Head Gasket Question

[chrisdavid]

We think we blew a head gasket on Saturday night. We got hot and lost a lot of water. When we got home we started the truck and realized we were pouring out a lot of water out of 1 exhaust, along with a lot of white smoke. We didn't find any water in the oil and the plugs look good. I'm thinking the gasket could be leaking straight to the exhaust.

 

Does this sound right?

 

If so, How in the heck do I change the head gasket on this 305. I'm not a mechanic, but would like to do it myself. Please help so we can get back to racing in Houston on the 4th.

 

Thanks,

Chris David

#52 Pro Truck

Cell 832-731-3890

[supertx]

It's possible you blew a head gasket but it is more likey that you cracked the head.Drain the water pull the header remove the intake .take off the rocker arms then the head bolts.If you don't see where the head gasket blew take the head to your machine shop and let them pressure test it .

[jwmbishop]

Chilton guides are an easy read and follow for instructions on the R&R - you just won't have all the crap a street car has. Get one for an older (pre 84) chevy truck and it will be most relevant.

 

When you got the cyl head off look real close at the head gasket flame ring (the ring around the cyl) - a lean condition will look like a micro midget has been beating on it with a microscopic ball peen hammer and it will appear dull grey on the edges exposed to combustion (clean the carbon off with MEK or TriChlor - brakleen - to see the true color of the metal). the bridging to water usually occurs at the upper "shared" head bolt hole to the flame ring cyls 1 and 8 being the most common in a single even overheat. Multiple event overheats typically burn 4 AND 6, or 3 AND 5. the reason I bring this up first is because rarely do gaskets fail. Something injures it first (usually overheating either the coolant or the combustion) - then it fails and fixing without curing will end up frustrating the heck out of you. Make sure you find the cause! My experience with street engines has been that the most common issue is radiator maint - while with racing engines the most common is fuel mix. A lot of guys set the jetting early in the season and go racing and never really check it later (like when the air temp is higher and/or humidity is down). So here comes late summer heat wave and pop goes the motor.

 

The fact that you lost a lot of water should be no problem as long as you did not put any in while the thing was hot. Pressure test for sure tho. You can accomplish this by investing one time in 4 big C clamps or enough bolts and nuts to clamp both heads together face to face with a sheet of rubber between em. then just make plates for the water openings in the intakes sides with one of em having an air inlet - add 30 lbs of air and you will know IF they are leaking. Unfortunately you won't know where - but if they are holding then you won't need the trip to the machinist. And this way you are now tooled up to field test any time! Alternately if you are handy with a torch and can get your hands on some 1/4 inch or thinker plate you can use a gasket as a template to make a plate that will enable you to check one head at a time - and see in the chamber while the pressure is applied!

[chrisdavid]

Thanks for the help guys.

 

As an update.....

We got the motor out of the truck. We started slowly breaking things down. We found that the head had a LARGE crack in it. The block also appeared to suffer some damage.

 

I love learning new things, despite how heartbreaking my find was, I have learned a lot in the process. We are selling out our 305 equipment and switching to a crate motor!

 

THANKS SO MUCH AGAIN! I appreciate all the guidance of this website!

 

Thanks,

Chris David

[jwmbishop]

Just please - make sure you understand that the crack is a result of an overheat (I have had many people argue with me on this). Yes once the crack is present it will be a contributing cause of future overheating - but its original creation is a RESULT of.

 

In other words don't just throw that crate motor in it, go on doing what you been doing and have IT overheat as well! verify everything you will use on it is correct and working! Make sure you understand what happened in your specific case so you won't have it repeat.