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Discussion Starter #1
Hi folks!

I have a 2000 VW Jetta TDI, in Sault Ste. Marie, Ontario, Canada.

I'm the second owner, taking it over in mid 2006, with about 186k km on the odometer. The car is silver, and has been far more reliable than any other car I've owned up to this point (and fun, and gets great mileage when you're nice to it, and decent mileage when you're having too much fun).

I've had a Scangauge II plugged into the machine since the middle of 2008, and it's helped me learn what does and doesn't promote better mileage with the car.

About me: I just wrapped up school, and being in the transition between school and the World of Work again, need to keep it in good running order without the use of an outside mechanic.

My car is now rolling around 325-330k right now (forgot to take a look at it before posting), and it's almost on que for the timing belt as far as mileage goes given the last time I had it done in 2007.

The past month, unfortunately, I've had my share of knocks with the car.

Mid April, a cracked pan on a sewer grate that was half a foot above the pavement, hidden in a puddle gave me a great scare.

And first week of May, the water temperature started rising. As most owners know already, the gauge on the instrument cluster doesn't give much indication of overheating -- the water temperature dial will stay up near the top of the dial through a pretty wide range of temperatures.

That scanguage seems to monitor a different temperature, because it was the only indication that I had a problem brewing, not the normal dial on the cluster. It was steadily, all winter, and well into spring, showing peak operating temperatures around ... 70-72C. Only a series of hill climbs up the escarpment in the middle of town here would make it go a degree or two higher, but that said, the temperature would always moderate to 70C.

The coolant in the overflow reservoir, when fully warmed, is maybe ... 1/2" below the min, and it's been on the slightly low side for some time, alas, but hasn't fluctuated drastically, indicating a coolant leak to cause this.

By mileage alone, I need to change the water pump and timing belt, so I'm embarking on that now.

The dealership out in Alberta, Canada I had the last timing belt done at, did put in a new belt, rollers, tensioner, and metal-impeller water pump, all.

I'm suspecting that there's an issue with the water pump, so the day after it was getting hotter, I parked the car, and it's only been run to put it into my parents' shop so I can do the timing belt on my own. No coolant circulating, then, temperatures will rise.

I certainly don't want to risk the water pump seizing and causing chaos with the rest of the engine as it puts the timing belt in a full stop.

Is there anything else that I should be checking regarding this overheating I had, while I have the car up on blocks? Or after I do the Timing belt/waterpump maintenance?

Thanks for hearing me out so far.
 

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Hi there, I'd look at replacing the thermostat too as that can give all sorts of temp issues and there's no indication wether it's already been changed or not, get a decent one though as I've heard of people having issues with the cheapy ones. Sounds like you've got most things covered though and I can't think of anything else off hand to suggest.:)

http://www.myturbodiesel.com/1000q/a4/a4-ALH-TDI-engine-index.htm

welcometomyturbodies
 

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While you have the engine "apart" you may consider replacing the temperature sensor (and "O" ring) and maybe the thermostat as well...

Is there any soot showing up in the coolant bottle? At the mileage and age of your car, a cylinder head gasket leak isn't out of the question, either...

All the best,

Yuri


PS: I assume your indication of 325-330 refers to kilometers rather than miles...
 

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Discussion Starter #4
Thank you for the input already -- I'll check into the thermostat and temp sensor after I pull the water pump tomorrow.

It'd be nice, in a way, if it were only a thermostat that caused my scare. That temperature fluctuation made me push up the TBelt job by only about two weeks from when I intended.

And yes, YMZ, the 325-330k is kilometers, not miles. No soot in the coolant, it's the normal pinky-red hue. And no coolant in the oil that I could see, in prior oil changes, or when I had the cracked pan.

I'll check things as best I can... at least this head will be easier to lift and change the gasket vs. the early Tempo I had years ago (no *AXLE* to remove on a Jetta before you take the head off, like that beast).
 

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When you pull out the old water pump, see if the impeller is loose on the shaft... If it was slipping, that would explain your overheating... (it happens regularly with the VW plastic/composite impellers, which is why many people prefer an aftermarket water pump... BTW: where did you get your parts kit?)

The thermostats on these cars can be tricky... be sure to clean the mating surface on the block really well (plastic "Brillo" pad), and don't over-tighten the bolts... use a new "O" ring... this is a common place for leaks, and once the engine's put together, absolutely no fun... Occasionally the plastic hose adapter that keeps the thermostat in place warps... only about $8 so many people just replace it...

