Hi all,
I have a 2004 Passat w/1.8T. Last Thursday I noticed coolant leaking from the front of the engine. Once home I was able to remove the timing belt covers to reveal the water pump leaking. After changing the water pump, I refilled the coolant but did not know of the bleed hole method at the heater core. I was able to restore the fluid I'd drained out to swap the water pump so I figured I was good to go. BTW, I ran the engine after I had filled the reservoir a couple of times and squeezed the hoses to get as much air out as I could. Anyway, test drove it a couple of miles with no issues. Needle on dash indicated 190 as it always had. Ran the car for two days with no leaks, issues, etc. Then on Monday while in stop and go traffic I heard a bubbling sound and noticed the dash gage climbing past 190. Pulled over and shut off the engine. When I checked the coolant reservoir, it was below minimum as some had boiled over. Had the car towed home where I filled the coolant reservoir and started it up to see if it would boil over again. It didn't. I then hooked up my OBD reader to see what temp the coolant was running at. It was right around 205 for about 20 minutes with the car idling. Took it for a test drive on the highway and the temp slowly rose to around 215 and stayed for about 5 or 6 miles. When I came to an exit ramp it rose slowly to 228. At this point I was thinking the thermostat was ticking so I changed it with a vw thermostat (189 degree). Refilled the coolant system using the heater core bleed hole method and went for another ride. The car still will creep up to 230 and showed evidence of coolant being released by the cap. Now thinking the head gasket was blown I tested for exhaust gases in the coolant. No exhaust gases were present after running the engine at around 205 degrees for 10 minutes. What's the normal operating temp of these 1.8's. I now realize the dash gage is absolutely worthless as it's programmed to stop at 190 for a huge range of actual temp according to my OBD reader. The only other issue with the car is a code for lean idle mix. I found one of the preshaped rubber hose elbows torn coming from one of the steel lines off the turbo feeding back along the passenger side of the engine. Not sure what it is. (maybe EGR function?) Any ideas on why it's running hot? Sorry for the length of post. I just wanted to make sure I left nothing out which might help with the troubleshooting. Thanks for any light that can be shed on this.
I have no documentation to actually back it up, but at 228f, your aux fan should have come on by then. Does it work when you turn on the AC? What is the outside temp where you are in the "United States"?
Thanks for all the feedback. As far as codes, P0171 lean bank 1 is the only code. I changed the CTS on the lower hose and the electric fan now turns on around 170 (according to the OBD reader) and stays on thereafter. I didn't sense any "higher" speed once the engine got to 228. After changing the CTS I took it for a test drive on the highway. For the first 7 miles it ran around 205 and climbed to 215 when at the off ramp waiting to pull out. I then turned around and got back on the highway but pulled over to let it idle in gear for a few minutes. After about 5 minutes it was at 228/230. I got out to check the reservoir to see if there was any bubbling going on. No bubbling but there was a little coolant dripping from the overflow outlet. Level in reservoir was right around max. No leaks from the CTS. Started driving home and the temp on the reader indicated 224 and then 221 after about 5 miles. It seems once it gets hot it takes longer to cool off. By the time I got home it was back around 208. Stopped at the bottom of my driveway to wait for my son to get off the bus. After about 5 minutes idling it was around 235. I stepped on the gas slowly bring the rpms to around 1400 and te temp immediately started to drop. within a minute it was down to 221. So now the big question, is this normal behavior for a 1.8T as far as temps and running scenarios? I never had the OBD reader on before the water pump change so I have no real knowledge of how the engine temp behaved in traffic or on the highway. As I said earlier (and has been noted elsewhere) the gage on the dash is useless. It only seems to have two settings, 0 and 190 regardless of the engine temps.
Tomvw - "NOTE: These temps are as the coolant leaves the radiator, not as reported to the ECU or shown on the gauge." How would one measure the temps at the lower hose as apposed to the ECU which, I assume, is where the OBD is getting its reading? Is the CTS also the temp sending unit or is that located elsewhere on the engine?
2002GLXV6 - I'm a little confused with the, "1ft fan level is on at 197º-206º (off at 183º-196º), 2nd fan level is 210º221º (off at 196º208º)". On my 1.8T the "first fan" (driver's side) is directly driven off the accessory belt so it's on anytime the engine is running. The second fan did come on when I turned on the a/c switch but, as I said earlier, came on again around 170 degrees following the CTS change. Prior to the CTS change the second fan would only operate with the a/c switch. My car is a 5.5 from what I can tell from the stickys posted above. Are some of the earlier 2004's equipped with two electric fans?
VAGguy - I'm located in CT and the temp while I was driving this afternoon was around 70. Where I stopped for 5 minutes 7 miles from the house was a strip of highway that was just paved this morning so the road was very hot when I got out to check the coolant reservoir. I figure that simulates August road conditions around here. I'm also assuming the little coolant I did see dripping from the reservoir overflow is normal for the conditions today. I'm just not sure as I've never paid this much time scrutinizing every fluctuation in the engine temp before.
