I've read through tons of posts, how-to's, and back-and-forth discussions here regarding HOAT coolant, CRD cooling problems and the when's/why's & how's of flushing these bizzarre systems we've got. But, I've not seen anything specific about a system as dirty as mine. Check out the photos at the end of this post.

Sorry that this is such a long post, I haven't found any others with problems just like mine, and I thought someone out there might want to see some of this. The specific questions that I have are highlighted in blue. If I've missed a helpful thread somehow - please, someone point me to it. Otherwise - here we go:

Summary - 2005 Liberty CRD, 94,000 miles.

Initially in the summer, I noticed car overheating under load (mostly on mountain roads - uphill). Gauge would nearly top out, but pulling over or heading downhill would cause gauge to immediately drop back down to normal. Driving around town, the car performed fine.

When winter came around, I started noticing that it would take forever for the motor to warm up (according to dash gauge), and cabin heater output was ice cold.

At this point, I mistakenly thought that the viscous clutch was bad because the fan would free spin, regardless of what the temp gauge was reading. Even with the radiator blocked off, the fan would still spin easily. (Turns out that it probably wasn't bad - the radiator just wasn't releasing enough heat to make the clutch engage).

Replacing the fan clutch made a little difference, but not much.

Next I replaced the thermostat, thinking it was partially stuck. My scanner would tell me that the ECT was at about 160 - untill I hit a sizable hill. Then it would climb rapidly. After replacing the t-stat, most of the symptoms remained, except the motor would warm up quicker, and to a more normal temp. (By the way - the thermostat was stuck partially open).

I have to note that the top radiator hose was always hot to the touch, making me think that I was getting flow from the water pump. (now that I compare it to the hose on my other CRD - I realize it was maybe not as hot)

Next I notice on the metal lines going to the heater core - one is too hot to touch, the other barely warm. BTW - am I correct in saying that there is no heater control valve, only a blend door to control heat output. Heater core should be getting full flow always. Therefore all the posts and the FSM stating that the heater should be "full on" when flushing (or turned off to keep scale out of the heater core) are incorrect?

I take the car to a pretty decent diesel tech who does a full cooling system diagnosis and checks the head gasket. It was he that pointed out that the radiator was ice cold regardless of t-stat, dash gauge, etc. He suggested that the radiator must be partially clogged. Also suggested that I try flushing the heater core.

I disconnected hoses going to heater, attach some lengths of 5/8" garden hose with various fittings, a funnel, etc.... and poured in some diluted radiator cleaner. Let it sit about 10 minutes. Backflushed under pressure. Repeated 3 times. Running the output hose into a clean bucket - I was able to catch quite a bit of crap. Looked mostly like sand with a few black flakes that looked like paint from the inside of a fitting or something. Hooked it all back up, burped the bubbles. Heater worked great, even when the viscous coolant heater wasn't engaged.

Took the car to a different shop that has the proper flushing equipment. Showed my little bottle of gunk, talked about symptoms. System was supposedly flushed, said he was getting flow. (Although, I'm not sure how much - see photos below).

After this, feeling that the radiator was still cold, I decided to start tearing into it. Starting with the radiator and working back to the water pump if necessary. It took about 4 hours to get the radiator and hoses out - dealing with the fan/clutch (again), shroud, radiator support, charge air cooler, airbox, battery, etc.

At this point, I have to ask: has anyone else had the trouble that I had getting the radiator out? It's not as simple as the FSM makes it out to be. The charge air cooler (which is also indirectly fastened to the a/c condensor) is hooked on to the front of the radiator with interlocking tabs. Which means in order to lift the radiator high enough to disengage the plastic pegs that drop into the grommets in the frame - I had to remove the grill, remove the hood latch support, take the electric fan loose, then push up the whole mess and prop it in position with some chunks of 1x2 under the CAC. Only then could the radiator be lifted high enough to disengage the bottom end. Anyone else run ito this?

So anyway, after wrestling the radiator out and pointlessly peering into the various holes - I stuff a garden hose into the outet and turn it on full blast. Seeing more water coming back out at me than out of the other end, I toss the the radiator into the back of the other Libby and drive 25 miles to the nearest radiator shop. He does a flow test, then soaks it overnight in some kind of aluminum-safe cleaner, attempts another flow test in the morning - then calls me, anxious to cut the tank off to see just what could be plugging this thing so solidly. So we're looking at it together with the inlet tank off, talking about the evils of HOAT coolant, and the whole while he's pushing one of his skinny flat rods into different tubes - I don't think he was able to push all the way through any of the tubes except for maybe just a few.

