new engine rebuild over heating....help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Blue4x4 · 06-29-2004, 10:51 PM

Just started the new rebuild and found it to be overheating. This is what I've found:Engine runs fine with no t-stat. I've put in 2 new t-stats and still have the same problem. T-stats are 180 degrees. The upper hose off the t-stat is cool, but the heater hoses are HOT. And the gauge is pegged. Any suggestioins?????

cdowns · 06-29-2004, 10:56 PM

wadda yu need a thermostat fer in nevada????

Blue4x4 · 06-29-2004, 10:59 PM

LOL......we need these things here in our state.

walker · 06-30-2004, 12:10 AM

Are you sure you have the t-stat in the right direction? Bulb side goes to the engine. Also are you sure you have the right direction water pump? My ol' dad made both those mistakes, it was on a F**d though so thats all right. Only other things I can think of is a damaged impeller on the water pump, causing weak flow, bad sending unit(or mounted in a bad spot). Maybe try a 160* t-stat.

72 CustomCamper · 06-30-2004, 12:19 AM

Off the wall thought, but the head gaskets could be on wrong and blocking the water passages...

Chuck

Tx Firefighter · 06-30-2004, 12:26 AM

You said you started the fresh rebuild and are having this problem.....

It's an air lock under the thermostat.

That's why it will work fine without the thermostat. The closed thermstat won't allow the air to burp out of the block as you fill the radiator with coolant. The thermostat is the highest point in the block and all of the air rises to there.

An air pocket will insulate the stat and keep it from seeing how hot the coolant is. The engine gets hot, but the thermostat doesn't open up.

Open the new thermostat with your hands and put two or three aspirins in it to hold it open. Now install it and add coolant to the engine. The aspirins hold the stat open and allow all of the air to burp out and the engine block to fill up completely with water. Once the engine runs and the coolant circulates awhile, the aspirins will disolve and the thermostat will work normally from now on.

jhow66 · 06-30-2004, 12:39 AM

Hey Tx Fire' that is one great idea! I was going to tell him to drill a small hole in the themo flange to release air. Got to try that next time.

Tx Firefighter · 06-30-2004, 12:49 AM

Quote:

Originally Posted by jhow66

Hey Tx Fire' that is one great idea! I was going to tell him to drill a small hole in the themo flange to release air. Got to try that next time.

Drilling a hole is probably the best way. I got the idea from some import car thermostats that come with a little bleeder hole in them. An 1/8 inch hole will do the same thing. Only problem is, last time I did that, the drill bit caught and ripped the thermostat out of my hand. 7 stitches later, I was back at work with one good hand and the engine job to still finish up.

Aspirin doesn't cut skin like sharp thermostat edges do.

jhow66 · 06-30-2004, 12:52 AM

Quote:

Originally Posted by Tx Firefighter

Drilling a hole is probably the best way. I got the idea from some import car thermostats that come with a little bleeder hole in them. An 1/8 inch hole will do the same thing. Only problem is, last time I did that, the drill bit caught and ripped the thermostat out of my hand. 7 stitches later, I was back at work with one good hand and the engine job to still finish up.

Aspirin doesn't cut skin like sharp thermostat edges do.

Also if your engine has a "head" ache will cure it.

Blue4x4 · 06-30-2004, 08:41 AM

Thanks all...I will try the asprin trick as soon as I get off work.

72LOWBOY · 06-30-2004, 09:07 AM

Tx Firefighter Great Idea! Have To Add That To The Bag Of Tricks

dubie · 06-30-2004, 10:04 AM

mine is running hot to and I have a fresh rebuilt 350. I ran it for a while last night and then this morning when I took the upper rad hose off to remove the rad, it looked dry, like it hasn't seen any coolant yet.

Tx Firefighter · 06-30-2004, 04:45 PM

Quote:

Originally Posted by dubie

mine is running hot to and I have a fresh rebuilt 350. I ran it for a while last night and then this morning when I took the upper rad hose off to remove the rad, it looked dry, like it hasn't seen any coolant yet.

burp that air pocket out of there brother and your problem will no longer be a problem.

crazy longhorn · 06-30-2004, 06:50 PM

Thats a slick trick.....take 2 or 3 aspirins call the doc in the morn! What I usually do is hook the lower rad hose, & fill the block up to the bottom of the stat, then drop the stat in , bolt the housing & top hose on & fill it the rest of the way full on the rad side. Sometimes you still get a little airlock, but not bad enough to peg the guage

crazyL

06-29-2004, 10:51 PM	#1
Blue4x4 Senior Member Join Date: Mar 2003 Location: Sparks, NV Posts: 790	new engine rebuild over heating....help Just started the new rebuild and found it to be overheating. This is what I've found:Engine runs fine with no t-stat. I've put in 2 new t-stats and still have the same problem. T-stats are 180 degrees. The upper hose off the t-stat is cool, but the heater hoses are HOT. And the gauge is pegged. Any suggestioins?????

