Hot Rod Forum banner
1 - 20 of 30 Posts

·
Registered
Joined
·
7 Posts
Discussion Starter · #1 ·
I have a 1996 Impala SS with a marine 502 motor that has always had an overheating issue but if I only drive it in the fall or winter it stays under control but it still tries to get hot. I decided to install a new be-cool rad the other day and it still wants to overheat.

I did a test yesterday by putting a 24 inch fan in front of the car with the hood closed and started the engine. I let the car idle for about 15 minutes and the temp went to about 215 degrees. I then held the RPM at 2000 and the temp continued increase 220-230 and then at 235 I increased the RPM to 3000 and the temp came down to 195. I let the car come down to an idle again and the temp went to about 220 and I then decided to shut it down. The motor is a 502 with Performer RPM heads with a Hogans Ramjet Style Fuel Injected Intake. The water pump is a reverse rotation Edelbrock #8853 that I just had rebuilt by Edelbrock because it started to leak.

I do not know much about the computer control system on these cars. I have been reading some things on line about overheating and more than once people have been talking about timing and fuel.

I need some help.
 

·
Registered
Joined
·
145 Posts
Did you try changing the thermostat? Maybe try a 180 in there? Maybe even try no thermostat and do the same test. Also what are you using as a fan? Electric or mechanical? I delt with the same issue recently on a SB 350. Ended up going with a flex fan and installing a new 180 thermo.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #4 ·
I had the car at a local shop 2 or 3 months ago to have them see wht they could do with the overheating issue and they said they put a new thermostat in it but I do not know what temp stat they installed. They more or less gave up and told me to find a shop that knows race cars. I know that you can get a bad part even though it is bran new so I am going to install another new one myself this weekend. Does anyone know if there is a certain brand thermostat that is better than the rest.

The car has the original factory electric fans that pull the air through the radiator. The 2 fans are 13 inches in diameter and seem to move the air pretty good.

I am pretty sure that I got all of the air out of the system because I had the front of the car as high as I could get it and pulled a hose off of a fitting that is on the front of the intake until I got good fluid. I then pulled a pipe fitting out of the top corner of the radiator and kept putting in some fluid until I got a solid streem of fluid. I'm not sure about the mix but I would guess 60/40.
 

·
Hotrodders.com Moderator
Joined
·
6,391 Posts
What is your timing set at. The fact that it coold down at 3K rpm may be due to the timing being more advanced from mechanical advance.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #7 ·
I am also thinking the timing could be the cause but I purchased the car with this motor in it already and I was told that they tied everything into the original computer system. I'm not sure but I know that it's not like the older cars where you could play with the weights in the distributor and twist the distributor until you get it set where you need it. These new cars have everything set by the computer and from what I understand you can't just do things like the old days. I guess I also need some help on what I need to do to get the idle timing set so the computer doesn't change it back somehow. This is all new to me and I need help, I could also just be scared of the computer because I don't know enough about it since this is my first computer controlled fuel injected car.
 

·
Registered
Joined
·
2,999 Posts
I always use Stant T stats, but there are other good ones too. I doubt it's the stat, but it's a cheap thing to replace. I always drill an air bleed hole in my stats when I install them. Something around 1/8" in the outside perimeter will allow any trapped air to get out while you're filling your coolant mix.
Not sure about your Edelbrock water pump. Is it a high flow, or regular? If it's not a high flow I'd consider getting one. Sounds like when it's circulating faster it runs cooler.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #9 ·
1996 502 Impala SS Overheating Issues

I have tried to upload some pictures of the engine. If this does not work i will try again tomorrow. Maybe someone can see something wrong with the way it is set up.
 

Attachments

·
Registered
Joined
·
145 Posts
Could it be that the radiator and twin electric fans are just not enough to handle the bigger engine? Bigger engine means more HP. More heat? Also on these computer controlled engines I would think you would need that controller to be reprogrammed for this motor? Sorry maybe you said the ECM came with this motor? I'd have to read back. But you have had shops look at it. I would think they would have suggested that if they thought it was needed. My gut tells me maybe the radiator is too small for the application. Wasn't the stock engine in that car a 5.7L? My brother in law had one back in the nineties. Can't really remember what power plant was in there though. Maybe call Griffin or a company like that and see what they recommend. Compare that to what is stock?
 

