CRD Overheating - The Tale of Two CRD's

e010584 · **Posted:** Wed May 22, 2013 3:42 pm

Although it is clear that there has been a number of folks experiencing overheating issues, it doesn't appear there have been clear fixes or solutions summarized to help me out on my wife's CRD. While my CRD has never had any overheating issues even with the electric fans removed, hers has unresolved overheating issues after replacing the thermostat and clutch fan without finding any real problems. The oddest thing comparing the two is that hers has always came up to temp quite quickly compared to mine ramping up slowly and, even though it regulates fine around town, it always runs too hot when climbing hills. Now that mine is unfortunately down with a cracked head, I'm tempted to swap out parts to further troubleshoot but obviously don't want to do more swapping than necessary.

At this point I'm almost convinced it has more to do with too much heat being added to the system rather than removed and would think something like the viscous heater or EGR would be too of the more likely culprits. I though the viscous heater only comes into play when it is really cold and should be a non factor once warm and visually obvious that it is a non factor if the clutch isn't engaged to turn it. I had already unplugged the sensor to disable the EGR but this obviously doesn't rule out a stuck open EGR valve. I'm even beginning to wonder if there could be any fuel scheduling issues as hers never seemed to get as good of mileage as mine.

Any thoughts and advice would be greatly appreciated in advance of experimentation.

Glend · **Posted:** Wed May 22, 2013 6:24 pm

Get a radiator specalist to check the flow though the radiator, I know of cases of core tube blockage that were responsible, most likely due to the use of alternative coolants or hard
water reacting with stock coolant and forming sludge deposits in the core.

audiboy86 · **Posted:** Wed May 22, 2013 9:45 pm

I would start with the thermostat easy to swap and one of the weak links in our cooling systems. Also a cooling system pressure tester would be great to have also.

geordi · **Posted:** Wed May 22, 2013 10:14 pm

Is the egr system still stock? The thought you have about the system having more heat added than removed is a good one. The Diesel engine is very efficient, and should never run hot under normal conditions.

e010584 · **Posted:** Thu May 23, 2013 1:17 am

Yes, the EGR system is stock with the exception that I have the normal ORM (connector unplugged). And already did a new thermostat and fan clutch as previously noted.

racertracer · **Posted:** Thu May 23, 2013 5:44 am

e010584 wrote:

And already did a new thermostat and fan clutch as previously noted.

Others have experienced coolant leaks soon after replacing the thermostat.

Trapped air in the head soon after a thermostat replacement may be the cause of head gasket problems. It becomes evident when cabin heat doesn't come on when the heater fan is turned on. The heater fan blows out cold air even though the temperature gauge on the dash is at the proper half way mark.

Improper amount of coolant replacement and trapped air in the head may be the problem. This mostly due to trapped air that remains in the head.

Here is the scenario for a head gasket failure:

1. Thermostat is removed without properly draining the cooling system. Proper way to drain the coolant is by the drain valve at the bottom of the radiator and catching the fluid in a clean container so that it can be reused after it is filtered.

2. Instead coolant is partially drained through the thermostat hole in the head and also through the upper coolant hoses but remains undisturbed in the lower parts of the engine.

3. Thermostat is replaced and coolant added to the system, but the air that is now trapped in the head is not removed, leading to overheating and head gasket failure.

There will be no indication on the temperature gauge that an overheating condition is occurring because the temperature sensor is not submerged in coolant, it is instead surrounded by air pockets that is preventing it from taking a proper reading.

This is the reason why the engine computer will not perform the "cutting off of fuel procedure" to prevent the engine from overheating, it never sees the problem because the temp is reading fine.

I believe that the temperature sensor is in the wrong place and should be in a lower location that will keep it surrounded by coolant at all times and that the designers of this engine need to reconsider its location in the new engines if they haven't already done so.

Proper coolant draining and refilling during a thermostat replacement is key to preventing a head gasket failure. Eliminating air pockets in the head should be the number one objective.

