Overheat -- again...any help?
Thread Starter
Instructor
Joined: Mar 2008
Posts: 221
Likes: 0
From: Farifax Station VA
Overheat -- again...any help?
engine overheated last week. I flushed and refilled. drove the car at about 60 mph for 20 minutes....then engine began venting fluid into expansion tank again. because the car ran withour a problem for a good 20 minutes, and then began overheating...I think the thermostate is good...what else could it be...the radiatorand all the hoses are in good shape...how can I tell if the water pump is going bad?
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
About the only a waterpump will make you over heat is if the impeller came off, and thats not very likely, I would look other places first.
1. is the air dam in place and in good shape
2. are the seals for the radiator to mount and shroud in place? and on top of the rad to hood?
3. Lower hose has the spring in it?
4. What fan do you have? Is the fan clutch good?
5. What radiator cap?
6. What temp did it get to?
7. What is your base timing and all in timing set to?
Most of the time it is come combination of the above that is the problem.
Does it get hot when on the highway or in traffic? What is "HOT"
1. is the air dam in place and in good shape
2. are the seals for the radiator to mount and shroud in place? and on top of the rad to hood?
3. Lower hose has the spring in it?
4. What fan do you have? Is the fan clutch good?
5. What radiator cap?
6. What temp did it get to?
7. What is your base timing and all in timing set to?
Most of the time it is come combination of the above that is the problem.
Does it get hot when on the highway or in traffic? What is "HOT"
Thread Starter
Instructor
Joined: Mar 2008
Posts: 221
Likes: 0
From: Farifax Station VA
i thought I would add one more thing...
when on the highway at 60...the car runs around 170 deg...it was only at idle when I stopped at the traffic light that the fluid began venting overboard and the temp began to rise. just so I am clear, the radiator had basically vented all of the fluid overboard, and then the temp began to increase.
when on the highway at 60...the car runs around 170 deg...it was only at idle when I stopped at the traffic light that the fluid began venting overboard and the temp began to rise. just so I am clear, the radiator had basically vented all of the fluid overboard, and then the temp began to increase.
Drifting
Joined: Feb 2005
Posts: 1,879
Likes: 38
From: Los Gatos CA
Generally speaking, if she runs OK at freeway speeds, your radiator is OK, and your speed allows for plenty of air flow across radiator. In traffic, air flow is dependent on your fan, clutch and ducting. I use an ac fan (7 blade I think) and a thermal clutch.
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
^^X2. Check the fan clutch.
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Burning Brakes
Joined: Jul 2008
Posts: 923
Likes: 37
From: Green Bay Wisconsin
i thought I would add one more thing...
when on the highway at 60...the car runs around 170 deg...it was only at idle when I stopped at the traffic light that the fluid began venting overboard and the temp began to rise. just so I am clear, the radiator had basically vented all of the fluid overboard, and then the temp began to increase.
when on the highway at 60...the car runs around 170 deg...it was only at idle when I stopped at the traffic light that the fluid began venting overboard and the temp began to rise. just so I am clear, the radiator had basically vented all of the fluid overboard, and then the temp began to increase.
Take a look at your heat riser valve on your exhaust system. It should be open when the car is warmed up. If it is not operating correctly it would hold back exhaust and cause the car to overheat when idling.
The heat riser opens with a bi-metal spring and sometimes gets hung up when old/rusty.
Good Luck,
Douglas in Green Bay
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
With the engine warmed up, running and hood up. Watch the fan while you turn off the key, if the fan turnes more that 1/2 to 1 turn the clutch is bad.
Still need to verify seals in place
Still need to verify seals in place
Instructor
Joined: Aug 2009
Posts: 112
Likes: 0
From: Caledon Ont
Did all this start happening after the flush? First off don't guess at the T-stat if your not sure. For the price of one and the damage a bad one can do just change it.
With engine hot run you hand across the entire surface of the rad especialy near the lower rad hose, start at the top near the upper rad hose which should be the hottest point and feel for soft or flkinging fins...if you find cold spots on the rad or like warm spots its your rad. There shouldn't be much of a variation between the hottest and coldest spot, maybe 10C, you can also remove the rad send it to a rad shop and have them check it and eliminate that variable.
With engine hot run you hand across the entire surface of the rad especialy near the lower rad hose, start at the top near the upper rad hose which should be the hottest point and feel for soft or flkinging fins...if you find cold spots on the rad or like warm spots its your rad. There shouldn't be much of a variation between the hottest and coldest spot, maybe 10C, you can also remove the rad send it to a rad shop and have them check it and eliminate that variable.
Pro
Joined: Jul 2005
Posts: 517
Likes: 7
From: Peoria IL
If it doesn't overheat on the highway, you have enough radiator capacity and your thermostat are likely OK.
Since you are mostly having trouble at low speed, the fan clutch and shroud are the most likely culprits. If your fan shroud is in place (not missing) and is in good repair (no big gaping holes), consider replacing the fan clutch. They're about $50 at the local parts store and are critically important to keeping it cool during "city" stoplight-to-stoplight driving.
Since you are mostly having trouble at low speed, the fan clutch and shroud are the most likely culprits. If your fan shroud is in place (not missing) and is in good repair (no big gaping holes), consider replacing the fan clutch. They're about $50 at the local parts store and are critically important to keeping it cool during "city" stoplight-to-stoplight driving.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Radiator seals are around the fan shroud.
I didn't use staples to attach my new seals but just used 3M weatherstrip adhesive - seems to hold OK.
I know this sounds like a lot of work but after nearly 30 years the old foam seals are mostly gone.
And the seals do make a difference and are important to good cooling.Hopes this helps,
cardo0
5th Gear
Joined: Aug 2009
Posts: 5
Likes: 0
What year
What year vette do you have? If you have an 81 or 82 with the extra electric fan we sell a part to help your car run 25 degrees cooler on in town driving. I use it on my 81 and its perfect no air dam even required.
NelsonComp
NelsonComp
Melting Slicks
Joined: May 2005
Posts: 2,209
Likes: 12
From: Montgomery Alabama
Cruise-In VII Veteran
St. Jude Donor '06
Could be your timing, or it could be your radiator cap.
My 454 ran about 190 on the highway, but bumped up to about 220 while idling in traffic, or cruising. The thermostat was opening at 14 PSI and peeing on the ground when I stopped. I am not sure if it ever got over 240. I checked the thermostat on the stove with a candy thermometer, and it opened up at 165 so I put it back in. I put a 16 to 18 PSI cap on the motor, added an overflow tank, and retarded the base timing a bit and increased the mechanical advance to compensate. These three items cooled off the motor while cruising a good bit. Now it rarely goes over 210. I bought some water wetter, but never put it in. Did the Hot Rod Power Tour with no issues.
My 454 ran about 190 on the highway, but bumped up to about 220 while idling in traffic, or cruising. The thermostat was opening at 14 PSI and peeing on the ground when I stopped. I am not sure if it ever got over 240. I checked the thermostat on the stove with a candy thermometer, and it opened up at 165 so I put it back in. I put a 16 to 18 PSI cap on the motor, added an overflow tank, and retarded the base timing a bit and increased the mechanical advance to compensate. These three items cooled off the motor while cruising a good bit. Now it rarely goes over 210. I bought some water wetter, but never put it in. Did the Hot Rod Power Tour with no issues.
