1971 Mustang overheating

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Dallas

Well-known member
Joined
Jul 8, 2013
Messages
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Location
Italy
My Car
1971 Convertible Mustang 351 C 2V H Code automatic transmission
Hello people

My 1971 351 C Stang has an overheating problem so I'd like to check the thermostat. Since I'm from Italy it's impossible to find a new thermostat here so I have to order a brand new one in US and wait a couple of week to have it. In the meantime I'd like to see if it could be possible repair the actual one ( if the overheating problem is caused by the thermostat ), and I'd like to ask you how can I check if the actual thermostat is working properly. The overheating happened last saturday the car was running perfectly when I realized that suddently the arrow on the temperature indicator was on the H letter. Do you think that the problem could be the thermostat or the water pump or what ?

Could you also tell me a US made brand of a good radiator to install in my Stang ?

Thanks a lot

Dallas

 
Hi Dallas. You can check the thermostat is opening by dropping it into a pot of boiling water. If it opens it is OK.

Possibilities:

Bad thermostat

The guage is not reading correctly

Clogged radiator

Low coolant

Bad water pump

Sitting too long on a really hot day idling?

Can you tell us more detail around the circumstances of overheating? How hot was the day, what we you doing at the time, How long it has been running perfectly for you, did any coolant come out of the overflow, etc?

I have a Be Cool aluminum radiator on mine and I like it:) I also have a Summit Racing universal aluminum on my XB Falcon 351C and it works well too.

Greg

 
Thanks a lot Greg

I was luck to find this website and have tour assistance because here in Italy where I live noone is expert in US car and also if I live 30 minutes from Ferrari plant, Lamborghini, Maserati and Pagani Zonda can you belive that there is no mechanic expert to mantain a US V8 ?

Anyway I was drivng on saturday night at about 75 miles per hours for about 30 minutes now here in Italy the outside temperature is about 82 F°. When I arrived at home I've seen the arrow on the temperature indicator all on the right part on the H.

My car is not in a perfect shape but I use to drive it for a long time without any problem, the engibe it's not fresh but I've never had any serious problems till now. Last year I change the water pump, the thermostat, alternator, spark plugs, spark plug cables, new gasoline tank and floater, I've made the valve new, carb restoring and now I have this problem. I've also noted that when the arrow was on H letter on the indicator for a second the engine seemed to lose power, but just for a second

I post a pic of the engine

Thanks a lot

Fran

DSCN7413.jpg

 
I was luck to find this website and have tour assistance because here in Italy where I live noone is expert in US car
It is hard to find anyone where I live that knows anything about these cars.

San Francisco Bay area USA.

You are not alone ;)

mike

 
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+1 to stat or water pump...Specialy driving at 75 and it still got hot....I would run some radator flush anyways...Check the stat in boiling water, even that is not for sure cause it could still be opening too late..Water boils at 212..Your stat should be opening in the 180-195 range.....But atleast shows you it is trying to work...If i was you..I would order a new stat and maybe a water pump...Sure mite take a week or 2 for you to get the parts..But way worth it..Not worth taking a chance on a old thermostat..They need to be replaced once and a while anyways.

 
just to add another detail there is a anti collapse spring located in the lower radiator hose, usually when the time comes to flush/boil or replace the radiator then that spring has usually fallen apart as well.

at high rpms it keeps the coolant hose from pinching off which can cause overheating while over 55 mph even with the cooling fan spinning.

the 302 has a similar spring but it is smaller then the 351 version.

i would reverse flush the system and see how much junk comes out of the motor. then inspect the hoses and the lower anti collapse spring located inside the lower hose just before the inlet to the water pump.

change the coolant and you can test the thermostat in a pot of boiling water to see if it opens.

there is also a restriction inside the thermostat housing for the 351 460 engines it looks like a washer with a hole in it. and it flush mounts to the bottom of the thermostat when installed and it directs the coolant through the thermostat correctly.

thermostat_restrictor2.jpg


also make sure you have the correct thermostat a 351C is very different from a 351W engine.

the cleveland thermostat opens upwards when heated. the winsor opens down. many people install a Windsor version and when the thermostat tries to open it hits the bypass plate and is stuck closed.

cleveland

new_thermostat.jpg


 
Thanks a lot

Today I tried to check the thermostat but I've discovered that I have't the right wrenches because in Italy the wrenches are in mm and in US in inches

Tomorrow I will look for wrenches in inches

I've just take off the pipe from the radiator to the thermostat and after when I re install in ( just tightening the clamps ) I tried my Stang and the temperature level was right

Maybe the indicator doesn't work properly

I've check the radiator and I haven't seen any leakage

Maybe I should buy a pistol to check the temperature of the engine

I will keep you updated about it

Thanks again

 
All of the suggestions are good ones. I would start by verifying that it is overheating, an infrared thermometer aimed at the top hose and the base of the thermostat housing is the best way. If it's not overheating the sending unit or gauge are malfunctioning or the wire to the sending unit is grounded. If it is overheating start with checking the fan belt tension, then thermostat, hoses, water pump, and finally the radiator.

