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Guys ,

 

Need some advice ....

My 351CJ is running hot when driving ( and idling ).

 

My radiator was restored last year so it should be clean , i have a new 351C thermostat , restrictor plate is where it should be.

 

When i bought the car it had an electric fan , with a temp sensor build in the radiator at the lower hose ( if that is the right position i realy don't know ), when should an electric fan starts working ??

 

How can i test if my water temp sender ( located in manifold near water pump ) is okay ?? ( it's a 351C sender , so that should be Okay )

 

Do i need a new waterpump ??

 

Realy don't know where to start .....::help::

 

JB

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[button=http://www.7173mustangs.com/thread-1972-351cj-q-code-mach1]Visit My Garage[/button]

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Others might have some different ideas... However I would assume placing the sensor in the bottom hose is the wrong place. That is the side the water will be coolest at in process, and being different outside temperatures would effect the temperture difference I don't be leave you would even calibrate it correctly. I have had over heating issues in my CJ-5 and I put two temperature guages in, one in the head and one in the lower hose so I can actually monitor things. I have seen the head at the temperature of 190 and the return line at 140. They fight back and forth depending on the thermostate and work load. That would be the same in your car, so once again to me that is imposible to get right.

 

Alot of people use sensors that activate in a ratio of power to temperature. That way the fan slowly powers to 100% at the maximum temperature you want it at. They are pretty common and I am sure a couple of guys here could point you to a few.

 

A good way to test the issue would be to hot wire the fan on when you get your heating issues. If it happends frequently when idiling that should be an easy way to find out if it is directly tied to your fan. If I was a betting man that would be what I think it is.

 

Before you replace things take one variable out at a time. I would get a thermo gun (under a hundred bucks at sears) and verify all your temps. Then if the problem still goes past that you can post a diagram here with your temps and someone else might have another idea!

 

Hopes this helps,

 

Brandon

Yea, Though I cruise through the valley of the Shadow of Rice, I will fear no Turbo, For Thine Torque art with me. Thy forged rods and crankshaft, they comfort me.

 

Thou preparest a strip before me in the presence of four cylinder enemies: thou anointest my heads with high octane; my quarter mile victories runneth over.

 

Surely Horsepower and RPM's shall follow me all the days of my life: and I will race on the streets and strips forever.

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I agree, whenever I've installed an electric fan the temperature sensor was mounted in the upper hose or in the fins near the upper hose.

 

As for the gauge, if you disconnect the wire at the sending unit and use a couple of resistors you can check the gauge. Connect the wire to a 73 ohm resistor and ground the other end of the resistor, and with the key on the gauge should read cold. With a 10 ohm resistor the gauge should read hot.

 

You should get similar readings if you check the resistance of the sending unit. Do not use teflon tape when installing the sending unit, it can insulate the unit and keep it from grounding. A sealing/anti-seize compound with metal in it works best (like copper).

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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The temp sensor should be in the fins near the top of the radiator from the hose that comes out of your thermostat housing.

I strongly agree with Brandon about the IR temp sensor gun but consider that a high flow water pump (not Edelbrock) will cost less than the IR gun. I'm not a fan of swaptronics but I'd guess your water pump isn't pushing efficiently anymore. I had the same problem on my 70 Mustang and it ended up being the water pump. All in all it cost $50 to replace and took about 4 hours.

-Former 70 & 72 Mustang Owner.

-69 Torino GT, Formal Roof, 351W, Edelbrock 600 cfm, Edelbrock 351W Performer RPM intake, headers, AOD trans, dual flowmasters w/H pipe, Pertronix II Billet, 3.5 TRACLOC g/r, 15" Magnum 500s, 100A alt, aluminum radiator, electric fan, Pro-car seats, mini-starter...owned since Dec 13.

-70 Mach 1, 351W, Edelbrock E-Street EFI, VHX instrument cluster, Hooker headers, dual flowmasters, Pertronix II, 15" Magnum 500s, 150A alt, aluminum radiator, dual electric fans, Pro-car seats, mini-starter

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Harbor Freight has a non-contact for $12 and a laser/IR for $21, they are very handy for a variety of troubleshooting and testing.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Harbor Freight has a non-contact for $12 and a laser/IR for $21, they are very handy for a variety of troubleshooting and testing.

