit overnight. It would help locate from a vertical standpoint where it is coming from. If it is toward the water pump, look under it and see if there is a telltale sign of leakage. If there is, time is short, and you should consider water pump replacement.

 

How much is leaking out each night? A clean piece of cardboard under the car is a great way to find a leak. If the coolant is going into the combustion chambers, you can usually smell or see it in the exhaust and your spark plugs will be cleaner than they should be when you pull them from the block.

 

with the newer vehichles, they no longer presure test them for leaks. they put a dye in the system, and use a ultra-vilot light, to scan for leaks, instant visability.

 

We still do pressure tests on new vehicles. The only time we use dye is if there is absolutely no signs or evidence of a coolant leak, which is slim to none.

 

About how much coolant have you had to add to the system since you realized there was a leak? Is this a 3.1L V6? Pull the PCV valve and the oil fill cap and flip them over. Is there any yellowish to white residue on either one? Or are they simply covered with a little oil? There are a few known areas for coolant leaks on the 3.1L, lower intake gaskets leaking internally and externally, head gaskets, heater hose fitting in lower intake manifold, front cover gaskets, and the occasional water pump. Also, I have replaced a number of heater cores in these as well. Might want to check the front carpet inder the dash for moisture.

 

Now it seems that when the car is started for the first time in the morning and I am driving it and it is warming it the temp. guage, after about 5 to 10 minutes, goes all the way over to hot and I have no heat. After letting it continue to run the guage goes back to the middle and the heat is fine.
I'm sure I may have a faulty guage but why would I have no heat and the minute the guage reads normal I have heat again. Once I turn the motor off and it sits for a few hours and I turn it back on the guage does not go all the way over to hot. It seems that all this occurs the first time I run it in the morning.

 

Thermostat. Your thermostat should open between 180 and 190 degrees, but yours is hanging too long and needs replacement. Once it opens, after heating your engine almost too much, it opens and you have heat.

 

The thermostat was replaced, radiator cap has been repaced because they did pressure test and said that is what needed to be done. I'm going to a new service station on Monday and I told them that I have written down what the car is doing. If they do another pressure test, which I'm sure they will, it will be the 4th time this has been done. Could the thermoastat not be installed the right way. I have never heard of it being installed the wrong way but you never know.

 

Did the car overheat before the thermostat was replaced? I've seen cars with a warped head gasket do this after overheating.

 

Do you find the coolant level down in the overflow reservoir?, or the radiator?, or both?

If you ever find that the level is down in the radiator, that means that your closed cooling system is no longer closed, and you have either an external or internal leak.

What happens then, is, when the engine cools down, it can no longer suck the coolant out of the reservoir back into the radiator, as it should. It can only do that when there is no leak, internal or external.

Therefore, if the radiator coolant level is lower than the very top where the overflow tube is, right under the cap, you have some kind of leak.

When you shut off the engine hot, depending on what position a particular piston is in, this can determine, if there is say a slight head gasket leak, and depending on it's position, may cause different things to happen with the coolant after the engine is shut off. Depending on the position (on intake vacuum or compression stroke, let's say) it shut off at, one time, you might notice that coolant tries fly out the radiator cap when you open the radiator cap after the engine has sat overnight and its cool. Then on another day, depending on the piston position, you might find the coolant level down in the radiator. [This is something I actually have experienced.]

This question has been asked by Mr. Dummas, and I too would like to know how much coolant you are losing over what period of time and mileage driven. And have you removed sparkplugs to see if any of the insulators inside is almost pure white, indicating a steam cleaning effect from coolant getting into a cylinder.

Also, have you made sure your PCV valve is good? You need the PCV valve working to get rid of blow-by gases that can build up the internal crankcase pressure in the engine, and if that is happeneing the pressure may be adding to your problem.

Has anyone conducted pressure tests on the engine when it is hot and not just cold?, to rule out some crack that expands or contracts with heat?

 

It appears to me that is is less than a quarter cup of less than that of anti freeze. The car was driven about 10 miles yesterday and sat for about 3 hours. I have also noticed it when I drove much less than that say about 1 mile. I really appreciate all of your information. It seems that mechanics don't like you telling them what you think it may be. After all of the money I have spent on it I think I should deserve to have it fixed right. I opened the overflow tank on Wednesday and there was hardly any anti freeze in it so I filled it up. I am goint to look at it tomorrow, since is won't have been driven all day today, and see how much is in there.

 

Make sure the reservoir is filled to the cold water level mark AND the radiator is filled to the very brim. Then after it is driven and then cools down enough, see if the radiator is still full and what the level now is in the reservoir.

 

Ok here is the lastest update. I took the car across the street to the place I have been having it fixed. When the car was running but still cold and they had the hood opened the guy noticed steam coming up from just about where the leak on the ground from the anti freeze would be. He put his finger under the hose and said that I need a new hose because, when the engine is hot the hose expands and the leak is sealed, but once the engine starts to cool down and the hose contracts the antiz is leaking out of the hose. It's not much anti freeze but they are going to replace the hose on Monday. As far as the temp gauge going over to hot is may have an air bubble in it from the air getting into this hose. It's worth a try.

 

Hoses are cheap. If that's all it is, you got off easy.

 

Yes, I agree. I also told them that if that does not fix the problem I am going to another service station. I was actually standing beside the guy when I noticed the wet spot on the ground. I hope this is the end of this problem.
Thanks for you help.

 

One last question before I go to the service station. Now it seems that when the car is warming up I have heat and then I don't, this is when the temp guage goes over to hot, and then when the guage goes back to normal I have heat again.
I tend to think that if I do need a new hose that the new hose will stop any air from getting in and slove the heat problem aslo? I don't think it is the heater core because there is not wetness on the drivers side.

