View Full Version : Diesel engine cool-down

05-24-2005, 12:58 PM
How many of you let your diesel engine cool down (Not pulling anything) before shutting her off. I guess I'm asking is it necessary to let it cool down when lets say, you drive down the freeway for maybe 15 to 20 miles and hoop out to go into Wal-mart or whatever?

05-24-2005, 01:37 PM
Let it idle for about 30 seconds for general driving conditions as you stated. The goal is let your Pre-turbo EGTs get to around 300 degrees.
Obviously DC feels that your turbo will last at least though the warranty period wihtout the need for this, otherwise we would have decent guages from the factory. But if you have the intent of keeping your rig for 200+K, I'd highly recommend a good set of guages.

05-27-2005, 04:22 PM
Let it idle for about 30 seconds for general driving conditions as you stated. The goal is let your Pre-turbo EGTs get to around 300 degrees.
Obviously DC feels that your turbo will last at least though the warranty period wihtout the need for this, otherwise we would have decent guages from the factory. But if you have the intent of keeping your rig for 200+K, I'd highly recommend a good set of guages.

This is our first Diesel. I don't have a clue about the gauges your speaking of. Yep, I like to keep it as long as I can, that way I can recoop some off the extra cost of buying diesel over gas.

05-27-2005, 08:14 PM
When I just run around without the trailer attached, I just let it idle for less than a minute, and turn it off. If I'm pullin and come to a stop,I let it run for at least 4 to 5 minues, as a cool down. I'm sure it can hurt it doing it that way,and must help??

06-09-2005, 03:28 PM
If you can, do a search for a local Diesel Performance shop. They can help you out with you decision to get guages. If not, do some reading on
www.turbodieselregister.com - in fact you should visit there every now and then anyway, you can learn a lot from reading the forums there.

Cool down is important if your running hot. Just remember that extended idling is also considered "undesireable" by Cummins. No specifics were ever given, but theres been a lot of speculation as to why.

06-09-2005, 04:27 PM
Get the gages. I installed mine after 30,000 miles with half of them towing a 10.4K 5er. I discovered that when towing up steep grades I had been overheating my turbocharger by flooring my throttle. I also learned that when securing my engine I had not been allowing it to cool enough.

Similiarly I found that when backing my 5er into spots that the transmission temperatures rose quickly and that if I did not get the job done fast the transmission would overheat. When in bumper to bumper traffic towing at 10 mph the transmission temperature would rise alarmingly.

I believe the abuse of my transmission that I had done lead to the premature need to rebuild it. I have had an additional tranny cooler installed which has helped quite a bit.

2000 Quad Cab 2500 Auto w/4:10 rear end. DTT 89% VB, TC, Mag HI-TECK Pan, Smart Box, EZ, PAC Brake, Pillar gage mount with EGT, Boost, and Tranny output temp, Miller Manufacturing Truck Bed Cover, with RBW 5er hitch, and
Rigged to tow a 29' Automate 5th wheel.

Dr. D
10-27-2005, 06:51 PM
If I have just pulled-off the freeway, I let it idle for 30 seconds to let the turbo cool-down.

10-28-2005, 12:38 PM
Have a 2003 Quad Cab Dually, HO, NV5600 6 speed trany. I have installed a pyro for reasons of cool down and shifting when towing big hills while under tow. Am full timing in 34' fifer weighting 15100 lbs. Would not be without the guages.

10-28-2005, 02:51 PM
If you expect to tow with your diesel you need to add the gages. Mine are Banks gages and I like them. They are pillar mounted on the drivers side door pillar. I have the Exhaust Gas Temperature (EGT) gage on top and I watch this closely when towing in hills and back off on my throttle when the EGT is over 1250. I use this gage more than any other gage when towing. Thinking back to pre gage days I know I routinely exceeded 1250 when towing in the hills. And I found that my idling the engine to cool the EGT pre-gages was not nearly long enough. So far my turbocharger is still working properly. My boost pressure gage in in the middle and frankly I do not pay alot of attention to it. The bottom gage is the transmission temperature gage. I watched it like a hawk at low speeds, such as towing in a traffic jam, to try to keep the temoperature below 200. When backing into a site the temperature routinely would go up to 240 and I would secure the backing, shift to neutral and speed up the engine to cool the tranny oil. Over a year ago I had a third tranny oil cooler added which dramatically lowered the oil temperature by increasing the cooling. The mechanic found a second check valve in the system which he removed increasing flow.

