300-6 cooling problems

[austin]

hello everyone i have 1969 f-100 with a freshly rebuilt 300-6 out of an 1983 f-150 the problem is that it runs a little hotter than i want it the gauge sits right in the middle of M on the temp gauge

how can i make it run a little cooler? i am sure it may need a fan clutch

[m-mman]

First thing to check is the ACTUAL operating temp.

Dash gauges are worthless for determining actual operating temp. There is a reason they are not calibrated in degrees. A gauge could easily be showing 3/4 and the temp could be only 180 degrees. They just are not that accurate. They were only intended to show change during operation from minute to minute (like knowing when to stop when climbing a hill on a hot day)

What you need to do is get a real radiator thermometer (or even a meat thermometer) and put it in your radiator water when the gauge is reading the area where you are concerned. Once you know what the acutal temp is, then you can consider what you want to do about it, if anything.

Any other method and you could end up spending lots of time & money for no real gain.

[fordman]

the top answers could be:
correct sized thermostat for the engine
clutch fan
fan shroud
4 clogged radiator /cooling system.

[austin]

while i dont have a fan shroud i am not sure about t-stat and my rad could be clogged with grasshopers ill have to check i guess

i think i will remove the t-stat for now and see if it will run a litlle cooler

[NM5K]

I would not remove the stat. Then the engine will run too cool.
I kind of doubt you have any real problems, unless it shows
obvious signs of overheating.
The gauge doesn't really mean much. You should not need a
fan clutch if you are using a stock solid fan.
It would be a good idea to verify the actual water temp
before going any farther. Unless you verify that it's
actually overheating, you may be trying to fix a problem
that doesn't exist.
If you are actually overheating, it's probably a shot radiator..
I'd use the standard 195 degree stat.
If it never boils over, etc, you may not have a problem at
all.
Removing the stat will make the engine run too cool,
which is not good.

[austin]

i pulled the t-stat today and it still got just as warm as usall

i hvent messured the the temp any other way than the temp gauge in the truck expect for durring the first start up and it got to hot that day and blew the radiator hose so im figuring somthing is wrong

i forgot to mention the fan was bent when i first got the truck about 2 years a go so i straighted it out i am wondering if a bent fan would have mess up the clutch fan?

[NM5K]

Are you sure that fan has a clutch? Maybe it does, being from an 83..
A bad clutch would show up more at idle or real slow speeds.
Overheating at speed will usually be a plugged radiator, unless the
stat is stuck.
I don't know that a bent blade would mess up a clutch.
I do know that an unbalanced fan will lead to water pump
bearing problems if it lasted long enough. But that would
not effect cooling. If the fan sounds normal now that you
bent it back to shape, it may be good enough for gov work.
It's possible that the hose was just shot, and blew with normal
temps.
If it's really overheating bad, you will hear it boiling bubbling
when you shut the engine off. And blow steam if hot enough.
"13 pounds pressure with a stock cap."
How does it run since you changed the hose? Does it boil when
you kill the motor. A normal system won't really make any noise
when shut off. There are other signs of overheating too.
IE: a hot engine is much more likely to ping. If you get more
pinging when you think it is hot, it may well be running hot.
Right now, the #1 thing is to find out if you are really overheating
or not. If it's showing the classic signs, then you can narrow it
down. It's usually a plugged radiator on the old trucks.
But if it runs fine with no symptoms, you need to check the
temp. It might be ok.. You don't want to chase your tail on a
non problem. You can't trust those gauges in many cases.
IE: mine reads real low compared to normal. It's obviously
whacked out, but it's still usable as I know if it goes up to
"normal" range, I'm overheating.

[austin]

its an existing problem it has boiled over a few times with a 16 lb cap and when that hose blew i hit the engine with of those laser thermeter thingys i dont rember how hot it was but it was hot! and i was about to shut the motor off when KABOOM there whent the hose

i would like thank all of you guys expseacialy NM5K for the help

i am going to order a clucth fan and see if that fixes it

[NM5K]

I've got one of those red dot thermometers.. I oughta test it on the engines,
hoses, etc and see how close it gets. My coolant should be around 195 degrees
all the time. I was thinking red lighting the hoses might give the most
accurate reading, but I keep forgetting to test it. I guess hitting the radiator
might be close too.
I'm gonna have to test it and see what gives the most accurate reading.
If you have a regular fixed fan now and are overheating, I doubt the fan is
the problem. Most likely the radiator. If it gets worse the faster you go,
it's the radiator. At high speeds the fan is not needed. So if you overheat
at cruising speeds, it's almost always the radiator if the stat is ok.
I've got a stock fixed fan and no shroud and never overheat at any speed.
But I have a good clean radiator. I had to buy a new one not long after
I got the truck. Due to the age and often abuse, shot radiators are
common on these old trucks. Heck, my 68 truck is 41 years old..
Pretty old for something that gets driven most every day.
With any vehicle that old, if it hasn't had the radiator replaced or rebuilt,
it's probably about due.