·
Registered
Joined
·
4,385 Posts
Buy or borrow an infrared heat gun and see what the temps are into and out of the radiator. Sitting still with the fans running you should get about 15 degree drop when everything is at operating temp.
 

·
Registered
Joined
·
2,999 Posts
My Camaro always ran pretty hot since I first got it in 1973. I always worried everytime I got into trafic, even in the winter. I finally decided I had to try and cure the problem, so I went to the largest radiator I could find. Even had to open up my core support and fabricate new lower mount to get it in the car.
End result was it ran 160 degrees most the time, and even in hot weather I never ran over 175. I upped the T stat to a 170, and it runs 170-180 in all kinds of driving.
You may need to get creative and see how much room you have for a big radiator. They also make double pass radiators that cool even better and fit the stock mounting. Not cheap at around $500, but they work better than std. single pass. Be Cool and Griffin both have direct fit, or slightly oversized width to handle high performance engines in your Impala.
 

·
Hates: Liver. Loves: Diesel
Joined
·
6,341 Posts
First of all... Kudos for putting a 502 in your SS. Nice :)

Secondly I will second LocalBoy's words... You have effectively added 70% more of everything; displacement, power potential, fuel capacity.... but you've only modestly increased cooling capacity. This isn't just an "upgrade the pump and radiator" proposition. You need some serious cooling under that hood.

Ditch the electric fans. They are made to cool 260 hp. You have not only chosen to go with a non-reverse cooling motor, but you've also gone to a BBC which doesn't have much more coolant capacity than a SBC.

All the radiator in the world won't make up for airflow. Make the air MOVE. Given the original specs of the LT1 that was in there, you should have TONS of room for a mechanical fan. You might give up 5 hp at redline, but with a 502 marine engine, you should capitalize on the torque. Unless this is a race-only application, you won't notice 5 hp.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #14 ·
1996 502 Impala SS Overheating Issues

I understand the cooling fan issue and I thought that would be my next step but I called Be-Cool tech support and they don't seem to feel that it is a fan issue. I need to try and find out the CFM rating of the stock Impala fans because the guy at Be-Cool said that he would be glad to sell me a set of fans but he thought I should do more research before I spen the money on the fans.

I took the car for a ride last night which the outside temp was about 85 degrees. The route I took ranged from speeds of 30 to 45 mph and was about 4 miles around with hills flat areas and stop lights. The car seemed to be staying around 180 for the first 2 time around but on the third trip the temp would start to rise when I would come to a stop light and even when I took off and got up to 45 mph in high gear the temp kept on increasing.

The temp continued to rise to about 210 driving at a steady speed of 45 mph so I desided to drop down into second gear while maintaining the 45 mph. Once I was in second gear going 45 mph the rpm went to about 2750 and the temp came down to 180 almost instantly. I kept the car in second gear for about 1/2 mile still going between 40 and 45 and the temp held at 180. I came to a stop light and the temp started to rise and once the light changed I only let the car shift into second gear and drove home still at about 40 mph with a 180 temp.

I feel that the test I did last night tells me that it is not an air flow issue because I maintained a 40 to 45 mph (with electric fans) and when the rpms were low in high gear the car wanted to get hotter and when I down shifted into second gear raising the rpms the engine got cooler.

I now feel that it is a coolant flow issue like a thermostat not opening all the way or the Edelbrock water pump does not flow enough water to cool at lower rpms. I measured the crank pulley at a 7.750 diameter and the water pump pulley is about 5.625 diameter which matches the Z06 corvette a friend of mine has. I don;t know if this difference is diameters is correct for this motor but maybe I need a pump pulley diameter change.

I desided to change the thermostat today so I drained the fluid and un-bolted the housing and to my surprise there was no thermostat, someone has put a restrictor plate in place of the thermostat that has a 1 inch diameter hole in it so the motor has constant water flow. Why would someone do this and could this be my problem? I don't know the exact volume of water that can flow through that 1 inch hole compared to an actual thermostat but I would assume that the 1 inch hole in the plate would flow more water than the thermostat.

If it is not an air flow issue from the electric fans and it's not the thermostat the only thing that is left is that I need a higher flowing water pump or a pulley change. I don't want to make to much of a pulley change because I would think that I would start burning up bearings if I spin the pump to fast.
 

