Engine coolant temperature gauge reading 3/4 hot

[thejaw77]

I have a 96 Discovery 1 SD, 4.0 engine, 93000 that is running hot. This all started when the water pump failed. Here is a list of what I have done?
Water pump (twice)
Fan clutch
Thermostat (failsafe)
Coolant sensor
Sender unit
Radiator flush and flow check (twice)
System pressure test (passed)
Block test (passed)
Serpentine belt and tensioner
Expansion tank cap
I have tried to purge the system of air using every method available for 3 weeks (lifting front end, lifting expansion tank, blowing through heater hoses, loosening connections till coolant flows?to name a few). I?m not losing any coolant. No white exhaust smoke. No coolant leaks. No noise from heater core (hot air to cabin). After 3-5 mins of operation the guage is already at ? hot (under load). After 1 min of operation the intake manifold is too hot to touch (idle). The skinny hose from the radiator to throttle heater plate is very hot after 1-3 min of operation (idle). The transmission oil cooler pipe from the upper radiator corner (below skinny hose) gets very hot also with 3 mins of operation (idle).
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(Could be related) I am getting a P1316 misfire causing excessive emissions, and P0304 misfire. I?m running new 8mm kingsborne wires, +4 plugs and new ignition coils.
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Any ideas?

 

[Roving Beetle]

First idea is to NOT use black as a type color on this forum ..... copy and pasted here:

I have a 96 Discovery 1 SD, 4.0 engine, 93000 that is running hot. This all started when the water pump failed. Here is a list of what I have done…
Water pump (twice)
Fan clutch
Thermostat (failsafe)
Coolant sensor
Sender unit
Radiator flush and flow check (twice)
System pressure test (passed)
Block test (passed)
Serpentine belt and tensioner
Expansion tank cap
I have tried to purge the system of air using every method available for 3 weeks (lifting front end, lifting expansion tank, blowing through heater hoses, loosening connections till coolant flows…to name a few). I’m not losing any coolant. No white exhaust smoke. No coolant leaks. No noise from heater core (hot air to cabin). After 3-5 mins of operation the guage is already at ¾ hot (under load). After 1 min of operation the intake manifold is too hot to touch (idle). The skinny hose from the radiator to throttle heater plate is very hot after 1-3 min of operation (idle). The transmission oil cooler pipe from the upper radiator corner (below skinny hose) gets very hot also with 3 mins of operation (idle).
(Could be related) I am getting a P1316 misfire causing excessive emissions, and P0304 misfire. I’m running new 8mm kingsborne wires, +4 plugs and new ignition coils.
Any ideas…

 

[thejaw77]

Thanks! I noticed that it was difficult to read...but then it was to late. Thanks for correcting it!

 

[fishEH]

On the bright side you're running 1/4 cool.

 

[thejaw77]

Anyone have any experiance with bad sending unit (not "matched" to temp gauge)? Or a temp gauge out of calibration?

 

[SGaynor]

There are 3 settings for the OEM temp gauge:

Cold
OK, and
"Your engine is toast"

It is not an accurate gauage, so 3/4 is meaningless. You will need a proper temp gauge (ie, ScanGuage) to get real coolant temps.

 

[thejaw77]

According to my freeze frame data the coolant temp was 99 degrees c (211 degrees f). The gauge was reading at approx. 230 degree f. Do you know what the temp is when the needle is exactly in the middle...195 degrees f???

 

[thejaw77]

At this point I'm suspecting the temp gauge sending unit or gauge calibration. I bought the sending unit from advance auto. From what I have read they sending unit needs to be a genuine part so it is "matched" to the original gauge. Otherwise the resistance will be incorrect and the guage will read likewise.

 

[DarylJ]

Do you know what the temp is when the needle is exactly in the middle...195 degrees f???

Comparing to live data on mine, dead center is anywhere between about 182 up to around 215 or more.

Think of it as a dummy light. Not a gauge.

 

[SGaynor]

According to my freeze frame data the coolant temp was 99 degrees c (211 degrees f). The gauge was reading at approx. 230 degree f. Do you know what the temp is when the needle is exactly in the middle...195 degrees f???

At this point I'm suspecting the temp gauge sending unit or gauge calibration. I bought the sending unit from advance auto. From what I have read they sending unit needs to be a genuine part so it is "matched" to the original gauge. Otherwise the resistance will be incorrect and the guage will read likewise.

Did you not read what I just wrote?

They are not a true temperature gauge. TDC doesnt mean anything.

 

[mbrummal]

get rid of those plugs. that will probably fix the excessive emissions code. just go with the champion coppers.

 

[Ed Cheung]

Get a new radiator.

 

[thejaw77]

I have changed the plugs 3 different times and two different wires tring to get tid of the misfiring. First had the champion copper, then +4's, then back to champions. The radiator is'nt the issue as it has checked out to be a good radiator. Ii's been flushed twice and flow checked by a radiator shop in town that has been doing radiator for 40+ years. He says it's a great radiator.

 

[Tugela]

If you have eliminated the plugs and the wires as possible sources of the misfire, then if you keep working your way back up the electrical system the next component to check is the coil pack.

 

[thejaw77]

All new ignition coils. Battery measures correct voltage. New alternator. Has anyone had these kinds of issues involving the engine ecu?

 

[Tugela]

All new ignition coils.

Note to self: pay closer attention next time, that was mentioned in the first post.

You've got a good one for the Discoweb edition of Stump the Chumps.

 

[gabriel]

have you checked your fuel pressure?

 

[thejaw77]

I have installed all new fuel injectors, fuel pump and filter. I have not checked the pressure, but I have taken off the hose going from plenum to the pressure regulator and there is no fuel leaking from the regulator.

 

[thejaw77]

If I hold the brake pedal down...then very gently release it just enough for the truck to move slowly forward...but still holding the brake to control forward motion...the truck gerks forward very softly. Is this due to low fuel pressure?

 

[gabriel]

low fuel pressure can cause a lean condition but if you replaced the fuel delivery system then probably not; especially if p0304 stayed before and after. I know you mentioned "system pressure test" above is that the same as compression test? If not, maybe a stuck exhaust valve then on cylinder 4?