This guy's been in business since the 70's and claims he's never seen one like this. Especially on a car that's only 5 years old.

So, is this what the HOAT coolant does? I'm thinking that sometime in the last 5 years, when this Jeep was mostly driven by my son - that maybe someone who did an oil change also did him the "favor" of topping off the coolant level with something wrong? Or maybe even some dipstick mechanic at the Jeep dealer when they did one of the three EGR replacements that have been done.

In the pictures below - could the stuff be some kind of leak sealer maybe?

When I took the now dis-assembled radiator back to the shop that did the system flush - he tells me that it looks to him like it's casting sand that was left in the block.

So now, as I sit in Colorado, waiting on a radiator coming from Detroit via Tampa, I'm wondering what I should do about flushing the system out before I put the new radiator in? The guy who thinks the mystery material is sand claims that it's probably all in the old radiator now, and I don't need to do anything radical as far as flushing goes. Says it will go another 100,000 miles. But then again, this is the same mechanic who thought he was getting flow through the radiator when he "flushed" the system!

Anyone with any advise - please jump in. Otherwise, my plan is this:

Once the radiator and hoses arrive, (providing we've got no sub-freezing weather coming) I going to take the garden hose with a pressure nozzle, hook it up to my water heater, and spray into any and every hose, port, etc that I can access. I'm leary about trying to use any type of chemical cleaner (trying to fill the block, hoses, viscous heater, etc) because I know it's gonna take 3 - 5 hours to get everything reassembled, and I don't want any residual cleaner sitting that long anywhere in the system. Is there anything in the system that might be damaged from this flushing with garden-hose pressure?

After every thing is connected I'll do several fresh water flushes till I (hopefully) get clear water draining out. Then, blow out whatever I can with the shop-vac trick. Then probably a couple more flushes with distilled water. Then a refill with Zerex G-05 diluted 50/50 with distilled water. Any special additives that ought to go in the tank?

Before I do all the freshwater flushing - should I use a chemical cleaner after the system is up and running? I really don't want to knock anything loose that's gonna plug up the new radiator. Who knows how much crud is lurking in the block, viscous heater, etc. And since I'm not sure what the gunk is - I don't know what it would take to disolve it, or if it even can be disolved. Some of the stuff truly does look & feel like fine casting sand. But there's also some shiny little flakes and some globs of stuff. Note - I took the pix a couple of days ago when the radiator was still damp, having just come from the radiator shop. Now everything has pretty much dried to the same consistancy - soft crumbly powder.

I'll probably take the old radiator and bandsaw it into chunks today and see if I can soften up the crud with some various solutions.

I'm thinking maybe I'll do the citric acid flush - any reason that I shouldn't? I've already resolved myself to the possibility of having to remove the radiator again after flushing and having it back-flushed at the radiator shop if necessary.

Should there be any reason to get into the water pump at this time? I'm pretty sure that the root of the evil is the plugged radiator, but......? I'm planning to do the whole timing belt/idler/WP thing on both CRDs this summer when it's a bit warmer. I assume that the pump is working since I'm now getting heat in the cabin and can see flow through the overflow tank.

Any advice will be greatly appreciated. I'll post more info as I get results.

Doug


Most of the tubes of the radiator are plugged solid


The entire inside surface of the radiator end tank is coated with a thin layer of pinkish white powder. There's also some big mounds of this substance stuck in various places. They break off easily and crumble to dust. You can also see a pile of goo that had collected in the bottom of the tank. I wonder how much of this stuff in collected in the various nooks and crannies of the cooling system?

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2006 Liberty CRD Limited
Fumoto, Samco, V6 airbox and nylon fan, Gen 2 fuel head, Kennedy lift pump, Magnaflow, Autometer EGT, boost and trans temp gauges, DieHard P5, BFG 235/75-16 Long Trail TA's, PowerStop brakes & Prodigy P3, AirCoils, Euro TC, GDE FT Eco Tune

2005 Liberty CRD Limited
Flipped Spare

2011 17' Casita Spirit Deluxe

A little bit more:

I don't know if this is significant, but - as I'm getting ready to cut the radiator into pieces, I notice the discoloration that you can see in this photo. Looking straight across the radiator from the inlet side, you can see that the residue that's collected below the line of the outlet is different from what's collected above the outlet. The coating toward the bottom is thinner and more powdery. Above - much thicker, darker, and a lot more of the "flakey" material. It's a mystery to me.



