“ Help”on rebuilt 409 engine blowing water out overflow on radiator

[pvs409]

I have a completely rebuilt 1962 409 068 block, bored .30 over, with Ross pistons, 454 stroker crank, all new bearings, big block rods,
690 heads, new stainless valves, bronze guides, heads surfaced ( block was not surfaced to save #’s ). The block is level with a straight edge.

the motor has 150 mlies on it, it’s overheating( after it shuts off) - blowing water out overflow on Radiator when you stop after a drive. The level of the radiator makes no difference, it overflows even when the radiator is low. Runs 190 / 195 while it’s moving. Has new 4 core brass radiator, original stock 5 bladed fan, 409 shroud, new fan clutch. My other 1962 Impala 409 striker motor is fine the same cooling system.

the motor will start to overheat if idled too long - cools down when moving.

During a short run, the motor bubbles the water in the top of intake - without thermostat and housing - of the 2-4 single 4 barrel 409 intake water connection without the water pump connected and no fan.

Disaassembled motor completely at machine shop, crack checked the block and heads - ok
(they were crack checked before the original rebuild )
this machine shop has done 3 409 motors for me and one for a friend and other 348 & 409 motors, they could not find bad head gasket - the gasket area looked fine on the heads.

I do have one cylinder that was scratched vertically by a ring (3 inch long), hopefully honing it will work ( it did blow oil I out the front breather after a drive of a few miles) .
This ring scratch probably was probably the cause - the other 7 cylinders look good.
will have check clearances during honing on one cylinder - hope to avoid new .40 over pistons and boring block

what else can we check ? with engine disassembled...
could assemble it on run stand to run it again.

Paul

 

[1958 delivery]

some how might be related to cam timing. What cam, lifters etc?

 

[blkblk63ss]

During a short run, the motor bubbles the water in the top of intake - without thermostat and housing - of the 2-4 single 4 barrel 409 intake water
connection without the water pump connected and no fan.
Can you be a little more clearer on this?

 

[La Hot Rods]

Can they pressure test the head?

 

[pvs409]

Before removing the motor, we/they(my local restoration shop who has done 100's of Chevys and other models) removed the water pump, fan and upper radiator hose and the thermostat and the thermostat housing on top of the intake.

Ran the motor and the water remaining in the intake just below the thermostat housing bubbled during the run. I am not sure how many bubbles -enough to note that its not circulation of water creating bubbles (without the water pump)-I assume they ran it for few minutes, I was not there Enough for them to conclude that air is getting into the water creating bubbles..

I was frustrated so had the restoration shop do the removal after me and friends did this 62 SS 409 convertible for the last 6 years.
The same machine shop that did the motor, has it now. My friend assembled the block for me (he has done 5 -409 motors for me)

Paul

Pressure checking the head or even the block was my first thought -but I do not know....

Cam is Comp cams roller rocker -from cam card
gross lift intake .578 exhaust .589
tappet lift @ .006 duration lift 281 (intake) and 287 (exhaust)
Duration @.050 - 230 ( intake) 236 (exhaust)
Lobe separation 110.0
Lobe lift (intake) - .340 (intake) .347 ((exhuast)

 

[MRHP]

I would have thought somebody would have pressurized each cylinder with the valves closed and checked for bubbles in the coolant system. Easiest way for checking leaks in the chambers, heads, head gaskets etc... jetting and timing would most likely explain overheating. Good luck! Let us know what you find.

 

[MRHP]

Oh, and what pressure radiator cap, and did you test the opening pressure of it?

 

[blkblk63ss]

Are they sure that cylinder score is not a crack. My son's scout v8 developed a crack in cylinder wall which dumped antifreeze in and out exhaust. If that score is only three inch long and the ring is causing that score it would be full length of piston travel. Just wondering if that's a possibility.

 

[pvs409]

No crack in scratched cylinder - they just crack checked the block after disassembly.
Yes my machinist said the scratch is from a ring broken or clipped moving through the full cycle.
All good things to check as noted above.

 

[1958 delivery]

Did you check for gases in water?

 

[1964SuperStocker]

Oh, and what pressure radiator cap, and did you test the opening pressure of it?