 

And faily accurate.

Live, Laugh, love

ECTA, Ohio mile Landspeed record holder

C/GALT-136.36, AA/FALT 159.38 mph, New B/GALT Record 180.577mph- speed is the need !

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You indicate it always runs hot. Driving, at idle or cruzing down the highway?

How fast does it go to hot from a cold start and idle?

The electric fan only helps at slow speeds and stops, running down the highway it's the air pushing through from the speed. But sometimes electric fans have shrouds that actuall BLOCK the air flow from happening at speed.

Does it boil over or is the guage just showing 'hot'.

 

First thing I always check is the thermostat, pull it and put it in water on the stove and then turn the stove on and watch when it opens. Use a meat or other thermometer to test when it opens. (Okay, that's the second thing I check, the first thing is I have coolent in the system.). ;)

'Mike'

73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

 

Pics of modifications included in: [button=http://www.7173mustangs.com/thread-1973-convertible--3335]My Garage[/button]

 

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Harbor Freight has a non-contact for $12 and a laser/IR for $21, they are very handy for a variety of troubleshooting and testing.

 

Wow, that's awesome. Based on your post I just ordered the laser version, Item #93984, and used coupon code 65149244 for 25% off. Total with shipping was $23.56.

 

http://www.harborfreight.com

-Former 70 & 72 Mustang Owner.

-69 Torino GT, Formal Roof, 351W, Edelbrock 600 cfm, Edelbrock 351W Performer RPM intake, headers, AOD trans, dual flowmasters w/H pipe, Pertronix II Billet, 3.5 TRACLOC g/r, 15" Magnum 500s, 100A alt, aluminum radiator, electric fan, Pro-car seats, mini-starter...owned since Dec 13.

-70 Mach 1, 351W, Edelbrock E-Street EFI, VHX instrument cluster, Hooker headers, dual flowmasters, Pertronix II, 15" Magnum 500s, 150A alt, aluminum radiator, dual electric fans, Pro-car seats, mini-starter

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Lower hose restriction or collapse is always a source of overheating in our cars. Relocate the sensor and be sure your lower hose has the long coil inside. This prevents the hose from squeezing shut when it gets hot/soft and the waterpump is spinning up and sucking water from the rad.

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Lower hose restriction or collapse is always a source of overheating in our cars. Relocate the sensor and be sure your lower hose has the long coil inside. This prevents the hose from squeezing shut when it gets hot/soft and the waterpump is spinning up and sucking water from the rad.

 

HIGHLY concur with this statement above. You either need a spring or one of those incredibly inflexible rubber hoses that are ribbed for her pleasure (I'm just sayin'). I looked at a 70 Mustang a few weeks ago and the temp maxed out at idle in a few minutes. The lower hose collapsed and was made of some cheap rubber. I told the owner but he didn't care, he just wanted $5400 and the car gone. Link to spring is below.

 

http://www.cjponyparts.com/product.aspx?p=HW769&utm_source=google&utm_medium=merchant&utm_campaign=shopping&gclid=CKfjp5T-rroCFSlo7AodaRMApQ

-Former 70 & 72 Mustang Owner.

-69 Torino GT, Formal Roof, 351W, Edelbrock 600 cfm, Edelbrock 351W Performer RPM intake, headers, AOD trans, dual flowmasters w/H pipe, Pertronix II Billet, 3.5 TRACLOC g/r, 15" Magnum 500s, 100A alt, aluminum radiator, electric fan, Pro-car seats, mini-starter...owned since Dec 13.

-70 Mach 1, 351W, Edelbrock E-Street EFI, VHX instrument cluster, Hooker headers, dual flowmasters, Pertronix II, 15" Magnum 500s, 150A alt, aluminum radiator, dual electric fans, Pro-car seats, mini-starter

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When it comes to temperature, what should the temperature be when it's warmed up? My '73 Mach-1 had a 4v Cleveland, iron heads and aluminum intake, aluminum radiator and dual electric fans. My temp is constantly at 200'-220'. Is that too hot?

