Re: Coolant temp on the high side, car drives fine w/ VAGCOM log graph

fastalan

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Re: Coolant temp on the high side, car drives fine w/ VAGCOM log graph

I seem to have a problem with my coolant temperature reading on the high end however the car drives just fine.

Below is the graph generated by my VAGCOM log. note: If the pic is too big I will try to fix it afterward.



Here's the story

1) Went to Cypress Mountain to check out the snow last weekend and on my drive up to the mountain, 4th gear accelerating, the red coolant warning light along with the alarm came out with temp needle moving fast toward the red zone. Since I can't just stop right away on this stretch of road, I slowed down dramatically, shifted into third gear, pretty much crawling slowly. As soon as I slow down the temp started to drop back toward normal and by the time I've found a safe place to park, the needle was almost back to the normal range. Turned off the engine, opened up the hood to check around, the radiator, the hoses, the engine bay just did not feel like it has been overheated. Ambient temperature was about 0 degree Celsius. So I got back driving, again in third gear going uphill with a constant speed. Then as soon as I shifted into 4th gear and started accelerating with any kind of load, the needle started to move toward the right. I decided to turn around and on the way back I turned on the heater (the heat was pretty hot) and carefully drove home without drama.

2) Coolant reservoir is a bit lower than the min, about 0.5 cm lower. I noticed a slight drop in coolant early this year, and including topping up this time, I've put in about 300-400ml of coolant.

3) Tried to look around the car from the topside of the engine bay, including the belly pan near the timing belt cover, and hoses that I can physically see, I really can't spot any coolant leak.

4) The above graph is from today's drive to work. I log it and I can see that if the sensors were telling the truth, the temperature reading seemed really high! It seemed to me that once the car has warmed up, with temp at over 110C, the two radiator fans, as hard as they spin, can't seem to drop the temp down. However, turning the heater on max did reduced the temp reading quickly. You can see from the graph I had to park the car, let it idle in order to cool down because during one section, again, I accelerated under 4th gear and I can see the needle wanting to move to the right. I also let the car idle quite a bit at the end also trying to reduce the coolant temp, both time with heater on maximum. The coolant warning light did not come out today.

5) Coolant has been flushed once by the dealer back in Sept 2012, 60000 km. I now have over 150000 km.

6) Coolant color is real nice pink, no dirty stuff inside the coolant bottle. The two needles (the sensor pins) seem clean enough. I refilled with Canadian Tire OEM Coolant for Porsche/Audi/VW, meets VW TL 774F.

7) My car has the VW Canadian spec block heater, if I plug it in a few hours before I drive, the temp needle will register a few clicks higher from left, but once I started the engine with coolant flowing, the temp needle do drop down right away. So at least the coolant is still being pushed around this part of the system.

8) I change the engine oil a few weeks ago, it looked just like what used diesel oil should look and smell like.

What could be the problem causing the high temp while driving? A dying and weakening water pump? Bad sensor? Could some kind of partial blockage or area with bottleneck, like the far end of the cooling system, around low pressure EGR or engine oil cooler area, cause this problem.

What other VAGCOM parameters can I tick to log in order to provide more data to help the diagnosis?

If I drive gingerly, with the heater on, I can more or less keep the coolant temp in the 95c to 110c range, but this is not a normal behaviour and it definitely won't work in summer.
 

turbobrick240

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Maybe a blockage in the radiator, or failing thermostat?
 
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fastalan

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Maybe a blockage in the radiator, or failing thermostat?
Been reading some similar stories on this forum regarding 09 models and my car is 2009 built 2010 car.... if it's just a worn out radiator, it can be fixed. Even a blown head gasket can still be fixed but I rather not see this happening. I have to get the coolant checked first by a shop to see if this can eliminate head gasket issue.
 

fastalan

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Richmond BC
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I've just checked the upper and lower radiator hose after a drive. Car all warmed up, the upper hose is very warm and the lower hose is "very cold". Could this point to any trouble? The engine continues to run hot via VAGCOM monitoring and the only way that I can drop the coolant temp down is by running the heater.

note: reading through various car webpages, could this be a bad thermostat?
 
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meerschm

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I would find a new thermostat.

an older log on my car looks quite a bit different. this is coolant temp

 

meerschm

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you can look in the HVAC controller and log coolant temp and temps in the plenum, but this will only verify that heat is getting out of the heater core. if it is sluggish, you could suspect a clogged heater core.