Last thing is to change that stupid rubber elbow which is sheared off. That "100 seconds" of bleed air is annoying. Would that be responsible for the P0171 lean code? I have noticed the car does not have the normal zip since it's been leaking. Thanks again for the feedback.
2002GLXV6 - I'm a little confused with the, "1ft fan level is on at 197º-206º (off at 183º-196º), 2nd fan level is 210º221º (off at 196º208º)". On my 1.8T the "first fan" (driver's side) is directly driven off the accessory belt so it's on anytime the engine is running. The second fan did come on when I turned on the a/c switch but, as I said earlier, came on again around 170 degrees following the CTS change. Prior to the CTS change the second fan would only operate with the a/c switch. My car is a 5.5 from what I can tell from the stickys posted above. Are some of the earlier 2004's equipped with two electric fans?
The 1st and 2nd fan level both refer to the electric fan, not the belt driven fan. This would be the fan on the passenger side. The fan should according to the Bentley manual have two speeds. I know mine on my V6 kicks into high when the temp goes up.
tomvw - As far as related components being changed, i just changed the water pump and the hydraulic belt tensioner. the timing belt looked brand new. it must have been changed by the previous owner. i've put around 30000 on it in the time i've had it.
Tomvw - As far as related components being changed, i just changed the water pump and the hydraulic belt tensioner. the timing belt looked brand new. it must have been changed by the previous owner. i've put around 30000 on it in the time i've had it.
If you don't have evidence that proves the belt was replaced within the last 80,000 miles and 7 years, you should replace the full kit now.
You can't check a timing belt by looking, it can look fine and fail the next time you run the engine.
The only CTS is at the back of the head, the fan control is done by the Fan Thermal Switch in the lower radiator hose.
Make sure you have the correct part in the hose, a CTS in there would cause problems. That might be the only cooling problem.
That is most likely the cause of the P0171 code, replace that and check for any other air leaks.
There should be ZERO NIL No coolant dripping, (my cap hasn't been off for about 2 years)
Usually you won't see any bubbling when overheated, you might if you loosen the cap. (CAUTION that can be dangerous)
There is one electric fan that runs at 2 speeds, 2002GLXV6 was referring to Low and High speed.
Without the AC on, the fan shouldn't come on at all before the engine reaches operating temp and the thermostat opens.
You could check the temp at the Fan Thermal Switch with an infra red thermometer, but I don't see much value in that.
Odds are that if your water pump failed, then the previous owner didn't change the timing belt. Anyone that would've DIY'd the timing belt replacement most likely would've researched it to know to change the water pump at the same time. Most shops worth their salt would've known to change the wp at the same time, too.
I bought my '03 at close to 120k miles and the previous owner lied in a text message that the TB had been changed but later admitted after my WP failed that it had not been done. Basically, the cheap plastic wp impeller design saved me. The TB I replaced looked fine to me, too, btw.
It's interesting to see your repair items that are occurring. I'd guess your car has between 110k to 130k miles. That same elbow broke on mine too...the one toward the front of the engine on the passenger side. You may want to look at the plastic, yes plastic, coolant flange at the back, passenger side of the engine with a mirror or from underneath to see if it has cracked yet. It could be introducing air into your system. Also, check the plastic (yet again, plastic) heater core inlet/exit pipes to see if one of them is cracked like mine was (very slow leak). I guess it's also possible that could introduce air into your system.
Just came across this thread and you're describing a problem that is identical to mine, except for the leaking. I have the same air pump hose broken, same P0171 code, and same temperature readings from the Torque app. I made some temporary repairs to the hose and cleaned my MAF. After doing that my P0171 code went away and stayed away for past two weeks. Forum contributors suggested that it was most definitely my water pump going bad. Since I was nearing my t-belt change time I decided to do the full kit. Yesterday I installed my new timing belt, water pump, t-stat, and related parts. So far my temperature has remained in the normal range (but I've only had one day of driving). I can tell you with almost 99% certainty that the water pump was not at fault, as many here have suggested. It was the thermostat. Along with the kit, I replace that rubber air pump elbow with a new one. I drove the car about 7 miles, parked it for about 20 minutes, then upon starting it back up my P0171 code came back. So I'm now back to solving that problem again.
It would be my suggestion that you check two things regarding your overheating problem. Get another thermostat in there and check the plastic water neck carefully, maybe you got a faulty t-stat brand new out of the box- it's been known to happen. Then also check the bottom of the coolant overflow tank. I just replaced mine last fall because of a crack. The car is getting old. It's interesting to hear that mrau92me is having similar issues regarding that hose...