 
Thanks Don

Appreciated

 
could also try this.

pop the plug off the coolant sensor, clean the top of the sensor well with some sand paper then clean the pop on connector in the wire really well, and then reconnect, if the connection has corrosion the ohms will read higher then normal and the gauge may think the engine is overheating when it isn't you can use some dielectric grease on the connection after you clean it to protect it from corroding in the future

 
Sorry

Where is the temperature sensor ?

I'm not an expert but for sure I will do a best job than the so called italian mechanics

Thanks

 
its located screwed into the water pump housing by the alternator.

you will see a single wire going to the water pump housing where the heater core hoses come out by the alternator.

the oil sensor is located on the back/top of the engine behind the intake manifold

 
Thanks again

Tomorrow I will look for the wrenches in inches and I will check the thermostat and the temperature sensor

I will also buy a pistol to detect the temperature

Thanks a lot


Since you are a technical expert I send you some pics of the engie of my Stang

I know that is not in the best shape but it's hard and costly for me restore it completely

DSCN7412.jpg

Reggio nell\'Emilia-20130618-01374(1).jpg

 
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A few thoughts of mine that are mostly duplicates of what you have heard.

Power loss and momentary spiking of the gauge at the same time may indicate an engine ground problem. Electric gauge sending units work by altering the resistance through the ground wire. When the ground is poor, the resistance is altered.

Ignition systems also fire to ground, which happens to be the spark plug-a poor engine ground likewise will cause power loss, and it often occurs under load, because the engine twists against the motor mounts which then separate a bit by design. The mounts are steel bonded to rubber and bolted together. The bolt acts as the ground when the true grounds fail. Unfortunately they don't do a great job of it.

Look at the engine ground to chassis strap, it is going to look like bare flat braided wire. If it is corroded, rusted, loose or otherwise not making a solid connection fix this. I am inclined to believe this is your problem.

If your inspection does not reveal a problem here, check the condition of your radiator cap-it holds pressure at a set specification and when it is worn or incorrect your radiator's cooling capacity is severely reduced. I notice on your picture that someone added an overflow tank, but it appears not to be hooked up. This suggest the cap has probably been replaced at some point. Verify that it is correct for your vehicle.

Check the belt that drives the water pump, make sure it is snug and not slipping or sliding on the pulley. Water pumps fail-but they are easy to change and available inexpensively here in the states. It is a couple hours work or less. When they fail, they often leak through a small hole that is built into the housing. If this weep hole is draining you probably need a water pump.

Inspect the hoses for signs of collapsing or leaks, if they are swollen near the clamps it is time to replace them.

If you car is actually overheating (and it is just as likely that it isn't) and you have done all of the above, I would start with replacing the thermostat with a new and personally tested unit. Coolant should be flushed with engine running and the heater on and set to hot, until you get clear water and then drain completely and refill with 50% water/50%coolant mixture.

There should be a seal between the radiator and the AC condenser that you can make easily out of a scrap of any heat resistant plastic. (I cut down one from a 2000 Lincoln I bought at the junkyard for $3.00) This helps, but isn't always necessary. Also your condensor looks to be a little dirty and banged up. You can get a fin comb for straightening out the damaged fins and increase airflow more than you might imagine. I am unsure if your fan uses a clutch or is just a solid hub. If it has a clutch it will look like a finned plate between the fan and the water pump. If so, you can spin the fan and if if spins freely on a hot engine, it is bad.

Pay attention to the thermostat being a cleveland specific one as mentioned earlier-also if you remove it, there should be a small brass plate called a restrictor plate underneath it. If this is missing, it needs to be replaced.

Griffin makes a nice drop in radiator for our cars about $300.00 US

Milodon makes a nice aluminum high volume water pump for about $100.00 US A remanufactured iron pump will cost about 1/2 that amount.

If you need a water pump, then you need a new belt, to perform a good flush, fresh coolant, a new and correct and tested thermostat and a radiator cap. Factory radiators, if not leaking, are adequate to cool unmodified conditions in 95 degree weather with the AC running-unless your radiator is full of gunk that won't flush out or leaking or damaged, you probably don't need one.

 
Lots of good info above. Best advice is to confirm it is really overheating. In my experience it is unusual to see the temp gauge all the way to H and not have already noticed a driving problem. I suspect a ground problem too.

When you got home and it was 'hot' what happened when you shut it off?

And one piece of advice not yet provided. If you find it is really hot do not attempt to add water to it while it is hot. The cold water can actually cause expensive issues. Instead, dump water on the raditor while the engine is running until it cools down some.

 
1. Radiator caps also wear out. When the spring gets weak, the cooling system does not stay pressurized and the water boils sooner than it should.

2. Also...expecially since you have to mail order your thermostat, make CERTAIN you get the correct thermostat. To determine this you first need to see if you have the famous WATER BYPASS installed in your engine.

You will have to drain about 2 gallons of water from your radiator, remove your thermostat housing, and peek into the housing hole.

Do a search for bypass on the site, and you should see lot's of good stuff-photos,instructions.

If you can't find it, give me a PM.

 
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