Also - I cut part of the tank off of the outlet end of the radiator, and this is what I found. The whole inside of the tank and the end of the core is coated with a thick snot-like substance. It's still wet and slimey after sitting empty for 3 days. This slime dries out in about 15 minutes, and leaves behind a thin, soft film. I imagine that in a couple of days this will dry to the powdery residue that I've found everywhere else.

With what I've heard, I'm thinking now that this is definitely a HOAT compatibility issue, and that sometime in the past someone added something "un-approved" to the cooling system.

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2006 Liberty CRD Limited
Fumoto, Samco, V6 airbox and nylon fan, Gen 2 fuel head, Kennedy lift pump, Magnaflow, Autometer EGT, boost and trans temp gauges, DieHard P5, BFG 235/75-16 Long Trail TA's, PowerStop brakes & Prodigy P3, AirCoils, Euro TC, GDE FT Eco Tune

2005 Liberty CRD Limited
Flipped Spare

2011 17' Casita Spirit Deluxe

I think this is the best guess.

Long read, so I may have missed this point:
You can probably assume that your heater core is contaminated as well.

I don't think that the citric acid flush will do any harm but you need to ensure that operational temperatures can be met (working thermostat) to be able to flush out all of the acid.

viewtopic.php?f=5&t=56486

The issue, for me, is I have removed all the coolant that I could and the refill is still only 9.5 liters of a possible 12.5. Either the specs are wrong or coolant remains (hides). You don't want that much acid still in your system. Purists don't even want that much tap water in their systems!

Probably the best guess although who knows what. The best I can tell is OAT antifreeze does not like to be mixed with the old green antifreeze and will cause cloudyness and some perciptaion of solids out of the fluid. HOAT is not supposed to behave that way if mixed with green but doing so is not advised. I've also seen stop leak do strange things; totally clogged my tstat on a 1993 Cummins with a black goo. So if I was to guess someone refiled with a mix of OAT and green antifreeze and tossed in some stop leak just in case. I do agree that your heater core was likely plugged but you say that after backflushing the heater works fine so I suspect the core is ok. I cannot answer your question about flow thru the heater core except to note that 1) there is no visible flow control valve on the heater lines as there was on my Dodge and 2) both the 2005 and 2006 FSM text regarding the heater core say fluid flows at all times. Since the flow is from the tstat, to the viscous heater, and then to the heater core and nothing about the viscous heater suggests a valve inside it I'd assume the system is free flowing which I find a bit of a surprise. So go with the citric acid flush. I have yet to try a system backflush followed by a drain to see if it clears all the antifreeze but I can say stoutdog did a cycle of 7 drain/fill with 2 gallons demineralized water/repeat and that cleared all the antifreeze color out of his system so it should do the same for citric acid.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

Since it's near impossible to remove all the water in a system after a flush if you were to use premixed 50/50 you would end up with too much water and not enough freeze protection

I've always added half the total cooling system capacity of stright antifreeze then water. That way I'm assured of having close to the correct amount of antifreeze in the system.

For your heater, since you know what's inside I would give it another back flush with the hose and call it good.

Could it possibly have had dexcool put in it? The color is closer to G5 then the yellow stuff

On the possibility of casting sand a little birdie told me Chrysler instructed VM to get their aluminum castings from India

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Atlantic Blue 06 CRD Limited (his)
Joined by a 2000 XJ Classic (hers)

Casting sand is not impossible although doubtful but what is described is definitely not casting sand.

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Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

I watched the flushing of a Hercules D2300 water jacket last week and was stunned by the amount of casting sand and other junk that came out of the water jacket.

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Mail Rated 2005 Red CRD Sport with large rectangular hole in top right behind the EVIC and above the heated leather seats.
2004 Jetta TDI

I would look into mounting a coolant filter if you think that more casting sand is lurking in the block. NAPA makes one that gets good reviews on larger diesels. May have to get creative to make it fit,though.

I worked in a radiator shop in another life (family owned business) tearing down and rodding out radiators payed my way through school. In my experience your pictures look just a little worse than average, although I do agree with your guy that it is horrible for a 5 year old vehicle. Cross contamination is probably your culprit.