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Something's wrong there?

I've got a standard radiator and fan and mine sits on the thermostat temp at 180. 190 on really hot days....

I'd say your gauge is not accurate or your t/stat isn't doing the job...

Just my 2¢.

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Jim

 

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Ok..thanks

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Also, check if you have correct sparkplugs.....mine had Heat Rating 17. Just changed to Heat Rating 4 (spec is 5)....has helped a lot. suggest NGK6630 (reco by another member)

 

Also, not all 351C thermostats are same. Try Robertshaw brand. Specifically designed for 351C.

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yeah 210 to 220 is too hot in my opinion. I think 185 to 200 is about right.

-Former 70 & 72 Mustang Owner.

-69 Torino GT, Formal Roof, 351W, Edelbrock 600 cfm, Edelbrock 351W Performer RPM intake, headers, AOD trans, dual flowmasters w/H pipe, Pertronix II Billet, 3.5 TRACLOC g/r, 15" Magnum 500s, 100A alt, aluminum radiator, electric fan, Pro-car seats, mini-starter...owned since Dec 13.

-70 Mach 1, 351W, Edelbrock E-Street EFI, VHX instrument cluster, Hooker headers, dual flowmasters, Pertronix II, 15" Magnum 500s, 150A alt, aluminum radiator, dual electric fans, Pro-car seats, mini-starter

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mine was running in 210 range. (even after using Robershaw thermostat; roding radiator etc)

 

Pressure tested and found coolant leaks in heater core and water pump.

by-passed heater core, replaced water pump w/ high flow pump.

 

Still was a bit hot.

 

replaced spark plugs as mentioned above. Tuned carb w/ vac.

Drove for 80 miles round trip (85-90F weather; 90 mins in between)...temp never reached above 195F

 

This is my everyday car...it is a bit cooler outside (Los Angeles)....Temp normally hoovers ~180F

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Guys ,

 

Many thanks for the advice , so basicly i need to put a temperature sensor in the upper range of the radiator.

I saw a product on the Mustangs Unlimited site , part Da22501

Adjustable Temperature Sensor for Electric Fan.

 

Adjustable thermostat allows fan to come on at selected temperature, so range can vary, instead of only 1 choice. Includes adjustable sensor, wiring & bracketry needed to install as well as instructions.

 

This sensor slips inside the upper radiator hose & lead.

 

The range of temperature adjustment is from 180 to 240 degrees.

 

Is this something that i could use ??

 

JB

hvrju1.png

[button=http://www.7173mustangs.com/thread-1972-351cj-q-code-mach1]Visit My Garage[/button]

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Guys ,

 

Many thanks for the advice , so basicly i need to put a temperature sensor in the upper range of the radiator.

I saw a product on the Mustangs Unlimited site , part Da22501

Adjustable Temperature Sensor for Electric Fan.

 

Adjustable thermostat allows fan to come on at selected temperature, so range can vary, instead of only 1 choice. Includes adjustable sensor, wiring & bracketry needed to install as well as instructions.

 

This sensor slips inside the upper radiator hose & lead.

 

The range of temperature adjustment is from 180 to 240 degrees.

 

Is this something that i could use ??

 

JB

 

I'm not a fan of these adjustable thermoswitches, especially the kind that are installed in the radiator fins. A clean, simple, effective, and durable solution is to source a Spal thermoswitch (they are sold in 185*F and 195*F ON temperatures), install it in one of the openings of the thermostat housing, and use it to ground a relay (or relays) that power a fan assembly.

 

Don't forget, one of the best fan assemblies out there costs roughly $100 new and fits the '71-73 Mustang radiator pretty ideally!

1971 Mustang fastback: 10.3:1 C90E 408W hydroller - CDAN4 EEC-V w/EDIS8, girdled, lowered and caged

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