Everything is brand new, still overheating.

[Jim S]

I pulled the trigger and bought a 350 long block freshly professionally rebuilt.  I have a brand new aluminum Avanti radiator. I have a heavy duty racing water pump and electric fan.  The new engine needs to be run a 2,000 rpm for 30 mins to break in.  I can't run it for 15 mins without the temp guage pegging to 240 and it overheating. I've purged the air out as well.  I am lost why this thing won't run cooler.  If I can't fix it soon, it will have to be sold at a huge loss.  A friend told me that Avantis have an inherant air flow problem through the radiator.  He said some people got more flow installing an air dam.  Has anyone tried this? Or does anyone make an aftermarket add on?

 

Edited Saturday at 03:43 AM by Jim S

[Gunslinger]

Yes…an air deflector directs more air to the radiator that would otherwise create turbulent airflow under the car.  It serves no purpose idling but really helps at speed.

[wildfelr]

RQB3263/81/305 .... THERE ARE STILL SEVERAL THINGS YOU CAN DO ... ALL TOGETHER  MAY HELP  .... INDIVIDUALLY NOT SO MUCH ...AIR DAM WILL HELP DOWN THE ROAD ... I GOT MINE FROM  MICHEAL PHILLIPS IN PA....I BELIEVE HE IS THE ONLY MFG./SUPPLIER.....PICK A TARGET TEMP I SUGGEST 200 DEGREES RUN IT TO THAT POINT AND SHUT IT OFF AND COOL DOWN... TIME  IT  AND DO IT AGAIN ...EACH TIME IT SHOULD TAKE LONGER UNTILL IT WILL RUN AT 200 CONTINUOUSLY ... THIS WILL INDICATE YOUR ENGINE BREAK-IN IS COMPLETE ... CHANGE THE OIL AND FILTER .... ALSO INSTALL A TRANS COOLER AND GET THAT HEAT OUT OF THE RADIATOR ... I NEVER COULD UNDERSTAND THAT ... REMOVE THE HEAR RISER VALVE FROM THE EXHAUST MANIFOLD ... IS YOUR ELECTRIC FAN BLOWING THE RIGHT DIRECTION ??   BE SURE THE THERMOSTAT IS 180 WITH 4 OR 5  .. 3/16 HOLES DRILLED  .... HOW ABOUT  THE WATER PUMP IMPELLER  NOT IMPOSSIBLE IT HAS THE WRONG IMPELLER... IVE SEEN IT BEFOR ...ALSO IN THE SUMMER TIME I SPACE THE HOOD LATCHES UP  3/4 INCH REQ LONGER BOLTS... 5 MINUTE JOB ...AND SWITCH BACK AT THANKSGIVING .... 

[wildfelr]

RQB3263..... MICHEAL PHILLIPS  215-260-8377  AIR DAM SUPPLIER MANUFACTURER 

[wildfelr]

RQB3263...... BRAND NEW DOESN'T GUARANTEE CORRECT OR QUALITY .... WELL THATS ANOTHER STORY.....CHECK WATER PUMP BELT TENSION ...  AND IGNITION TIMING....IN COMBINATION BUT MORE THAN LIKELY ONE THING RESTRICTING AIR OR WATER FLOW AND NOT A MAJOR PROBLEM WITH YOUR NEW ENGINE..... INTERESTING KEEP IN TOUCH HERE... BILL IN FLORIDA

[Jim S]

Thank-you everyone.  I guess I have my work cut out for me!

[wildfelr]

RQB3263..... EXHAUST/TAIL PIPE/MUFFLER BLOCKAGE ...COLLAPSED MUFFLER.....ANOTHER POSSIBILITY 

[Kodjo]

I tried an electric fan also. It makes less noise as the original fan on the waterpump. But, the engine did overheat and I needed to go back to the original mechanical set-up.

What also could be the case is that the temp sender in your fresh new block is not according to Avanti spec. I did put an resistor in series with the temp sender to get correct readings. You can also try to put the old sender in your new 350.

So, this did not work although I put a lot of effort in it:

[wildfelr]

RQB3263..... I SEE NO REASON WHY THIS FAN SHOULDNT WORK JUST FINE..... I THINK JIM'S   PROBLEM IS SOMEWHERE ELSE .... VERY NICE INSTALLATION ..JIM'S PROBLEM IS EITHER INADEQUATE AIR FLOW OR WATER FLOW.... AND THERE ARE MANY CAUSES FOR BOTH....MOST LISTED HERE..... MAKE A LIST AND ELIMINATE EACH.... KEEP IN TOUCH

[wildfelr]

RQB3263..... ALSO.... THIS IS MY SUMMERIZATION MOD  LOOKS LIKE UNTIL THANKSGIVING WHEN I REMOVE THE 3/4 INCH SPACERS UNDER THE LATCHES, PUT THE LATCHES DOWN IN THE REGULAR POSITION FOR THE WINTER (OR COOLER WEATHER IN FLORIDA) AT THAT TIME THE SPACERS GO ON TOP OF THE LATCHES FOR STORAGE TILL SPRING .... THIS HAS TO LET ENGINE COMP HEAT OUT .....EASY AND CHEAP ....BILL IN FLORIDA

[Gunslinger]

The racing water pump could be part of the problem.  If it's a reverse flow water pump that might be a problem but a racing water pump may circulate the coolant faster than it can be cooled.  

[wildfelr]

RQB3263 .... OH YES !! I LIKE THAT ...... I THINK YOUR ON TO SOMETHING ....YAAAAA

[Ron Dame]

It looks like everyone has already mentioned what I was thinking, but if the  ignition timing is retarded, it will run hotter. Same with a plugged exhaust. I don't think that either would heat so fast that you couldn't complete break-in though. Second, get an infrared temperature reader and see if it is really hot, or if it is a gauge issue. As an aside, my Champ had the wires to the gauge reversed, and within minutes of starting, the gauge would peg, but then soon drop. I never understood why it would act that way, but once the wires were in the correct place, it acted normally. My point being, don't rely on the gauge only. Third, I like the idea that the racing water pump may be designed for serpentine belts, thus runs backwards with conventional belts.

Keep us informed!

[A0136]

Jim

Checking water pump rotation, ignition timing and actual temp with heat gun as suggested above should be checked.

Other possibility’s and thoughts.

Thermostat installed upside down.

Lower radiator hose collapsing.  Does the lower hose a wire spring installed?

Running the engine without a pressure cap, 

Leaking head gasket, cracked head or block. These will allow combustion gasses into the coolant.

A fresh rebuild that has tight pistons will heat up quickly. 

Good luck hope you find the problem quickly. 

Steve 
 

 

[Kodjo]

10 hours ago, Ron Dame said:

My Champ had the wires to the gauge reversed, and within minutes of starting, the gauge would peg, but then soon drop. I never understood why it would act that way, but once the wires were in the correct place, it acted normally.

This is due to the construction of the gauge: It is a balance between the voltage of the battery and the resistance of the temp sender.

I would suspect the temp reading here. check temp sender and gauge!