what should the running temp of 2.5td be?

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Chefdaddyscoti

Active member
I have a 2.5td that i finally have dialed in running well. I live in Texas and summer heat is upon us.

My question is... what is the proper running temp.

running around town in cooler weather under 80 degrees the gauge stays in the center, maybe a little past that. In these hotter temps on the freeway after running 15 minutes or so, it gets to the edge of the white line on the guage.

After i get off the freeway it will get a hair in the black, but then go back down.

i realize that the fan clutch may need to be replaced or the radiator flushed but before I start that process, I wanted some opinions from you guys that have been running these motors for years.

Would it be ok to add an electric fan behind the radiator to run from a switch inside the truck when needed?

I know these motors can crater easy when running too hot.

I will be putting a 200tdi or 300tdi in the near future, but this motor is running great and dont see the need to replace it yet.

Thoughts?
 
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Leadvagas

Member
I run a Revotech electric fan. The clutch fan IMHO is shitty at best. The Revotech is designed for a 300TDI, comes as a complete kit with controls and all. I have a manual switch on the dash, mostly to turn the fan off when doing a water crossing. A couple of things, don't waist your time with junk yard fans, put your temp sensor in the return line to the block not in the out let to the radiator. Your fan on temp should be around 180. I also put a good temp gauge on my 300. There is a temp sensor location in the head. I left the factory temp gauge on the block.
 
javelinadave

javelinadave

Administrator
Staff member
Scott,
Don't forget your truck has the aerodynamics of a brick. All defenders run warmer when going highway speeds in the summertime. Slow it down to 55 or 60 and it will run cooler.
Also the fan clutch is for sitting in traffic and not highway speeds so if you have resistance when it is hot it is doing its job.
Check your radiator with a laser temp gauge to be sure that it is cooler at the bottom than the top. I good flushing may help or perhaps have a radiator shop clean it out.
 
Jeff B

Jeff B

Well-known member
Also, consider getting a gauge that actually tells you some helpful information.
"Somewhere in the middle, a little past the line, almost to the small crack in the cluster..."

Leaves a little to be desired! :)




.
 
Uncle Douglas

Uncle Douglas

Well-known member
Callsign: delete
Chefdaddyscoti said:
i realize that the fan clutch may need to be replaced or the radiator flushed but before I start that process, I wanted some opinions from you guys that have been running these motors for years.

Would it be ok to add an electric fan behind the radiator to run from a switch inside the truck when needed?

Thoughts?
Click to expand...

Flushing the radiator is basic maintenance. Its a amazing how many rover diesels I drop the lower radiator hose on and orange rusty coolant comes out. Please flush your cooling system before flushing money on an electric fan. If the radiator is full of rust and scale, no amount of airflow is going to improve cooling.
Antifreeze becomes acidic after a couple of years and not flushing & changing it can destroy a cooling system from the inside out.
 
RBBailey

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Leadvagas said:
...put your temp sensor in the return line to the block not in the out let to the radiator...
Click to expand...

  1. Where is best possible spot on 300?
  2. And off of what Uncle Doug was saying -- yearly flush?
  3. Let's say you have a properly sorted temp gauge, and one hot day you notice it climbing -- at what point do you shut it off and pull over?
On most drives so far, I've seen 180 to 185 depending on what the truck and ambient temp is doing. I've experimented enough to know that during the fall and winter I will have a hard time getting the truck past 100 or so before I get to work.
 
L

Leadvagas

Member
RBBailey said:
  1. Where is best possible spot on 300?
  2. And off of what Uncle Doug was saying -- yearly flush?
  3. Let's say you have a properly sorted temp gauge, and one hot day you notice it climbing -- at what point do you shut it off and pull over?
On most drives so far, I've seen 180 to 185 depending on what the truck and ambient temp is doing. I've experimented enough to know that during the fall and winter I will have a hard time getting the truck past 100 or so before I get to work.
Click to expand...

I don't know if it's the best possible spot, but my temp sensor is in the lower rad hose after the first T coming from the radiator. My fan comes on if temp at that point exceeds 180 degrees, fan shuts off when the temp is below 170. My goal is to dump 25 degrees at the radiator. So T-stat opens at 180, coolant enters rad at 180 and leaves at 155 give or take, as temps in the engine rise over 180 to 205 plus t-stat stays open coolant leaves rad at 180, fan comes on and we get about a 30% increase in heat rejection from the rad. If temps continue to rise at the T-stat the condenser fans come on at 210 or so, providing max air flow for max available cooling. That's my current strategy, I also run a bigger intercooler and 2 1/2" straight pipe exhaust.