There are some similarities but but the OPs issues are NOT the same as yours.
As you replaced a few parts at the same time you have no evidence of what fixed your problem, but I can tell you that
the thermostat did NOT cause all of your issues.
Tomvw, might be a good idea to at least humble yourself a little. The thermostat absolutely did cause my overheating problems, and I do have the evidence as I have a defective thermostat in a box in my garage (as well as a perfectly good water pump). You obviously don't know everything about overheating issues regarding the 1.8T VW engine so I would suggest you try to learn from your mistakes. We're all here to help each other, and when possible try not to lead them in the wrong direction. Take your poor attitude and stuff it in your hat- you are by far not an expert here.
tcervinsky, Tomvw gives excellent, knowledgeable advice 99.5% of the time; proof is, he almost always agrees with me (GRIN). Try to look past his occasional lack of patience.
Tomvw - Thanks for the explanation of the two speed fan. I misread 2002glxv6's response. As of yet I haven't been able to discern two speeds of the fan no matter how hot the engine is. It only seems to have one speed. I see what you and others mean about the appearance of the TB being deceptive. According to the CARFAX on this car, there was a predominant amount of service performed at a specific dealership. I'm going to call tomorrow to see if I can get a copy of the service records to know for sure if/when components have been changed.
As I said earlier, I'm scrutinizing these temps as I'm driving with my OBD reader hooked up. I wonder if my car was reaching these temps all along. What are the normal range of temps for the 1.8? Has anyone recorded/observed temps around 230 before? With no exhaust gases present in the coolant system I'm still puzzled as to why this engine appears to run hot. The learning curve is pretty steep on this car as I try to understand its normal operating parameters. Thanks again for everyone's feedback. Every bit is helpful to a rookie.
Fallon,
After completing my t-belt service, along with the water pump and t-stat, I have begun monitoring my coolant temps via the torque app on my android phone. Previous to the service the app displayed a temp as high as 240* before the dash gauge would move off the "normal" 190* mark. Now that the service has been done (and I found my culprit to be the thermostat) my normal cursing temp display on the phone app to be around 205* with a peak of 214* going up a hill at 65mph. And once the car was up to operating temperature the dash gauge never budged from the 190* mark. So it does seem that your car is still running a bit hot.
Have you figured out the P0171 problem yet? A car running lean will tend to run hot. Do you hear any "pinging" when the engine is under heavy load? If the dash gauge is still reading "normal" 190* and you've stopped any leaking coolant (and the level stays where it should) I would begin focusing on that code problem. Keep monitoring the temps though, and just for grins and giggles- when your temp starts climbing over the 220* mark try downshifting the car for a mile or so and see if it starts cooling off. Maybe also see if running the heat on high help reduce the temps a bit. Just curious.
The only CTS is at the back of the head, the fan control is done by the Fan Thermal Switch in the lower radiator hose.
Make sure you have the correct part in the hose, a CTS in there would cause problems. That might be the only cooling problem.
What is the situation here, do you have the correct "fan thermal switch" or is it a CTS as you stated ?
The temps you are reporting are well within the normal range.
The CTS is at the back of the head and is checking the coolant where it is at the highest temp, this is what is reported to the gauge and ECU.
The fan thermal switch is where the coolant leaves the radiator and is at its lowest temp.
The temps listed by 2002GLXV6 in post #4 are the coolant temp at this point.
The fan high speed is only likely to be activated while driving with AC on, in heavy stop go traffic, on a very hot day.
It sounds like you might have a leaking reservoir cap, preventing it from attaining the correct pressure.
Ok, now it's getting a little murky. I went to the Advance auto online and looked up "engine coolant sensor" and part #WT5129 came back as "in-stock". When I pulled the old switch out I noticed it had a flat bottom and a blue top and the new one had a projected nub and a green top. Somewhere on this site I read that the fan switch was a "green top". After changing it, the fan started working so I'm thinking that's the way it's suppose to happen. NOW, I go back to Advance auto online and type in "engine coolant switch" and up pops a picture of the flat bottom switch (#TFS689) with the blue top I removed. If you go to Advance auto and look them both up it appears they have the same plug connection. Should I be using the "blue" flat bottom switch in the lower hose or is the "green" nub ended sensor correct. I can't believe there's two switches/senders with identical plugs.
