So, I decided to get my cooling system flushed. I just bought the car and it seemed like it was never done before. Well, I drove it home last night. No problems. My wife went to go start the car today and it is leaking coolant. After idling for a while the leak stopped. Now that is has been cooling down, it is beginning to leak again. I sort of figured this would happen after getting rid of 17 years of sludge (it is a 1994 Z28). It just bugs me that the shop wouldn't have noticed something leaking before they gave it back to me.

It is hard to tell where the leak is coming from. I think it is coming from the passenger side on the bottom somewhere. I don't think the radiator itself is leaking. It is just hard to tell where it is coming from. It is pooling up on top of the plastic underneath the rad and dripping off of that in two different places. Plus since my car is lowered I can't crawl up underneath to get a good look. I definitely DO NOT want to put stop leak int the radiator. That is just pretty much introducing sludge into the system for it to plug up the leak.

I did schedule an appointment for this Friday to get the transmission flushed also. I am going to try to move that to tomorrow so that I can have them fix the coolant leak also. I am just a little concerned about getting that flushed and then it developing problems with my transmission also. I am not having any issues with the transmission. I would just like to get it done since the car has 131,000 miles on it. Should I risk it and get it done or just let it ride?

 

this defiantly is confusing coolant usually leaks after the car has been running and builds pressure... make sure all the hose clamps are tight

 

Confusing?!?! Yes. The only explanation I could think of (this is a stretch) is the components are heating up with the system and (and if we remember our middle school science) when things heat up they expand thus sealing off the leak. I know, but I DID say it was a stretch. Especially considering the pressure that builds up in the system. You would think that would overpower the expanding theory and just force the leak even more as the system got to operating temp.

I am still leery about the transmission flush.

 

just have an old fashion trans fluid change where they pull the pan and change the filter and refill. that way there is less of a chance of the trans failing. the coolant leak could be like you said but could be its just such a slow leak that its getting blown away when your running so you dont see it. best to do a pressure test on the cooling system.

 

So here is an update. A week ago I had the shop pressure test my cooling system and they didn't find anything. I drove all week without any issues. This morning I started the car to get ready to go in for my trans flush and she was leaking again.

Drove about 20 miles to the shop and the leak was very minimal when I got there. I told them about it and they said they would look at it while they are servicing the trans. They pressure tested again and didn't find anything. They said it might be the lower coolant hose leaking at the radiator, so they replaced the old "spring style" hose clamp with a screw down type. Hopefully this works.

This only seems to happen when I start it up first thing in the morning after it has sat all night and cooled off. Once I get it to temp I don't notice a leak. Any Ideas? I have the front end up on jack stands right now (that is another story), so I think tomorrow I might start her up while she is up and see if it leaks.