Overheating L300 diagnosis?

sck_nogas

sck_nogas

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Staff member
This morning, was going to drive out to the desert to go hiking with friends... My L300 had been sitting for days, and had not noticed any issues. She started up just fine in the cool 50F degree morning, and I began to drive. Within 10-12 minutes, I was already at 210F+ and climbing. Since, I was meeting friends in 10 more miles, I kept an eye on things and kept the temperature below 230F. Stopping at the gas station, I checked my overflow, and it had green radiator fluid in it, was not blowing white smoke... I did a visual inspection of my fan and it was spinning quickly. Confused, I added some water to the overflow tank to bring it up to the "MAX" level and then left my Delica at the Park & Ride. 6 hours later, I got back to the park and ride and checked things out...
  • Radiator has healthy looking green fluid at the top of the fins
  • Overflow tank has minimal fluid in the tank
  • Fan coupling didn't feel "too" bad (have a replacement from https://delicapartsusa.com )
  • No broken fan blades
  • No leaks seen from the radiator
  • No fins damaged or blocked
  • Oil was dark and black
So, I'm thinking it could be
  1. Faulty thermostat, staying closed and causing the engine to heat up. Can pull the thermostat and do a water pan temperature test fairly easily...
  2. Faulty water pump, but not seized, since wouldn't that cause the fan to not spin?
  3. Air in the system, but it would have worked up to the radiator by now, IMHO...
  4. Something blocking the flow of coolant (somewhere) [thus a flush and fill can remediate]
Any other suggestions? How can I check the water pump for functionality?
 
How is the radiator cap? Any gurgling when parked after being driven? I always checked water pumps the crude way, pull a hose and start engine real quick and observe flow. Can also check if radiator is plugged with dirt within the fins. I like to hose mine out every once in awhile.
 
DustAngel said:
How is the radiator cap? Any gurgling when parked after being driven? I always checked water pumps the crude way, pull a hose and start engine real quick and observe flow. Can also check if radiator is plugged with dirt within the fins. I like to hose mine out every once in awhile.
Click to expand...
Radiator cap is tight. It's the one that came with my DelicaWorks Aluminum radiator.

Yes, it gurgled when I drove it this morning.

Did not think about watching the flow... That's brilliant! (and messy!)

As for washing the radiator out, I'll check that as I've driven it through both Death Valley and Mohave in the past 3 months.
 
Although radiator cap can be tight, does it maintain proper pressure? I have a tool that tests this. Check the rubber seal on cap and spring to be sure.

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You state that the overflow tank "has minimal fluid in it" after sitting and you had just filled it to the max line (hot)... that probably means it pulled more coolant back in than it should have normally (the tank should have fluid above the min line when cool).
And you also state that the coolant in the radiator is "at the top of the fins"... the top chamber should be full and the level should be well above the fins; that sounds like it wasn't able to get enough coolant from the expansion tank.

All of this makes me think the coolant level was quite low; probably due to a leak... water pump front seals are known to leak just sitting/cold when they first start going bad.
 
All good points here. Let the van cool off completely and then check the radiator and make sure it's completely topped off with coolant. Also check the overflow for proper level. Start the van and let it run for 20 seconds and then shut it off. Remove the radiator cap slowly and observe any escaping pressure. Is there any? This is an important step in the diagnosis. Close the cap and start the van back up. Let it run for 10 minutes. Check for proper heat from the front and rear air conditioning. Air can get trapped in these systems if the coolant drops too low which will cause all kinds of issues. A stuck thermostat is most likely at this point but a failing head gasket will also begin by rising coolant temps. Keep us posted!

K
 
Along the Thermostat issue, since I have a D4BF, I was looking for right size with a lower opening temperature

The stock Hyundai 2551042100 82.0° C thermostat which has the following specifications,
  • 56mm outer diameter
  • 28mm Diameter 1
  • 44m fitting depth
  • 70mm height
There is an Ashika 38-0H-H10 76.5° C thermostat option, but that's harder to find/get in the States

However, in looking at the "other" vehicles in the RIDEX version of the thermostat, it seems that this is used across vehicles and thus

There is a Mitsubishi ME191593 76.5° C thermostat for Pajero/Monteros with the same specifications.
  • 56mm outer diameter
  • 29mm Diameter 1
  • 44m height
So, is that a decent option? Any thoughts?
 
sk66 said:
you also state that the coolant in the radiator is "at the top of the fins"... the top chamber should be full and the level should be well above the fins; that sounds like it wasn't able to get enough coolant from the expansion tank.
Click to expand...
^this. The radiator should be full up to the radiator cap, there should be no air in the radiator at all. If there's air in the radiator, you're losing coolant somewhere.

If it's being pushed out the expansion tank (try putting a rag under the tank's overflow hose to detect this), you likely have severe overheating or a head gasket leak (engine pressure pushing too much coolant into the expansion tank, which overflows)

If the expansion tank isn't overflowing but the level drops lower and lower every time the engine cools, you're losing coolant to a leak somewhere. Fingers crossed for this option.