I think there is really only one sensor in the actual coolant path

I also would suggest a real coolant flush. (hooking a hose to the system and pushing water through in various directions and paths, collecting coolant for proper recycling)

this would mean accessing and disturbing coolant hoses.
.
 
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turbobrick240

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I'd start with a new thermostat- which unfortunately is more difficult to access on these cars than most others. If that doesn't fix the problem, I'd suspect a blocked radiator.
 

fastalan

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The owner of this youtube account did a timing belt plus thermostat replacement video. The part for the thermostat starts at 21:35

https://www.youtube.com/watch?v=hRgsWbJXhXs

It looks like a nightmare really....

I once had a fault code relating to the valve position of the high pressure EGR valve, I don't remember the exact code. I was trying to remove the EGR valve and attempt to clean it out. The whole system from the throttle body, egr valve down to the charge pipe are really jammed packed behind the radiator with very little room to work around. My car also has the VW Cold Weather Intercooler Repair Kit installed right between the EGR valve and the plastic charge pipe, making it almost impossible to disassemble anything. Maybe there is a trick or a proper procedure to take things apart that I just don't know. So at the end I simply did a good clean out of all the gooey sludge inside the intercooler lower pipe and the problem simply went away.

So looking at the video, changing the thermostat pretty much requires taking almost everything from the throttle body to the down pipe apart .... this looks like a rather complicated job. Maybe I have to take it back to the dealer because the modification of the intercooler kit was done by the dealer.

I haven't scheduled my emission fix yet but at this stage, I highly doubt my cooling system can handle the extra thermal load after the fix has been done.
 
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meerschm

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at this point, if you have the fix scheduled, and do not see any MIL (check engine light)

I would make an appt, and take it in.

after the fix, they really should be on the hook for anything that makes the light come on.

(the Canadian fix may differ, so check the terms.....)
 

fastalan

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Mike, you are smart guy, that's exactly my tactic :D

No MIL light, no code, potentially a bunch of parts to take off, no work manual to follow, not nice to work on cars outdoor in Vancouver's rainy November.... I have good experience with this dealer anyway both in past service visits and parts, so I will let them tackle the issue this time. Hopefully it is not something too serious.
 

fastalan

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Update:

New thermostat did fix the overheating issue but barely a month later, problem again. Coolant dripping down from the center front area of the engine, right around the approximate area of the thermostat. The Tstat housing looks dry from the top but I can't really see anything further below. One of the cable running north south below the engine is all covered with coolant, also the fabric covering the oil pen is also all wet. I noticed the leak when I took a look below the car this morning then see a drip of colored fluid out of the hole from the dust shield.

Half of the coolant is now gone from the reserve bottle... I did periodically check the coolant level after the repair but after couple days of normal operation, I thought all are ok, until today... Dealer did the work so the car will have to be towed back to dealer on Monday, not going to drive it.

Overall so far, not a good experience.
 

fastalan

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The thermostat part number 03L121111AC has four coolant outlets (see below picture).



I did a very careful visual inspection and it seems that for outlet A, B and C, these three coolant outlets are perfectly dry, no sign of leakage. The D outlet is situated behind the main cylindrical body of the thermostat. I don't have the tool to view this area (perhaps an endoscope would work), but the wire harness that loops from top of the engine, around the oil filter canister happens to continue loops below the area near the D coolant outlet and that harness at its lowest point is accumulating and dripping coolant. There are also wet areas deeper down, I can't exactly identify the location of the engine, maybe part of the cylinder block wall (forward side), but the wet area is pretty much in close proximity to the D coolant outlet.

Does anyone know where does the D coolant outlet lead to?
 
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fastalan

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If we view the video link in post #8, starting from 24:42, the presenter of the video talked about the 2nd hardest part and he was referring to a pipe that extend from right to the left with the O-ring. I believe this is the pipe that connects to the D outlet. If you freeze the video clip at around 23:27 ~ 23:28, you can also see this pipe extending horizontally in front of the front block.
 

fastalan

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I was able to view a portion of the outlet D (or inlet D) of the thermostat, using a flashlight through a gap on the left side of the intake manifold. I can't say there is any leaking, the plastic part seems clean enough and the fitting tight.

Below is the picture of the belly pan. Coolant seems to accumulate on the left passenger side, toward the rear. Could the location of coolant accumulation indicates other leaking issues such as water pump?

