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Overheating-'01 F250 7.3L

3K views 22 replies 7 participants last post by  ArcticDriver 
#1 ·
Driving on the highway and noticed my temp guage rising (75mph) so i let off the gas and it would lower back down to normal temp but would occasional rise and lower. Got back to my place thinking it was because of my ac condenser with a majority of the find bent so I removed it but its still overheating at speeds from 45 and up. All fluid levels are fine, no white smoke other that the little at startup, very small oil leak but levels are good, top radiator hose it hot but no pressure, only upgrades are 4in tb mbrp exhaust and ts 6 position chip (i use it on the lowest setting for a little better mpgs), just replaced the water pump and thermostat which is a 203 from thoroughbread diesel, belt is new, hoses are not collapsing and this has been an on and off thing for a few months.
 
#2 ·
You can have your degas cap pressure tested and replace it if less than the rated psi, a low pressure release cap will drop your boiling point. Can you confirm that the 203 degree thermostat is opening and the upper hose is getting flow.
 
#4 ·
We looked over a few things. Hoses, thermostat, if it was clogged and nothing. Went for a test drive and it spiked around 70 mph at a qtr mile distance then went back down to normal temp. On my way back it operated at normal temp, even got her up to 85mph to make sure and nothing, no spike at all in temp. Could it be slight clogging?
 
#5 ·
Where did you get the 203? Is it a modified long stem or a stock 203 short stem? The modified shave a high failure rate. The short will cause overheating in our trucks. Radiator internal blockage is high on my list if the thermostat is ok.
 
#7 ·
I don't know if they've changed the manufacturing, but there were an awful lot of problems when that one first came out. I'd put the old one back in.
 
#10 ·
Test that 203 stat you took out in a pot of boiling water and see at what temp it opens.
 
#12 ·
If you purchased our long stem 203° Thermostat (even through a dealer), here is some information in regards to the breather hole:

Question: Does your thermostat have a way to bleed air from behind the valve?

Answer: Yes. There is a small calibrated "V" notch cut into the side of the disc for air bleeding. Do not drill a hole in the disc as this can change the opening temperature of the thermostat. Our thermostats went through extensive durability and flow testing to make sure they were perfect.

In regards to your issue, do you have any actual temp readings for your oil or coolant or just the gauge on the dash right now?
 
#14 ·
The main thing that gets me about it overheating is it's completely random as for one day driving down the highway it will be fine but let's say I drive the same way/speed limit the next it could have a temp issue. If it happens again I'll try to record it and show you on YouTube.
 
#15 ·
Is the gauge your only indication of overheating? If so it could be the gauge or sending unit.
 
#18 ·
The t-stat is rated for the temperature it begins to open and should fully open approximately 10* above that rated temperature so like you said, it tested "good".

A couple of things to watch for when you heat it in water:

1) Make sure it is fully submerged.
2) Don't let it make contact with the bottom of the pan.
3) Increase temperature of water at a slow rate.

You might consider buying a ScanGauge-II because it will also provide you EOT (engine oil temp) and several other useful reading like TFT (trans fluid temp) and its only about $140 on the Advance Auto website once you include the 15% or 20% Discount at check-out.
 
#20 ·
Arctic thanks for the advice and i had my buddy test it because I don't have the right tester and he said it is working properly. Update- there has been no overheating since I replaced the tstat so i think it was just bad luck with the other tstat. I'm installing an egt, trans and boost guage tomorrow along with replacing my up pipes that connect to the y pipe. I still need a eot guage which i will get next payday. I went to the local stores for a laser temp reader and they were all sold out but i called today and they have one so I'm running in after work so hopefully they're still open.
 
#21 ·
Did you replace the degas cap? If you did not, I bet that is where your problem is.
 
#23 ·
The newer version spring is actually a larger diameter spring as well for the very reason you mentioned.
 
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