Speed Vs RPM Vs Heat

Systems, Types and Experiences

Speed Vs RPM Vs Heat

Postby ctcarguy » Tue Aug 29, 2017 3:22 pm

I am having a cooling problem and am searching for answers. I noted that my engine runs at 2000 RPM@ 40 and 3000 RPM @60. This is with a 1966 transmission. Does this seem normal? First gear is a Granny gear! I usually start in second. I'm wondering if a past owner change the differential ratio? This leads me to my cooling problem. Car is cool at idle and seems OK for at least awhile at 40mph. If I go faster, the car overheats sometimes reading 240+ and does not want to cool down when idling. FYI - I have a ProSpeed electic water pump, 1.5" copper pipe (goes over tank), a 2 row (each 1") aluminum radiator and 16" electric fan on a shroud with electronic controller. When it overheats, the block temperature (mechanical) will go to 240 and the temperature of the radiator coolant pipe going to the radiator is 200 to 220 or so. The fan is on but the radiator does not seem very hot. The cap is 16 lbs and does not release. I also have a hose attached to the top of the thermostat (190F) housing with valve to let out air. I used IR temperature measurement and neither shows the radiator or hoses near 200. I can only fill with the pump running. today I put in almost 3 gallons after it spewed out the radiator when open. Note: I had a Mr. Gasket radiator cap with thermometer that is supposed to tell you when it is safe to open - Bogus!

I replaced the spewed out antifreeze with water for testing and plan to put in a 160 thermostat with a 1/8" hole for air. Any thoughts? I can't trust this car until I figure this out. Attached is a picture of my set up. The hose from the thermostat enters the top of the radiator and the hose to the pump is on the bottom. All pipes are insulated and separated.
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Larry Boardman
Weatogue, Connecticut
ctcarguy
 
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Re: Speed Vs RPM Vs Heat

Postby Richard Miller » Wed Aug 30, 2017 8:46 am

in another post . Matt Nall notes his car ran 3500 at 70 ,, so your rpm seems in ballpark . mine about the same ..do you have a spoiler / airdam up front ? front radiator opening under the bumper ? air can recirculate when stopped , idling , from bottom of trunk back to front ,, spoiler helps some . when in motion spoiler helps create lower pressure under trunk ,, without one the air can go under car about as easily as thru radiator .. like some others I have spoken with ,, once car boils over only shutoff and cool down seems to recover ,,you write that "the block temperature (mechanical) will go to 240 and the temperature of the radiator coolant pipe going to the radiator is 200 to 220 " this does sound like circulation problem ,, trapped air is a possibility .. maybe some others here will check in with some better ideas ,, I currently have a mechanical pump , but others have used electric pumps and like them ,, one thing you can do is run pump and fan after engine shut off for a cool down cycle ,, I am thinking of trying that if I install electric pump .. look at it with an eye toward making sure no air is trapped in system and air cannot bypass radiator ,, cooling is one issue we all have dealt with at some point ,, good luck ,,
Richard Miller
West Covina, Ca
'65 V8 Vair
Richard Miller
 
Posts: 142
Joined: Tue Mar 01, 2016 6:25 pm

Re: Speed Vs RPM Vs Heat

Postby ctcarguy » Wed Aug 30, 2017 9:25 am

Thanks for the reply. I do have a spoiler in front and have the radiator enclosed to direct the air into it. Air is a possible but I keep bleeding and not getting any. The RPM still seem high but since the ratios are the same as stock, I can see why. I ran the car at 2000 rpm (not moving with trunk open) and the temp maxed at 190. At 2500 to 3000 (not moving with trunk open) it when right up within a few minutes. Moving or not,the temp rises at anything over 2000. It takes about 10 minutes to come up to temp from cold. When driving at 2000 or less, I can drive 15-20 minutes without a problem. At higher RPM, even at 2500, it starts to climb and will hit 220 within minutes and keep going. Air is the enemy in this system. I wanted to run the pipes under the tank but it is just too close to the ground and I fear hitting them. I wonder if ovaling the pipes under the tank and making a skid plate might work. Not a lot of clearance.

Another local V8Vair has the radiator in the rear and he says he has solved the issues. I also have 2 ATV radiator fans on the rear firewall to exhaust heat from the compartment. Does not seem to affect the cooling.