As far as coolant maintenance goes, I don't know if it's mandatory to do an annual flush but it wont hurt. I use Motorcraft diesel rated antifreeze mixed 50/50 with distilled water. I check it with test strips every quarter, keep the PH at 9 or above and the silicates low. I also run a coolant filter that I change annually.

I shut it down/pull off when my temps are over 230 on my temp gauge reporting from the head. At that temp the coolant is boiling in the head for sure and you get steam occlution, which means coolant wont flow.

I don't know how far your winter drive is, but I live at 10k feet and I get operating temp in about 15 min in my truck in the winter. Either you need a muff or your T-stat isn't closing 100% and or your fan is coming on to soon. Or something else is going on.
 
L

Leadvagas

Member
AdamSanta85 said:
That sounds way low. Stock fan on 2/300TDI is like 205. Thermostat fully open at 190.4. The fan is supposed to come on after the T-stat is full open.
Click to expand...

It is low compared to stock, but remember that is 180 coming OUT of the radiator. The coolant coming out of the head is around 205 to 210 if I am dropping 25 degrees at the radiator. Also I am in the mountains, not on the flats. I live at 10k feet, so my density altitude is about 73% of sea level with very low humidity most of the time. If I run a stock thermostat and a mechanical fan I am always on the verg of over heating. My set up works for me, may not work in every circumstance.
 
RBBailey

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Sounds like a really good set up. I think it would be overkill for most of us, but your consistent driving conditions would call for it.

I'm taking readings off the standard spot at the thermostat. My daily commute is only 6 miles. Last week I saw the temps go up to flirt with 200 when I found myself stuck in traffic in a parking lot on a 90 degree day for about five minutes directly after a long, low hill at 60mph. I didn't yet have my fan installed. I am experimenting with using an electric only, and as such, I may add a temp gauge at the bottom of the radiator, as you suggest.

Right now, with my cooling system being stock, but refurbished, I have no problem keeping it cool as long as I'm moving. I'm keeping a close eye on everything as my project continues into this full-use stage. May even be taking it over 200 miles today.
 
RBBailey

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
So what you could do is test it when you put it in, then when you see a drop in pH, like a point, it is time to renew.
 
RBBailey

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
Instead of starting a new thread, and since I can't find the other one that was addressing this issue:

I'm not able to get my 300Tdi up to over 180 until I've had almost 20 minutes of mixed driving. This is with no fan running, and 60% of the radiator covered.

I think someone on here mentioned that my thermostat might be leaking, which would make sense, except that the top radiator hose does not get warm at all till I get to that 180 mark. If it is leaking, I would think the small amount of coolant getting through is not enough to keep the truck so cold.

I tried to cover 100% of the radiator, and it did bring the temps up a bit quicker, but it got up to 190-195 on level ground, mixed driving. Since those are the temps I was seeing under load, low speed, when the outside air temps were at 90 degrees or more, I went back to the 60% covered radiator.

I'm not really sure what to do, or what I should expect for winter driving. But even when I purposefully take the long route, I'm never getting up to normal 180-185 temps, which I think can't really be good.
 
javelinadave

javelinadave

Administrator
Staff member
Healthy 300Tdi engines run very cool. What you are describing sounds normal to me. If you suspect the thermostat it is a $7 part that takes 15 minutes to swap. A small price for piece of mind if you want to swap it out.
 
nas90tdi

nas90tdi

Well-known member
I agree with Dave. Sounds pretty normal. You and I have the same basic weather currently and mine never gets to temp just running around for a few minutes like you are describing. I am lucky to see 150 in 10-15 minutes of start and stop driving with no real load on the engine.

You will find that your truck can drop down from 180 to the 130 range if you are coasting downhill a lot in cold weather. They just don't generate much heat until they are really working.
 
RBBailey

RBBailey

NAS-ROW Addict
Callsign: KF7KFZ
OK, I'm hearing the same thing from the blokes at PCRC. Interesting. Good to know I'm not looking at any real issues other than just not having any heat till I pull into the lot at work!
 
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