Really hot coolant temp

JoeBillHill

JoeBillHill

Active Member
Driving around as of late my temp guage has been all over the place. Even climbing little hills in Seattle it is wanting to rise up to 1/2 or 3/4. Going up over stepper rises where I'm keeping my egts (post turbo) around 1100 the needle is pushing up against the top mark.
I feel like my coolant system is pretty new with a new radiator 4 years ago, new fan clutch last year, and new water pump/thermostat this year.
I don't know if there's a way to pinpoint a problem in the system but if anyone has suggestions I'd be curious.
 
My needle was behaving erratically as well, I switched out the temp sensor and that fixed it right away. Might be worth a shot, it’s cheap and done in five minutes. Although, in your case, there is a correlation between engine load and needle movements, in mine it was just all over the place regardless of how hard I was pushing it.

Fabian
 
If you are holding post turbo EGT's at 1100 for a long(ish) length of time I would expect the water temp to rise and probably eventually overheat. 1100 post turbo could be in the "just safe" range (1300) or in the "asking for trouble" range (1400)... some would say it's barely safe even if it's pre turbo temp.
But if you've owned the van for 4yrs I would guess you know the characteristics... if it seems suddenly different w/o obvious reason I would guess a sticking thermostat. At least that should be the easiest/cheapest to isolate...
 
Hmmm good to know. I've owned it for almost 5 years now but still don't really know how to drive it.
I've been adjusting the fueling per growlerbears tuning writeup so possibly I've just been running it too rich.
I'll keep my eye on it and if I feel up to it when I'm putting a diesel heater in I'll take a look at the thermostat.
 
JoeBillHill said:
I've been adjusting the fueling per growlerbears tuning writeup so possibly I've just been running it too rich.
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If you've increased fueling, then yeah... you're really going to have to watch it on climbs. The throttle pedal is really more of an EGT control rather than a go-faster control.
 
It could possibly be the thermostat as I replaced it with a new water pump a couple months ago. I don't know if I got too much gasket maker in there and it could have gummed up the thermostat. seems like that would take a lot of goop though.
For how slow the van goes I still feel like a fighter pilot some times with all the gauges I have to pay attention to. I haven't been driving it any differently than I have before and I keep an eye on the EGT and temp gauge. Even if it is running richer shouldn't the EGT's be the tell all on how hot the engine is? Even if I'm going slow but belching black smoke and at 1000 degrees would it be the same if I was perfectly tuned, cruising, and at 1000 degrees?
 
Krazykraut said:
My needle was behaving erratically as well, I switched out the temp sensor and that fixed it right away. Might be worth a shot, it’s cheap and done in five minutes. Although, in your case, there is a correlation between engine load and needle movements, in mine it was just all over the place regardless of how hard I was pushing it.

Fabian
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And I replaced the temp sensor a few years back unfortunately. I wish it was that, as it was a nice easy little project.
 
JoeBillHill said:
Even if it is running richer shouldn't the EGT's be the tell all on how hot the engine is? Even if I'm going slow but belching black smoke and at 1000 degrees would it be the same if I was perfectly tuned, cruising, and at 1000 degrees?
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Pretty much... in reality you are measuring localized gas temps which are generally much hotter than the head/block, and they fluctuate much more/more quickly. But eventually they will heat up to match.
From what you've said/done I would say it's just the new fueling rate/ratio... you can detune it to run cooler/weaker on climbs/acceleration, or you can just be aware it's going to run hotter at high loads.
 
sk66 said:
Pretty much... in reality you are measuring localized gas temps which are generally much hotter than the head/block, and they fluctuate much more/more quickly. But eventually they will heat up to match.
From what you've said/done I would say it's just the new fueling rate/ratio... you can detune it to run cooler/weaker on climbs/acceleration, or you can just be aware it's going to run hotter at high loads.
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Ok. I've been trying to detune it to get in that optimal zone. I'll keep keeping my eye on it.
 
Came down from Seattle and a few spots on i5 made the temps start climbing up to a little over 3/4. Egts didn't go past 1k. Mostly 850 or 900.
Took the thermostat out today and it is working fine.
I'm in the middle of installing a bunk heater so i plan on flushing the radiator when i get a minute.
 
Just checking- your EGT is measured *after* the turbo? You've fitted the probe somewhere other than in the EGR blanking plate? Hmm.

The problem with measuring post-turbo is that a cold turbo, or one that's making a lot of boost, can absorb a lot of the heat so you're never quite sure what temperature the head is seeing. The difference is usually between 100-300F, but that's a fairly wide range. Your 1100F on the gauge could be 1400F pre-turbo if the turbo's cold and you're making 14psi.

sk66 said:
The throttle pedal is really more of an EGT control rather than a go-faster control.
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^What he says. It's a "go-faster" control up until the point where the engine isn't making any more power, then it's an "increase EGT" pedal. The trick when climbing hills is to find the point where pushing the accelerator more doesn't result in any more speed (or, alternatively, letting off the accelerator to the point where the EGTs come down without losing any speed).