Larry
Simsbury CT
Larry Boardman
Weatogue, Connecticut
ctcarguy
 
Posts: 69
Joined: Sun Dec 28, 2014 9:13 am
Location: Simsbury CT

Re: Speed Vs RPM Vs Heat

Postby Richard Miller » Wed Aug 30, 2017 1:37 pm

okay well that is interesting ..( I hate to see a question posted and no one replies ,, so I feel that my reply should have a warning " this is my opinion and may not be correct") but I would hope for a conversation , maybe someone will weigh in .. I wonder if you have head gasket problem ,, or timing issue ? interesting that it is sensitive to rpm to that degree ,, obviously engine working harder will generate more heat but that seems excessive ,, for what it is worth I originally ran my pipes under the tank (1 1/2 copper ) clamped to the flange at front of tunnel .. occasional scrape was at about 18 inches to rear of that point ,, but it did make system U shaped with no high spots in between ,, and easy to fill and bleed ,, you could probably run the pipes in the tunnel , thru the flange , and dip under the tank .. thing is the tank bottom is between the wheels so it rises and falls with the tires ,, go over a speed bump or driveway and it stays clear ,, as I said , my scrapes occurred rear of that ,, my pipes were below the tunnel .. and my car is lowered and had short (23 inch diameter ) tires at the time ,, rear radiator sounds great ,, afew have made it work okay.. but it seems to be difficult to get airflow thru ,, Doug Hargrove has a video of airflow test he did ,, he found no natural air flow so he makes it work with a large radiator and big fans ...anybody have an idea why Larry's car is overheating with RPM?
Richard Miller
West Covina, Ca
'65 V8 Vair
Richard Miller
 
Posts: 142
Joined: Tue Mar 01, 2016 6:25 pm

Re: Speed Vs RPM Vs Heat

Postby Modesto Hargrove » Thu Aug 31, 2017 5:10 pm

Have you checked water flow? If the flow is to slow the radiator can not do it's job. With the electric pump you would not have to run the engine to check the flow.
Modesto Hargrove
 
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Re: Speed Vs RPM Vs Heat

Postby ctcarguy » Thu Aug 31, 2017 5:48 pm

I worked on the car for several hours today. Drained the system and removed the thermostat. It was a 180 and tested (in boiling water) OK. I replaced it anyway with a 160 with 1/8" bleed hole. I put the front of the car up and refilled the system, periodically running the water pump and opening the bleed on the t'stat housing while refilling the radiator with water for now. I did this several times until the level stayed about 1" below the neck. I did find the t'stat housing was leaking, allowing pressure and coolant to escape. This is new. I tightened it down and plan to put 2 gaskets in. I used forma-gasket but that was not enough. I stopped the leak and took a drive. Max temp was 180 - VERY Happy... until about 3 miles in the block gauge starting rising. The radiator was under 180 and the fan was off. No question it was an air bubble. I let it cool with the pump on and the fan kicked in. After about 5 minutes, I continued on with no problem for another mile or so. I think the problem is two fold, trapped air and lack of pressure from the slight leak at the thermostat. Tomorrow I will put in the new gaskets and give it another test.
Larry Boardman
Weatogue, Connecticut
ctcarguy
 
Posts: 69
Joined: Sun Dec 28, 2014 9:13 am
Location: Simsbury CT

Re: Speed Vs RPM Vs Heat

Postby Richard Miller » Fri Sep 01, 2017 8:28 am

post your results after you get it fixed ,, we would all benefit from knowledge of what works ,, good luck
Richard Miller
West Covina, Ca
'65 V8 Vair
Richard Miller
 
Posts: 142
Joined: Tue Mar 01, 2016 6:25 pm

Re: Speed Vs RPM Vs Heat

Postby ctcarguy » Mon Sep 11, 2017 6:55 pm

Update: The problem persisted that after driving 6-5 mile, the car will suddenly overheat even in mild temperatures. When I stopped once when it overheated, I shut the motor off and then just turned the ignition on to keep the electric water pump going. I noticed neither it or the fans were running. At home I spliced in a light into the water pump circuit. Sitting in my garage running for about 20 minutes, it suddenly started to overheat and I noticed the light was out AH HA! The water pump, front and rear fans and fuel pump all run off a separate line from the battery . The independent circuit panel in front has fuses for each and a circuit breaker for the fan. Back at the battery there is a 50 amp breaker protecting the line. It turns out the circuit breaker would open suddenly leaving the water pump and fans off. I replaced the breaker with a 40 amp I had and measured the draw. Maximum was 15 amps. Drove the car with some gusto for 6 miles tonight with a maximum temperature of 205 in the block and 170 from the radiator. This is with only water in the system which is not the best heat transfer liquid. Now I will drain it and put in antifreeze. I think the problem is finally solved. The funny thing is I left a spot on the dash for a light to confirm the water pump was running. I think I will put it in finally.
Ah the fun of a V8 Vair! Next stop is Clarkes Corvair Meet on Saturday. Lots of work to do yet but it will be presentable.

Larry
Simsbury CT
Larry Boardman
Weatogue, Connecticut
ctcarguy
 
Posts: 69
Joined: Sun Dec 28, 2014 9:13 am
Location: Simsbury CT

Re: Speed Vs RPM Vs Heat

Postby Richard Miller » Tue Sep 12, 2017 8:16 am

excellent news ,, glad to hear you found that ,,I think I will install a "run light" when I put electric pump in ...
Richard Miller
West Covina, Ca
'65 V8 Vair
Richard Miller
 
Posts: 142
Joined: Tue Mar 01, 2016 6:25 pm


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