I was just going to ask about the radiator cap. Just figured out I need a different one after a couple long drives. I was also going to mention pressurize each cylinder individually. My other guess is the intake has an issue.
Which intake is this? I hate the exhaust crossover in the 881 but your intake isn't cracked anywhere is it? If by chance it has some junk in it blocking a water passage then that might explain "water bubble" issue. If that water doesn't move freely then it will get a hot spot which may explain some of your symptoms.

 

[wristpin]

Before removing the motor, we/they(my local restoration shop who has done 100's of Chevys and other models) removed the water pump, fan and upper radiator hose and the thermostat and the thermostat housing on top of the intake.

Ran the motor and the water remaining in the intake just below the thermostat housing bubbled during the run. I am not sure how many bubbles -enough to note that its not circulation of water creating bubbles (without the water pump)-I assume they ran it for few minutes, I was not there Enough for them to conclude that air is getting into the water creating bubbles..

I was frustrated so had the restoration shop do the removal after me and friends did this 62 SS 409 convertible for the last 6 years.
The same machine shop that did the motor, has it now. My friend assembled the block for me (he has done 5 -409 motors for me)

Paul

Pressure checking the head or even the block was my first thought -but I do not know....

Cam is Comp cams roller rocker -from cam card
gross lift intake .578 exhaust .589
tappet lift @ .006 duration lift 281 (intake) and 287 (exhaust)
Duration @.050 - 230 ( intake) 236 (exhaust)
Lobe separation 110.0
Lobe lift (intake) - .340 (intake) .347 ((exhuast)

Running engine with just enough water in block to have it up to the bottom of the thermostat housing and saw bubbles. Water under a low pressure area such as the eye of the impeller of the water pump with flash to steam (bubbles) at 180°F. To base decisions on that test is a waste of money and time in my opinion. Pressurizing each cylinder and listening for air flow at intake and exhaust ports is a PITA but reliable test. Loosen all the rockers so theres no guessing if valve is 100% closed.

 

[1958 delivery]

If I'm reading you right I had a ZZ crate engine that did the same thing. It had an overflow tank and no matter how low the water level was in the radiator it would always fill the overflow yet never overheat. I had no idea what was going on but I sold the car.

 

[427John]

No crack in scratched cylinder - they just crack checked the block after disassembly.
Yes my machinist said the scratch is from a ring broken or clipped moving through the full cycle.
All good things to check as noted above.

I think what blkblk63ss is trying to say is the scratch should be 4 inches long.

 

[Hoyt99]

We used the smog machine to sniff the radiator and see if there were gasses present, like 1958 Delivery suggested, and if there were combustion gasses, it started To narrow down the possibilities. And if no gas present, it eliminated a lot of stuff.

 

[wristpin]

If I'm reading you right I had a ZZ crate engine that did the same thing. It had an overflow tank and no matter how low the water level was in the radiator it would always fill the overflow yet never overheat. I had no idea what was going on but I sold the car.

I had an issue like that with 427. Switched to a different type overflow catch tank and problem was solved. The origional one was basically a sealed container with small vent in top that the radiator over flowed into. The new one had radiator vent into the bottom of the container with vented top. Both were about .75 gal

 

[409newby]

My car did that no matter how full the radiator was a overflow tank fixed the problem, not sure how they got by without a tank when new

 

[blkblk63ss]

My 327 puked out occasionally after shutting engine off. I have a aluminum radiator and was using parts store radiator caps. I went and bought a GM cap from Chevy dealer and installed a recovery chrome cylinder type tank mounted vertically next to radiator. I don't even think it dumps any antifreeze in it though. The GM cap seems to seal better.

 

[1958 delivery]

My car did that no matter how full the radiator was a overflow tank fixed the problem, not sure how they got by without a tank when new

You guys are missing the point, the water overflowed even when radiator was half empty, has nothing to do with having an overflow tank or not. Something continually pushed water out but didn't show signs of overheating. No idea what it was, sent it down the road-problem solved.

 

[MRHP]

Did magic push it out.....not. The heat soaking of the motor raised the pressure and temp of the coolant making it expel out the overflow. The cap either was not sealing properly or not high enough pressure. Mystery solved!