2.8l running hot

[78shane]

Hi guys my 2.8l has started to run hot, not overheating just sitting under half way when it has always sat just above cold, ok so here is the story, on the weekend I ran out of diesel, i know stupid but anyhow got fuel still running like dream, but i have had this annoying leak for quite some time now so decided to remove all bash plates and spray with degreaser so i could get a better look did this started her up and immediately started weepi g from behind harmonic balancer, ok so now i know where leak is decided to leavr bash plates off tilk i have time to fix and now its running hot the only ever time it has ever run this hot is when towing the boat up long hills, could the bash plates off be causing this as i would have thought it have more air or should i try a radiator flush

[TimTams]

gauge should be sitting half way... if not, either the gauge or sender (usually sender) is faulty and it's probably not running hot at all. I'd sort that out first. Mine sits about a mm under half way at all times

[78shane]

I dont know the gauge has seemed to work since i have had the car could it be that running out of fuel has caused shit to block the injectors and now its running lean

[bilgeboy]

gauge should be sitting half way... if not, either the gauge or sender (usually sender) is faulty and it's probably not running hot at all. I'd sort that out first. Mine sits about a mm under half way at all times

X2 and I'm on my second motor.

[TimTams]

I dont know the gauge has seemed to work since i have had the car could it be that running out of fuel has caused shit to block the injectors and now its running lean

i would be confirming 100% whether your engine is actually running hot or not. If it was overheating, it probably would have stopped due to a cracked head. Ten bucks says your gauge has been playing up, or your thermostat was stuck open. Mine sits a mm or two below the centre normally and never moves from that spot

if the injectors were blocked it would manifest as a miss or hesitation. diesels can't run lean, less fuel just equals less power

[78shane]

Ok cool maybe i have unstuck the sensor while cleaning ill keep an eye on it

[pharb]

I dont know the gauge has seemed to work since i have had the car could it be that running out of fuel has caused shit to block the injectors and now its running lean

Diesels run cooler when lean, hot when overfueled. Although that is a very simplistic statement. They are an excess air motor, meaning the engine will always take in as much air as it physically can and the engine's output is regulated by varying the available fuel. At light throttle the engine runs lean, at full throttle the engine runs rich.

A petrol engine's output is controlled by regulating the amount of air entering the engine by manipulating the throttle butterfly. The ecm then measures airflow or volume and injects a suitable amount of fuel to keep the air/fuel ratio right.

My old 4m40 NJ always sat with temp needle just below horizontal, except for onece when I saw it heading upwards very quickly. By the time I had pulled up it had pumped a heap of coolant out. A bit more to the story but that is the only time it has varied in nearly 500,000km.

[als008]

Like TIMTAMS said.... mine also sits just under the Half mark. Ive never seen it go over that.

[ThunderPie]

one reason for overheating could be a clocked waterpump if water and not a proper cooling fluid was been used.

also rust clocks up the radiator and the therostat over time when water was used.

flushing the radiator with lots of fresh water and replace water pump plus thermostat might fix that problem.

I had the same issue on my last motor, ended up with a blown head during towing a boat

now the temp gauge is always in the middle and my madman moniter says water temp. 74deg most of he time.

I also changed to a large front mount intercooler which helps a lot to keep the engine temp. down
EGT is mostly 360deg C on standard fuel pump setting.

intake temp. of the air after intercooler is below 80deg C.
I alway can touch the pipe which goes into the intake manifold even after a long ride with my bare hand.

[erad]

The bash plate comes in 2 pieces. The front piece covers as far as the radiator. By removing this piece, you are allowing the fan to short circuit and draw air from under the car instead of pulling it through the radiator core. Put that plate back on and you should be OK, providing nothing else is failing eg the viscous clutch in the fan couplling or some blockage in the cooling system innards.

[Martynhpajero]

The bash plate comes in 2 pieces. The front piece covers as far as the radiator. By removing this piece, you are allowing the fan to short circuit and draw air from under the car instead of pulling it through the radiator core. Put that plate back on and you should be OK, providing nothing else is failing eg the viscous clutch in the fan couplling or some blockage in the cooling system innards.

Yep. Just worked that out on my NL 2.8. Mine was also missing the plastic fill-in panel directly under the radiator. Made one from aluminium sheet and made a big difference.

Sent from my SM-G906K using Tapatalk

[erad]

i would be confirming 100% whether your engine is actually running hot or not. If it was overheating, it probably would have stopped due to a cracked head. Ten bucks says your gauge has been playing up, or your thermostat was stuck open. Mine sits a mm or two below the centre normally and never moves from that spot

if the injectors were blocked it would manifest as a miss or hesitation. diesels can't run lean, less fuel just equals less power

Two things:
1 "Your thermostat is stuck open" If this was the case, the engine would run cold. Sadly, when thermostats fail, they tend to fail in the closed position, causing overheating.

2 "diesels can't run lean, less fuel just equals less power" This is how diesels operate. They suck in a gurfull of air every stroke and squirt in the amount of fuel that your right foot tells the engine to deliver. Little or no power, - minimal fuel injected. Maximum power, as much as the pump can deliver.The air/fuel ratio varies enormously, unlike petrol engines which require fairly precise mixtures in order for the engine to fire at all. The ideal ratio for petrol is something like 14.7:1, whereas diesels can go up to 200:1. If you squirt too much fuel in, you get black smoke coming out the exhaust - this is unburnt fuel.


78Shane said: "Ok cool maybe i have unstuck the sensor while cleaning ill keep an eye on it". Temperature gauges are actually a small ampmeter, with the temperature sensor varying its resistance as the temperature changes. The hotter it gets, the lower the resistance. If the gauge connection was dirty (or even not connected at all), the gauge would be reading low because the current in the circuit would be low or not at all. The only way a temperature gauge can mis-read high is if there is a short circuit in the wiring somewhere.

There are basically 3 reasons for overheating:
1 Not enough cooling air going through the radiator core - slipping viscous clutch, fan belt or air bypassing the fan.
2 Thermostat not opening at all or not enough
3 Blocked inner cooling water passages.

[bilgeboy]

Not sure if its the case with modern cars, but a stuck open thermostat can cause overheating also. the water doesnt hang around long enough in the radiator long enough to cool, and the water gradually heats up. I had an old falcon that I killed out of sheer hubris because I thought the gauge was broken after I removed the thermostat.... was sure the science in my head was correct....

[erad]

That is wrong. The faster the water can flow through the radiator, the more heat can be extracted. Probably what was happening with your Falcon was that removing the thermostat allowed more water to flow through the system, dislodging rust particles which blocked the radiator.

[78shane]

Cheers for all this info guys i am now at the stage where i have put a new 3 core radiator and a new thermostat in it and it is still overheating eg. My temp guage reads half way and making the trumpet sound as it sends coolant into the reservoir so no difference i now need to check the fan clutch and i have not put the plates back on only as its been easier to work on with them off but if this is the case and it will keep cooler with them on i will put back on, is there anything else i need to be looking at i dont want to buy a new head only to find out it is something else much cheaper and easier. Once again thanks for all the info