tc, Thanks for the info. I drove in this morning tracking temps again and noticed it ran around 205 - 215. It seemed to fluctuate with no real change in demand on the drivetrain. When I got to work I let it idle for 2 or 3 minutes and it went to 226. Again I raised the rpms slightly to around 1300 and it cooled down to 217 within a minute. I know what you mean about the reservoir bottle cracking. I replaced mine in October. The thermostat was purchased at a VW dealership ($34) and I noticed when first run the reservoir coolant got warm when I read 190 on the OBD reader. I was wondering about the lean condition myself but because I hadn't been tracking the temps previously I have nothing to compare the readings to. Based on some of the other responses it looks like I'll have a little digging to do into the engine hose fittings behind the engine. The hard plastic air lines running everywhere look like a vacuum leak waiting to happen. I can only guess how brittle some of those lines are and am a little leery of pushing around much in there. Hopefully the smoker I made will highlight any leaks in the system. One other thing I noticed, when I removed the old thermal switch on the lower hose, was a sludgy residue on the sensor end. I'm wondering now if a complete coolant flush is in order. I'm sure that couldn't hurt. I hope there's a sticky on flushing the B5.5 system. I'm still trying to pick up on a higher speed to the electric fan. Would the switching capability be located in the fan assembly itself or is it something fed from the engine control module? If nothing else, the coolant level seems to be the same. I haven't added anything since the CTS change.
I was not referring to cracks in the reservoir you would probably notice that, I meant as I said the cap or its seal.
Could you please answer the question in my previous post ?
Sorry Tom, We seem to be overlapping texts and I'm not the quickest typist. The cap was new with the reservoir in October when I changed them. Do caps go bad quickly if subjected to boil over? I was wondering about the cap releasing prematurely when you said your cap hadn't been off in two years. I dismissed it seeing as it was new in October. I guess I could try swapping it as soon as I straighten out what should be in the lower hose.
I don't know which is which by colour, PN, or shape, the older CTS was blue the newer is green, I don't know the colour of the fan thermal switch.
And to make matters worse, some parts suppliers list them incorrectly.
You can check with a meter, the CTS will always show a resistance (dependent on temp) across either pair of pins.
The fan thermal switch will be open circuit (infinite ohms) between all pins at ambient temp, and at least the low speed contacts will close in boiling water creating a short circuit (0 ohms).
As you have replaced the reservoir and cap they are probably okay, but it wouldn't hurt to check that it is holding pressure.
[As you have replaced the reservoir and cap they are probably okay, but it wouldn't hurt to check that it is holding pressure.[/QUOTE]
I'm thinking I could tee a pressure gage in the return line at the top of the reservoir bottle to check system pressure. Has anyone checked their system in a similar manner?
[
I'm thinking I could tee a pressure gage in the return line at the top of the reservoir bottle to check system pressure. Has anyone checked their system in a similar manner?
I told you how to check a CTS and Fan Thermal Switch with a meter.
Now gigi123 has listed PNs and descriptions.
Make sure to get the correct part in there and let us know.
I doubt you have had it hot enough to activate the fan high speed.
The fan switch is flat, and it has part # 8D0 959 481B. It has a blue top.
The coolant temp sensor has a "projected nub", it should have green top (latest revision) and has part # 059 919 501A. The CTS used to have a black top (early models, I think 2004 came from the factory with green).
That could explain the single speed on the fan. The switch I pulled out had the audi symbol on it along with ELTH and blue top. Would that be an OEM switch?
Looking up the p/n gigi123 gave at napa is either a $25 or $60 part. Unfortunately the $60 one has all the same markings of the switch I removed. It'll be in this afternoon. I'll let you guys know how it works out. I have been monitoring my temps with the OBD reader and it only approaches 228 when stopped for extended periods. I'm thinking that's where the higher speed would kick in. Thanks again for all the help.
Well, went to pick up fan switch at NAPA only to find when he pulled it out of the box to show me the part, it looked like the $25 version. I told parts clerk to bring up the on line image of the part I ordered and sure enough the image with the audi symbol along with the correct part # popped up. Then I had him bring up the on line image of the $25 version and bingo it was the same as the part he was holding in his hand. He then said something about the image on line being a "representation" of the part I ordered and I told him they should state that on line. I then went to Advance auto as they had a version online depicting the correct switch with the audi symbol and p/n on the body. When that parts clerk brought up the image of the switch on the store computer it didn't match their online image even though it listed the same p/n. It's pretty discouraging that these stores will bait with the correct image only to substitute it with a cheaper/different version. I can't speak to the durability of the no-name versions but paying three times the price doesn't sound like something worth risking. I'm wondering if the only source of the real switch is the dealership which is pretty tough as far as prices go. Does anyone know a reliable source for the switch with the dark blue top, audi symbol, ELTH, and p/n on the body?
I am not defending your local parts store but you have to understand how manufacturing and branding works. Elth is the OEM manufacturer for VW/Audi. The will manufacture the sensor and mark the VW part number on it as well as VW/Audi logo. VW puts it in a VW box and sells it at their dealerships. Now, Elth might also manufacture the same switch for other clients (advance auto parts for example) but it will not have the VW/Audi logo on it, not the VW part #. Simply because of branding issues. In other words, I am not sure what you are buying from your parts store but keep in mind what I described above.
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