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2006 CRD GDE ECO/HOT Tunes and TCM swap and HD Mopar Torque Converter, EHM
2003 Jetta TDI 155K all stock
1957 International V8 Diesel

Here is an interesting web link I found of a class action law suit handed to GM, from customers who experienced engine catastrophes from using their version of antifreeze called "Dex-Cool".

http://www.dexcoolsettlement.com/notice.pdf

There may be some truth to cross contamination and I wonder if mixing Hoat and Dex-Cool could create the brown sludgy coolant mix found in the sectioned radiator pictured above.

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2006 Liberty Limited CRD, Deep Beryl Green, Yeti tune, Arp studs, new cams, rockers, lifters, TB. "Green Monster"
2005 Liberty Sport CRD, Deep Beryl Green, GDE Hot Tune, ARP studs. "Rocket"
1982 Fiat 124 Spider Convertible. "Fiona"

It's been known for around 10 years or more the trouble that Dex-Cool causes

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Atlantic Blue 06 CRD Limited (his)
Joined by a 2000 XJ Classic (hers)

I didn't get the memo.

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2006 Liberty Limited CRD, Deep Beryl Green, Yeti tune, Arp studs, new cams, rockers, lifters, TB. "Green Monster"
2005 Liberty Sport CRD, Deep Beryl Green, GDE Hot Tune, ARP studs. "Rocket"
1982 Fiat 124 Spider Convertible. "Fiona"

I sure did,at least once a week I'm replacing lower intake gaskets on a GM V6(3.1/3.4/3.8/4.3).I even have done a few 3.5's and 3.9's in which GM claimed to have fixed the issue with OAT coolants and gaskets.


OAT coolants(DEXacool,any prestone coolant,most "green" coolants found now,and any CAT coolant) is known to eat some plastics and if you had some OAT coolant in your system could be the residue from the plastic parts in your cooling system.Another reason if HOAT coolant was always used is the coolant change interval was to great,sure they claim it can go 5 years or 150k but in reality it's more like 3 years and 50k max before you need to flush it.Cast iron block and alloy head does not mix well with any coolant for extended periods of time.

Most green coolants (i.e. Prestone) are IAT (Inorganic Acid Technology), not OAT (Organic Acid Technology). Dex-cool (OAT) was unique in having additives that eat certain plastics. VW has used OAT coolants for years, and while you can add Dex-cool as a topoff, it is strongly recommended to use the OEM G12 coolants instead. The VW system is completely sealed and normal coolant changes occur during timing belt changes on a TDI - every 100k miles - since the water pump is driven by the belt and is a good thing to replace while you're in there, just like the CRD. The G12 coolant leaves the inside of the engine looking like the day it was cast, so OAT coolant isn't bad by design. GM screwed it up.

The CRD uses HOAT (Hybrid Orgainic Acid Technology) coolant. It seems many automakers are switching to this style of coolant. From what I know, it can be mixed with standard "green" IAT coolant without issue, but then the service life of the mixture becomes that of the IAT coolant - a few years at best. I don't know what effect mixing OAT (or Dex-cool) with HOAT has, though.

I did a bunch of research on coolants recently for work and it is astounding how many variations and formulations there are, even within the 3 basic types. To play it safe, I wouldn't mix types whatsoever except in dire emergency and even mixing different brands of the same type would make me nervous.

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'02 Jetta TDI Wagon 5 spd (mine)
'10 Outback (her's)
'05 CRD Sport (hangar queen)

Excellent thread with lots of good information.


Correct me if I'm wrong but here is what I gather.


1. Only use specified HOAT coolant.

2. Don't mix coolants.

3. Don't wait long to flush system and replace coolant, 45,000 miles / 2.5 years max.

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2006 Liberty Limited CRD, Deep Beryl Green, Yeti tune, Arp studs, new cams, rockers, lifters, TB. "Green Monster"
2005 Liberty Sport CRD, Deep Beryl Green, GDE Hot Tune, ARP studs. "Rocket"
1982 Fiat 124 Spider Convertible. "Fiona"

If you buy the Zerex G-05 stuff, which is 5-year coolant, I'm sure 5 years is fine...

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2006 Jeep Liberty CRD, Limited
GDE Eco Tune, GDE TCM Tune, Bauer 203* Tstat, Amsoil EaA 201 Filter, Clean MAP, Samco CAC Hoses, Magnaflow Muffler #12226.
New Mopar Fuel Filter, K&N Filterminder, Fumoto Oil Drain Valve
225/75R16 Hankook Dynapros

Every single prestone coolant on the market today is a OAT coolant regardless of color.You can not just assume that if it's green it's a IAT coolant anymore as all the "universal" and "all makes/models" coolants are green and OAT.

