That's my question. Does your engine temp fluctuate in cold climate? My previous post on this page says I fixed my original fluctuation problem and it did. But I only drove it in warm climate. This is the very first winter im driving it in. Its a 1977 ford f250 4x4 460 c6. in the past 2 years its had a new radiator, water pump, t-stat, hoses, temp gauge, intake manifold gasket and the heater works perfectly. Now this is whats happening. temp ran great all 2013 in the summer at 190* no fluctuation and all summer 2014 190* no fluctuation. this is the first winter and with the 180* tstat in, the temp ranges from 160 cruising to spiking to 190 when stopped and sometimes to 210* to 220* then falls instantly back to 190. That's a 60* temp sweep. I opened rad cap to see if I have flow movement from the water pump and I looked as though it does. remove tstat and ran it to comfirm and it definatley has flow. changed the upper hose cause it was cracked and installed a lower 160* t stat. Ran it again and and now it runs 170 and sometime fluctuates to max 190*. that's a 30* sweep. Now let me correct with with the original 180 tstst in it would spike everytime on deceleration and stopping and every so often it would spike to 200 210 220 while cruising. with the 160 tstat installed it does the exact same just only spiking to 190 max and occasionally spiking to 180 while driving. So im asking is this normal? Which I don't think it is. What are yalls temps doing during the summer and winter? thanks much appreciated.

 

What are your outside temp??? if cold enough cover grill to slow airflow thru radiator and see if that helps. We had to do this in Alaska all winter long...

 

temps here in dallas this past couple weeks are in 40's

 

190F maximum is probably too cold. I run the 195F t-stat and temperature is fairly constant in my 79 F250 460. 205F coolant outflow from block when running at idle. Temps colder than 195 start to exponentially increase wear as temps decrease. You running a shroud and is your radiator clean or scaled up with corrosion? They heat soak when shut off, but shouldn't swing that much in temp when running normally. Should increase some when coming to a stop.

 

I ran a 180 t-stat that kept the 460 at 190 to 200 for the past 2 summers here in texas. Then it started spiking to 220 here in the winter and now I for test measures am running 160 and it keeps it at 170 to 180 and sometimes spiking to 190. My rad is clean outside and in. I plan on getting a new 180 t stat and trying it again.

 

Something doesn't seem right. When I was living in Michigan, I had the stock thermostat 195F. Temperature stayed constant once thermostat opened even when driving in 20-30F weather. I didn't see your other thread so maybe you already did this: boil your thermostat with a candy thermometer to make sure its opening at the right temp? I've used failsafe ones since I pulled the OEM one and had no issues.

 

I did check all three of my t stats. they all check good. Im about to burn this mother ****er to the ground im so aggravated. Ive triple checked everything. There is nothing else to check or replace. In the past 2 years, ive replaced radiator, waterpump, hoses, cap, t stat, even the intake manifold gaskets, and the heater works great. ive jacked the front of the truck up and burp the system multiple times. Ive checked for a head gasket leak with a head gasket tester. I pressure tested the radiator system. Its still spiking temps like its getting air into the system only this winter. it worked great the past two summers and I thought I had it fixed but this is the first winter ive driven it in and its just acting up. the next step is to change the temp sensor out with a new spare I have but I know that's not going to fix it cause its already been changed aswell in the past two years. im at a loss

 

There are FOUR different radiators, TWO different fan shrouds. Which types does the OP have in his truck?

 

Your 77 460 4x4 begs the question. Was the original radiator retained in swap or is it a radiator for a 460 since your truck did not come from the factory like that? Can you measure your core size? If the radiator is too small that could be the issue or heavily contribute.

 

It originally had a 351 and so was the radiator. that's why I changed it to a 460 radiator from lmc truck. I ordered a fan shroud when I changed the rad but it didn't fit even though it said it would. I got all that from lmc truck. Besides it ran perfect in the past two summers. I didn't drive the past winter. Its not overheating to the extent that temp rises and never falls back down. the only time it rises or spikes up for just a brief moment s coming to a stop and I mean just a second or two and then the temp stabilizes. it will never rise just idling. ever. Do you guys really think the shroud is completely relevant. because its ran normal temps in hot dallas weather. also I don't run one on my 65 mustang with a stroked 306 and it runs cool all day long with factory rad size.

