LOST JEEPS :: View topic - CRD running cold?

The viscous heater actually serves two functions. The one mentioned in this thread is that of assisting the engine to warm a bit faster. But the second function is the reason why I keep mine connected on my CRD--the viscous heater also serves to help keep the engine warm when the engine is operating in very cold weather or when extended idling. I don't like to extended idle any vehicle, but it is occasionally a necessity for me in very cold weather. Concerned about "wet stacking" when diesel engine temperatures drop too low when idling in very cold weather, I spoke with a Chrysler factory tech several years ago about it. He said that a primary reason for the viscous heater was to put a cooling CRD engine in very cold weather under enough load to maintain operating temperature--without resorting to elevating the idle RPM. In my experience with my '05 CRD (bought new and run in a lot of cold weather), the viscous heater functions just as designed. My CRD will maintain temperature--even when idled for extended periods in subzero weather--without the idle speed increasing.

As for the block heater, I've never bothered using mine, unless the temperatures are below 0° F. If a CRD is not starting easily at temperatures above 0° F., it's got issues.

Author:	slusho [ Fri Oct 11, 2013 6:50 am ]
Post subject:	CRD running cold?
Hi all, i have been a Jeep guy for about 20 years now (1st was a 94 Cherokee Sport new off the lot), and recently purchased an '06 Liberty CRD Limited. It runs great, gets mileage in the upper 20's on the highway, and is a great tow vehicle. Here's the issue; I live in Florida, and we just had our first sub-60 degree night, and when I drove to work (about 35 miles), it never warmed up past the hash mark between cold and normal. Is that an issue? I feel like it may cause some issues as it cools down, and i dont want to have to change the timing belt/water pump/etc just yet. It seems like a thermostat issue, but i will say that the heat blew strong and hot at the same time, so I'm not sure. Thanks in advance!

Author:	Hexus [ Fri Oct 11, 2013 7:30 am ]
Post subject:	Re: CRD running cold?
Well, it could be the thermostat (a lot have had issues with them). It could also be the temperature sensor that plugs in at the back of the thermostat. 60 or even sub-60 isn't that cool honestly. Even that diesel should warm up some more than that. You might want to check your viscous heater (Read the Noob guide, good pictures in there) to ensure that it's working as well, that the clutch is in fact engaging. Whether you want to or not, what kind of mileage is the engine at? Are you 100% positive the timing belt has been done if over 100,000 miles? Check those things and report back, I'm going to assume there's no CEL (Check Engine Light), but if there is, get any codes scanned. Thanks!

Author:	flash7210 [ Fri Oct 11, 2013 8:19 am ]
Post subject:	Re: CRD running cold?
I live in FL and what you describe was pretty normal for me before I installed the in-line thermostat. Low 60's isn't really cold enough to activate the viscous heater. But it isn't warm enough to allow engine temp to come up to normal. You probably need a new thermostat. You could go with a factory replacement thermostat but I installed one of these:

Author:	papaindigo [ Fri Oct 11, 2013 10:17 am ]
Post subject:	Re: CRD running cold?
X2 on Hexus comments on timing belt to which I would add read Sir Sam's NOOB guide and download manuals. The proper place for the temp gauge to run with a good thermostat once the engine is warmed up is just a hair left of dead vertical. Below that your OEM tstat is stuck open or opening too early, been there done that, which is a common failure mode about every 40-50K miles. Options - 1) replace OEM tstat, runs ca. $120 with gasket and I can send helpful how to hints if you email me or 2) install an inline tstat either literal in the hose (with a clamp to hold it in place and a small hole in the skirt to bypass a bit of coolant during the warmup process) or the housing that flash7210 shows which is a Meziere WN0072 Inline Thermostat Housing with a ca. 195F tstat. That's a bit hotter than the OEM 180F tstat but GDE says a bit hotter is better. FYI unless you have pulled your viscous heater relay so it never runs (I have) the viscous heater runs all the time if the coolant is below a certain temp regardless of the ambient temp. I don't recall what that temp is but I do know a GDE tune lowers it to about 145F. My point being that if you have a bad tstat and the coolant temp never reaches the viscous heater cutoff point then the viscous heater is running unless the relay is pulled. I can tell you that with a bad tstat and a disabled viscous heater (gets rid of that parasitic drag) the mpg (city and hwy) penalty for a bad tstat is ca. 10%

