Thread: Cracked Head ?

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I have a 383 that heats up in slow traffic. Uses some oil and has a disapeering Anti freeze- Am I looking at a bad head gasket or cracked head?
I has been over 240 at one time -Fan belt broke. Just tring to get some idea of what to look for when I can get it in and apart.
Thanks in advance
ED

Hey Ed,

When you start the vehicle up can you detect an antifreeze smell or white "steam" coming from the tail pipe(s)? Also does the oil look like a choc./vanilla shake?

Both are good indicators that you have what you think.

Regs

No signs of water in the oil and I have not seen it in the exhaust. Its in a GMC Panel and its kinda hard to see back there. However it is not fast. I can drive all weekend and it will only be down about a Qt of water. My son in law says he can tell when I am pushing the throttle when he is behind me.

Ed,

If you have no signs........it's possible that the radiator is your issue. It may not pass the water & it ends up boiling out. I'd first do a pressure check of your whole system first. That will usually detect leakage in any of the water system.

Also if you updated your engine (which the stroked 383 you have) the heat that this engine will thro may be a bit to much for the stock radiator??

When the engine is in the normal range of "heat" do you have any power issues?

Regs

The excessive heat 240 degress may have done in your thermostat and it is stuck closed. just a possibility. Still as REGs points out you could have a radiator issue, do a pressure test to rule out leaks, either it is a water flow problem or an air flow problem. Do you have a fan shroud around the radiator ? It is also posible that the radiator could be blocked up from slag and rust from the engine. Do you run a radiator pressure bottle ?

If your pressure test shows the cooling system to be not holding pressure, then do a leak down test on the cylinders to see which cylinder is allowing compression into the cooling system... When you know which hole has the pressure problem, lot easier to find the culprit rather then just shotgunning new parts at the problem.....

A quick check to see what hole has possible water injection problem is pull the plugs..........the 1 with no carbon & lots of moisture on it may be the culpret (unless you've changed the plugs recently)!!

regs

The Radiator is a two year old Griffin Aluminum. Yes it has a shroud. Have not pressure checked yet. It will be a week or so before I can get it in. Engine runs good at normal temps. . The catch tank has never overfilled and run over. The thermostat has been checked. As far as throwing parts at it, This would make a good excuse to replace the 71-72 350 heads with something better.( didn't have any money left when it went together)

I think my cooling problem is airflow. Truck heats up in slow, stopped traffic. Cools back down when it starts moving again. I have seen 230-240. You can feel the heat coming out once it start moving. Today I started the truck and let it idol in gear in the garage. Temp went up past the thermostat (180) to 200 opened the hood to let hot air out, no change. Shifted to neutral and increased the idol and the temp drops. It does have a shroud but it could be tighter to the fan. It has a 17” 6 blade Flex-o-lite SS fan. I have been thinking about going to a 7 Blade 18”. Any other ideas?

In my opinion those Stainless flex o lite fans are hopeless. Heres why, when they try to pull the air through, the pitch of the fan blade flattens out,so they cannot pull through the volume of air required for cooling. You have basicly tracked the problem to airflow by your process of elimination.
Get a multibade stock fan with the thermostatic clutch hub and mount that up. Should solve your problem. You actually pick up horsepower and save gas on these fans. Because they only work in slow or stopped traffic. Because radiator temp goes up this causes the spring in the clutch hub to expand and engages the fan to the driveshaft, this pulls the air through when you need it most or rather when your engine needs it most. When you are in high speed criuse the airflow through the radiator cools the fluid and as a consequence the spring in the fan clutch contracts and disengages the fan which "idles" and you save a few horsepower that drives the fan.