A little help please. I have a 1990 F250 that is getting hotin the afternoon. I changed out the T-stat with a Ford one a month ago. Whiledriving in to work, about 33 miles I am running at 1/3 to ½ on the factory gauge.On my trip home, after about 12 miles it starts to get hot up to the top of theL. The rest of the trip home it stays on the L. I generally drive between70&75mph the entire trip. If I slow down to 55 or jump off the freeway thetemp will drop down to the A. The truck has over 320K on it currently. I livein Phoenix so it is going to get hot here soon – Sunday should be 108+. Lastyear I changed the hoses & flushed the radiator. The water pump looks to benewer? I have owned the truck for the last 4 years and put 30k on it. Is ittime for a new radiator?

I also own a 2000 F350 7.3 dually 4x4 and just picked up a1992 F350 idi 4x4. Just sold a 1994 F250 idi 4x4 – I just love the old diesels.Got rid of my 2005 Excursion 6.0 – hated not being able to work on it easily J

 

The gauges in these old Fords are known to be less than accurate. You might try changing the temp sensor. There are 2, the one in the drivers side head is for the overheat light in the dash.The one for the gauge is in the block IIRR. Although with 320K, the radiator could be getting blocked if the previous owner neglected the coolant, or used water that had lots of minerals.

 

The water in Phoenix is very very hard. The buildup on our swamp coolers is bad. The well water for our golf courses is very salty too. The part that concerns me is that the guage is great in the am but not the afternoon.

 

i used to be real worried about mine doing the same thing, then i added an aftermarket temp gage. i found it was always at 195-200, unless climbing a long hill under heavy throttle at low speed, then it would start to crawl up.
i suspect that if you buy an aftermarket temp gage, you'll find out that you aren't really getting too hot. in any case you'll have confidence in what its reading

 

Im with Josh,it sounds as if the temp sensor is being effected by under hood radiant temps rather than providing an accurate engine cooling temp.
the clue to a failing temp sending unit: "the guage is great in the am but not the afternoon."
try at least swapping that out as suggested or best yet as also suggested swap to an aftermarket mechanical temp gauge for a true accurate,regardless of under hood temp readings.
once you have an accurate coolant temp,you can go from there.

 

I installed one of these in my truck: http://www.ebay.com/itm/BRAND-NEW-2-52mm-RED-DIGITAL-WATER-TEMP-TEMPERATURE-GAUGE-FOR-CAR-MOTOR-/300744135953?pt=Motors_Car_Truck_Parts_Accessories&hash=item4605bf5511&vxp=mtrEasy to install, accurate(enough), consistant and nice. Only downside is it doesn't read under 104F, so you can't watch the temps climb when it's cold, but once it gets above that point it responds fine.

 

X3 or 4, put a real gauge on it, you'll never look back! And you can add one, and still keep the dash one working.


Just install the sender in the temp light sensor hole, your overheat light will no longer work, but by the time that thing would even light up, it be to late anyways, so it's useless, and with a real gauge, theres no reason you would get to the point of overheating....



And I personally like the Sunpro, it's chrome, works great, and very easy to read at a quick glance compared to the Equuis I have in the motorhome.




What's funny to, is notice what the dash gauge reads in my van here, and i'm running on 192*, in the motorhome, the dash reads right in the middle or higher all the time, and it only runs around 180-190.

That proves it right there those gauges are garbage.

 

sunpro seems to be ok for mechanical gages, but i've found their electric ones to be horribly inaccurate. john has a mechanical one, so its fine, but if you choose an electric gage, you'll want to spend a little more for better quality

 

Thanks for the advice - I like the 104 guage especially when it gets as hot as 122 here in Phoenix - It will be 110 in a couple weeks if not a couple days -

 

Hi I just bought my first 1990 F350 7.3 IDI diesel it ran hot pulled thermostat out to get it home but it still ran hot with the thermostat out what could be the problem

 

]Hi I just bought my first 1990 F350 7.3 IDI diesel it ran hot pulled thermostat out to get it home but it still ran hot with the thermostat out what could be the problem?

 

They will overheat without a thermostat, the water moves too fast through the cooling system to be efficient. Secondly, the fault was likely not with the thermostat but probably a clogged radiator or bad water pump. Youve given no details as to conditions when it got hot, how fast it got hot etc. I suggest you start a new thread and give as detailed description of what was going on as you can.

 

The truck has set for 18 years I replace the glow plugs all gas lines all brake lines drain all the fluids out put all new fluids in drove it maybe 10 minutes when it ran hot when I took thermostat out I drove it for maybe 20 minutes before it overheated again just tried flushing out the radiator in a bunch of muck came out of it

 

I... can't see any logic in that.
There's no way that not having a thermostat could do anything but keep the engine really cold.

 

The theory is the water just moves through the radiator too fast to effectively cool it enough before it re-enters the engine. I cant think it out either but i know it to be true first hand. The 302 in my ranger overheated, like instantly one day, i pulled the t-stat and drove out to the valley. About every 20-30 minutes i would have to let it cool off because it would just keep climbing. This was fall so not that warm even low 90s.

Sounds like you figured out your problem. If there is oil in the coolant it will cause overheating as well, can happen if the oil cooler goes gunny bag.