10-28-2005, 05:45 PM
If you trade into a new truck every 2 to 3 years then I wouldn't worry about it at all. Like was said above - Dodge isn't worried about anything happening through the warranty period.
If you keep your truck for a good period of time past the warranty period then I would have boost & pyro gauges in it from day one. In our 2004.5 Dodge I can easily peg 1600 pulling some hills out here in Wyoming without a chip in it. I know the new cummins is built to take higher temps but 1600 is pushing it and without gauges I would never know. I've got all the power I need but have to back out of it due to the temps. If I didn't have the pyro I would most likely just keep in it pulling the grade cuasing who knows what damage.
For cool down if I haven't been pulling or running hard then I just let it idle for a few seconds and shut down. If I've been pulling then I wait until it cools down to 350 which sometimes takes up to a minute or two.
For the cost its cheap insurance to have a pyro and tranny temp (Automatic). The boost gauge isn't really used by us that often however we get our best fuel mileage at 10psi & under.

12-21-2005, 07:22 PM
I also tow with gauges. I agree that they are essential for towing. On the 03 and newer dodges you can get the Pillar column that has a gauge mount built in. Then look for a dual guage for boost and exhaust gas temperature. The one I chose is made by SPA Technique. Works really well and will hold the highest temp and boost until you reset it. You can also set alarm setpoints for boost and EGTs. I believe Genos Garage still supplies the pillar mount.

Jack in Alaska
12-30-2005, 05:48 PM
I agree on the pillar mount SPA combo gauge. It has EGT/Boost in one gauge. Have used it for 4 yrs. w/o problem. I also have a Westech fuel pressure gauge mounted under the edge of the dash by the x-fer case lever.

The EGT is most important when towing. I found that my EGT starts to go north of 1300F in 4th when the pedal is down. I just let off a little to prevent my CTD from melting and being blown out the tailpipe. UUGGHH. What a terrible thought.

12-31-2005, 09:51 AM
On my truck, there are no gauges, other than the trans temp,and I've asked the dealer about ordering them for my dash. They have said with the engine/trans you have, gauges are not necessary??? I do always allow the engine to idle at least 2-3 minutes after pulling for cool down, and do watch the trans temp when in traffic, or backing. Very few trucks like mine do have the gauges your talking about, wonder why.

Doug in Bermuda
01-31-2006, 10:21 AM
This topic was just kicked around a boating forum that I frequent. Boat diesel engines have a tougher life than road vehicles. With the effort required to overcome the resistance of the water, they are always in effect pushing their loads uphill. There are no flat spots, no coasting downhills getting a break.

Most of us give our engines at least 5 or 10 minutes 'cool down' period after running hard. For most this will be during the period of traveling from open water to our berths in a restricted near idle speed area.

07-02-2006, 01:04 AM
Hauled a 33' Okanagan GVW 15K with a RAM2500, chipped W/HD Torque converter etc. I had BD X monitor guages on the post and used them extensively. However, my exhaust temp never reached over 1000 degrees in heavy mountain pulling. On the hottest of hot days my tranny never got above 210-215 and usually ran @ 185 on level ground while towing. I had the automatic engine shut down installed that would shut the engine down at 325 exhaust degrees, that usually took about two or three minutes to go from 700-800 degrees down to 325. I always had to make sure the exhaust brake was turned off, otherwise it will take three times as long to cool down. The most important thing about keeping your exhaust temp down is: Don't try to be the first one to the top of that big hill, or to put it another way, DON'T put the peddle to the metal. rjttam P.S. My 96 Ford, F250, outfitted the same as the 03 Dodge would run up over 1300 degree in a heart beat. Also, important to note that when not towing or working hard, a 30 second cool down should be sufficient, or if you forget too do it occasionally, it's not a big deal.

02-14-2011, 12:20 AM
Before shutting your engine let diesel engine cool down because overheating causes some serious engine damage. To avoid overheating problem check the coolant level periodically. So when you stop the car after long driving, don't shut the engine off. let it idle for sometime to cool down the turbocharger.
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