Author:	kjjet [ Fri Oct 11, 2013 11:05 am ]
Post subject:	Re: CRD running cold?
The OEM thermostat's are very expensive and have lots of issues. I installed a Stant 13519 195 degree thermostat in the top hose. Cost $15 !! Works perfectly keeping the temp just a tick under 1/2 on the gauge. It takes one clamp. Lots of people have installed them see post: viewtopic.php?f=5&t=64333 Good luck KJJET

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Author:	CATCRD [ Fri Oct 11, 2013 10:05 pm ]
Post subject:	Re: CRD running cold?
kjjet wrote: The OEM thermostat's are very expensive and have lots of issues. I installed a Stant 13519 195 degree thermostat in the top hose. Cost $15 !! Works perfectly keeping the temp just a tick under 1/2 on the gauge. It takes one clamp. Lots of people have installed them see post: viewtopic.php?f=5&t=64333 Good luck KJJET Same here! Plus dozens of other members. Do it!

Author:	slusho [ Fri Oct 11, 2013 10:41 pm ]
Post subject:	Re: CRD running cold?
Thanks everyone, the thermostat was what i was thinking, i don't know why i was thinking it was buried under something significant; I guess it is just that everyone does them whiile they're doing the timing belt. The engine only has about 85k on it, and I would like to put it off till next year. I really like the idea of the inline model, I'll probably do that this weekend. Does the viscous heater do anything really useful in a climate like Florida's? We do actually get 3-4 hard frosts a year here.

Author:	papaindigo [ Sat Oct 12, 2013 8:58 am ]
Post subject:	Re: CRD running cold?
The purpose, such as it is, of the viscous heater is to provide a bit of a boost to the engine warm up cycle mainly because diesel engines are generally a bit slow to warm up. The benefits are a) a tiny bit of mpg improvement during in town colder weather driving due to quicker warm up and b) a bit more in cabin heat sooner in cold weather. Frankly plugging the engine in, ideally with a timer set to come on like 2 hrs before crank up, will do a lot more to get things warm than the viscous heater if the ambient temp is in or below the lower 20s F which we can see here in north FL. My son, stoutdog, has his viscous heater relay unplugged and had no issues when he was in Flagstaff, AZ and the Grand Canyon area in winter months in well below 20F weather. Mine has been unplugged for a couple of years now and I don't notice any warm up issues. With or without the viscous in summerish N FL weather I hit full operating temp (fully functional OEM tstat) in like 3 miles of in town driving and on a really cold winter day it might take maybe 6 miles unless I plug the block heater in in which case it takes 3 miles. In all cases the temp gauge is starting to rise within 1/2 a mile.

Author:	DOC4444 [ Sat Oct 12, 2013 6:47 pm ]
Post subject:	Re: CRD running cold?
When your thermostat is opening too early, the VH never stops running, costing you 3-4 MPG. Pull the VH relay until you do something about thermostat. BTW, some people have gotten into serious trouble with overheating with the inline thermostat. KJ CRDs do not tolerate ANY overheating. It starts getting expensive VERY quickly. Read all the threads about all the things that can go wrong before taking that route. Safer to simply replace OEM. I have an inline and have removed it. DOC

Author:	TJ2 [ Sun Oct 13, 2013 3:13 am ]
Post subject:	Re: CRD running cold?
+1 Papaindigo I put the block heater on a two hour timer when temps get below 40F. +1 DOC RacerTracer comes to mind about the Stant t-stat. I've had one on shelf since the 'cheap fix' came out. Would put it in during dead of winter when working on a vehicle is not an option. The FSM says running the 3.7L cold will cause sludge buildup. Am I the only one who thinks that could happen on a CRD?