Some have tried burping the engine after a thermostat replacement on their CRD and it was difficult, it took a few drives before all the system was completely filled with coolant and that is not the proper way to do it.... driving it with air pockets in the head is a dangerous thing to do.

It takes a minute for the head to overheat when it is surrounded by air.

papaindigo · **Posted:** Thu May 23, 2013 8:57 am

Thoughts:
1. is the wife's CRD losing coolant? If so check for head gasket leak; IIRC crank up a cold engine briefly (mere seconds) shut off and see if the coolant tank is pressurized by removing cap.
2. unless you are absolutely positive that only HOAT coolant has been used and even then it would be prudent to check flow thru the radiator and the heater core. I suspect a shop would need to check the radiator although it may be possible to DIY. However on the heater core all you have to do is disconnect both lines and gently backflush with a hose.
3. disable the viscous and see what happens. Easy to do just pull the R36 relay in the power distribution center. It engages/disengages based on coolant temp, don't know what sensor is used, so it runs on startup even in warm weather but is supposed to shut off when coolant temp reaches a certain level, don't recall exactly what but may be ca. 145F.
4. determine if your wife's CRD is actually running hot. I say this because 1) the temp sensor on the back of the tstat is not infallible and 2) some 05s at least came from the factory with a temp gauge calibrated for a gas engine so they read hot (see http://www.greendieselengineering.com/f ... st/19.page). You can pickup an Infrared Thermometer from Amazon for under $25 and measure actual temps at various locations. You might PM geordi for the readings he got a while back; I know he posted them but finding the post is another matter

e010584 · **Posted:** Thu May 23, 2013 10:32 am

More good thoughts. No issues loosing coolant and no changes with thermostat change or fan clutch. The viscous heater clutch would have to be engaged to be an issue and it is apparent that it is not turning.

Glend · **Posted:** Thu May 23, 2013 12:23 pm

You won't be able to tell f the radiator is blocked by simply trying to flush it as the flush can bypass the blockage and flushing solutions will not remove the stuff, only rodding out the tubes can clear it. Once again get a radiator pro to check the flow then move on to other things from there.

e010584 · **Posted:** Thu May 23, 2013 12:38 pm

I had already had the radiator done on my CRD, so swapping it out alleviates any ambiguity but, based on my previous observations comparing the operational characteristics of the two, I still believe my wife's CRD is somehow getting more heat input. The cooling system is fully adequate for any of her day to day driving around town and his only taxed when we are heading out of town up the hills into the mountains. This also supports some of the EGR thoughts in that higher EGT's would obviously drive higher heat input compounding the issue.

e010584 · **Posted:** Thu May 23, 2013 11:05 pm

From the FSM:

NOTE: An EGR Valve that is stuck partially open can cause this DTC to set. Hard starting, rough running
and black smoke from the tailpipe are signs of an EGR Valve that is stuck open.

None of these apply, so is the EGR valve fine?

flash7210 · **Posted:** Fri May 24, 2013 9:48 am

You should find a way to removed, block off, or disable your EGR valve.
Your engine will last a lot longer.
The FCV butterfly is pretty much a useless item. As long as it stays open
It's fine.
I don't trust any of the gauges in this thing. Get a temp gun and keep it with you.
Drive up a mountain and when it gets hot, stop, pop the hood, and shoot the engine
to get a more accurate temp reading.

e010584 · **Posted:** Fri May 24, 2013 11:12 am

Not convinced it's the radiator but desperation is setting in and I'll probably do the swap tonight to put it to a test tomorrow.

audiboy86 · **Posted:** Fri May 24, 2013 12:02 pm

I wouldnt remove them i would just take it down to radiator shop and ask them how much to rod the radiator. Also what Coolant type are you using?

e010584 · **Posted:** Fri May 24, 2013 12:05 pm

Already had mine rodded and functionally checked on mine. Would definitely have hers rodded while out.

papaindigo · **Posted:** Fri May 24, 2013 12:30 pm

Ok but I'll try one last time. Before you go to all the trouble of swapping radiators why not spend $20 or so, might could borrow one from like AutoZone, on a IR temperature gun and check what the actual temp under load is on both vehicles? As noted earlier what appears to be over heating could be a bad temp sending unit or a miscalibrated gauge (TSB is out on this). Not saying that's the problem but I do like to start with simple approaches before moving on to more complex ones.

