Hot Rod Forum banner

Burning Coolant?

9643 Views 20 Replies 10 Participants Last post by  Perkster029
Hello! First post here.

I have a 74 Camaro with a totally rebuilt engine, sbc 350. This is my first project car, so I paid a shop to do it for me.

The problem is, coolant seems to go missing, and there are no pools, leaks, or steam that I can see. Except, the exhaust is cloudy, and acceleration makes it worse. It isn't noticeable when the car starts up, but after a minute or two, it gets worse. "Worse" means there is visibly white-ish smoke being expelled, but nothing you can't see through and it dissipates rather quickly.

Is it possible I need to simply re-torque the heads? Did I blow head gaskets? Maybe an intake gasket? I'm fairly new to this, so assume you know more than I do and feel free to point out why an idea I have is wrong.
1 - 20 of 21 Posts
OK so did they check the heads for cracks? Did it overheat? Coolant in oil?Can you see bubbles in the radiater with it all the way full? Pull all the plugs and see if you have a one or two cylinders with water. Pressureize the radiator and see where its going. Could be intake gasket leaking too.
I would say yes to a head gasket. I heard of a trick once to check it, when the engine is cool take off the radiator cap, then start the car. If you see an abundance amount of bubbles in the water than your gaskets gone. (I could be wrong, this could be for a cracked head). I am kind of surprised you haven't said anything about having an overheating problem...
The heads were new, and the block was tested and it was good.

As for overheating, not that I know of. Though, since coolant is probably being burned, I guess it's very possible.

Also, I don't drive her. I just start her and leave her parked in the garage every now and then.

The oil looks completely normal, but I've read in a few places that this can happen and still be burning coolant. (Is this true?)

Tomorrow I will pull all the plugs and check, and also start her up with the cap off. I'll report my findings.



First thing I noticed today was that there were two small pools of coolant on the intake manifold. One, on the right next to the hose, was from me not tightening the hose properly. After dabbing it away and tightening the hose, fixed. The one on the left troubles me a little. I dabbed it all away with a cloth twice, and there is still a minuscule amount that collects there.

Checked the dipstick. Seems like normal colored oil to me. Oil level indicator was good. Any discoloration in the picture seems to be from the flash.

After pulling every plug (which with these headers is a SERIOUS pain), they all looked identical to the picture. (Ignore the metal shaving, that's from pulling it out in between the headers). No obvious fouling that is apparent to me.

Next, I pulled off the radiator cap and started her up. First, both exhausts were vaguely smokey, but not cause for concern. Soon, the driver side had quit and the passenger side was still doing it. Both sides were squirting out droplets, presumably water. (Note: I live in Dallas, TX. High humidity is a constant, not sure how that affects things). After some time, which I presume is the engine heating up, the passenger smoking got a little worse. Coolant levels started to fall, and bubbles appeared in the radiator. The bubbles we're out of control and were perfectly normal looking bubbles, no strange colors. It was like a pot of water that had just barely started to boil.

The coolant had gone down about 3 inches at this point, so I turned her off. Engine still sounds like a dream, and as far as I can tell is smooth as can be.


See less See more
You should be able to smell antifreeze burning
I would think so too. Is it possible that the smell of old car running/gas without any cats is simply overpowering it?
You should put a pressure tester on it and see if it holds pressure.
Why are the plug shells so rusty on a fresh rebuild. It is possible that if you only start it and never drive it there is condensation in the exhaust system. It may not ever get hot enough if you are just starting it in the garage to clear the moisture out of the exhaust. You say the coolant level went down in the radiator, does it return to normal after cool down. For you to internally leak 3" worth of water from the radiator you should have steam so thick you would not be able to see.

Now that you have fixed the leak, I would fill it when it is hot and then keep an eye on it to see if it still goes down.
As stated above the exhaust will usually smell like antifreeze if it is burning it.
I'm not sure why they have rusted, as far as I know they've never gotten wet and the plugs were brand new (3 years ago when I put them in). I'm a college student, so my Camaro comes after schoolwork, sadly, so it takes a while to get things done. Hopefully, I'll finish up this summer.

