Where is my coolant going???

[muttruck]

This truck is my son's. It was given to him so there are many unknowns. I sent him to school with my car. It runs reasonably well, but the engine is tired. I have discovered the engine is about a 1977 305. He replaced the intake manifold when he first got the truck. I have discovered I am loosing coolant. I have checked the water pump for leaks tightened all of the hose clamps and never see coolant on the ground or frame, the oil is not foamed or discolored. The radiator was fairly new when we got the truck. I am pretty sure he sealed around all of the bolts into the heads. Any ideas?

[Ace in the hole]

If you don't see leaks and it's not ending up in the oil, most likely its going out the tail pipe. Sounds like it's getting into the cylinder somehow, maybe a bad head gasket.

[airdale94]

If he just replaced the intake gasket I would suspect something he did. Or a head gasket like Ace in the whole said. What was the reason he replaced the intake.

[68gmsee]

I agree with above posts... Most of the time it's a leaking head gasket. When the engine warms and as the the water gets hot, it is forced through the head gasket into the pistons.

I've never had it done, but the best way to find out is by having a shop do a leak test. That way you'd know for sure.

[Sport/Truck]

Originally Posted by airdale94

If he just replaced the intake gasket I would suspect something he did. Or a head gasket like Ace in the whole said. What was the reason he replaced the intake.

Probably just to put a new aluminum intake on is my guess.

I had a `99 Chevy Tahoe and it “used’ antifreeze. It sounds like your dilemma , on mine it never had puddle, couldn’t see any evidence of a leak. I had the system pressure tested and nothing showed up…..until the next day! It ended up being the intake leaking and it was running down the hot engine and evaporating.
I would suggest having you system pressured tested at a rotator shop. They can sniff for head gaskets leaks too. Just keep in mind that if it’s a small leak it may not show up with his test (like mine), but it helped it leak more making it easy to find the next day!
Good luck, and keep us posted on what happens.
s/t

[WorkinLonghorn]

Does it have an expansion tank? If not you will lose coolant as it expands especially if the cap leaks. Also,if the coolant is getting into the cylinders then you will see evidence of this on the spark plugs assuming you do use anti-freeze.
You can put a piece of cardboard infront of the radiator and get the motor real hot and turn it off and look/listen.

[Rooster's 67]

If you pull the spark plugs out, water in the combustion chamber will remove all carbon from the ceramic of the plug making it nice and white. The cylinder with a white/clean plug is the one with a coolant leak. That is a little cheaper than paying some one to run a coolant system pressure test for you.

[blue 71]

if if has an automatic trans, might check the fluid in it
even though the radiator is fairly new it could be leaking back
into the trans through cooling lines. just a thought.

[Longhorn Man]

While these are all good things to look for, I say search the outside of the engine real close first. Odds are, it is an external leak, and you don't see if for many reasons (like was already posted) Basicy... i agree with him!

[muttruck]

First of all I want to thank all those who took time to reply. Your suggestions have given me many good ideas of where to start. I should post a picture of this thing so you will understand why I sign on as muttruck.

Please allow me the time to share my humorous/humbling journey since last September. It is a 71 3/4 ton 2 wheel drive frame, 72 body, and a 77 engine. When my son got the truck it was a nice combination of light body rust and gray primer. Before he left for school his friends decided to paint the truck for him. They had recently painted the church bus and it came out ok from about 50 feet so I thought "it can't look any worse than it already does and will likely look better. He had been working the week before removing the rust and priming. The day this happened he was headed out the door with our compressor hose. I asked him where he was headed. He told me "to paint the truck". I said "oh that is great who has the sprayer"? To which he replied "oh we are'nt using the paint sprayer, they bought 12 cans of red spray paint"! I will let your imaginations take over from here, but needless to say if I were in grade school someone would or should have beat me up by now. The things we do as parents.

