overheating p38 diesel

[paddocks1967]

has anybody had any dealings with a eratic temp gauge mine is bouncing all over the place going from 12 oclock 2 three quarters then back 2 12 oclock then into the red then back to 12oclock checked hoses seem fine not losing any water ghanged water pump and viscous fan starting 2 get p d off any help anybody

 

[Sean]

how quickly does the guage do that ?

 

[paddocks1967]

Hi Sean,

could be driving for half an hour then the gauge starts going up and down past the 12 o clock mark. even if it settles for a while at the 12 mark it keeps bouncing back up and down for the rest of the journey!

pat

 

[Sean]

that's be the guage at fault then unless you have some form of super heater and cooler than is able to heat up or cool things that quick

 

[wills]

Hi Sean,

could be driving for half an hour then the gauge starts going up and down past the 12 o clock mark. even if it settles for a while at the 12 mark it keeps bouncing back up and down for the rest of the journey!

pat

So it's moving quickly up and down then, too quick to actually be the at the temps shown?? Does the coolant temp sensor have one wire or two wires going to it AND has it been changed recently?? If its been changed can you see any signs of white tape around it, like plumbers PTFE tape stuff??

-Wills

 

[paddocks1967]

there are two wires on the sensor ,have been cut and rejoined dont know when had the cylinder head gasket renewed in october skimmed and presure tested dont know if they cut wires when stripping engine

 

[wills]

Well, it could be quite a few things I guess, number one thing I would suspect is the re-joined wires, how has this been done?? Butt connectors or what??

On vehicles before a certain VIN there was a single wire coolant temp sensor that had an earth via the head itself, this was later changed to a double wire temp sensor with its own dedicated earth due to the symptoms you are describing.

I would double check the connections on the joined wires, I bet one of the wires has a dodgy join or something.

Also, I take it you have confirmed no overheating is present using a infra-red thermometer?? Are your rad hoses rock hard or soft after a journey when the needle starts bouncing around??

Lastly, please use at least SOME punctuation in your replies, your posts have been very difficult to read, its like one long sentence with everything all bundled in!

-Wills

 

[Sean]

Lastly, please use at least SOME punctuation in your replies, your posts have been very difficult to read, its like one long sentence with everything all bundled in!

-Wills

you posh boys are a bit fussy

 

[paddocks1967]

no, hoses are not rock hard,after journey hoses have pressure,but can still squeeze them the wires are connected by butt connecters.

 

[wills]

no, hoses are not rock hard,after journey hoses have pressure,but can still squeeze them the wires are connected by butt connecters.

hmmmm, I would suggest removing the butt connectors and re-splicing the wires properly using solder and heatshrink tubing to start with.

Once the vehicle is up to temp, if you sit idling does the temp gauge start creeping up and up or not??

-Wills

 

[paddocks1967]

even when idleing,needle still moves up and down,but not as much.

 

[wills]

So while sitting still the temp will climb but also come down as well?? Does it change temp with differing electrical loads, i.e. when the A/C compressor engages??

Have you re-done the connection yet??

-Wills

 

[mikeateves]

I've noticed recently that the temp guage on my '96 P38 diesel tends to fluctuate quite a bit but only when warming up. Once up to temperature it sits at 12 o'clock. I suspect mine is the early single wire variety but will have to check. Maybe its a symptom the sensor is on the way out - or just a poor earth connection.
mikeataves

 

[paddocks1967]

HI, I definatley think the problem is with sensor or the wires,went a long drive 2day gauge going right into the red when going up steep hills once at top needle goes from red to 12 oclock in matter of seconds, jumped out checked hoses,water,fan belt everything fine,done this about 6 times throughout the drive, so i think it must sensor