Indeed. I see that. It appears Prestone doesn't offer the "classic" green coolant any longer. Zerex still offers a IAT green coolant, and I'm sure there are others. But you are absolutely correct - color really means nothing. Pink, red, blue, green, yellow, orange, purple - they are all coolants of varying technologies and manufacturers.

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'02 Jetta TDI Wagon 5 spd (mine)
'10 Outback (her's)
'05 CRD Sport (hangar queen)

OK, so I've come to the conclusion that whats plugged my radiator is most likely NOT casting sand. Upon closer inspection - the consistancy of the substance once dry is more that of flour, no real graininess to it.

I'm pretty sure that this is definitely the result of some bad chemical reaction between the HOAT coolant and the god-knows-what that was obviously put in the system at some time or another.

I've taken some of the chunks of the radiator that I cut, small enough to put in a large coffee can, and tried dissolving (or even loosening) the offending residue by boiling on the stove in various cleaning solutions. Nothing I've tried so far has produced a result any better than just plain, cool, tap water. All it does is make the deposits soft while wet. It still takes quite a bit of work to knock the material off, even wet. Then when it dries it's a tough, thin film.

I've tried boiling in:

- straight tap water
- water with liquid dishwashing detergent
- tap water again
- strong solution of citric acid mixed with water
- strong solution of Zerex Super Radiator Flush mixed with water

All with the same result, which is basically nothing.

So, as far as the rest of my cooling system, block, etc is concerned - obviously the residue is there to stay. I don't think that anything I could do is gonna cause it to break loose.

As long as there aren't any major passages clogged or parts gummed up, I guess it's not going to do any harm. Who knows? I'm hoping that the thin film that I suspect is coating everything internally is not going to break loose and continue to clog radiator(s). I guess that I'm just going to flush the system as completely as I can with hose water 3 or 4 times, then distilled water a couple of times, refill with the proper mix and then.... hope for the best. I'll closely monitor the ECT and get the radiator flow checked again this summer when I do the timing belt, water pump, etc.

It's obvious that there are a lot of folks out there who understand just how evil this HOAT coolant can be. Unfortuneatly there are also some monkeys at Jiffy-Lube and the local stealers that don't get it. I personally am going to print some labels for the coolant tanks on my two CRD's that say "Zerex G-05 or Mopar HOAT coolant ONLY"....

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Oh, no! Maybe it's Ectoplasm !

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By the way - just for grins, I soaked a chunk of the radiator in some Klean-Strip Brush Cleaner. (Not that I would ever put anything like this into the engine). It's a nasty cocktail of acetone,methanol, methylene chloride, toluene and xylene. After soaking for about 4 hours - it actually did soften up the crud inside the radiator tubes enough that I could push a hacksaw blade all the way through. BUT - it still didn't actually dissolve it.

If there's any chemists or engineers out there who would like to investigate this any further - send me a message, and I'll mail you your very own chunk of my radiator you can play with.

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2006 Liberty CRD Limited
Fumoto, Samco, V6 airbox and nylon fan, Gen 2 fuel head, Kennedy lift pump, Magnaflow, Autometer EGT, boost and trans temp gauges, DieHard P5, BFG 235/75-16 Long Trail TA's, PowerStop brakes & Prodigy P3, AirCoils, Euro TC, GDE FT Eco Tune

2005 Liberty CRD Limited
Flipped Spare

2011 17' Casita Spirit Deluxe

[quote=If there's any chemists or engineers out there who would like to investigate this any further - send me a message, and I'll mail you your very own chunk of my radiator you can play with.[/quote]

You may be starting something.

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2006 Liberty Limited CRD, Deep Beryl Green, Yeti tune, Arp studs, new cams, rockers, lifters, TB. "Green Monster"
2005 Liberty Sport CRD, Deep Beryl Green, GDE Hot Tune, ARP studs. "Rocket"
1982 Fiat 124 Spider Convertible. "Fiona"

ColoCRDx2, I would like to know how many miles and months ago your cooling system was flushed!

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2006 Liberty Limited CRD, Deep Beryl Green, Yeti tune, Arp studs, new cams, rockers, lifters, TB. "Green Monster"
2005 Liberty Sport CRD, Deep Beryl Green, GDE Hot Tune, ARP studs. "Rocket"
1982 Fiat 124 Spider Convertible. "Fiona"