Yes I know you are in Phoenix and yes I know how hot it can get there. I've been there and my son stoutdog's 06 CRD spent 3 years in Tempe while he was in grad school at ASU. The cooling system is plenty up to the heat as his gauge sat like a rock just left of vertical even pulling out of the valley on the way home (2 of us in the KJ plus several hundred pounds of stuff plus kayak on roof plus 1000 or so lbs in 1000 lb empty weight uHaul 5X8 trailer) at 105F, we left in the early am before it got really hot. On the other hand my 05 appeared to overheat pulling an 1800 lb boat on a dead flat Florida road at 90F until I had the temp gauge reflashed per the TSB although I'll confess I practically had to put a gxx to the head of the service writer who wanted to do all sorts of stuff for, err to, my wallet before they would hook up the flash tool even with the TSB in hand.

e010584 · **Posted:** Fri May 24, 2013 12:41 pm

Already have an IR temp gun but can only check the one vehicle under load at the moment due to mine being down with a cracked head. Don't believe I'm getting bad indication on the wife's as it has had other tell tale signs of thermal distress during overheat events. We've had mine loaded to the hilt and pulling trailer up the mountains with no electric fan without ever having issues.

The radiator is already out of mine and had been rodded and it certainly wouldn't hurt to have the wife's rodded, so it's not really a wasted effort. I actually need to get them up the hill for the summer break and looking at doing a solo trial run up the hill for the holiday weekend.

papaindigo · **Posted:** Fri May 24, 2013 1:10 pm

Understood. If you have the IR gun you could pm geordi for the readings he pulled off his; no overheating indicated as I recall but it's good baseline data. Another thing to consider - does that vehicle have the OEM fan clutch? It's pretty well know that clutch is weak at best, prone to early death at worst, and won't fully engage until well up into an overheat cycle (ca. 230F engine temp IIRC). If so I'd recommend tossing a Hayden 2905 clutch in there while you are at it - much stronger clutch and kicks in at an engine temp more like 200F so it stops the rise before it starts. Works fine on stoutdog's 06 even with kap's modified tstat with a 195F tstat.

I saw a post asking about the coolant you are using. I presume you know that only HOAT coolant should be used (Mopar, Xerex G-05, or Motor Craft Premium Gold). Using or mixing in any other coolant, including "universal", has been know to gunk up radiators and heater cores.

e010584 · **Posted:** Fri May 24, 2013 1:15 pm

Hayden fan clutches on both. Will probably swap them just to further trouble shoot knowing everything worked fine on mine. Understood on HOAT.

geordi · **Posted:** Fri May 24, 2013 1:29 pm

I'm here, and Papaindigo has the right idea, always check the simple stuff first.

I don't remember the exact numbers that I got with the infrared gun. I pointed it at the head behind the alternator (Not the valve cover, it is tough to get there) and at the thermostat on the front passenger corner. At normal operating temperatures, the readings I got closely matched what the thermostat was supposed to be reading.

At the time, I had an in-hose thermostat that was (IIRC) 185 degrees or so, and that is what I remember getting from the factory thermostat housing as well as the head. The main thing is to validate whether the gauge is reading accurately on the dash, against the actual IR. If not, then you have the gauge / sensor failures, which I would suspect are FAR more common than actual cooling problems.

On the clutch fan - ANY clutch other than the Hayden severe duty unit... ARE JUNK. I wouldn't trust the factory ones to survive longer than the first 100 miles. Whether you pull out the metal fan and replace it with the V6 plastic fan is up to you, but absolutely, get that clutch out of there.

CRD Overheating - The Tale of Two CRD's

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