Engine Temp gauge fluctuations

[texcl]

So my 93' 7.3 F-250 has always had a jumpy temp gauge whan pulling a load. this last weekend I was pulling a 7k# travel trailer and noticed on the way down that the temp would go from the n to the o back and forth. when going up hill it would go to as high as the r but never crossed the half way mark on the gauge. Is this normal or do I have a bad thermostat or sending unit?

 

[no mufflers]

I would just put in an aftermarket temp gauge and save your worries. my 91 did the same thing, I tried several things to fix it and it ended up fixing it self. if its bouncing around quickly then its not the thermostat. all the temp sending units are before the thermostat.

 

[texcl]

ok good point. It doesnt use coolant and will have a little pressure in the radiator even after sitting for days, so I assume there are no block leaks. Where should my temp gauge be when pulling a load and are there any easy to install accurate temp units out there?

 

[HS108]

Normal for a stock guage, mine would be all over the place in the Hills of PA when I was hauling my jeep.

I have a new Isspro Temp gauge in my basement waiting to go in, just gotta get time.

There are plenty of different ones out there, from 20 to 100+ bucks. Just do a google search for one with good reviews and that fits your budget.

 

[no mufflers]

I have several gauges, all are auto meter short sweep electric. I put the sending on the thermostat housing. its cast but I had no problems drilling and tapping it.

 

[texcl]

what about installing an adapter toi the top radiator hose to accept the temp sender, would this be an accurate spot once the thermostat is open?

 

[whiteboyslo]

what about installing an adapter toi the top radiator hose to accept the temp sender, would this be an accurate spot once the thermostat is open?

Should be, but another option that many of us use (myself included) is to install it where the 'OVERTEMP' switch is. There are two coolant temp sensors/switches in the system. One controls your gauge, the other turns on the 'CHECK ENGINE' light if you start running too hot. Use the second one. You technically lose the 'CHECK ENGINE' light for overheating situations, of course, but if you have a gauge, that shouldn't be an issue. The sensor you want to replace is at the very front of the driver's side cylinder head.

Mike

 

[no mufflers]

you would probably get an accurate reading but I'm not sure that would be the best way to do it. you could take out one of the factory sending units and use that hole. you would loose the temp gauge in the dash.

^^^he beat me to it

 

[texcl]

I though the sender on the front drivers side was the actual temp gauge sending unit? it was really acting up today when I moved my 27' travel trailer. I need to pull a 7k# trailer in about a week so I think I'll go ahead and order the thermostat parts just in case and the after market temp gauge. what size adapter do I need to replace the water temp alarm sending unit?

 

[whiteboyslo]

I though the sender on the front drivers side was the actual temp gauge sending unit? it was really acting up today when I moved my 27' travel trailer. I need to pull a 7k# trailer in about a week so I think I'll go ahead and order the thermostat parts just in case and the after market temp gauge. what size adapter do I need to replace the water temp alarm sending unit?

The two sensors are in close proximity to one another (actually connect on the same harness IIRC), but the one in the head is the sensor for the CHECK ENGINE light.

My computer won't let me post a direct link, but if you Google 'idi temp sensor' and look at the first pic (red engine), it will show the two sensors I'm talking about. Not sure on the fitting size, but my gauge came with additional fittings. I think most do.

Mike

 

[FORDF250HDXLT]

My computer won't let me post a direct link, but if you Google 'idi temp sensor' and look at the first pic (red engine), it will show the two sensors I'm talking about.
Mike

got your six.

You must be registered for see images attach

 

[icanfixall]

The large sender in the drivers side head is the over temp switch. All it does is peg the dash gauge if the coolant reaches 242 degrees. You fluxuating dash gauge might be cause this switch is failing. Easy way to know if remove that wire and run the engine. If the gauge stays nice then your switch is bad. Another easy test it remove the wire and ground it. Now the dash needle will travel way past the L in normal. Can be down on a cool or warm engine. No matter really. This sender is a normally open circuit. It will close at 242 degrees but if its failing it can close and open very fast causing what you see on the dash.

 

[texcl]

good info I'll check that out.

 

[texcl]

so do yall know what size adapter I'll need to replace the temp light switch?

 

[texcl]

one last question, do yall use a mechanical or electric gauge? I'm going with the auto meter, sort of like the mechanical since it should eleminate electrical issues but unsure of accuracy issues ect...