Engine Steam Baffling Me

[70_440-6Cuda]

Having a strange issue with getting some white smoke / steam coming out of the engine bay at idle, but only sometimes and it is very faint.  Under hard acceleration I also sometimes get some coolant trailing up between the fender and the hood on the left side - the baffling part is, I'll be damned if I can find the leak, and parked in the driveway in neutral with the hood up and opening the carb to rev the engine - nothing.  No leak, no coolant spray nothing that directs me to any specific location.  Only seems to happen under a strong load - any suggestions how I can identify where the leak might be coming from? 

[Cudajason]

Having a strange issue with getting some white smoke / steam coming out of the engine bay at idle, but only sometimes and it is very faint.  Under hard acceleration I also sometimes get some coolant trailing up between the fender and the hood on the left side - the baffling part is, I'll be damned if I can find the leak, and parked in the driveway in neutral with the hood up and opening the carb to rev the engine - nothing.  No leak, no coolant spray nothing that directs me to any specific location.  Only seems to happen under a strong load - any suggestions how I can identify where the leak might be coming from? 

you could pressure test the cooling system.  should show the leak.

[anlauto]

Is it coming from the rad cap?

[RzeroB]

For hard to find leaks like this I would recommend trying a fluorescent leak detecting dye. It should leave a tell tale trail right back to the source of the leak. Something like this:   https://www.autozone.com/test-scan-and-specialty-tools/uv-light-and-accessories/p/autopro-antifreeze-coolant-leak-detector-uv-dye-1-oz/667633_0_0

[70_440-6Cuda]

Thanks for the insight - going to see if I can rent a pressure tester - seems the easiest way to solve the problem.

And I didnt even think to check the cap because of course I immediately think it must be something more complicated!

[Hood]

Possibly a freeze plug?

[70_440-6Cuda]

Possibly a freeze plug?

That is what I thought originally, but have not been able to verify - so annoying!

[Dmod1974]

Not sure about what engine and heads, but what about a leaking exhaust manifold stud that goes into the water jacket?  It'll turn to steam and evaporate almost instantly, which would make it hard to find.

[70_440-6Cuda]

It is a 440-6 with stock heads... I was looking at one of the rear exhaust studs, but cannot confirm - going to try a couple of the suggestions here and see if I can't find the problem this weekend

[Chryco Psycho]

I agree , the exhaust studs are the first place I would look .

[blown motor]

Keep us posted.

[70_440-6Cuda]

So with my missing hood pin hood removal procedure, I am now driving the car with no hood.  I have not done much other than move it in and out of the garage, but had some clear weather and took it for a spin the other day and can clearly see water spraying out from the direction of the thermostat housing.  Also, it only sprays water when under hard acceleration - sitting in the drive way revving the engine pretty high - no water anywhere.

Question:  PO capped the water pump outlets with rubber caps and hose clamps - any issues with capping off the water pump outlets, or should I rather install a loop?  I cannot tell if it it leaking there or at the t-stat, but going to change the t-stat, gasket, radiator cap and either loop or plug the heater outlets - thanks.

Hoping it is not leaking at the water pump housing....

[Dakota]

On the assumption the capped outlets are for the bypass loop, my 2 cents would be to put the loop back in service.  See text in the photo below. 

For what it's worth, I had a hard-to-find leak that turned out to be in the thermostat housing. It wasn't obvious until I removed the housing to swap the thermostat.

[RUNCHARGER]

I've installed plugs to replace the heater hose tubes lots of times. The problem you will have is getting those tubes out of the WP housing, they'll be rusted in hard.
It's quite likely the thermostat housing is either warped or corroded enough to leak. Hopefully you can flat file it and that takes care of it.

[70_440-6Cuda]

thanks @RUNCHARGER, going to replace the tstat housing as well - hopefully this weekend and see where it all goes