Coolant Leak

[dagnabbitt]

My 355 Blueprint started leaking coolant this summer. It has probably 3000 miles on it at most, it was installed last year. It started as a few drips and now its a puddle. The cradle/crossmember is full of bright green coolant most days. When I drive away it leaves a little trail behind me.

A friend of mine who I usually trust for stuff I am unsure about says that one of the water pump bolts is likely not sealed. I bought some permatex aviation sealant to do the job.

But first I took it to another friend who is more of an engine guy and he doesn't think that is it at all. He thinks that pulling out bolts and sealing them is unnecessary. He recommended just putting some Silver Stallion in the rad and seeing if that would solve the problem. I remember selling that stuff at the gas station I worked at when I was 16 and I always assumed it was a BS product. He builds engines and hot rods though, so I am inclined to try it.

The rad is a stock one that I had recored into a 3 row with restrictors, and I am running a 160 degree thermostat. The engine never, ever, comes close to overheating, and in fact I was thinking of changing that thermostat to a 180 or 190 but keep getting talked out of it.

Here is the kicker: no matter how much coolant leaks, the rad is always full. I check it a couple times a day and I couldn't add any if I wanted to.

I usually do my own research, trust my gut, and mess around without worrying about consequences: but with a brand new engine I am more hesitant to do that. What do you think?

[Wrenchbender Ret]

Craul around under the hood & under the truck & find where the leak is. Get an inspection mirror & look at the weep hole in the bottom of the water pump. A pressure tester is good for a job like this. Sealer will only workon certain leaks like the radiator or head gasket. Its best to find the leak & fix it. Its possible you are filling it too full & it is coming out the o-flow tube.
George

[Dead Parrot]

Check the hose connections and make sure the hose clamps are in good condition and proper tightness. Fairly common for new hoses to leak a bit if you didn't get them tight enough.

Check the level in your overflow container. They should be fairly empty to allow for coolant expansion as the motor warms up. If this is an older setup without an overflow tank, you normally left some air space in the radiator to allow for expansion.

For most OEM SBCs, a 195 was the equipped thermostat. If you plan on winter driving, install at least a 180 once you get your leak fixed.

[garyd1961]

Find the leak and fix it don't pour anything in the radiator. If you put stop leak in it you won't find the leak until you are left beside the road one day. Probably just a loose hose clamp or water pump gasket but whatever it is find it and fix it before you run it hot.

[dagnabbitt]

I have not added any stop-leak, I have been checking the levels though. I am wondering if it was simply overfilled from the start.

I have determined that it only leaks when it is cold, ie parked. What does that sound like it might be.

[RustyPile]

Originally Posted by dagnabbitt

I have not added any stop-leak, I have been checking the levels though. I am wondering if it was simply overfilled from the start.

I have determined that it only leaks when it is cold, ie parked. What does that sound like it might be.

Never mind what it "sounds like it might be".. Your 2 mechanic friends are just guessing and so are you.. And now you're trying to enlist more guess work from us.. Do what others have suggested.. Buy, borrow, or rent a cooling system pressure tester.. Go over the clamps and tighten each one.. Pressure up the cooling system to about 10 - 12 lbs.. Crawl around with a good light and check everything -- gaskets, freeze plugs, water pump weep hole, radiator seams -- everything, even the radiator cap.. If you have a recovery system, normally, you'll not lose any coolant.. If you don't have one, you have to leave a couple inches air space at the top of the radiator to allow for coolant expansion.. Otherwise, after warmup. coolant will be pushed out through the overflow tube on the radiator..

[dagnabbitt]

I suppose I should have mentioned that I have followed all the above suggestions, with the exception of renting a pressure tester. I've had a long week at work and simply haven't had the time to do so. Maybe this weekend, thanks for your help.

[geezer#99]

Clean off as much of the motor you can and then spray some baby powder on it.
Any leaks and their sources will show up quickly.

And the powder washes off easily afterwards.

[LS short box]

The national chain stores around here like Oreillys and Autozone let you borrow a pressure tester.
Back in the day as chev tech we would clean up any anti-freeze then pump up the pressure tester and walk away for a couple of hours. Then look for leaks.

[dagnabbitt]

Thanks, I will see if my local parts store will lend me one.

[AcampoDave]

Originally Posted by geezer#99

Clean off as much of the motor you can and then spray some baby powder on it.
Any leaks and their sources will show up quickly.

And the powder washes off easily afterwards.

Nice trick there Geezer. I never heard that one before.