To Longhorn Man, I have and will continue to watch the outside for leaks. the scary thing is I had a dream last night that I found a pin hole in one of the hoses...but I woke up this morning and realized it isn't that simple. I checked the hoses and tightened the clamps already.

To Blue 71. I have to keep a constant eye on the trans fluid. when I first started driving the truck the steering crossarm rubbed a hole in the cooling line and I had to put in a splice.

To Rooster's 67 Good suggestion I will do that. My number 8 I have to keep an eye on regularly. I think the valve seal is leaking pretty bad and I foul that plug every few months. The engine is tired!

To Workin Longhorn It does have an expansion tank, but I can't keep fluid in there for long.

To Sport/Truck, that is what I was thinking and why I posted. As I said my son replaced the manifold and did quite a bit of research on how to go about it. If I recall correctly he got a suggestion to make sure he sealed around the bolt holes to prevent oil seeping which could also have application to the water as well.

To Airedale 94 He replaced the stock manifold to get rid of the pieced together Rochester that came on it. He was insistent on not putting on a rebuilt Rochester. His money, he wouldn't listen to dad. The manifold is an Edelbrock and he replaced the Rochester with a Holley 570 Avenger if I remember correctly.

To Ace in the hole. My flawed thinking never considered the head gasket. The other day it was pretty cold here, I was letting the engine warm a bit before I took off and noticed both pipes had a little water coming out. I dismissed that as condensation from the hot exhaust hitting the cold pipes.

In closing I should say that this thing has worked its way into my heart. As quirky and ugly as it is I like it for some strange reason. I would love nothing more than to put a rebuilt long block in it, tighten up the steering and get the outside looking better. I do admire those of you who are able to restore your trucks. Some of those I have seen are really nice.

I hope I don't get my hand slapped for the lengthy e-mail. I felt responsible to reply to all who took time from their busy lives to write me. I also needed to express myself to those of you who understand. My wife just says "we need to get rid of it"! It feels like she is asking me to give one of my children away. I will keep it short in the future.

[72BLUZ]

Have You Pressure Tested The Radiator Cap. If Its Not Holding The Pressure It Will Let It Out Thru The Over Flow Tube. And Check All Things Listed In The Previous Posts

[nofords]

All this advice is good, but you're overlooking a common coolant leak in these old pickups. Heater core. If it steams up the windshield with the defroster on, you've found the problem....nofords

[muttruck]

Back at it after weeks of snowy, cold weather. Not ideal situations when you don't have a place to work but your driveway. Today is the first day the weather was good enough to look under the hood.

72bluz I have not pressure checked the radiator cap. It looks really new although that could be an issue..... or the wrong cap even.

nofords The defrost doesn't fog the windows and the carpet isn't wet.

Now for what I have been experiencing lately and what I found today. The right exhaust has been looking like a pressure cooker. It also has the peculiar smell of something burning in the cylinder other than oil or gas. Much more condensation than the driver's side, with little wisps coming out of the pipe after the engine is shut down. Aha! The engine has been running more and more rough as well. Today I went back and checked the manifold bolt torque and they needed to be re-torqued. My number 8 cylinder is always fouling ( definitely weak) so I cleaned the plug. I also checked the plugs on the right side and none were nice and white as rooster's 67 suggested earlier. It likes to use oil so I checked the oil, low but no signs of water in the oil. I did notice the underside of the oil cap had a light colored mung on the underside kind of like water and oil mixed. I didn't know if this was cause from condensation as it has been really cold. Anyway, I cranked it up and let it idle. With the hood up, I did catch what smelled like hot coolant and the right exhaust is still smoking more than the driver's side, but the engine runs much better. It seems that as the engine heats up it runs better. I am thinking the different expansion rates of the aluminum manifold and cast iron block may be creating the leak as the gasket may not be sealed. The fact that it runs better when warm leads me to suspect the manifold gasket. Also the number 1 manifold bolt (Edelbrock torque pattern) always has oil puddled at the base of the bolt. A question for you? Would the engine still run ok with a blown head gasket?

Mutt