T1N sprinters "run cold"? Maybe not - it might be your thermostat

I posted on another thread about my 2006 2500 running cold in around town driving when it was 32degF outside. A lot of replies indicated this is "normal" and a lot of threads posted the same as well.

However, after running some other tests I decided it was not normal and decided to replace the thermostat.

The old one was completely shot. The valve rubber was completely gone.

Now it takes 15mins to get the van up to a stable 175 deg F. This is *in town* driving at 30mph - no highway. No heater booster. Plus I had the interior heater on as well.

Perhaps, as one unorthodox thread said, that the thermostats are crap and should be replaced every couple of years. Maybe that is why so many people think their "sprinter runs cold" is a normal condition.

General consensus on UK MB forums is that the thermostat on this generation of engines is indeed prone to a quicker degradation, so a replacement every couple of years is a good idea.

In Finland people have added a small Renault thermostat in the oem thermostat output side and they claim much quicker warm-up.

THERMOSTATS

The device in most internal combustion engines cars to maintain top pipe temperature and reduce peaks of thermal stress and maintain combustion efficiency.
So how long would you expect one of these things to last given the environment it lives in?
Its constant pulsation allowing slugs of hot coolant to pass to or from the radiator (depending upon design or operational method) is its Achilles heal.

So how long?
A year or say 15,000 miles?
2 years or say 30,000. Maybe five years and then the rig has done 75,000.
OR
Like most its out of sight and out of mind and when you ask a customer when was the last time the cooling system was serviced you get I dunno
Looks original to me and the van is 10 years old!
But you want this thing to cool properly right ?
For a device that costs about $75, its a cheap maintenance item that needs some attention from time to time but done on a regular basis.
So how often do you DIY'rs change out the thermostat and flush the cooling system?
Dennis

BenJohnson said:

I posted on another thread about my 2006 2500 running cold in around town driving when it was 32degF outside. A lot of replies indicated this is "normal" and a lot of threads posted the same as well.

However, after running some other tests I decided it was not normal and decided to replace the thermostat.

...

Click to expand...

To me your post here makes it sound like the advice given by the forum in your original thread was lacking and we are a bunch of hacks. That's not at all what I interpreted from reading through the thread again.

You were given information which I believe should have helped you diagnose your problems.

Added: Actually I don't disagree with the "Runs Cold" comments in that unlike a typical petrol engine, a Sprinter diesel will not attain the typical 180F operating temperature by just idling. That is not related to thermostat condition, it is the nature of the beast. I do agree that the
Sprinter should attain close to 180F even around town, but my experience is that it may take longer than 15 minutes when ambient temperatures are lower ... eg. below 10F. Ambient temperature will affect operation.

Your original thread.
https://sprinter-source.com/forum/showthread.php?t=52974

My opinion. Rather than anyone just blindly replacing parts, learning what is "normal" for your Sprinter and then watching your dash engine temperature gauge is a good way to keep on top of your cooling system operating condition.

I strongly recommend that this thread be visited by those questioning whether they have a cooling system problem.

T1N Engine Temperature Normal High Low
https://sprinter-source.com/forum/showthread.php?t=47965

vic

Even with a brand new OEM thermostat my T1N runs cold. If it warmed up to Normal operation temps after 15 minutes of city driving on a 0 deg Celsius day, I would suspect a cooling issue. My van barely runs hot even midsummer unless climbing long slopes.
p.s. fan clutch is operational, barely ever kicks in as the van is quite temp stable (I do baby it).

Patrick of M said:

Even with a brand new OEM thermostat my T1N runs cold. If it warmed up to Normal operation temps after 15 minutes of city driving on a 0 deg Celsius day, I would suspect a cooling issue. My van barely runs hot even midsummer unless climbing long slopes.
p.s. fan clutch is operational, barely ever kicks in as the van is quite temp stable (I do baby it).

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I can tell you Patrick my van is behaving the same. I have a new thermostat, all the cooling system is good, recent radiator, etc. It really looks like below 0c in city driving the engine cannot produce enough heat to stay at operating temp. My Aux cooling pump is recent as well. I understand why the Espar is required. I did one winter in Montreal without it. It was COLD. The only time I say the needle above 87-80c is when climbing a hill in hot summer temps. But just slightly. The fan clutch roar can be heard then.

Cool running is indicative of efficiency in the engine. Less energy being turned into heat and shed. Alot of the small European diesel cars are also available with Espar like diesel heaters. It ends up being a safety issue, you need heat to defog and melt ice on the windshield. Love my Espar. My last work van had a proheat X45, that was overkill, but midwinter getting into a genuinely hot van is sweet.

In my relatively new to me '06 2500 I noticed that on the first really cool day this fall it wasn't reaching operating temp on my normal drives. So I put a new thermostat in it. No change. I've noticed that if the ambient is below about 50F it struggles to warm up, but over 60F, it reaches op temp in a few miles. My 06 is a 140" wheelbase and I almost never have a load of any consequence. Were I lugging around 1000lb of tools all the time, I'd bet it would warm up better. With my foray into remapping the CDI I have noticed that the AFR in low load areas can be 19-21 to 1. Running that lean is going to be hard to make excess heat. One of my first tuning changes was to raise the cold idle speed to ~1k RPM. It seems to help a little sitting at the stoplights on cold mornings.

Duckmang said:

In my relatively new to me '06 2500 I noticed that on the first really cool day this fall it wasn't reaching operating temp on my normal drives. So I put a new thermostat in it. No change. I've noticed that if the ambient is below about 50F it struggles to warm up, but over 60F, it reaches op temp in a few miles. My 06 is a 140" wheelbase and I almost never have a load of any consequence. Were I lugging around 1000lb of tools all the time, I'd bet it would warm up better. With my foray into remapping the CDI I have noticed that the AFR in low load areas can be 19-21 to 1. Running that lean is going to be hard to make excess heat. One of my first tuning changes was to raise the cold idle speed to ~1k RPM. It seems to help a little sitting at the stoplights on cold mornings.

Click to expand...

If you haven't put the fan clutch on your test list, you should. When I finally changed the fan clutch on my 2004 it limited the highs and brought "normal" from a "tick" below 180F to a "tick" above. It closely matches my 2006 performance now. I believe that the 2004 fan clutch was in some midrange operation band. It wouldn't fully engage, but it wouldn't fully disengage either. (After replacement the raise above 180F was unexpected.)

My basic explanation is that once the thermostat opens that is the coarse adjustment, and the fan is the trim or fine control. If the fan remains engaged when it shouldn't be it can keep temperatures lower than optimal.

vic

On some YouTube video, the poster said you could get a cold weather thermostat or a hot weather thermostat for the Sprinter. And the wrong temp one for your weather could cause temp issues.

In this quick search, these thermostats have different temps.

OldWest said:

On some YouTube video, the poster said you could get a cold weather thermostat or a hot weather thermostat for the Sprinter. And the wrong temp one for your weather could cause temp issues.

In this quick search, these thermostats have different temps.

https://www.autozone.com/cooling-heating-and-climate-control/thermostat/dodge/sprinter-2500

Click to expand...

Different setting thermostats are available. The 195F stat design contributes to the engine passing emissions requirements, if that matters to anyone.

Before I messed with a different thermostat I'd do some sort of radiator air flow blocking.

vic