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Old 12-11-2003, 08:14 PM
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Chevy 454 overheating no matter what I do

Ok, here is what is happening and what I have done.

68 camaro w/ chevy 454 which is overheating

replaced radiator with griffin 2 1.25" tubes (6 core?)
replaced upper and lower radiator hoses
swapped out water pump
new 180 degree thermostat (works fine)
new 17" 7 blade fan
shroud

Still overheating.

What I have done is this:

I have adjusted timing mechanical only at 6 - 8 - 10 - 12 degrees and still overheating

I revved engine to 3500 RPM set mechanical and advance timing to 36" which left my idle a 1100 RPM (too high) and I was still overheating.

I timed the engine by vacuum, I adjusting timing until 20" of vacuum which left me at 1100 RPM (too high) and still overheating

I swapped water pumps to be sure it wasn't a pump problem, I can see flow but I don't know how "much" flow there should be. It is moving though. It has to be getting to the engine because if I shoot water through the front of the radiator core the engine cools down.

I replaced stock 2 core radiator with above mentioned radiator with a 16lb rad cap. I think this may be too much but it wouldn't cause overheating would it?

I put on a metal shroud that wraps around the top half of the fan. I can feel the air being pulled through the radiator but I am still overheating.

Any ideas?

Thanks
Rick

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Old 12-11-2003, 08:20 PM
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Rick,

not to sound like a ninny, but when is the last time the sending unit was swapped out?

after doing the above listed stuff, i was still over heating, it was a $4.85 freaking sending unit......

is the motor physically overheating, or is the gauge reading higher than normal????
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Old 12-11-2003, 08:26 PM
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sending unit?

I put a thermometer in the cool side of the radiator and it reads about 170 when my mechanical thermometer is reading 200-210.

I am not sure if the thermo gauge is functioning correctly, granted, but if cool side of radiator is 175 then hot side must be around 200. I don't want to warp a head.
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Old 12-11-2003, 08:27 PM
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If the car came with a air dam, is it still in place?
Does the system work off a overfill/ resevoir system that`s not in use or missing and the line plugged?
Have you checked the air/fuel mixture to see if it`s too lean?
have you ran a pressure check on the system to assure it doesn`t have a blown head gasket or cracked head?
Did you install springs in the lower radiator hose to assure it`s not collapsing?
Is the thermostat in place?
Check over the resevoir, if it`s not in use the system can`t burp itself and will overheat, if the air dam is missing, it`ll overheat, pull some plugs to see what color they are, if there white it indicates a lean fuel mixture which leads to overheating.
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Old 12-11-2003, 08:47 PM
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has an air dam (valance) and it is in place but this is sitting in the driveway. It is a resto project and has no plates so I can't drive it around. However, when I drive it around the parking lot it still overheats.

Plugs are a bit black, I get some black smoke when revving the engine so I would imagine I am running rich instead of lean.

Haven't done pressure check lately but a few weeks ago it was around 150 in all 8 cylinders, give or take a few pounds.

I didn't put springs in the lower hose but it is brand new. It doesn't look as though it has collapsed and I would hate to think that a 1 day old hose would collapse that fast. I will get springs though.

I have no reservoir, original radiator just dumped on the ground.

I ran with the cap off to try to let it burp out.

for a more accurate temp would it be a good idea to get a head temp gauge? That way I know ENGINE temp not just water temp?

Last edited by rakundig; 12-11-2003 at 08:47 PM.
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Old 12-11-2003, 09:02 PM
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200-210 isnt that hot, that what my 68 firebird with a 454 runs at....as long as it doesnt go above 220 it will be fine. I have a griffin radiator and electric fan and on the freeway it will run at 190 and around town its at 205
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Old 12-11-2003, 09:18 PM
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If you don't have proper pressure in your system your car will overheat. Even if you have a 16lb cap on the car it doesn't mean your system has the correct pressure. My dodge was overheating for a while too and I found a vacuum actuated valve between the heater core and the pump that had been removed. Got a new one at a junkyard, threw on a vacuum line and it worked like a charm. I think it restricted flow to keep the pressure up.

At this point its got to be something simple.

K
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Old 12-11-2003, 10:01 PM
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I am considering replacing head gaskets. I did that a long time ago (car has never been on the road) and I am thinking, the only thing left is that maybe some of the steam holes or whatever are plugged or I put the gasket on upside down (that would not be smart).

