Overheating

J

JGRacing

New Member
I am having an overheating problem that will not go away and I am about out of ideas. It is in a B-mod with a 350 Chevy running a 2-barrel 500 Holley. The engine ran one test on asphalt with no overheating problems (except the balancer knocking a hole in the radiator). The next test with a new fan, radiator, water pump, etc. it overheated. My first race out at Montgomery County it overheated and then did the same thing at Godfrey Friday. It has overheated with two different carbs and the plugs look good so I do not think it is too lean. The timing is only 32 degrees and I have checked with two timing lights to make sure. The water pump is moving water because when I pull the cap off of the water neck on the block it pushes water out. I have a restrictor in it instead of the a thermostat so that is not an issue. The strange part is that the temp goes up either on the track of just running in the pits and never hits a point where it seems to level off. It heats up more slowly on the track at speed but still went from 190 to 240 during the heat race and then really spiked after I slowed down. I am using 20% reduction pulleys and a mechanical fan with a pretty good shroud. I had an electric fan on it a few weeks ago and neither fans seems to make a difference.

Anyone have any ideas?

Thanks,
John
 
Hows the radiator? Get all that dirt off of it. flush it out
Radiator cap? Test it. Use a high pressure one 25 psi.
Do you use Water Weter? or anti freeze? Get rid of antifreeze. Use water wetter
Check radiator hoses make sure the lower hose ain't colapsing.

We're dealing with the same thing. Got hot at Godfrey Fri. Removed the restrictor. Replaced the Radiator cap. Got hot at Montgomery Sat.
 
I had a 28 pound cap on the water neck and on the radiator, but when it overheated, it built up enough pressure to inflate the upper hose to twice it's normal size. I got a 21-25 pound cap at the parts trailer (along with a new upper hose), put it on the filler neck and it at least bleed off pressure before looking like something would pop. I had about 25% antifreeze in it which will get dumped and water wetter put in. We checked the lower hose and it was not collapsing. The system gave me the same problem testing at I-70 Speedway with the radiator brand new so I do not think the outside is clogged. The only think I can think of at this point is the get the radiator flow tested and see if it might be clogged or just be defective. Is there somewhere in the St. Charles area that anyone would recommend to check the radiator? Also, I am going to shoot the garden hose through the engine and see if anything flushes out. The strange thing is that it just seems to not be cooling much at all. Just keeps getting hotter. Can anyone think of any internal problem with the motor that could cause this? I already checked for water in the oil and oil in the water and found nothing. Also, the oil filter has looked good when I took it apart.
 
There's a guy in old town St.Peters that races Late models or sprints. He has a Radiator shop. I'll try to get his name and address. Get off at Mid rivers and go right then left down towards QT. He's back in there somewhere. Engine wise Check timing, and make sure you're not running too lean. Can you get a pressure tester? Put that on it that'll show any leaks. What type of Fan do you have? Don't use one of those cheap flex fans. They flatten out and move no air.
We're going to put a restrictor back in. Sometimes you can have to much water flow.
 
Did you check to make sure that the fan is not on backwards, it does happen. I've been racing for 10 years and working on cars for 25 years and stupid me have even put them on backwards a couple of times.

If you have any gaps between the radiator and shroud seal them with some duct tape.

When I used to run on gas I would always put an air dam on the bottom of the radiator. Make it out of plastic and the full width of the radiator and as low as possible but leave yourself enough ground clearence.



|
| <------- make it straight down with a 45* bend at the
| bottom to stiffen it up.
|
\
 
I've had the same problem with a good electric fan and the new water pump mounted fan. I have a good shroud on it and will give the air dam a try. The more I think about this, the more I am leaning towards the radiator being clogged or just plain defective. All of these other ideas eveyone has posted are definately good ideas and things that I should probably do once I get the the main part of the problem taken care of. Thanks eveyone for your advice. I will let you know what I find out about the radiator.
 
5 gallons of the fuel is from October but was drained from the fuel cell and kept in a sealed fuel jug out of the light during the winter. Since then I have added 10 gallons of fresh fuel from 2 different tracks.

I'll give S&S a try. Keeping my fingers crossed that it ends up being something simple. If not, I might have to start strapping ice bags to the block before rolling out on the track. :)
 
Make sure ya got the right water pump on it, if you got one for a later model that had a serpintine belt then that pump is a reverse rotation pump and will not work with a v-belt, I've seen this happen often ..... and no flex fans, use a good steel fan,7 blade preferabaly and the fan should be half way out of the shroud as it has to throw air off the ends of the blades to work correctly.......
 
I have heard that if the radiator cap is lower that the gooseneck on the motor, this will not fill the motor up completly and you will not have enough water in the system to stay cool. They say to run an external overflow bottle or something that is higher than the gooseneck.
 
sportin is right dont know what you are running ford or chevy but does not matter check the houseing for the therm make sure the housing (from rad. to engine.) is lower then the inlet side of the rad. this will couse a system not to presurize and not do its its job (have had the same problem and this is what worked for me) if rad is lower then take an old peice of rubber and place it under the rad. intill it is above the housing and then fill the system up i use just water also we had to go to a 1 to 1 pully system and had to take some of the lower nose off the car we have yet to over heat the car runs about 180 to 200 that is where you want to run you start getting over 225 you are in trouble then
 
So how did you do this weekend? Overheat? We installed a 1" restrictor and brought the temp down. Then Advanced the timing and the temp went up. Richened up the carb the temp came back down. Pulled the Radiator Sun. and the bottom rows are all smased up. Going to straighten them up. We'll see
 
I will not be back at the track until June, so it gives me a little time to sort this out. I flushed out the block and radiator with a hose to see if anything might be clogging them. Water seemed to flow OK through both without any restrictions and nothing solid came out in the water. I am going to take the radiator by S&S and to get it looked at. I have the radiator cap on the block water neck so that should be letting any air out. I am still looking for something major to be wrong in the system because it does not seem to cool at all idling and cools very little at speed on the track.
 
As mentioned earlier try the 1 to 1 pulley's to speed up the water pump.
When we ran ran a gas motor in our mod a couple of years ago we couldnt keep it cool either.We tried high dollar water pumps twin pass radiators just about everything, later found out that short track's and underdrive pulleys dont mix.If you look over on the tech board on 4m.net they talk about 1 to 1 pulley's all the time,also the big gm 4 blade fan works well.
 
you said you have a water filler on the block? if so run a 21-25 lbs cap on the radiator and around a 15 lbs or so on the block fill one and make sure you fill the fluid from the block b/c if there is an air pocket in the thermastat housing NO water will move through the block
 
Mod,
Why run 2 different presures on your caps? With the 15 pd. cap you'll boil over at a lower temp. The presure is the same through out the system. So you might as well run a 15 psi cap on the motor too. We have our filler on the block. (It's the highest point) And run a 25 psi cap.

Might have cured our overheating. Our timing was advancing at hi RPM's. The nut that locks the dist. was loose. Will see what it does this weekend.
 
you run the lower pressure cap on the block so's that when it does get hot if there is a air pocket in the top on the filler (which is the higest point in the system) the air pocket will blead off at least that is what i was told last year by chris england and it semed to work for us? you can give it a try and rout your overflow out through the deck so's that when it does blow off you can se it blowing out hope this help's you

D.J.
 
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