·
Registered
Joined
·
145 Posts
I understand the cooling fan issue and I thought that would be my next step but I called Be-Cool tech support and they don't seem to feel that it is a fan issue. I need to try and find out the CFM rating of the stock Impala fans because the guy at Be-Cool said that he would be glad to sell me a set of fans but he thought I should do more research before I spen the money on the fans.

I took the car for a ride last night which the outside temp was about 85 degrees. The route I took ranged from speeds of 30 to 45 mph and was about 4 miles around with hills flat areas and stop lights. The car seemed to be staying around 180 for the first 2 time around but on the third trip the temp would start to rise when I would come to a stop light and even when I took off and got up to 45 mph in high gear the temp kept on increasing.

The temp continued to rise to about 210 driving at a steady speed of 45 mph so I desided to drop down into second gear while maintaining the 45 mph. Once I was in second gear going 45 mph the rpm went to about 2750 and the temp came down to 180 almost instantly. I kept the car in second gear for about 1/2 mile still going between 40 and 45 and the temp held at 180. I came to a stop light and the temp started to rise and once the light changed I only let the car shift into second gear and drove home still at about 40 mph with a 180 temp.

I feel that the test I did last night tells me that it is not an air flow issue because I maintained a 40 to 45 mph (with electric fans) and when the rpms were low in high gear the car wanted to get hotter and when I down shifted into second gear raising the rpms the engine got cooler.

I now feel that it is a coolant flow issue like a thermostat not opening all the way or the Edelbrock water pump does not flow enough water to cool at lower rpms. I measured the crank pulley at a 7.750 diameter and the water pump pulley is about 5.625 diameter which matches the Z06 corvette a friend of mine has. I don;t know if this difference is diameters is correct for this motor but maybe I need a pump pulley diameter change.

I desided to change the thermostat today so I drained the fluid and un-bolted the housing and to my surprise there was no thermostat, someone has put a restrictor plate in place of the thermostat that has a 1 inch diameter hole in it so the motor has constant water flow. Why would someone do this and could this be my problem? I don't know the exact volume of water that can flow through that 1 inch hole compared to an actual thermostat but I would assume that the 1 inch hole in the plate would flow more water than the thermostat.

If it is not an air flow issue from the electric fans and it's not the thermostat the only thing that is left is that I need a higher flowing water pump or a pulley change. I don't want to make to much of a pulley change because I would think that I would start burning up bearings if I spin the pump to fast.
So did the thermostat help? I would think it might. It would maybe keep the coolant in the radiator longer for it to cool. Hopefully it at least helped a little. Could be a combination of a couple of issues that need to be resolved. I'd probably look at the fans and radiator next. Let us know what you find.
 

·
Registered
Joined
·
7 Posts
Discussion Starter · #16 ·
I put 180 degree stat in it yesterday and it actually ran hotter and when I would rev the engine to 3000 rpm it did cool down but not as quick as it did with just having the disc in there with the 1 inch hole. I think that the next thing I am going to do just for a test is to take out everything and just let it flow straight through. The reason I want to do this is because when I had the thermostat housing off of the engine I noticed that whoever built this housing had to flatten out the 1.500 dia tube to get it to fit into the side of the thermostat housing and the size of the hole is restricting the flow as well. The reason it is restricting the flow is because when they welded the tube to the housing it appears that some of the weld came inside of the tube because of the thin wall of the tubing.

As I think I said before in this thread that I do not know how to set the timing on this computerized engine but I wanted to put a light on it at an idle. I put the timing light on it at Idle and it shows 38 degrees (the engine idles at about900 rpm) and when I would rev it to 3500 rpm it would go to 43 degrees.

Do these numbers tell anyone anything that might have to do with the overheating at the lower rpm's?

I need to figure out how to set the base timing so I can see where it is set.
 