An air/fuel gauge makes it much easier when you're tuning for maximum power/reliability. For reference, you want full load to be 19-22:1, and never below 18:1 for any length of time.
 
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No my probe is at the egr blanking plate pre turbo.
I feel like i still have a lot oompf left as i drove up the hills in the intestate and I'm not billowing smoke. Hardly any at all actually. Cruising at 10psi normally, up to 12psi too.
I agree an air/fuel guage would be a good idea and it's on my radar to get.
It just seems strange that before i could go up a hill at around the same egt and not worry about my temp guage but now I am.
 
JoeBillHill said:
No my probe is at the egr blanking plate pre turbo.
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Ok, then 1100 is very safe... I go to 1300 w/o concern, with occasional short extents at 1400 (that's pushing limits for sure). If held for any length of time the water temp will increase... that's just the way it is. But if it's increasing very quickly towards the limits, then I would have to suspect something w/ the cooling system.
 
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Hmm. 1100F pre-turbo shouldn't make the temps rise *that* much ("needle is pushing up against the top mark"), even on a slow uphill climb. At least, it doesn't on mine. The needle goes up, for sure, but it slows down and tops out at about 3/4.

-When you're climbing hills and such, you're doing it in 4th (or 3rd), keeping the engine above 3000rpm?

-Are you losing coolant? Keep a very close eye on that.

-Can you hear it when the fan clutch locks up?

It sort of sounds like your fan clutch isn't working- but you've said it's a new one. On mine it happens when the temp. gauge has been around half for a couple of minutes. The fan kicks in over 2-5 seconds and makes a loud, low-pitched howling noise.

I fitted a new (generic brand) fan clutch on my old engine which didn't work very well. Better than the worn-out 25 year old Mitsubishi one, but nowhere near as good as the Hyundai one that's on the new engine. With the old clutch you could sort of tell if the fan was working, but on the new engine the first time the fan kicked in the noise was quite alarming until i figured out what it was.
 
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Growlerbearnz said:
When you're climbing hills and such, you're doing it in 4th (or 3rd), keeping the engine above 3000rpm?
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Unless I start to feel it lug I'm in 4th. Around 2k I'll kick the OD off no questions.
Growlerbearnz said:
Are you losing coolant? Keep a very close eye on that
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I think I am. At least when i was driving and it was pushing the H temp line i lost some.

Growlerbearnz said:
Can you hear it when the fan clutch locks up?
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Tough to tell if I can hear it or not. I mean the engine is pretty damn loud around 3k but I'll stay listening for it. But yeah I would hope it's working since I replaced it last summer.
 
Did a coolant flush and found some gunk in my expansion tank. Don't know what is from except maybe from my water pump install. It's gone now though and pray never returns. Hopefully that was clogging up the radiator a little too and causing my temps. Fingers crossed.
In other news I finally installed a spigot on the block drain as i was always tired of getting coolant everywhere when having to drain it0305191050~3.jpg
 
Still doing the same thing. It's weird that the cab doesn't feel as hot as it would seem for how hot the temp guage is showing....
Maybe a test of the temp guage plug is in order
 
Sounds like you're on the right track- making sure that the engine really is getting as hot as it claims. Swapping the temperature sender is a good call (though yours is new, it might be out of spec).

Do you have an infrared thermometer? The radiator top tank on my engine is normally around 40-55C, rising to 65-75C when the engine gets really hot. An alternative is to stop and feel the top radiator hose every now and then until you get the feel for what "normal" is. Having said that though, it seems the engine itself runs a lot hotter than the radiator- maybe also check the temperature of the cylinder head next to #1 injector.

It's always a little concerning when the heater isn't as hot as it's supposed to be. That suggests an airlock somewhere, but these engines don't tend to need bleeding. Have you done anything innovative with the heater hoses?
Try opening the radiator cap, setting both front and rear heaters to full hot, and run the engine until it's warm while watching for air bubbles coming out the radiator. (It'll spill coolant out the open radiator cap as it warms up, sorry.)
 
Just purchased a thermometer and went over a pass. Needle was pretty close to the top.
Radiator cap 44C
Top hose 50C
Cylinder 1 (closest one to front of engine) right next to the injector 66

I just put in an auxiliary diesel heater but these symptoms were occurring beforehand and i just T'd into the rear heater hoses.
I bled the system when i installed it too according to that procedure.
I might still have the old temp sender but is there a range that's listed for the guage /sender? I was thinking of just boiling some water and testing them plugged in.
 
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