 

meerschm

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any leaking coolant will head for the lowest part of the plastic pan. so where it accumulates may not provide a lot of insight to where the leak is.
 

fastalan

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Hello everyone,

Yesterday:

- wiped out the belly pan as clean as possible
- rolled back my car to leveled drive way, coolant was about 0.5cm below the minimum line, so I refilled the coolant up to the min level and marked the coolant level with felt pen
- drove for 25 km in the morning and check coolant level every couple km, no changes in coolant level
- took belly pan off, notice minute accumulation of fluid, but the belly pen was still too dirty overall to pinpoint if these fluids were road moisture or new coolant.
- drove car as usual for the remaining of the day
- end of day I washed the belly pen as clean as possible

This morning
- installed clean and dried belly pan
- moved car back to the exact same level location where I refilled the coolant yesterday, engine completely cold, same coolant level as yesterday
- went out for a 15 km drive with a couple 2nd gear full throttle acceleration
- dropped the belly pan and below is the picture



- fluid accumulation toward the back of the belly pan are dirty road water
- however, the couple drops of fluid, on the lower left section of the belly pan, 10 inches right from the second belly pen mounting hole, is colored (pinkish ~ orangish), with thicker consistency then the dirty road water. This is definitely coolant.
- if I measure 10 inches right from the 2nd belly pan mount point, this leads to the charge pipe and you can see in the picture, a drop of fluid



- a closer look


Now I don't know if this is new leak or remnant of coolant from the bigger mess I discovered a couple days ago, or coolant remnant from when dealer changed the thermostat (almost a month ago..).

Making this diagnosis process even more complicated, when dealer changed the thermostat, they did overfilled the coolant bottle, an inch above the max line. Since I didn't have any tool to siphon out the extra coolant, I just left them in. The big leak discovered couple days ago might have been coolant expelled from the coolant bottle during normal driving, and on that same day, I drove the car in and out of a underground parking lot with an extremely steep ramp multiples time. I am not certain under what kind of condition would overfilled coolant get expelled out from the coolant bottle.

Right now, I don't have any conclusion. Ideally one might have to completely wash clean the engine/oil pen, lower block, everything around the thermostat with warm soapy water, with a completely clean area, then observe for new leak. To tackle this issue further is beyond my technical ability.

I plan to drive the car for the rest of this week and observe in the morning if the coolant level stays at the same level where I marked it with the felt pen. Will continue to check the belly pan for any new drip.

Any recommendation or other areas I should keep an eye on would be greatly appreciated.
 
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fastalan

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any leaking coolant will head for the lowest part of the plastic pan. so where it accumulates may not provide a lot of insight to where the leak is.
Yeah, my driveway is slightly inclined and driving up to the rhino ramp, might have shift the fluid. I really should check the coolant level on a completely level ground.
 

meerschm

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fastalan

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Richmond BC
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Yes, it's going back to dealer tomorrow. I can confirm there are accumulation of fresh coolant below the thermostat area along a horizontal ridge of the lower engine block. Some of the spots I really have to take a flash light and look very deep through an angle. I took some pictures and will show them to the dealer tomorrow. It looks like somewhere the coolant is leaking out from area behind the thermostat, then the leaked coolant flows down along the front of the oil pen, soaks the oil pen fabric cover, and depending on the amount of accumulation, car's motion and the parking angel, these can either drip out toward the oil plug side or through some other passages. The amount of drip has also been somewhat inconsistent through my observation the last couple days.

I was reading the thermostat post by mctdi
http://forums.tdiclub.com/showthread.php?t=371430

My back hurts just by reading through his thread. It maybe easier to fix had the engine been mounted longitudinally on another car, like an Audi A4 or on a VW pick truck. Really, what a pain just looking at the layout from a repair point of view.
 

fastalan

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Here is a good thermostat thread pertaining to this generation CR engine

http://forums.tdiclub.com/showthread.php?t=371430

Dealer still working on the car, looks like they need some new parts and have to redo everything again, finger crossed.

Things like this, for an "ordinary" car owner, sadly, is reason enough for me to not recommend buying used gen 1 car with high mileage or without some kind of solid new car warranty.
 

fastalan

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Got my car back from dealer about a week ago, so far so good, no more leak. I picked up a LED USB endoscope from Amazon that can be connected to my Android phone. It has semi flexible tube good enough to snake deep in for a close look.



Previously this connector, and the entire area along the front of the block, including the base of the oil dipstick tube were all covered with fresh sticky coolant. The picture resolution isn't super clear but good enough for general monitoring.
 

740GLE

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I've seen those smart phone snake cameras advertised, I just need a good excuses to pick one up, maybe in the next few years image quality will be crazy good then I can justify the purchase.
 
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