L300 Erratic Temperature's

[psychadelica]

Hey everyone,

My 92' Delica's temp gauge can really be all over the place. Driving normally down the street it sits about 1/3 the way up. Any steep hill like the Malahat for example can push it 3/4 the way up to the top. It can even just be a long slight gradient on the highway that will put it just over 1/2 way. Once I start heading back downhill it cools right down again. It never hits the red (or the white line below it) and it does the exact same whether it's -5 outside or +35. I've been watching the coolant and I am not losing any and I don't notice any obvious white smoke. I've been told it may be a failing head as this is a common symptom but I just wanted to check if there are any other possiblities before I drop $3000 on a fix.

The clutch fan has been replaced recently and the waterpump, thermostat, rad-hoses, and reconditioned radiator was done by the previous owner around 30,000km ago.


Thanks!

*fingers crossed*

[thedjjack]

I am interested to know what your piston temperatures are? You could have a fuel/turbo/injector problem 'Tuning" that is pushing the EGT very hot and the system just cannot cool it? Not sure how much faith I have in the stock gauges as well.

I would add a EGT gauge, Flush the cooling system, and replace the thermostat (I have had trouble with thermostats that are brand new on other motors). I also always drill a little hole in my thermostats to allow air to bleed past them.

[thelazygreenfox]

Psydeli
If you really must change a part try replacing the sending unit for the temp guage. Otherwise just enjoy driving your delica.

If you search a bit you'll find mentions of the same situations as yours. Don't worry be happy!! It's a big chunk of cast iron and aluminum and driving up and down hills will affect it that way. I owned an L300 for a while and loved it.

You can attach a thermocouple temp probe to the top of the block and read out the temp on a guage beside you to verify the dash reading.

All diesel engines have temp swings and it relates directly to the amount of fuel you push into the engine.
Enjoy
Wayne

[mararmeisto]

I would change the temperature sensor on the engine block. The two wires go two different places: one to the ECU to adjust glow plug circuit timing; one to the dash to show water temperature. If the gauge on the dash is jumping around, it could be a symptom of a broken sensor.

[jessef]

Careful driving up hills like the Malahat with your L300.

If pushed too hard, the head will crack.

Like other said, an EGT (pyrometer) gauge will give you the true reading you need when tackling long/steep hills. That will dictate whether or not you're pushing it too hard and when to back off on the throttle.

The stock gauge is all over the place.

[deli1733]

if your temp gauge is going up to 3/4 then you have a problem the stock gauge doesnt go all over the place. I'd change your thermostat again.

[Firesong]

One thing which isn't too crazy to check is your coolant hoses for the crap/caking inside them.
Might mean your rad is plugged etc.
Some of these are pretty yucky inside.

Could make a mess of the thermostat if you put a new one in.
Could also explain how doing some smaller or medium size things can make a huge
difference in the temp.

Pull off the hoses and look.

FS

[jessef]

Driving normally down the street it sits about 1/3 the way up. Any steep hill like the Malahat for example can push it 3/4 the way up to the top. It can even just be a long slight gradient on the highway that will put it just over 1/2 way.

if your temp gauge is going up to 3/4 then you have a problem the stock gauge doesnt go all over the place. I'd change your thermostat again.

3/4 on your stock temp gauge lugging up the Malahat is normal. Just like lugging up the Coq or any of the nice passes we have in BC.

1/2 or just above 1/2 cruising on the highway is normal operating temp.

1/3 to 1/2 normal street driving is normal.

The reason say the stock gauge is all over the place is because it is not the most accurate of gauges.

For the average L300, it sits just below 1/2 for most normal driving conditions but can vary from one to another.

I've had four L300's all of which have had the entire cooling system re-done (New rad, hoses, thermostat, waterpump, flush) and all four give slightly different 'visual' readings in the same spots going the same speed/rpm.

