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Author Topic:   car that just runs hot
bsioux352
Dirt Newbie

Total posts: 2
posted July 26, 2004 02:33 PM  
I was wondering if anyone could help me? We have a car that runs hot! After 6 laps 240 and will climb steadily. We have put extra plastic inbetween the front clip and radiator. We run a medium pitch 6 blade fan. We run an extended shroud behind that covers up right at half of the fan blades. We are running about 60/40 on water antifreeze repectivelty. So any help or suggestions would be greatly appreciated.

tilley88
Dirt Forum Champ
Total posts: 879
posted July 26, 2004 03:03 PM  
Set your timing between 34-36* total advance, fatten your jets and/or air-fuel mixture, run a t-stat without the center, block off the hole in the water pump that shoots water to the #2 cylinder, open your nosepiece up, make sure your brakes are'nt dragging, make sure your radiator is'nt corked up internally and externally, check for cracked heads or blown head gaskets, make sure your valve lash is'nt too tight, etc. I'm sure I missed a few things, but others will fill 'em in. I usually have the opposite problem, can't get 'er warm enuff.

WesternAuto17
Dirt Forum Champ
Total posts: 569
posted July 26, 2004 03:11 PM  
Do a search on overheating. There are 1.7 million posts on that.

Sounds kinda like some internal trouble, because the fan/shroud set up sounds right. The ducting in front of the radiator is good as well.

If it is ignition or jetting, fix it quick or you will buying a new powerplant.

[This message has been edited by WesternAuto17 (edited July 26, 2004).]

bsioux352
Dirt Newbie

Total posts: 2
posted July 26, 2004 03:13 PM  
We just recently had the heads checked over. Are timing is set at 36. We put in three sized bigger jets. We tried new plug wires, and plugs. We had already blocked the crossovers. I have checked the brakes. Thanks for the other info. I will start with them there and hope to hear some more new info.

racer17j
Dirt Forum Champ
Total posts: 5390
posted July 26, 2004 07:55 PM  
you might want to try distilled water with water wetter also

iowatoolman
Dirt Freak

Total posts: 369
posted July 26, 2004 08:44 PM  
if you are running a flex fan get rid of it get at least an 18 inch fan from jrmotorsports.com also change your water pump to an edelbrock victorjr waterpump and switch radiator to a griffin
i had the same problem did that and now i don't get over 190 temp after running on the track

marksracing
Dirt Forum Racer

Total posts: 79
posted July 26, 2004 09:22 PM  
WE WERE HAVEING THE SAME HEAT PROBLEM!! WE WENT FROM A 15IN 6 BLADE FAN TO A 17IN 6 BLADE FAN AND IT RUNS 200DEG ALL NIGHT.

Flanndad
Dirt Freak

Total posts: 255
posted July 27, 2004 05:59 AM  
With the car not running, grab the fan.
Can you turn it by hand?
My belt was tight but I had some power steering fluid on the pulley creating a slip in the belt at higher rpm.
I also had a 6-blade race fan, I went to the old GM 4 blade off of a 70's Suburban.
It pulled alot more air.
One more thing to try, pull the radiator out, drop it flat on a piece of plywood a couple of times, then spray it out real good from the backside, to remove any dirt in the fins.

One thing to try first, start the car up and put items of different weight in front of the radiator, piece of paper, piece of cardboard, a rag.
then after you clean everything out you will know if you are getting more airflow.

allzway
Dirt Maniac

Total posts: 136
posted July 27, 2004 07:19 AM  
We fought a cooling problem earlier this year.

First problem was running a flex fan...the change to a 6 blade made the car run 230+ which was a big improvement.

Still on hot nights it was getting too hot...so we went to the largest water restrictor and now the car runs 210.

Flanndad
Dirt Freak

Total posts: 255
posted July 27, 2004 08:03 AM  
I'm not a big fan of the 6 blade fan.
The way I look at it, the more blades, the more the fan turn's into a flat disk when at high rpm, less blades more pitch, I believe will get you more air flow.

sleadhead44
Dirt Maniac

Total posts: 109
posted July 27, 2004 10:16 AM  
Hey Flanndad, I havn't seen you post in a while, check your PM.

Scoot
Dirt Forum Champ
Total posts: 517
posted July 27, 2004 12:37 PM  
I would recommend running the 4 blade fan, and the cut out thermostat. I didnt have that great of a shroud and the entire nose is closed and it never got over 220. I only used the restrictor to get it warm quicker, otherwise it wouldnt run over 190. Also make sure you run a surge tank and make sure it is the highest part of the cooling system. Fill the radiator through it, you may have some air in the block, not allowing it to cool. If you get the most recent issue of Circle Track they discuss some cooling issues.

------------------
Scoot
Smith Racing Team
870-365-5989

merc123
Dirt Full Roller

Total posts: 28
posted July 29, 2004 09:39 PM  

 
We've had some overheating problems as well. We originally had a 21 inch radiator and a 6-blade fan. We replaced the water pump and used restrictors but it was running 240 in the feature race. The hot laps (6 laps) were alright though. We upgraded to a 27 inch radiator, rebuilt the shroud and got a 4-blade fan. We also made cutouts in the front bumper to allow for more air flow (see attached pic). The top cut out has a lip on it that is angled to direct the air down into the radiator.

We also noticed that during the races that mud was caking the radiator so we used 2 layers of mesh. 1 layer on the back of the bumper cutouts and one further back going from the bottom of the cutouts to the bumper frame and then curving up to the top of the radiator. That cut down on alot of the mud getting through. If we notice that mud is starting to cake the radiator though in the heat race we'll shoot it with a water hose before we race in the feature. That has helped quite a bit.

We overheat SOMETIMES but never in the lead (obviously) so it has something to do with the air flow. We're still working on it and so far it's managable.


[This message has been edited by merc123 (edited July 29, 2004).]

[This message has been edited by merc123 (edited August 02, 2004).]

WesternAuto17
Dirt Forum Champ
Total posts: 569
posted July 30, 2004 07:30 AM  
Running electric fans has taught me that the most important part of the cooling system is the plenum in the nose in front of the radiator. No fan (flex, 6 blade or electric) can duplicate the 50+ mph wind coming through the grille. A lot of cars waste that air by letting it go around the radiator instead of thru it.

Its all about the air flow to the radiator. My plenum is completely boxed in - top, bottom and both sides.

littlesister
Dirt Full Roller

Total posts: 48
posted August 04, 2004 09:27 PM  
I agree with the previous reply. Build you a good air box, that way all the air flow is directly to the radiator. Also, put you a fine screen in front to catch all that dirt.

    

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