 

<p>With a 460, or really any engine, the shroud is very important. I ordered a radiator from LMC as well about 1 year ago. I used my factory shroud. The ones from LMC almost fit but don't. (I tried a made in USA griffin radiator but for $700, you would think that it would come pre-drilled and set up for a shroud). Shroud is absolutely critical. You can get a "make a shroud" kit from summit racing for fairly cheap. I wouldn't run any vehicle without a shroud. You greatly increase your cooling efficiency and consistency. You have a viscous fan clutch or like mine, do you have a solid mounting? If clutch, then that could explain the rapid spikes with no shroud. I wont beat you up like other guys on the site but think about it: all of these trucks came with shrouds and all new cars since then have come with shrouds. I really cant recommend anything else til you have one.</p>

 

well I went ahead and ordered me a fan shroud from jeffs bronco graveyard. I will give it a try even though none of my my 1996 caprice didn't come with one and my 65 mustang doesn't run one with no temperature troubles. I will give it a shot. hey it cant hurt though. im also gonna run a secondary temp sensor just to confirm gauge is accurate. I will let yall no in the next week or so

 

I believe I posted on your last thread... I understand your frustration. A little bit of "hunting" during cold weather is normal as it warms up... but it should not go over stat temp by more than 5 or at most 10 degrees then the stat should open and drop it right back. It may drop below stat temperature briefly but should come right back up. It sure sounds like the stat is sticking or non-functional or you have air pockets... but you have replaced the stat several times and after driving for a while the air should be out unless there is a combustion leak adding gas to the coolant.

For your application a standard stat rated 192-195 F should be fine year around. I generally use the "better" AP store stats with no problem. A shroud can't hurt but shouldn't really make a difference in cool weather. An inexpensive aftermarket gauge sounds like a good diagnostic. Also pressure test the cylinders by hooking up compressed air one at a time and check for any air leakage back into the coolant.

 

Fan shroud bolts to the radiator support.

Which fan shroud did you order? There are TWO different types. The fan shroud used the Super Cooling radiator has a larger opening radius than the shroud used with the standard/xtra cooling and A/C radiators.

1973/79's with round headlamps: There are TWO different radiator supports. The support used with the Super Cooling radiator has a larger opening radius than the standard/xtra cooling and A/C radiators.

So...you need the fan shroud that matches the above criteria, otherwise it won't fit.

Carpenter has repro'd both of these fan shrouds. Has their Ford part & ID numbers (marked on upper left corner) and their measurement listed in his 1967/79 truck repro parts catalog.

btw: 1965/66 Mustang V8's with factory or dealer installed A/C have a fan shroud.

 

bluewhite. I agree wth you. im having with the 190 tstat its fluctuating some 60 degrees. from 160 to 220 when drivin and stopping. I believe im getting air in the system from an internal source. In the past two summers with the 190 tstat in in ran at 190 all day long even in bumper to bumper traffic. I have one of those head aet leak testers with the fluid that changes color when carbon dioxide is detected. Im gonna try the pressure check ithe cylinder with compresses air like you said to see if im getting any air in the coolant syatem.

Numberdummy. my truck is a piece together from two trucks i dont know what rad support i have. i ordered this size from jeffs bronco graveyard;
<TABLE border=0 cellSpacing=0 cellPadding=3 width="100%"><TBODY><TR><TD style="TEXT-ALIGN: justify" class="plaintext proddesc">Ford Part # D3TZ-8146-D Fan shroud casting # D4TA-CA or CB.
460 V8
2 1/4" deep 28 1/4" Wide By 25/1/4" Tall
1973-79 2WD F100 F150 Standard/Extra/Super Cooling
</TD></TR></TBODY></TABLE>
<TABLE border=0 cellSpacing=0 cellPadding=3 width="100%"></TABLE>
<!-- end sl_code here --><TABLE border=0 cellSpacing=0 cellPadding=3 width="100%"><TBODY><TR><TD style="TEXT-ALIGN: justify" class="plaintext proddesc">Ford Part # D3TZ-8146-D Fan shroud casting # D4TA-CA or CB.
460 V8
2 1/4" deep 28 1/4" Wide By 25/1/4" Tall
1973-79 2WD F100 F150 Standard/Extra/Super Cooling
</TD></TR></TBODY></TABLE>
<TABLE border=0 cellSpacing=0 cellPadding=3 width="100%"></TABLE>
<!-- end sl_code here -->ford part# D3TZ-8146-D
2 1/4" deep 28 1/4" wide by 25 1/4" tall
1973-19 2wd f100 f150 standard/extra/super cooling

Thanks for all your suggestions.