I have a family BBQ thing to go to now (Happy Memorial Day everyone!), but tomorrow I will get a pressure tester and let y'all know the results. I'll also try and get a good video of the smoke when it's at its thickest.

Also, you guys are great. Thanks for all the help so far!
do yourself a favor and stop looking for anything other than a blown head gasket!
I been there and done that!
We all know its the headgaskets!
time to pull the heads and get it done right.
all it takes is a couple days work and youll be happier in the end.
a little over a month ago i was in denial and was looking at anything other than head gasket.
look at my gasket pics:
See less See more
dawg said:
do yourself a favor and stop looking for anything other than a blown head gasket!
I been there and done that!
We all know its the headgaskets!
time to pull the heads and get it done right.
all it takes is a couple days work and youll be happier in the end.
a little over a month ago i was in denial and was looking at anything other than head gasket.
look at my gasket pics:
I hope you surfaced that head and checked the block.
Man, that looks bad!

Yeah, I know it probably is the head gasket (or worse, the head :( ). And I know once I tear it down I'll kick myself for wasting time. But, that's still better than pulling them off and have it be something else
Quick update: it's been raining and hailing for a day or two now, not very conducive to working outside in a garage. Haven't made it out there yet
Before you tear into it, whst mixture of coolant are you using? I had a similar problem a while back. It would suck the overflow tank dry almost every day. Took me forever to figure out that i didnt have enough coolant (too much water). Intake gasket could cause this too. Drive the car and see it its still smoking afterwards.

Really, you shouldnt have to do any work seeing as a shop built the engine, they should fix it. Simple as that!
Not coolant

As for the shop fixing it, I agree. Buuutttt, I've moved since then. I could haul it 4.5 hours each way in a trailer, but I'd like to avoid that. Plus, it's a learning experience!

So, I don't think my initial diagnosis of coolant was correct after all. After swapping out the first two pressure testers I got (one had a gauge that only read 7 psi, the other one didn't pump any air), I pressurized to 15 psi. I had to tighten a hose a wee bit more, and I found a smaller-than-a-pinhole leak in my radiator, but otherwise it held that 15 psi for several minutes.

Next, I relieved the pressure and started the engine up. After ten minutes, it had only reached 7 psi. Oddly, when I turned the engine off it jumped to 9 psi. When I checked, the coolant level was exactly where it should be.

I watched the exhaust closely through the whole thing (taking breaks to be able to breathe!) and noticed 3-4 times more liquid water droplets coming out of the smokey tailpipe than the other one.

Also, I took a video so you guys can see what's happening. There is a thin cloud outside the garage, too. YouTube quality was so poor you couldn't see the smoke, so I used Dropbox:

Smokey Tailpipe Video

I recommend downloading it if you want to see things a bit more clearly, the online stream is a little grainy.

Am I being paranoid, or is this a bit too much to simply be condensation?
See less See more
As for coolant, I just use 50/50
Well, let me just say I had the same problem. Rebuilt motor and coolant would disappear. Found out that the cars exhaust was a bit white and it was burning coolant..So then I took of the heads and found out that there was a tiny crack in the head gasket. You might have a small crack as well and try to inspect your exhaust very well and if you see some white smoke, you got it.
remove the heads as everyone else stated, send the heads to a reputable machine shop and have them checked then surfaced, also check the decks on the block corner to corner like an
[ X ]then across the center [---] use feeler gauges with a mechanics straight edge which is a precision tool and perfectly flat and straight, verify flat deck surface, when ready to reassemble install a head stud kit from ARP and make sure you put the assembly lube on the threads before installing in the block in order to achieve proper torque
To give people some closure,

I've concluded that (hopefully) the passenger side's rings just haven't seated yet. The coolant that I was losing is no longer an issue after I:

a) Bypassed the heater core
b) Found 2 small leaks from a not perfectly tightened hose
c) Found a pinhole leak on the radiator

So, I'll give it a few hundred miles, and then we'll see where I'm at.

Thank you guys for your help, it was invaluable!!
Don't gorget about the intake gaskets. An intake leak can suck a lot of coolant into the engine.

1 - 20 of 21 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.