Lately, my engine has been going over 190 for some reason. It's never done that before. I've hosed off my radiator thinking maybe there was some mud in it. No luck. I'm going to change to a 180* T-stat this summer. What do yall think could be the problem for now though?

 

How long does it go over 190? If for just a couple of minutes then drops drastically for a few minutes it's a sticky thermostat.<br>I like mine to run at as close to 200 as possible. The diesel likes heat.<br><br>Chris

 

Check for oil collecting on the back of the radiator from the oil bottle. This has been known to gunk up the radiator. Plus dont spray directly into the radiator because you will trap bugs and junk between the intercooler and the radiator and stop air flow.

 

I just take a water hose and let the water kind of cascade down the fins. No spray nozzle. I'll try cleaning the back side of it. It stays over 190 for a bit, then drops back down, then goes back up. From what I've heard, the cooler you keep an engine, the better it runs. To a certain extent. You can get an engine to cold. I'm thinking a 180* for the summer and a 190* for winter. The Texas heat is pretty tough.

 

I change my thermostat everytime I change coolant, about every 25 - 28K miles, and have only used the stock 190* T/stat. In the Sacramento summer heat, I get between 190 - 200* daily running empty going home up into the Sierra foothills, but as soon as I get off the freeway, it drops back down to the mid 180's.<br><br>Tom

 

Colder engine temps helping is a myth.<br><br>The above post about diesels like heat is correct.<br><br>If you could see a graph of bore wear vs oil temp, it would startle you as it did me. Cylinder wear goes up EXPONENTIALLY as the bore temp goes down. This is because the heat causes a tighter piston fit, and this reduces the piston slap.<br><br>Higher temps are GOOD for your engine IF you have an oil than can handle them. Most oils can't and that's why it's not so good. Higher temps burn off moisture and help the oil fight off acid formation (the additives work better at higher temps).<br><br>This is only true to a point. Once you go a little TOO hot, the oil will turn to sludge and if you get VERY hot, you will seize a piston. It is VERY unlikely that you will be able to get a CTD to get this hot if everything is working properly.<br><br>I would run a good synthetic oil to handle the high temps, and run AT LEAST the 190° year round. Even in the summer heat. If you run a little too hot for your liking (the engine may LIKE the heat, though) then you can add a cooling enhancer like Redline Water Wetter or Forty Below and such. These additives are very effective and also reduce/eliminate cooling system corrosion.<br><br>I have used Water Wetter in my Maxima for almost 100K miles and the original cooling system is surgically clean inside-- no corrosion at all.<br><br>HOHN

 

Blue, I agree with Stamey about the sticking thermostat. I'm on my second Dodge/Cummins, and both have worked fine in keeping temps well regulated, and both have the original thermostats. My old '99 still has its original, has 74K miles, and the only time it get above to 200 - 205 is when towing 15K in the warmer months. The new one in my sig is too new to count. I flush and change the coolant every 36K miles even though the recommended interval is higher, so I always know there is no coolant problem. I also change the hoses (all of them) every other coolant change whether they look to need it or not. I haven't had a breakdown in the last 22 years of driving. <br>Another thing I do (when engine is cold) is raise the hood and using the thumb spray LOW PRESSURE water from the garden hose from the BACK of the radiator towards the front, so that the bugs etc. are flushed back out the way they came instead of getting trapped deeper into the cooling fins. HTH.

 

Thanks yall. If it's not raining when I get home, I'm going to hose out my radiator. The front of my engine is kind of covered in oil. If that doesn't work, I'm going to change T-stats.

 

I just had this exact problem with my rig. I was looking at the radiator and noticed that it was coated in some kind of sticky goop that consisted of bugs, hair, dirt and oil. It formed a mat on the radiator. I attempted washing it off but it didn't work. I pulled the radiator and was shocked to see that at least 2/3 of the surface was completely obstructed. After removing it I tried washing it from the back but that didn't work to loosen the crud. Finally I mixed up some clothes washing detergent (great degreaser) and soaked it in that. I then connected my hose to the hot water spigot for the washer and blasted it clean. I could not believe the crap that washed out of it. It came out shiny. Now my temp stays below 190.

 

Well, I've only got 32,000 miles on my truck and I keep the truck clean. SO hopefully it's not that bad. I hosed it out today but I never payed attention to the gauge (to busy concentrating on the idiots on the road).