·
Registered
Joined
·
15 Posts
Hey so tell me PLEASE what was the results ?? PLEASE don't let this thread die like so many others without a final resolution. I have pretty close to the same overheating issue as you do. I have spent over $1,000, and thus far without any real positive results. 210 degrees all the time once I drive it. Have bought Griffin 4 core alum rad, a few different rated rad. caps, alum. reserve tank, various degree T stats, Tarus fan with custom shroud {works best} after 2-3 aftmkt. hi dollar fans, Weind Hi flo alum water pump {2}, {correct rotation varified 3-4 times} March Serp. system, even added a idler pulley to make sure there was no slop in the belt, of course all new hoses, base timing @ 20, total @ 30, absolutely no vac leaks, no lean issues, other than over heating {210} the car runs perfect. Once my car hits 210 it stays there regaurdless of MPH, or if I pull over and sit with the fan running. One thing I have noticed is the air being drawn threw the rad. once it is @ 210 is cool air ? And there is PLENTY of air being pulled threw. But then if it is sitting and idleing it will NOT go above 200 then the fan is running the air being drawn threw is warm/hot ? When it is at 210 the upper and lower hoses are hot, the tanks on the rad. are hot, but the air being drawn threw is cool like there is no heat/coolant in the tubes/fins of the rad. BUT THERE IS ! NOT air bound either. At idle it will go to 200 the fan comes ON, then cools down to 185 and goes off, during the time the fan is running the air is warm ! It will cycle without going over 200 like that for as long as it is sitting. Drive it, then it goes to 210 and will NOT go below 210 no matter what you do. Once in a while I have seen it go as high as 220. I have checked and replaced absolutely everything out of frustration I can think of. 3 water pumps, 3 radiators, 3 T stats, middle sized restrictor plate, 3-4 electric fans & shrouds, 50/50 coolant, new hoses, had the rear of the intake drilled and thread so the rear intake coolant passages are now connected. I am at a loss ? I have called 2-3 of these major radiator guys and I can't make any sense of what they are saying because they don't seem to understand I have tried everything their suggestions atleast 2-3 times already....LOL After all I have done my car {83 Camaro} has the 4 core alum rad, mid sized restrictor plate, 50/50 coolant, Wiend alum water pump, March pulley system, serp belt, 18 lb. cap and this is the best combination I have found and it still isn't right. Theres no reason why this car shouldn't run in 80-90 degree weather at 180-190 on a regular basis. I just don't know whatelse to try. And I am real tired of spending all my money and time trying to get it to run at a reasonable temp so it sits more than I drive it. Wanna talk about frustrations ?....LOL
 

·
current hot rod: CTS-V
Joined
·
1,821 Posts
I notice everyone says to change the thermostat out, but that will make 0 difference if you don't have have the electric fans set to come on at the right temperatures. You need to find someone who tunes, preferably with HP Tuners, and have them reset the electric fans come on at lower temperatures. For example, I put a 10 degree cooler stat in my 03 Cobra but the recommended tuning change required the electric fans to kick in 20 degrees cooler than stock. If they're still set at stock temps that explains your overheating problems. I would expect the two stock fans to be adequate when set to work at a lower temp.

Something else you should do is box in the radiator, it's what guys who do high performance driving events and auto cross do when they run stock cooling systems under heavy demands. Not the same car but it will give the right idea. School me on boxing in a radiator... - Ford Mustang Forums : Corral.net Mustang Forum
 

·
Registered
Joined
·
1,684 Posts
I see one thing wrong in the pictures. You need to make a fan shroud that will cover both fans. Something like these fans. Be Cool 75638 - Be Cool Qualifier Fans - Overview - SummitRacing.com Another thing to do is measure the diameter of the crank pulley and the water pump pulley and post here. Your crank pulley should be 5.750" or 5 3/4". Water pump pulley should be 5.250" or 5 1/4"
 

·
Registered
Joined
·
208 Posts
I see one thing wrong in the pictures. You need to make a fan shroud that will cover both fans. Something like these fans. Be Cool 75638 - Be Cool Qualifier Fans - Overview - SummitRacing.com Another thing to do is measure the diameter of the crank pulley and the water pump pulley and post here. Your crank pulley should be 5.750" or 5 3/4". Water pump pulley should be 5.250" or 5 1/4"
He posted it in #14 "I measured the crank pulley at a 7.750 diameter and the water pump pulley is about 5.625 diameter which matches the Z06 corvette a friend of mine has. I don;t know if this difference is diameters is correct for this motor but maybe I need a pump pulley diameter change."
 
1 - 20 of 30 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top