Option 5: air leak in the hose connecting the radiator neck and expansion tank? On cooldown that might suck air into the radiator rather than coolant from the expansion tank, which could slowly lower the level of coolant in the radiator.
 
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Well, I got a package from Germany....
thermostat - 2.jpeg​
And


So, I pull the thermostat and go to install the new one, but...
thermostat - 5.jpeg​
Web site says it should be 43mm high. But...
thermostat2 - 1.jpeg​
Seems a bit short
thermostat2 - 2.jpeg​
That won't actuate the bypass valve on the thermostat, so that won't work. So, let me do a boil test of my old thermostat to see if that works. Well, it starts opening around 179F/82C (what it's rated for) and at 195F/90C, it appears wide open.
thermostat - 4.jpeg​
Okay, so old thermostat seems viable. But, I'm still overheating? Let's replace the radiator cap? Found that the Murray 7513 radiator cap fits the DelicaWorks aluminum radiator. Still no good...

Here's a thermal video (thanks @InstrumentOfPeace for bringing it back!) of the engine at temperature
So, next up is look at/replace the water pump. Since the bottom hose is ice cold, when the engine coolant is at 200F and the top hose is at 150F, and the thermostat seems to open at the correct temperatures....So, if no pump, then no coolant flow.

Thoughts?
 
sck_nogas said:
Thoughts?
Click to expand...
Disconnect the top hose at the radiator and see how much flow there is. If/when the thermostat opens (or it's not installed) you should get a decent amount of coolant pouring out. If the thermostat is installed you'll get a bit of expansion flow as it warms up (or warm it up with hose connected first), but you'll know when it opens if the pump is working. If thermostat isn't installed then it should be immediate.

Edit: video shows cold radiator core and hot(er) top/bottom hoses? That sounds like bad water pump to me (or blocked radiator; but new/upgraded right?). Radiator temp should be hottest at top and graduate towards the bottom.
 
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sk66 said:
Disconnect the top hose at the radiator and see how much flow there is. If/when the thermostat opens (or it's not installed) you should get a decent amount of coolant pouring out. If the thermostat is installed you'll get a bit of expansion flow as it warms up (or warm it up with hose connected first), but you'll know when it opens if the pump is working. If thermostat isn't installed then it should be immediate.

Edit: video shows cold radiator core and hot(er) top/bottom hoses? That sounds like bad water pump to me (or blocked radiator; but new/upgraded right?). Radiator temp should be hottest at top and graduate towards the bottom.
Click to expand...
Trying to avoid pouring gallons of coolant all over my engine bay and driveway. :)

Video shows...
  • Engine running for 5-6 minutes with a bunch of higher revs (2,000-2,500) to get up to temperature faster
  • Coolant Temperature at 200F according to sensor mounted at AC cut off switch in engine
  • Hot (>150F) upper hose
  • Cold (<80F) lower hose
  • Top of Radiator near upper hose (~140F)
  • Top of Radiator away from upper hose (~100F)
  • Temperature coming out of front cabin heater is low (<85F)
  • Temperature coming out of rear cabin heater is lower (<80F)
So, there is a definite lack of coolant movement. So, blocked radiator (but it's <2 years old) is a possibility. Water pump is on it's way, I ordered it as a fail safe from Amazon 2 weeks ago.
 
As a lower temperature thermostat update. I ordered and received a FACET 7.8403 thermostat from Amazon...
thermo - 1.jpeg​
AND it's the correct depth!
thermo - 2.jpeg​
So, when I next darin the coolant and tear apart the thermostat area, I'll swap in the lower temperature one.
 
sck_nogas said:
So, when I next darin the coolant and tear apart the thermostat area, I'll swap in the lower temperature one.
Click to expand...
It won't really make any difference on the max engine operating temp... it opens earlier, so the engine is a little less warmed up before coolant begins to circulate, and a little cooler when it reaches max flow... ~ 10*f cooler.
And I don't understand why the cooler spec'd thermostat is for engines w/ turbo... what does a turbo have to do with it?

But that is what is spec'd for the engine; so that's what I would put in it as well (assuming I could easily enough).
 
Growlerbearnz said:
I assume it's to give the cooling system a little more headroom: a turbo'd engine can generate a lot more heat very quickly, but the cooling system takes a while to react.
Click to expand...
But more air also means lower EGT's ;) ...
I get it; more "performance"/"power" (try not to laugh) means more heat... but it would make more sense to me if the turbo was water cooled.
 
Growlerbearnz said:
If it's being pushed out the expansion tank (try putting a rag under the tank's overflow hose to detect this), you likely have severe overheating or a head gasket leak (engine pressure pushing too much coolant into the expansion tank, which overflows)
Click to expand...
Just got a call from the mechanic. It's looking like a head gasket... :(
 
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