By the time the stock gauge hits the red or close to it, the possibility of cooking the turbo/head can be high. There have been close to a dozen cracked 2.5 heads in the past year since the summer due to a combination of the driver driving it too hard up hills 'lugging' (low rpm/high throttle) and not proper functioning cooling systems.

There is a post/thread like this every month where either someone isn't sure about the temp gauge or it's already caused damage to the engine.

Bottom line.

Make sure your cooling system is good and don't take someone's word for it unless it is a trustworthy source.

If you want to monitor the heat of your engine, a pyrometer is a good addition to the stock coolant gauge.

Here's a few informative posts :

http://www.delica.ca/forum/overheating- ... -5575.html

http://www.delica.ca/forum/pyro-gauge-w ... -5819.html

http://www.delica.ca/forum/am-i-pushing ... -6643.html

http://www.delica.ca/forum/timing-belt- ... -9501.html

http://www.delica.ca/forum/new-head-or- ... -7309.html

http://www.delica.ca/forum/engine-temp- ... -6991.html

http://www.delica.ca/forum/overheating-3151.html

http://www.delica.ca/forum/overheating- ... -3437.html

http://www.delica.ca/forum/how-hot-is-hot-3282.html

[deli1733]

Thats weird my temp gauge has never gone above 1/3 on the malahat or anywhere.

[thedjjack]

Is the radiator full? An air bubble in the system will give erratic temperature readings.

I have rebuilt my cooling system and it never goes over 1/2. This was even driving in California on some step grades. (also a 5 speed so no automatic to cool as well as the engine).

I would think erratic temperature is indication of a problem that results in cracked heads rather then an early symptom of a head cracking.

Tips for big grades:
TURN OFF AIR-CONDITIONERS
If you have to turn the heat on full and open windows (heaters add cooling, do this in the summer).
Slow down over pushing hard.
Higher revs (lower gear).

[CVI]

i would check the basics first....is your rad full of coolant? Is the coolant reservoir full as well? What is the condition of your rad cap...make sure the rubber seal isn't cracked up. Sudden temperature surges might just mean you are low on coolant.

[psychadelica]

Hey guys, thanks for the tips.

As for your questions, yes, the coolant level is fine. Rad and overflow tank are topped up and not losing coolant. Hoses are fine and were replaced not to long ago. Radiator, waterpump, and thermostat replaced 30k ago. Clutch fan replaced recently as well. Rad cap appears new - no cracking of the rubber etc.

If it was a thermostat issue wouldn't that cause it to either not heat-up or instead overheat but not both?

I'm not pushing it too hard up hills either. It seems to act like this no matter the variables. 1 person or 7 people, -5 C or +40 C. It also doesn't have to be a hill as big as the Malahat either. It could get that hot quite quickly on a steep hill of 2kms or so. I notice a difference if I'm just going up some of the hills on the way out to Port Renfrew. In 15-20 seconds or so of going up a hill it starts to heat up more and more. I drove it to Salmo and back to Victoria with 4 passengers in the hot summer over the mountain passes and it acted just the same. Never would hit the red but did get pretty close to the white line. Driving back from Courtney to Victoria it climbed to about 2/3 the way at some points with just me in it. It's been doing it since about July 2010 and I don't seem to remember it doing that before when I bought it in around April 2010.

From others I hear that the temp gauge is supposed change very little. I'm driving a lender one right now while mine is in shop having other work done and taking it over the Malahat the needle doesn't even move from the 1/4 mark.

The shop starting to see these these symptoms more and more and it's almost always turning out to be a cracked head. Shouldn't I be losing coolant though?

[psychadelica]

Temp sensor has been changed and gauge is still showing crazy temps. Looking at the head next week at this point I think.

[jessef]

If you're not blowing white smoke and not loosing coolant, then you're probably fine.

Like I said, some of the L300's I've driven with the whole cooling system replaced are doing the same thing you're stock temp gauge is doing.

[deli1733]

Maybe the head gasket is just on its way out, i had a car that showed these symptoms. Isn't it true that you could have a blown head and not loose coolant if the head is cracked away from the water jacket?