What type of vacuum actuator? I am not familiar with this thing.
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Old 12-11-2003, 10:34 PM
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Ok here is the deal on over-heating problems I had with my 454 in a 73 vette. I was told to do just abought everything you did and I was still running in the 250 degree range and the faster I drove the higher the temp. So here is what I did I looked at what the engineers did when the vette was new

1) I installed the rad shroud as per new
2) I re-installed the chin spoiler or air dam under the rad
3) I sealed all the openings around the rad support and rad This is a vette thing
4) I re-installed the original copper rad as per new
5) I set my timing as per new

Guess what with a 180 stat The vette never went above 200 in the hottest day with the A/C on in stop a go traffic and I did have quite a few mods on the engine. Never try to outsmart the professional engineers. I also hope you were smart enough to have tested you temp gauge 1st.
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Old 12-11-2003, 11:23 PM
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Well, uh, I have not tested the temp gauge. But I am pretty sure I am overheating simply because when Temp gauge is reading 200 plus degrees a radiator thermometer on the cap side (cool side) reads 170-180. I have to be at least 20 degrees higher in the engine than the cool side of the radiator. Also, I start spitting water out the overflow tube shortly after I show 210 degrees.

I can try to seal my shroud. I wish I had a better one. Does griffin make shrouds that fit EXACTLY to their radiators? The cheesy one I have is a "universal". Maybe that means universally junky. It does help pull more air but still have the heating problem.

Just ordered a whole new gasket kit from summit. I really really really do not want to pull the darn heads again but I don't know.

What was the timing your vet engine had? My 454 is a vette 454 70-75' years.

Here is a quote from something on the web that makes an interesting question:

"Does your engine require additional timing advance at idle in order to idle properly? Radical cams will often require over 16 degrees of timing advance at idle in order to produce acceptable idle characteristics. "

I know I have an aftermarket cam. I have not set my timing that high because it seems.... well.... too high. Unfortunately since I didn't build the engine and the previous owner didn't either I don't know what is in it. I don't suppose there is any way to tell without breaking the engine apart is there?

If that is the case I may be overheating due to my timing being too retarded (der der). I can try to set timing at 16-18 degrees with my dialback timing gun and see if that helps.

Unless there are more suggestions?

I am still curious about the pressure of my rad cap and my thermostat.

Should I get a smaller rad cap (I have 16 lbs now)
Should I get a 160 degree thermostat (I have 180 now)

I don't want to freeze in the winter, but somehow I don't think that will be too much of a problem with the BB.

Rick

Last edited by rakundig; 12-11-2003 at 11:23 PM.
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Old 12-11-2003, 11:23 PM
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To answer some of your question

I set my timing at 10 degrees as per GM spec. You rad cap at 16 lbs is perfect your stat at 180 is perfect. Make sure you have the overflow tank installed and at least a 7-blade cooling fan. That should work.

Some of my mods on the 73 454 vette

Crane 272 Cam
Roller tip rockers
Headman headers
Edelbrock intake
Holley 650 dual pumper
GM HEI

Once I solved my over-heating problems I removed the stock fan shroud and the mechanical fan and I installed the dual Flex-a-Lite electric fans they cleaned-up my engine compartment and they work great. When driving above 40 MPH the electric fans almost never come on. But 1st solve your overheating problems that is if you are thinking of installing electric rad fans. You must also have your over-flow tank installed for your cooling system to work properly. Latter

Last edited by Auto-Part; 12-11-2003 at 11:33 PM.
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Old 12-12-2003, 12:04 AM
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not having overflow tank can cause overheating?

Dont know cam but here is the rest

Hydrualic roller rockers
17" 7 blade fan
Hooker Headers
Edelbrock Intake (Performer)
795 cfm edelbrock Q-Jet carb (4brl)
GM HEI
Griffin (big *****) Radiator (maybe 6 core?)
Universal shroud
Long water pump (GM)
Breathers on both valve covers (no pcv)
Getting vacuum advance from carb (should be same as off intake)

Rick

I was thinking of replacing the vacuum advance canister. Problem is I don't have a SUN machine or whatever handy so how can I be sure to curve the distributor the correct way.
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Old 12-12-2003, 03:33 AM
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Quote:
Does the system work off a overfill/ resevoir system that`s not in use or missing and the line plugged?
Quote:
Check over the resevoir, if it`s not in use the system can`t burp itself and will overheat
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Old 12-12-2003, 07:05 AM
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Rick, you shouldn't be spitting coolant out at 210, either your cap is defective,check or replace, or there's a small head gasket leak building too much pressure, check for bubbles in the rad. after it has warmed up and stabilized. Part stores carry gas testers for cooling systems if you can find one! Also will most likely need bottom half of the shroud.
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Old 12-12-2003, 09:14 AM
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why not get some royal purple additive and see if you get it to get rid of some extra heat?

K
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