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70 Camaro 350 overheat problem

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James West

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Discussion starter · #1 ·
The newly rebuilt engine has less than 50 hrs running time. It originally was running hot when I first fired it up, but after setting the timing and running it for a while, with a big fan, it was running at 190deg. I think it may have Air in the Cooling system. Since the engine does not have a bleed valve, I am not sure what the bleed procedure is. Does anyone have a way to bleed with out a valve?:)
 
#2 ·
You may need to burp the cooling system if you have an air pocket in the block. I had to do it to my 69 Vette after replacing the radiator. Pretty simple to do. I parked the vette on my steep driveway, removed the radiator cap, jacked the front of the car as high as possible with a large floor jack, started the car. This allowed the trapped air in the block to escape thru the radiator filler neck. You can see and hear the burping occur. :hurray:
 
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#3 ·
Like Terry suggests, getting the front up is the key.

Older cars do not have a bleeder nor do they have a overflow reservior. The bleed method is with a cold engine, remove rad cap and check coolant level.
Level should touch the bottom of the cap
Start the engine to get the engine to operating temp, turn off. Let cool overnight.
Recheck level again in the morning and top off.
It should only take a couple, maybe three, cycles to maintain level.

Since there is no reservior, check level every weekend.
You can add a reservior and a visual check every weekend of the reservior level will indicate the tightness of the system.
 
#4 ·
Was all the trash cleaned out of the water passages? The drain plugs at the pan rail removed and a coat hanger etc used to knock the scale and rust out??
Is it a used or new radiator?
 
#5 ·
I think we need to know a bit more:
190, is that idling or running on the highway?
What temp thermostat do you have?
What fan do you have? Mechanical/Electric, stock/aftermarket?
Do you have a fan shroud?
What is the timing set at?
What water pump do you have? New? Correct rotation?
How did you initially fill the motor with coolant? via radiator or did you poor water directly in to the motor via the waterneck opening on the intake?
 
Discussion starter · #6 ·
More Info:
- The engine was thoroughly cleaned, no rust and completely rebuilt w/all new parts
190deg, is that idling or running on the highway?
- Idling, no ext. fan
What temp thermostat do you have?
- 190deg
What fan do you have? Mechanical/Electric, stock/aftermarket?
- Mech, aftermarket, stiff 5-blade, 20"
Do you have a fan shroud?
- not originally, but I do now, no overflow reservoir
What is the timing set at?
- 15deg btdc @ 900 rpm
What water pump do you have? New? Correct rotation?
- Rebuilt, Yes
How did you initially fill the motor with coolant? via radiator or did you poor water directly in to the motor via the water neck opening on the intake?
- radiator
 
#9 ·
I fit runs at 190°F with a 180° thermostat, I'd say you're there.
Click to expand...
I disagree...
A stock system even with a 160 will not get any hotter than 170 under extreme conditions except hi altitude...will get to 180 /195 then....over advanced will not run a stock system hot, way underadvanced will..but that much u will have no power and MT the tank just going around the block.

No thermostat will run most stock cooling system sb hot

Stock system includes stock pump, stock clutch fan stock radiator, stock shroud.

Bleeding issues are way over rated...and basically only happen when the radiator is drained /refilled facing down hill.....or the engine is higher and/or heater lines than the radiator level.

Dont be fooled with the more modern cooling systems that have bleeders....one can not compare the overall operation or efficiency of modern vechiles with these over built 'over flow sysatems...they didnt put bleeders on them because they dont need them.

The other common issue is people put a new oil pump , even a water pump on a new engine....and dont manually clean the raditor cores !
 
Discussion starter · #10 ·
Still more info.
It was running normally at 190deg, before the overheat problem. It all started when I removed it from my garage after working on a transmission leak problem. The engine overheated while we were letting it warm up to check the fluid level. After it was running for about ten minutes, it suddenly stopped. The temp gage read over 212degs and you could hear it bubbling. I partially turned the cap and fluid started poring from the overflow pipe. I then closed the cap and let it cool down. I then check the fluid level and it was down, but you could still see fluid. We topped it off started it and drove back into the garage and that is where it has been up to now. I am now waiting on missing clips which are necessary for installing a new shroud. After that I will be back at the task of making sure there is no air trapped in the block (my original inquire). If that isn’t the problem, I will next replace the thermostat.
 
#11 ·
I would run a 160* thermostat and check that fan. You mentioned 20", wow thats pretty big. Most stock fans are 18". Make sure the pitch of the blades are aggressive, meaning BIG. What brand is the fan?? Do you have the correct spacer for the fan?? When overheating occurs, it usually is an airflow problem. Note: I said usually.
 
