My truck has been running a lil hot lately, needle right around the L. The other day I decided to check the hoses, top radiator hose is hot, bottom is ice cold... Today I went to NAPA and got a thermostat part #THM 385190 ( Store Locator | NAPA Online ), the only one listed, so i figured it was right. When I got home I noticed it has a jiggle pin in it. Is that right? I thought I had heard that it would cause over heating?? Help me out guys, I wana rip into her tomorrow (replaced my power brake booster today) but i only wana do it once. Do I have the right T-stat? Thanks

 

most will tell you to only buy a motorcraft thermostat only.im wondering if the radiator is plugged up though

 

with the lower hose cold,this means the radiator has done its job.
hot coolant in-cold coolant out see.

the stock gauge is 100% worthless.don't put any trust in it whatsoever.
if you want to know your engine temp,you need a real gauge.

motorcraft thermostat part # E5TZ-8575-C its 192* i think it said on it.but most say its 195* here iv noticed.not that,a few degrees matter lol.
also another suitable is the one from international.IDIdieseljohn says its a 180*.
this time of year,the higher the better,that way you get good heat.
plus i think the warmer,the better for fuel economy too actually.
i recall Festus (hey where has he been lately? hope he's ok.) has claimed,the hotter the diesel engine,the better for power to a point/within safe specs.

 

So are you saying there is probably nothing wrong with my t-stat? How much is the Motocraft t-stat? I assume my local dealer will have it in stock.

 

was this with your plow on and going down the road Roy?
mine came up a bit on me too. i forgot to angle it to the side.

 

I still havent put my plow on.

 

hey i thought i was late.i dont feel so bad now.
you guys get hit out there with the fist snow?

it's hard to say really without a real gauge.
it could be the sending unit went out.

did you pop the hood and see any indications that the truck was really overheating?
any steam? foggy windshield? lack of heat from the vents? etc?
how old is the radiator cap? what did the level appear to be in the overflow? pull the cap on that and see if it was steaming like crazy?
if not,and bottom hose is cool,id guess a faulty sending unit/poor ground.
that is of course if you know the rad is not plugged up like rupe mentions.

also,hows your mix? a good 50/50?

 

I did pop the hood, the top hose was hot, but not anything i coldnt hold my hand on... No steam, fogging, good heat... Who knows how old the rad cap is, and my over flow still had some coolant in it, only about an inch up from the bottom (I need to top it off). I was thinking the gauge was bad too but i dont wana mess around with cooling issues. The lower radiator hose is cold not warm but ice cold... I didnt think that was normal. As far as the mix, when I tested it the other day it was mazed out on my meter. So id say its more coolant that water...

I guess for now ill take that thermostat back and get a new gauge sending unit.. Do either of the ones shown in that pic control the fast idle? It will work if I jump from the battery to the solonoid with 12v.. Could it be related?

 

its not related nope.
in order to set the fast idle,you need to turn the key forward,while your waiting for the WTS light,press the accelerator all the way to the floor,let up off it,start the truck once the WTS light goes out.
she'll high idle for ya.

if your coolant was really this high,you'd have known it.
the lower hose is so cold,because we have a monster radiator in these rigs to keep her cool pulling massive loads in the summer.
shes likely to over cool in these low temps.
some people place cardboard to block part of the rad,or buy the grill inserts.try one of those,and at some point,you'll finally feel the lower hose stay a little warm.
but if you have plenty of heat in the cab,i wouldn't bother with that either.
of course the only way to know your temps,is a gauge.otherwise your left in the dark.the stock one,is more of a,,,,,i don't even want to call it a ballpark idea meter,cus there's no way of knowing.

autozone sells a water temp gauge for 40 bucks Roy.
they have one in stock in Waterville:
Auto Meter
Part Number:
2361

i can't believe there's no AZ in Augusta.what the heck.id try the auto stores in town first.likely around the same $.
you'll really want one for plowing.

of course you'll want to add some distilled water for a good 50/50 mix too.
thats really cheap at the grocery store,and will help keep minerals etc out.
if you need to drain some coolant first,then so be it.you want it mixed properly.

 

I plan on getting Oil psi, water temp, and egt gauges eventually. For now i went down to NAPA and got a new gauge sender for my stock gauge. Now its reading within normal levels again. Im still planning on replacing the t-stat with a motorcraft one.

As far as the high idle, it wont set unless I apply 12v to the solonoid itself. What tells the solonoid to turn on? Must be a temp sensor of some sort?

 

Fast idle and timing advance are controlled by a temperature switch down by the thermostat housing.



Easy to pull loose while working on almost anything near the alternator or engine wiring harness in that area.

Watch when you go to put it back on, two spade terminals that are not hard to bend or break if it is not turned right when you push down on the connector.