06-29-2004, 10:56 PM	#2
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	wadda yu need a thermostat fer in nevada???? __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

06-30-2004, 12:10 AM	#4
walker Registered User Join Date: Jul 2003 Location: north of Phx AZ about 30 miles Posts: 698	Are you sure you have the t-stat in the right direction? Bulb side goes to the engine. Also are you sure you have the right direction water pump? My ol' dad made both those mistakes, it was on a F*d though so thats all right. Only other things I can think of is a damaged impeller on the water pump, causing weak flow, bad sending unit(or mounted in a bad spot). Maybe try a 160 t-stat. __________________ Andy,Phx AZ '67 C-10 (Ahhh, done at last. Well there is that disk front end I want to put in and...) "23 C-Cab-sold '48 Ford 8N tractor(still working) '67 Scout(Now on the road) '70 MG B.-sold

06-30-2004, 12:19 AM	#5
72 CustomCamper huh ??? Join Date: Nov 2002 Location: Fredericksburg,Va. Posts: 3,369	Off the wall thought, but the head gaskets could be on wrong and blocking the water passages... Chuck __________________ 90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!"

06-30-2004, 12:26 AM	#6
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	You said you started the fresh rebuild and are having this problem..... It's an air lock under the thermostat. That's why it will work fine without the thermostat. The closed thermstat won't allow the air to burp out of the block as you fill the radiator with coolant. The thermostat is the highest point in the block and all of the air rises to there. An air pocket will insulate the stat and keep it from seeing how hot the coolant is. The engine gets hot, but the thermostat doesn't open up. Open the new thermostat with your hands and put two or three aspirins in it to hold it open. Now install it and add coolant to the engine. The aspirins hold the stat open and allow all of the air to burp out and the engine block to fill up completely with water. Once the engine runs and the coolant circulates awhile, the aspirins will disolve and the thermostat will work normally from now on. __________________ I'm on the Instagram- @Gearhead_Kevin

06-29-2004, 10:59 PM	#3
Blue4x4 Senior Member Join Date: Mar 2003 Location: Sparks, NV Posts: 790	LOL......we need these things here in our state.

06-30-2004, 12:39 AM	#7
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Hey Tx Fire' that is one great idea! I was going to tell him to drill a small hole in the themo flange to release air. Got to try that next time. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

06-30-2004, 08:41 AM	#10
Blue4x4 Senior Member Join Date: Mar 2003 Location: Sparks, NV Posts: 790	Thanks all...I will try the asprin trick as soon as I get off work.

06-30-2004, 09:07 AM	#11
72LOWBOY Registered User Join Date: Feb 2004 Location: Coral Springs,FL Posts: 100	Tx Firefighter Great Idea! Have To Add That To The Bag Of Tricks __________________ 72 Chevy LWB leaf spring rear,SBC 385 Fast Burn,Art Carr built 700r4,3.73 Eaton posi,one piece windows,lowered 4/5.5, 60/40 seat, shaved turn signals,shaved reverse lights,shaved stake pockets, stainless steel 21gall in rear, c-notched, vintage air,ps,pb,currently doing body work. 68 Camaro conv.327,turbo 350,pb,disc brakes,built it for the wife 38 Chevy Coupe on the back burner LIFE IS GOOD! SMILE

06-30-2004, 10:04 AM	#12
dubie Registered User Join Date: May 2000 Location: Flin Flon, Manitoba, Canada Posts: 8,855	mine is running hot to and I have a fresh rebuilt 350. I ran it for a while last night and then this morning when I took the upper rad hose off to remove the rad, it looked dry, like it hasn't seen any coolant yet. __________________ My name's Tim and I'm a truckaholic My 56 Chevy shop truck build http://67-72chevytrucks.com/vboard/s...d.php?t=562795

06-30-2004, 06:50 PM	#14
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,403	Thats a slick trick.....take 2 or 3 aspirins call the doc in the morn! What I usually do is hook the lower rad hose, & fill the block up to the bottom of the stat, then drop the stat in , bolt the housing & top hose on & fill it the rest of the way full on the rad side. Sometimes you still get a little airlock, but not bad enough to peg the guage crazyL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....



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