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285 degree overheat from not paying attention

V-6 Camaros rule!
Posts: 55
Joined: 12/10
Posted: 03/10/13 05:59 PM

Just got the ole chevy out from storage and let it run.  Wasn't paying attention, but evidently the electric cooling fans either failed or the temp sensor to activate them did.

Let it idle for about 30 minutes, heard it boiling over and just as I killed it, the rubber cap blew off.  Gauge read 285 degrees.  

This was a fairly performance new engine with about 300 miles/30 hours on it:  

387 stroker
edelbrock rpm performer heads
victor jr
comp .520/.540 roller cam

Did notice any water on the oil?

What else should I check before repairing the radiator and filling it back up.  Sure hope a didn't hurt or blow this engine up.  

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I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 03/11/13 08:13 AM

checking to see how fast the cooling system comes up to pressure..

depending on the head gaskets and head bolts... you might want to take the time and retorque the heads..  this is the reason i always use hylomar on my head gaskets.. but thats me..  especially with aluminum heads..

using a clear vinyl hose on the radiator output...   looping it over the hood catch so its hanging.. filling the radiator fully and the hose part way with coolant... when you start the engine.. watch the coolant in the hose... are you blowing any bubbles.. or just expanding..

you WILL also want to change your thermostat.. before doing anything else...  as with overheat conditions.. the wax in the thermostat will expand far enough to push past the seal and not leave enough to operate the thermostat properly.

if you have a compression tester... a remote starter button and an air compressor.. if you can hook your compression tester hose to the air compressor. then remove the valve core so air will flow out the end of the compression tester..

now.. you can use the compression tester hose and the remote starter to set each piston at TDC on the compression stroke  once there...  hook up the compressed air... with the cooling system filled and the cap off..  if you get bubbles in the cooling system.. you will have shown that there is a leak .. i use this to prove to customers that they have a blown head gasket.. i don't use the cylinder leak down tester hose as that has a restriction that limits the airflow..  

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I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 03/12/13 03:01 PM


I missed your post. But Wayne had you covered.
I don't know if you meant you had water on the dip stick
or you didn't have water on the dip stick. to be redundent
recheck the crank case. Anyway you can try this if you had
water on the dip stick.

If you didn't have a problem with the air flow, fans
thermostat etc,etc...

You may have had a faulty cooling system pressure cap,
whan the engine sat for a year it could have killed it...
If all those things checked out Okay, then maybe the next
part may help you....

1.You need a cooling system tester

2.Refill the engine with just water

3.Remove the spark plugs

4.Disarm the ignition

5.You may have to refill the cooling
system a few times, to remove the air
or unless you see water running out of
a cylinder. (Seen this happen)...

6.Pump the cooling system to what the
Pressure cap says. Or if you have a
service manual go by that. (Don't over
presureize the cooling system). You can
rupture the heater core or seals in the
water pump, or damage the radiator.

7.Pump it up and watch the pressure, if
the pressure drops  very fast it could
be air in the coolingsystem. (NOTE plug
off the overflow linethat goes to the
recovery tank).

8.Once you get the pressure where it may
hold. Let it sit. If you have a big enough
leak in the cooling system, you'll see the
water rolling out of the cylinder, or it
maybe filling up the crank case. So if the
oil level goes up thats a blown head gasket.

9.Have a helper crank the engine while
you watch the engine for any water. If
you have a blown head gasket, water will
come from 1,2, or more cylinders depending
on how many cylinders were affected.

10.If you don't get any noticeable water
from any cylinders, then you can have a blown
head gasket that blew out in an area where you
will only find water in the oil.

Whatever the case maybe you will need to pull the
heads off the engine.

"COVER ALL THE LIFTER VALLEY".... so you don't get
any grit in the oil....
When you do remove the heads. Remove the (4 dowel
pins 2 from each side). You can still Clean the
bulky heavy stuff the razor blade, lacquer thinner.
  Using wet/dry 220/240 grit sandpaper wrapped around
a piece of 2"X4". Run the sandpaper across the top of
engine block. "CRISS/CROSS" the patterns.
In different directions doing this as
many times as it takes to clean the top of the block.
You'll see what I mean. This helps clean the top of
the block, and this helps the new head gasket have a
mating surface. Then reinstall the (2) Dowel pins on
each side. Bevel the leading edges so the dowels go in
the heads easier. I have been building engines for
  When I am using a steel shim head gasket, I
use a $.99 to $1.99 can of Aluminum Spray paint. I
apply (2) light coats then can get tacky between coats
or if you don't feel safe and want to spend $5.99 a can
for the newer gasket adhesive then go ahead. (If you use
the $.99 to $1.99 aluminum spray paint you will see just
how tough it is to clean of the block, and the heads on
teardowns.....Don't forget to use sealer on the head bolts
where it's needed. Grin  Cool


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Posts: 7841
Joined: 12/09
Posted: 03/12/13 03:05 PM

+1 Bob

A good way to tell if there is water in the oil is to take the dipstick and dribble oil on a hot exhaust manifold.,. if it sizzles then there is water.
But if it only smokes, then it is only oil.,. no water.

When The Flag Drops.,.


The Bull ***t Stops.,.

P. Engineer, Engine Builder

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I mow my lawn and find Chevys
Posts: 2738
Joined: 08/09
Posted: 03/12/13 10:56 PM

Hi there,
You can  loosen the sump drain plug 1/2 way
when engine is stone cold and see if the oil
is like Brylcreem hair oil color or any water
simply runs out like about 1/2 cup fuel that
has not yet mixed with the oil.
 Good luck...Skyeking  

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I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 03/13/13 09:09 AM

"Great Tip"....
Your absolutley correct. The water will come
out first, if I remember

I wonder how many of our younger Gear Heads
remember or even heard of Brylcream. I know
at the Dollar store in the US they still sell
it. Grin  Cool


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I love my Chevy Chevette!
Posts: 7
Joined: 02/13
Posted: 03/13/13 09:50 AM


Yourself & Wayne covered the technical side admirably.
As did skyeking, which I love the Brylcreem analogy, just one question;
"Does a Dab still Do Ya?

Just asking....  
Gregorio Lonewolf

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I mow my lawn and find Chevys
Posts: 2738
Joined: 08/09
Posted: 03/13/13 04:27 PM

Hi there agent 11,
Only have 1/2 of the ist content.
All down the sides.Have still got
a Tub unopened after 6 years.
Cannot blame Cancer for natural baldness..
 Welcome to the Den of Verbal iniquity
where all the Berbal Vandits hang out except me.  

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