Author:	papaindigo [ Sun Oct 13, 2013 9:14 am ]
Post subject:	Re: CRD running cold?
I favor plug in, when it's an option, over using the viscous although I don't think you need to plug in unless the ambient temp is going to be somewhat below freezing. At ca. 40F unplugged and no viscous and good OEM tstat mine warms up to normal in the routine 3 miles or so. Now if I was at a location where plug in was not an option and temps were dropping to below 20F I might consider plugging the viscous relay back in. I've participated in the inline tstat discussion off and on since the beginning and personally decided not to go that route. I did early on and still do recommend that folks who go that route make sure there is a small hole in the inline tstat skirt. That's an ancient mechanics trick to a) prevent catastrophic overheating by allowing at least some coolant to flow past a failed shut tstat; b) provide for some circulation past the wax pellet housing so the tstat gets a proper temp reading and opens in a timely manner; c) ensures during coolant change that no air or old coolant gets trapped in the system behind a closed tstat. From my perspective, I know others have a different opinion, the inline is a good temporary fix but it's not something I'd run long term.

Author:	kjjet [ Sun Oct 13, 2013 9:45 pm ]
Post subject:	Re: CRD running cold?
CATCRD wrote: kjjet wrote: The OEM thermostat's are very expensive and have lots of issues. I installed a Stant 13519 195 degree thermostat in the top hose. Cost $15 !! Works perfectly keeping the temp just a tick under 1/2 on the gauge. It takes one clamp. Lots of people have installed them see post: viewtopic.php?f=5&t=64333 Good luck KJJET Same here! Plus dozens of other members. Do it! Best $15 I have ever spent on the CRD!!

Author:	railguy [ Sat Dec 07, 2013 1:05 am ]
Post subject:	Re: CRD running cold?
The viscous heater actually serves two functions. The one mentioned in this thread is that of assisting the engine to warm a bit faster. But the second function is the reason why I keep mine connected on my CRD--the viscous heater also serves to help keep the engine warm when the engine is operating in very cold weather or when extended idling. I don't like to extended idle any vehicle, but it is occasionally a necessity for me in very cold weather. Concerned about "wet stacking" when diesel engine temperatures drop too low when idling in very cold weather, I spoke with a Chrysler factory tech several years ago about it. He said that a primary reason for the viscous heater was to put a cooling CRD engine in very cold weather under enough load to maintain operating temperature--without resorting to elevating the idle RPM. In my experience with my '05 CRD (bought new and run in a lot of cold weather), the viscous heater functions just as designed. My CRD will maintain temperature--even when idled for extended periods in subzero weather--without the idle speed increasing. As for the block heater, I've never bothered using mine, unless the temperatures are below 0° F. If a CRD is not starting easily at temperatures above 0° F., it's got issues.

Author:	papaindigo [ Sat Dec 07, 2013 7:52 am ]
Post subject:	Re: CRD running cold?
Interesting thought but subzero weather is not happening here nor is extended period idling although if travel ever changes that I'll keep this in mind. I will note that I use the block heater beginning at 25F or below mainly because it produces cabin heat way way sooner than the viscous ever did when it was plugged in.

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Author:	kjjet [ Sat Dec 07, 2013 11:52 pm ]
Post subject:	Re: CRD running cold?
railguy wrote: The viscous heater actually serves two functions. The one mentioned in this thread is that of assisting the engine to warm a bit faster. But the second function is the reason why I keep mine connected on my CRD--the viscous heater also serves to help keep the engine warm when the engine is operating in very cold weather or when extended idling. I don't like to extended idle any vehicle, but it is occasionally a necessity for me in very cold weather. Concerned about "wet stacking" when diesel engine temperatures drop too low when idling in very cold weather, I spoke with a Chrysler factory tech several years ago about it. He said that a primary reason for the viscous heater was to put a cooling CRD engine in very cold weather under enough load to maintain operating temperature--without resorting to elevating the idle RPM. In my experience with my '05 CRD (bought new and run in a lot of cold weather), the viscous heater functions just as designed. My CRD will maintain temperature--even when idled for extended periods in subzero weather--without the idle speed increasing. As for the block heater, I've never bothered using mine, unless the temperatures are below 0° F. If a CRD is not starting easily at temperatures above 0° F., it's got issues. I totally agree. If the viscous heater is working correctly. There should be no changes in temp between idle and highway when cold out once then engine is warmed up. But a lot of us have this issue. I think its time to make sure its working? As for using the block heater. It makes for easy smooth starting. I have started my CRD at -6F after sitting for 3 days in the mountains. As long as the battery is good they should start.