Need experts help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sfcharr · 07-29-2014, 07:45 PM

I have a 69 C10 with a rebuilt 250 6 cylinder. The truck runs great, but lately I've noticed steam coming from the exhaust manifold above the the exhaust pipe flange when I first start the truck. In a few seconds the steam burns off. Today it appears that I'm leaking coolant on the ground under the exhaust manfold. Any ideas how to rectify this situation short of removing the head and having it inspected? The truck is completely stock and runs great with the exception of this coolant leak. the radiator is down abouit 1/2 gallon but that is from approximately 2000 miles from driving this summer.

Any advice would be appreciated

**70cst** · 07-29-2014, 10:11 PM

Here is a bump for you.

Ok mechanics ... how about a helping hand

Tinkermc · 07-29-2014, 10:12 PM

Check around the filler neck for the top hose.

kneesnthebreeze · 07-30-2014, 12:00 PM

you may want to drain the oil and see if there is any coolant in it, would be another cheap and easy way to see if the gasket is damaged, if no coolant, just put the oil back in the motor and look for other possibilities but at least it wouldn't cost you anything but time. May also save you from destroying the motor. just a thought.

nzc10 · 07-30-2014, 12:45 PM

Hey there I would pressure test the cooling system and take note of where the coolant is leaking from and go from there possible external weeping head gasket or maybe a frost plug

**Zeke's Garage** · 07-30-2014, 02:25 PM

Not sure if you've got a temp sender in the driver's side of the head, but it might be weeping a bit from there and running along the block to the exhaust. You can put in a bit of UV dye in the coolant and using a cheap UV flashlight see where the leak is coming from. The testing dye with a pressure test of the coolant system while everything is cool makes it easier to find small leaks like this.

Good luck with it.

smoked68 · 07-30-2014, 02:54 PM

Just went thru this with my 65 mustang, noticed white smoke out one side of exhaust. It was coolant. Pulled off intake and inspected. looked good but had to replace gaskets anyway then so before I did I thankfully checked head bolt torque and had a stripped bolt. A retap and new gaskets fixed the issue. Good luck. Sounds like head though if youre leaking no where else. good luck

sfcharr · 07-31-2014, 03:57 PM

Thanks for all your help and advice. Sounds like a winter project. I'm going to drive it through he summer and enjoy it. I will monitor coolant and oil levels.

Wrenchbender Ret · 07-31-2014, 04:25 PM

You have 2 freeze plugs on the head behind the manifolds. They can leak & run down behind the manifolds.

07-29-2014, 07:45 PM	#1
sfcharr Registered User Join Date: Aug 2010 Location: Castle Rock CO Posts: 76	Need experts help I have a 69 C10 with a rebuilt 250 6 cylinder. The truck runs great, but lately I've noticed steam coming from the exhaust manifold above the the exhaust pipe flange when I first start the truck. In a few seconds the steam burns off. Today it appears that I'm leaking coolant on the ground under the exhaust manfold. Any ideas how to rectify this situation short of removing the head and having it inspected? The truck is completely stock and runs great with the exception of this coolant leak. the radiator is down abouit 1/2 gallon but that is from approximately 2000 miles from driving this summer. Any advice would be appreciated

07-29-2014, 10:11 PM	#2
70cst Senior Member Join Date: Feb 2001 Location: New Madison, Ohio Posts: 21,373	Re: Need experts help Here is a bump for you. Ok mechanics ... how about a helping hand __________________ A husband can be right...or...A husband can be happy. 67-72 Chevy and GMC Trucks...The Classic Truck for the Classic Folk. 1970 CST Two tone green, 402BB, 400 Automatic, Tach, Buckets, AC, AM-FM, Tilt, GM CB, GM 8 Tract, LWB, etc JOHN 17:3...The better side of "LIFE" Remember: Everyday is a good day...Some are just gooder!

07-29-2014, 10:12 PM	#3
Tinkermc Registered User Join Date: Jul 2011 Location: Farmville, Va Posts: 3,026	Re: Need experts help Check around the filler neck for the top hose.

07-30-2014, 12:00 PM	#4
kneesnthebreeze Registered User Join Date: Jul 2014 Location: Jefferson GA Posts: 13	Re: Need experts help you may want to drain the oil and see if there is any coolant in it, would be another cheap and easy way to see if the gasket is damaged, if no coolant, just put the oil back in the motor and look for other possibilities but at least it wouldn't cost you anything but time. May also save you from destroying the motor. just a thought.

07-30-2014, 12:45 PM	#5
nzc10 Registered User Join Date: Feb 2014 Location: Palmerston North New Zealand Posts: 58	Re: Need experts help Hey there I would pressure test the cooling system and take note of where the coolant is leaking from and go from there possible external weeping head gasket or maybe a frost plug

07-30-2014, 02:25 PM	#6
Zeke's Garage Senior Member Join Date: Feb 2010 Location: Kennesaw, GA Posts: 288	Re: Need experts help Not sure if you've got a temp sender in the driver's side of the head, but it might be weeping a bit from there and running along the block to the exhaust. You can put in a bit of UV dye in the coolant and using a cheap UV flashlight see where the leak is coming from. The testing dye with a pressure test of the coolant system while everything is cool makes it easier to find small leaks like this. Good luck with it. __________________ -- '67 Chevy Stepside 250 Inline 6 Megasquirt Fuel Injection T5 5 speed conversion Ferric Oxide impregnation throughout

07-30-2014, 02:54 PM	#7
smoked68 Registered User Join Date: Oct 2006 Location: Rock Hill, SC Posts: 421	Re: Need experts help Just went thru this with my 65 mustang, noticed white smoke out one side of exhaust. It was coolant. Pulled off intake and inspected. looked good but had to replace gaskets anyway then so before I did I thankfully checked head bolt torque and had a stripped bolt. A retap and new gaskets fixed the issue. Good luck. Sounds like head though if youre leaking no where else. good luck __________________ 1968 chevy shortbed, Dark Shadow Gray 4 bolt 383 Stroker,Weiand Super Charger, disc brakes, 9 inch, 391 gear, 20" Eagle wheels, muncie 4 speed/ Hurst shifter, 4/7 drop, Hedman midlengths, 3 inch exhaust w/ 2 chamber flows. 1966 Mustang with 306 roller, c-4, 9 inch Detroit locker rear. 1965 Fastback Mustang w/347 stroker, top loader 4spd, 9 inch detroit locker. 1966 Mustang coup, 306 roller, c4, 9 inch. 65 Cobra, 427, T6oo, 9inch, of course. First gen Hayabusa, airbox mod and running 2 exhaust cams.. Zoom Zoom Zoom

07-31-2014, 03:57 PM	#8
sfcharr Registered User Join Date: Aug 2010 Location: Castle Rock CO Posts: 76	Re: Need experts help Thanks for all your help and advice. Sounds like a winter project. I'm going to drive it through he summer and enjoy it. I will monitor coolant and oil levels.

07-31-2014, 04:25 PM	#9
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: Need experts help You have 2 freeze plugs on the head behind the manifolds. They can leak & run down behind the manifolds.



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