Yuri
 

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BTW: where did you get your parts kit?)
Dieselgeek, way down form San Antoine. I live on a border town, it's trivial to hop the border to pick up fuel, food, parts, within reason. I've bought parts from the d(st)ealerships at times, and online on autopartsway.ca for the car before. The timing belt kit is important, and DG's kit and shipping matched autopartsway BUT had all the bolts and screws they throw in, too. So, that choice was easy.

And I read about the danger/horror of that plastic adapter/shroud long before, thank you for the reminder there. The thermostat, or the temp sensor and related parts for both aren't much to tack on to this.

xxxxx
Is there already a walkthrough here for the thermostat? If not, I can take pictures and mock one up to add to the fray.

Edit: I see there is a walkthrough for the thermostat here: http://www.myturbodiesel.com/1000q/a4/water-pump-replace-TDI.htm
But, not for the temperature sensor. If the TB/WP change doesn't yield a separated impeller as the cause for my rising temperatures, I'll check the both, and take pictures for the sensor so there's material for a walkthrough.
 

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There was no walkthrough since it's pretty simple but I just added it to the thermostat replacement writeup since it could be related to people thinking about thermostat problems. If you want to take pics of a new sensor or the old one pulled out, it would be helpful and I can add it to the article.

Here are the additions:
If you think you're having a glow plug problem that is solved by unplugging the cooalnt temp sensor, it's probably bad. You can verify this by reading it through VCDS engine measuring blocks, group 7. Here is a screenshot of a normal warmed up engine. On a cold engine, these temperatures should show ambient temperature.

To replace the sensor, look on the driver's side cylinder head. This view is on an engine out of the car, looking at it from the left side of the car. Remove the clip and pull the sensor out. Make sure the engine is cold or else the coolant system will be under pressure and spray out and scald you.

 

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Discussion Starter #8
My (initial) post-op timing belt change.

The car's back together after ... well, having to reposition the timing belt after the first no-start and struggle through.

First off, thank you all for your help and suggestions so far.

Post-Op:

  • I goofed with the Impeller pump position, and had to re-set the belt. It was advanced by about 4-5 teeth on that IP sprocket, which probably meant I was fueling the wrong cylinder at the wrong time.
  • I found that taking off the front cover and the right hand/passenger side headlight gave me better access to remove bits like the upper intercooler pipe;
  • The above gave me more access to look at the IP sprocket position. But I still needed a small flashlight and small mirror to sight the lock hole.
  • The water pump impeller didn't seem to be in trouble. There might've been some signs of coolant dripping from the water pump on the bottom.
  • The timing belt had quite a few cracks on it, on the outside, fine little ones that well... I wouldn't trust.
  • More surprising to me, was the fray of the outer side, and poor condition of my serpentine belt. I'm glad the Dieselgeek kit I bought included one, because I had only changed that last year.
  • Using some self-made tools to do the TB change did work, but of course I would not recommend that to anyone not willing to shoulder ALL responsibilities and liabilities for following that path. If I had not pulled a head off another engine before tackling this job, I would've been much more cautious, and probably bought or had a local machine shop make some of the lock-down tools.
  • I could not believe how much sand was stuffed into my car from over winter! This in part, is due to me not replacing the busted bottom engine cover / side skirts over several winters.
Next time around will be easier -- the only HARD part that stumped me was the Injector pump sprocket lock position. I will not stress this enough: sight this one carefully, use a mirror and a light, if need be, for those who are planning to do this job the first time.

So far on the test drive, about 8-9 miles worth, I didn't see any return of the rising temperatures that caused me to park and do the timing belt slightly ahead of plan/budget.

I'd say the temperature was down a little bit from normal.

I did spot the temp sensor after seeing the picture posted in thread by chittychittybangbang.
Mine is black, which from searching around about it, it appears that means it's one of the original sets used in the early MkIV TDIs (mine is model year 2000). I'll monitor the temperatures the next few days, and see if there's any problems under a bit more stress, or not.

I have a bit of coolant left over to top up if I do have to drain and check it next few days after I hill climb up and down the escarpment in town. That'll be the true test, because that was what I found was building up most of the heat the last time.

Now, I don't have VCDS/Vag-com to monitor my timing and do the fine tuning, but I did an initial mark and pray, and the gear positions at TDC looked pretty much as I'd started. As soon as I can, I will check on that. For now, i'll trust my ears, and the initial timing I had based on what the dealership did the last TB change.
 

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I like adapting stuff for my own tools aswell but what went wrong with the pump? How'd you manage to goof it up?:D
 
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