#12 ·
James West said:
Do you have a fan shroud?
- not originally, but I do now, no overflow reservoir
Click to expand...
James West said:
I am now waiting on missing clips which are necessary for installing a new shroud.
Click to expand...
So when the car did overheat at 212, was the shroud on or off the car? If it was off, then that's big deal as already mentioned air flow is a major factor.
 
Discussion starter · #13 ·
Correction:
My memory was off, the fan has 6 blades and is 18”in dia. (non flex) and appears to have a good pitch.
It is 3.5”away from the radiator, well inside the shroud. The Radiator is oversize from the original stock unit.
I will change the thermostat to 160-170 deg.
If it isn’t trapped air in the block, maybe it was caused by not having a shroud.
 
#14 ·
If you get a chance, post a pic of the fan. Although it is always recommended to have a shroud, I never noticed a significant difference with it on or off. That has just been my experience though.
 
#16 ·
Why are you going colder on the thermostat? The thermostat only affects the min operating temp, not the max temp. If it overheated with a 190 it'll still overheat with a 160. 190 is fine. It's possible the thermostat stuck in the closed position that day when it overheated.
 
#17 ·
The temp gage read over 212degs and you could hear it bubbling. I partially turned the cap and fluid started poring from the overflow pipe. I then closed the cap and let it cool down. I then check the fluid level and it was down, but you could still see fluid. We topped it off started it and drove back into the garage and that is where it has been up to now. I am now waiting on missing clips which are necessary for installing a new shroud. After that I will be back at the task of making sure there is no air trapped in the block (my original inquire). If that isn’t the problem, I will next replace the thermosta
Click to expand...
t.

1/ If boils at 212 deg that means the cap is stuffed....the idoit light comes on at 235 deg, and even 220 thu hot is not too hot for a sb chev to damage
2/ If you loosen the cap, the drop in pressure will cause to boil..that is normal.
3/ The fliud level will drop as u describe...that is normal...the orginal radiators have marks on the side for hot and cold level about 1 " and 3" below the top.
4/ Air trapped IS NOT your problem NOR is the thermost

The fan needs to be only just out od the shroud not right inside...look at a computer fan...notice how it is shrouded at the tips? that stops air spillage spinning off the end of the of the blades...without the shroud it doesnt draw hardly any air and if the fan is too far inside the shroud it just cavitates the air around inside, not draw it thru.

Dump the fan, get a std stock fan and correct shroud...you issue will be gone.
 
Discussion starter · #18 · (Edited)
I finally got my Shroud installed and it was not easy. If you are interested in pics of the shroud/fan installation, send me your email address and I will send you the pics. I am not a Premium member, so I don’t seem to be able to post pics. I did not notice if my idoit light came on, but the temp could have been as high 235deg. I agree that when I released pressure at the cap, the water will boil out the overflow and did, but I am still do not know what caused the engine to stop running. Thanks!
James West (westjk@uwmail.com)
 
#19 ·
I did not notice if my idoit light came on
Click to expand...
Hmm. all due respect ok....
Basic driving is not just getting a lincence, or being awarer of what is around the car...it also invoves being aware if the car....If an idoit light comes it one SHOULD be ahere of it as much as a red stop light.
If you are interested in pics of the shroud/fan installation,
Click to expand...
Yes we are.
you can post the pics on another server host then hot link back to your post.
The down side is userful techo pics disappear as they expire.
Which I thinbk mods should be able to load certain pics to this server...
I disgree thu

There are old threads that have very good pics (or had lol) of how a fan fits in a shroud...compare yours in the mean time

but I am still do not know what caused the engine to stop running.
Click to expand...
explain that again
 
Discussion starter · #20 ·
I e-mailed Shroud pics to another member and got this input + my answers.Just read your last post. OK just as I expected, the shroud did NOT help. Do you still have the A/C condenser in front of the radiator. (NO) I see the car was originally an Air Conditioned car, correct?? (Yes) One other note. REPLACE THAT GLASS GAS FILTER ASAP! They break and gas spews all over and you will have a fire!!! (Good Point) Let me know.
Note; I just ran the car (Shroud installed) for about 20min @ idle speed (900rpm) with a box fan in front, about 2ft away. The temp did not go past the thermostat setting 190degs and it did not shut down. Maybe the Shroud did some good? I did not try it without the Box fan.
James West
 
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