I have been trying to track down a small coolant leak for a week or two now, and can't find it for the life of me. I first noticed the leak last week when my low coolant light came on. I checked the radiator, and sure enough it was a tad bit low, maybe a quart or so. I topped it off, and it was fine for a week (daily driven, a couple hundred miles a week). Then the light came on again, so I checked, and it was low again, still only a quart or so. Now it's to the point that it's about a quart low every time I drive. Even if the light has been on before and I don't top it off, it takes a half hour of driving before the light comes back on. It does not overheat at all. I drove the car for over 1k miles since I finished the engine swap before this happened.

I checked all the hoses, radiator, etc. The only place that I have been able to see any coolant is toward the back of the engine. I noticed a few drops dripping from the starter bolts and the torque convertor shield. I also noticed a small puddle of coolant on the ground under the backside of the engine. I have looked there while the engine is running, and I don't always see it dripping, only sometimes. There's no sign of the coolant being sprayed in the engine bay. While the engine was cold and slightly warm, I ran my fingers around the banjo bolts for the crossover line, as well as on the backside of the heads where it meets the block to see if the head gasket is leaking, and I am not finding anything. I also checked the heater core lines, water pump and knock sensor, and they're fine.

Some background on the car / engine:

- I have about 2k miles on the engine since it was swapped. I bought the shortblock used from a member here, which now has ~5k on it total.

- I assembled the longblock with stock heads which were checked and resurfaced by a reputable machine shop, which also swapped the valvesprings and set the install height. I used a sealed power engine gasket kit and used the head gaskets from that kit (unknown specs). I also bolted the heads on with ARP bolts with thread sealer.

- During the engine swap I deleted all A/C equipment, including the evaporator core and the box. There is a HVAC delete panel on the firewall.

Anybody have any other ideas? Anything else I should check? Sorry for this being so long, but I'm thrying to be thorough with the info.

 

You might try this
Block drain plug

Also I'm not sure how the camaros work with the heater core, but on my yukon it had a valve that would restrict flow of coolant to the heater core. It would leak so slowly that I couldn't trace it to there, but if the defrost/heat was on it would leak much faster. If you have something like that you may want to check it just in case.

 

To begin with, the Lt1 is known for having bad Low-coolant sensor problems, even if the coolant is not low. The light may come on intermittently for no apparent reason. If you find that the radiator is a quart low each time, have you tried seeing if it goes beyond that one quart, i.e. continues to leak? Is your overflow at the correct level? If the radiator was completely full, it would not pull any coolant from the overflow. If it was low, it would pull coolant from the overflow and your level in the overflow would be down that amount.

You want to make sure there is no leak in the overflow too, i.e. cracked plastic. Any leaks in front of the engine will be blown back thus making it more difficult to see where a leak is actully coming from. Have you checked the cap----since a bad cap will not alow the correct pressure and the radiator may boil over at a lower temperature which might overflow the overflow container, dumping some coolant.

I would have the system pressure checked to see if there are any obvious leaks. If the system continues beyond the one quart loss, you might dump some dye into the radiator which can be seen with a black light pointing to the actual point of coolant leakage. Let us know what you find.

 

Might check the freeze plug on the side of the block.

 

I did check the drain plug...I'm going to take a closer look at the heater hoses though.

Yeah, I'm aware of the faulty light problem...I also had that before. I haven't let it go more than a day without topping it off, maybe I'll try that. I did check the overflow, and it was bone dry. Now that I think about it, when I finished up the engine swap a couple months ago, I don't remember putting any coolant in the overflow tank at all. The radiator cap is fairly new...I replaced it a couple years ago (car hasn't been running for a year and a half until recently). Those are cheap though, so maybe I'll get a new one. I wanted to pressure check the system, but those tools are expensive, and I don't know anybody with one I could borrow.

I didn't check the freeze plugs directly, but I did look on the sides of the block to see if the head gaskets were leaking there. I'll have to check those.

Thanks for the ideas guys. Keep em coming.

 

BTW: You needn't do the pressure check yourself. Most shops, especially radiator shops can do a quick check for little cash. Ask around and get the cheapest price---if you still have problems.

 

When you mention the amount that has leaked out, along with the location of the drops, I'm still surprised that the problem isn't in the banjo bolt area. If you think about it, if the leak was lower vertically in the system (i.e. a block freeze plug), if the car sat long enough, eventually all the coolant would leak out down to that point. Therefore, since it seems that you're not losing much coolant, my guess it's something toward the top of the engine compartment (like that banjo bolt ). Hopefully you can get it pressure tested and figure it out that way.
Oh yeah, one more thing. I'm pretty sure this isn't your problem and you probably checked already, but what does your oil look like?

 

Definitely the banjo bolts are leaking. Get some coolant in the overflow tank, that way it won't suck air when it cools down.

 

The oil looks and smells good. No sign of coolant in it. That was actually the very first thing I checked. I'm going to put some in the overflow tonight after work and top the radiator off. I've driven it a little more the last couple days without topping it off, so I'll see how low it has gone. I'm also making an appointment to take it to a radiator shop to get pressure tested, if I don't track it down myself first. I hate taking it to a shop, since it's just throwing money away, but I just don't have the $100+ to go out and buy a pressure tester.

Thanks for the help guys.

 

Good luck, let us know what you/they find out.

 

Autozone "loans" them....you pay for it, use it, then bring it back, then they give your money back. Part of their "Loan-a-tool" program.

The pressure tester I used from them, I actually kept....was a life saver tracking down my brother's coolant leak.

 

Cool, I didn't know they had those in their loaner program.

So, the situation just got a little stranger. Yesterday after work I went home and checked it. I had driven it for 100 - 150 miles without topping off the radiator, but lke I said, the low coolant ligh came on every time I drove for more than a half hour. I took the radiator cap off... and it was full. I checked the overflow, and it was still dry. So, I just filled the overflow with clear water. I took the car to a cruise night last night, and sure enough on the way there the light came on. I was there about an hour and a half, then came home, and the light didn't come on on the way home. I checked the radiator this morning, and it was full, and when I checked the overflow, it was where I filled it to and looked like it was still just clear water. So now I'm not losing coolant... aye aye aye

 

I'm having a similar problem with mine too, i gave up with mine, it holds pressure, no coolant in oil, no smell in radiator, doesn't run hot, doesn't loose coolant in overflow tank, just in the radiator after 100-150 miles it'll go down about 1/2 qt., i know its not much, but its pissing me off, the damn thing doesn't leak anywere, nothing/nadda lol, heck, my old truck had a slow leak in the radiator (it was visable) & would leave a quarter size puddle on the ground, but after a year i never added much of anything in it, if any that i remember.

 

I chased disappearing coolant for a couple of months before the leak finally revealed itself. Cooling system would hold pressure, nothing on the driveway, oil was fine, but I was having to refill every couple days. Not a lot, maybe a pint or so. It turned out to be a crack in the plastic radiator tank on the passenger side. It took a hot summer day for the crack to finally expand enough to start spewing coolant.

 

Typicall radiator cracks leak the most in the winter when its cold and contracts making the crack larger, doesnt make sense it would appear more in the summer...odd