[austin]

okay maybe it is a radiator because i tried driving about 65mph and it still didnt cool off i also ran the heater and that didnt help. is there any way to clean the radiator or should i just look for a new one?

[fordman]

yes the radiator can be flushed out or boiled otu at a radiator shop. you can try vinegar in htere and use that to flush it. or get oen of those flush kits. if your radiator is real old it could develop leaks if the radiator is boiled out. but you could get lucky with that.

[NM5K]

I guess you could try flushing it super good, but that probably
won't really do the trick if you want a really reliable cooling system.
You can either have it rebuilt at a radiator shop, and they rod it out,
etc, or you can buy a new one. I decided to go with a new one as
I knew I would be having the truck for a while, and it gave me a lifetime
warranty.
I'm not sure how long they warranty the ones at the radiator shops.
I'm glad mine had the warranty as I'm on the 3rd one so far..
The first two had a quirk where the top seam would push out and
eventually spring a leak at the soldered seam. I never overheated,
so it was not due to excess pressure. Just a design quirk I think.
I noticed that the 3rd one I got had that top seam bent in at the exact
place the first two had pushed out. I'm guessing the bend makes it
stronger and less likely to push back out the other way.
So far so good on this one.. I guess I've had it 2-3 years??
Forgot..
I'm pretty picky about my cooling systems.. It's really hard on the
engines to overheat bad.
On my 05 Corolla, a severe overheat is the kiss of death to one
of those engines. Once fried, might as well chunk it and get a new one.
So I keep the coolant clean, watch the temp gauge like a hawk, etc..
Due to the strict emissions gear on that car, the temp gauge is like
it's glued in the same place once warm, and that car warms up fast.
So if it changes any at all, I know something is up and to shut it down.

[austin]

well okay then it sounds like i will order a new radiator this ones got 40 years on it and at least 400,000 miles on it i think not sure though

quick question has any put in a bigger radiator with a 300-6? the fan is kind of close to the radiator

[fordman]

let me start this way. the 6 cyl radiator is a narrower radiator than a v8 from side to side. the 6cyl radiator is 18 3/8 inches wide from side to side. most of the standard v8 radiators are 19 1/4 wide from side to side. these are the core dimensions. hieght is going to be ok. it wont matter with your radiator. but the difference in the size of your radiator will matter for two reasons. 1 if you order a v8 radiator it will have the v8 radiator hose size outlet on it. so youll need as special hose that goes from one size tothe other size. 2 the v8 radiator is wider so you will have to cut your core support open wider to let the radiator moutn properly. unless you have the van type radiator in a v8 core support. then you wont have to do that.

lmc says that your correct radiator for a 1969 with a 6 cyl is part number 43-3008. that radiator core is 19 1/4 wide x 26 3/8 widex 1 7/8 thick.with 3 rows of tubes in it. a radiator that large for a 6 cyl is way large enough for sure. that is so close to a v8 radiator that if you want a orginal radiator that is larger you would have to go up to a super cool radiator. which is 2 1/4 thick with 4 rows of tubes. which is for f350 trucks and 4wd with a v8 engine. so you dotn need a bigger or thicker radiator.

[austin]

let me start this way. the 6 cyl radiator is a narrower radiator than a v8 from side to side. the 6cyl radiator is 18 3/8 inches wide from side to side. most of the standard v8 radiators are 19 1/4 wide from side to side. these are the core dimensions. hieght is going to be ok. it wont matter with your radiator. but the difference in the size of your radiator will matter for two reasons. 1 if you order a v8 radiator it will have the v8 radiator hose size outlet on it. so youll need as special hose that goes from one size tothe other size. 2 the v8 radiator is wider so you will have to cut your core support open wider to let the radiator moutn properly. unless you have the van type radiator in a v8 core support. then you wont have to do that.

lmc says that your correct radiator for a 1969 with a 6 cyl is part number 43-3008. that radiator core is 19 1/4 wide x 26 3/8 widex 1 7/8 thick.with 3 rows of tubes in it. a radiator that large for a 6 cyl is way large enough for sure. that is so close to a v8 radiator that if you want a orginal radiator that is larger you would have to go up to a super cool radiator. which is 2 1/4 thick with 4 rows of tubes. which is for f350 trucks and 4wd with a v8 engine. so you dotn need a bigger or thicker radiator.

okay i got lookin at a v-8 radiator and i noticed the difrence thanks

okay my last question has anyone put a shroud on the six?

you guys rule thanks a millon