 

Hey fit4me, I had an experience I am going to share with you. It may or may not be the same problem you are having. If it is, you may want to scrap the car unless my recent fix works for you. Mine cost over $2,000 to fix the first time around.

I have a GM vehicle with one of their purported "one of the best ten engines in the world" - the now infamous 3.8 liter V6. That sucker comes with a composite plenum (engine cover) which incorporates tiny channels for antifreeze coolant liquid to flow through. The EGR valve then goes into that plenum and the heat of the gases flowing through it is too high for the composite material to handle so the material cracks leaking coolant into the engine's V and flooding the engine with coolant. When it happened to me, the engine would not start (had to get the car towed to get it fixed), but before that, I was losing about a half gallon of coolant every 100 miles or so!

The mechanic did a pressure test and everything seemed OK, so he figured it was a leak through the gasket between the plenum and the engine block and the leak was so slow that the heat of the engine evaporated it. So he replaced the gasket after cleaning up the mess inside the engine. Took the car home only to find a few days later that the leaking persisted. Took the vehicle back and he then replaced the plenum ($600!) and gasket again after cleaning up the mess in the engine a second time. Total bill was over $2,000!

A few years later, the coolant loss started again.....

These plenums are of poor quality materials unable to handle their task and GM should have recognized that and fixed this problem a long time ago. Instead they keep pumping out the same old crap destined to fail. I complained to them and didn't even get a response back! Aluminum plenums on cast iron blocks caused problems at the gaskets due to the different contraction/expansion rates of the two metals. So they went to composite, and now this! Why didn't they go to all aluminum engines?

To make a long story short, the second time around, I dumped some Prestone granular stop leak into the rad. That was years ago and it's still holding - my theory is that the tiny particles of stop leak are filling in the cracks in the plenum and stopping the coolant from leaking into the engine and mixing with the gasoline - have you tried that yet?

quickcurrent

 

No, I have not tired that yet but that is a very good idea. I love my Corsica and don't want to get rid of it because it has only 60000 miles on it. I will buy that stop leak and the next time it happens I'm going to use it. Thanks so much for letting me know.

 

fit4me, Don't buy or use any stop leak product. They will screw up your cooling system unless it's absolutely the last resort such as not keeping the car.

 

I know you said you changed the thermostat, but they can come from the factory bad, and you have classic thermostat problems. I'll leave it alone.

 

Got my car back today and they replaced the upper radiator hose. I told them this was their last chance to make it right and they weren't too happy with me. OH well. I must say that by them being right across the street from me was a plus but their are a few other stations that might appreciate my business. Time will tell. Hopefully I will see no more leaks.

 

Where did you hear that! Mine was starting to leak years ago and it's going strong. It's saved me a couple of thousand bucks. I'd rather spend five bucks than two thousand, but to each his own....

 

When your heat output decreases from your heater, you will find, after backflushing the heater core, chunks and bits of radiator sealant particulate that didn't adhere to anything but wound up in the heater core on the windward side and clogged up the core. The sealants can save alot of money if they help stop a leak, but they will stop up a heater core just as well.

 

Agreed chandler, but that's a potential side effect I am willing to accept given the cost of re-doing the $2,000 every few years. One can always use just part of a bottle of stop leak to mitigate that effect, adding little by little until the leak is stopped thereby causing minimal damage to the heater core, etc. Of course if the vehicle had been built properly to begin with, the problem I encountered would never have surfaced!

 

OK, here we go again. Got my car back on Monday with a new upper radiator hose replaced. I haven't driven much until today and as the car was warming up after starting it for the first time after about 5 minutes the temp guage went over all the way over to hot, again no heat. I stopped to get gas and when I started it again the gauage was still all of the way over as I sat a a very long red light. Once I gave it gas to go the guage went down and I had heat again.
I am taking it to a different service station on Monday and they asked if I had all of the receipts for the last year for evrything that had been done to the cooling system. I have all of the receipts which they can have but what would cause me not to have it when the guage goes up. They said that replacing the upper radiator hose would fix this....

 

Couple of questions and I didn't want to re-read the whole thread:

1. Is it still leaking?
2. Has the water pump ever been replaced? Almost sounds like the impeller in the water pump has rotted off.

[Where's carguy when you need him? ]

 

I will check to see if it is still leaking tomorrow morning. Yes, they said they did check the water pump. I'm thinking mabye it is a bad sending unit

 

I have had all of the test done because by temp guage tends to go to 3/4 or all the way over to hot. The upper radiator hose was repaced because I discoverd where a leak was coming from and they told me that replacing the hose should fix the leak and the guage. If my guage tends to go to 3/4 or over could it be a bad guage or sending unit? Is there any way possible to see if it is a bad guage or sending unit? It's been running great for the last week but I didn't think it would last. I know it is not overheating because they have done pressure checks, replaced the thermostat and even replaced the radiator cap. Any suggestions?

 

It BEHAVES like the water pump belt is slipping, then finally grabs after a while. The impeller suggestion could cause this.

So can a load on the electrical system of the car cause the alternator to run harder which puts resistance on the turning of the alternator which then can cause the alternator-water pump belt (if you have that set up) to slip. It slips for awhile till it gets hot and sticky and then grabs and turns normal again. But usually with THIS scenario you hear the belt squealing.

But also so could low coolant level in the engine side - not the radiator side of the thermostat. Then when the thermostat opens, the coolant level drops way down and makes the sending unit send false information. Also then the level drops at the radiator.

Have you made sure the radiator level, not just the reservoir, is up to the top?, and then have you idled the car to see what happens with the radiator cap off, when the coolant tries to circulate when the thermostat opens?

My car behaved the asame way and i thought it was the fan sending unit.