2002/2003 overheating problems Help Please?

I have done much research on here. Here are my problems, then my ideas based off reading the many threads on this forum Please confirm or correct as appropriate, offer suggestions, ideas, etc.. Thank you for your help:

1) 2002 Jetta TDI automatic:
day 1 cabin heat dissapears. day 2 overheats quickly after putting in gear (drive up hill, lowgrade, 1/2 mile). Day 3, replace thermostat AND coolant Temp Sensor, coolant, (aprox 1.1 gals). Test drive. no cabin heat, engine overheats after driving 1/2 mile up low grade hill (we live between two hills)

Ideas, replace pump and belt next. If that does not work then go for radiator. If that does not work, go for head gasket.

2) 2003 Jetta TDI manual
Over heats driving up mountain. Let cool, turn on cabin heat full blast, drives up mountain ok,just barely over 190. several tests confirm heavy loads cause over heat, cabin heat full blast keeps it at 190 as long as I keep it below 2000 rpm up hill and 2300 rpm level ground. from cold start to heat up is normal. it appears to be pumping coolant and heating up normally. jump tested fans and replaced fan control module, tests all same.

first thing, I plan to replace coolant Temp Sensor, then go to thermostat, even though thermostat seems to be working ok. Then if necessary on to pump, then radiator, then head gasket all if previous fail.

Does anyone see anything in these two that shout "obvious"? does anyone have any suggestions, corrections, etc.?

I share the rest of this for understanding, not pity:
I am a poor boy back yard mechanic with limited experience, a disabled veteran, doing my own work out of necessity (my military pension barely cover's the $100 monthly payment on each of these vehicles). So buying a better manual or paying a garage are not options. esp when I have a friend who can order oem parts and give them to me at cost (he's not a mechanic though, unfortunately). so I need to do as much as I can myself. I am slow and take sometimes more than a day to do what others can do in a couple hours but I find this forum sometimes more valuable than my haynes manual that was given to me.

So please, anyone with any insight, please offer as much help and suggestions as you can. I am very grateful for it. But please don't be offended if I don't heed suggestions that essentially say something like (take it to a dealer or mechanic). I am doing what I can with what I have. I do NOT get welfare or food stamps and I am not begging for charity,only asking for help to keep it within what I can manage with what little my self employment brings in.
.
thank you

case number one sounds like a bad pump, the plastic impeller is cracked and moving little or no coolant. the 03 maybe a stuck thermostat?

when they "overheat" what is the symtom? is it blowing coolant out the cap?
or is the gauge just pegging?

if you do come up with a diagnosis of bad pump then that means timing belt time.
if you take a crack at that job just read up on the service and don't cut any corners,
use the right tools etc. you don't want to trash your motor with a botched t-belt job.

ps i dont think anyone cares about your personal situation per se, people come here looking for advice which can be taken or not, right? that being said there are many knowledgeable and generous people on this board who freely give great advice, every day.

Case number one is as mentioned most likely a bad water pump. Plastic Impellers are known for coming loose causing this exact issue. I wouldn't do the CTS and thermostat just yet until I had ruled out the bad water pump. You can confirm the pump is bad by removing the upper small diameter coolant hose going to the reservoir. You should have a small amount of flow from the tube to the coolant reservoir when the engine is running. If not, that's your culprit and proceed as necessary.
By the way, the coolant system removes heat from the auto tranny, and if it's not circulating coolant and keeping things cool you run the risk of cooking the tranny and engine. Please don't drive this particular car until you get it sorted out.
Case number two sounds like it could be a stuck closed thermostat. We know coolant is pumping through the system since you get heat from the heater core, and since you can regulate the engine temp some what by running the heat. That's good news since the replacement T stats are cheap at the autoparts store. In any case try not to drive it much until you get that T-stat replaced.

Ok, Thank you. I will check the pump as suggested.

On the over heating for 2, I haven't let it get to 260, once I saw it getting too hot I pulled over and turned the engine off, key on, and let it sit until it fell below 190 then proceeded so I don't know if it would blow coolant or not.

I can replace the tstat and see if that works. I would have thought with the tstat stuck closed it would not get coolant into the cabin but perhaps I misunderstood something.

FlanMaster said:

Ok, Thank you. I will check the pump as suggested.

On the over heating for 2, I haven't let it get to 260, once I saw it getting too hot I pulled over and turned the engine off, key on, and let it sit until it fell below 190 then proceeded so I don't know if it would blow coolant or not.

I can replace the tstat and see if that works. I would have thought with the tstat stuck closed it would not get coolant into the cabin but perhaps I misunderstood something.

Click to expand...

Even with the T-stat fully closed to the radiator you will still have coolant flow through a bypass loop which includes the heater core among a few ancillary items. Also, the dash temperature guages are woefully inacurate for example when it reads 190, the actual temp can be any where from approx 160-230. So who knows what your actual temp actually got up to. From experiments with higher temps T-stats some have run as high as 230 F actual coolant temp with no indications of problems. You may consider putting a digital thermometer in the coolant reservoir to confirm to some extent your temp readings from the cluster.

josh8loop said:

Even with the T-stat fully closed to the radiator you will still have coolant flow through a bypass loop which includes the heater core among a few ancillary items. Also, the dash temperature guages are woefully inacurate for example when it reads 190, the actual temp can be any where from approx 160-230. So who knows what your actual temp actually got up to. From experiments with higher temps T-stats some have run as high as 230 F actual coolant temp with no indications of problems. You may consider putting a digital thermometer in the coolant reservoir to confirm to some extent your temp readings from the cluster.

Click to expand...

Thank you. I was unaware of the bypass even after all my research. I missed this completely. I am getting ready to go out and try the t-stat now on the one vehicle and then check the pump on the other as you suggested.

I will probably be without access to internet all weekend But can post results next week.

Where is your hovel located? There may be someone nearby that is looking for a home made meal in exchange for helping.

Case one: Is likely a defective coolant pump (as others have said).
Case two: Needs a bit of trouble sshooting. See this thread:
http://forums.tdiclub.com/showthread.php?p=1107836

You can feel the impeller from the thermostat mounting boss, with thermostat removed. Naturally, the engine will be off, with a helper, MANUALLY turn the engine over while watching the back side of the impeller with a strong light and mirror.

I would place a 90% probability it is the coolant pump.

Keith_J said:

You can feel the impeller from the thermostat mounting boss, with thermostat removed. Naturally, the engine will be off, with a helper, MANUALLY turn the engine over while watching the back side of the impeller with a strong light and mirror.

I would place a 90% probability it is the coolant pump.

Click to expand...

very good suggestion, digging out thermostat a lot easier than pulling
a suspected pump....

these are all very good suggestions. Thank you. on the 2003 I followed the trouble shooting thread and managed to replace the t-stat. everything is great.

On the 2002 there was no return. I did not have access to the internet until now so I did not see the post about seeing the pump before I ordered it and the replacement timing belt. I will go out this afternoon and remove the t-stat to check in case I need to cancel the order for the pump (only have until 6 pm gmt -5).

If anyone catches this part I do have a related question. Is there an easier way to catch the fluid from the block? I drain everything from the radiator and reservoir but the block maintains a level of fluid. I tried rigging a hose and funnel both at the coolant temp sender and at the tstat before but still had major spillage that ran all over everything and required several pans underneath to try to catch all the dripping. I've even tried closing and opening the reservoir while manipulating the upper hose trying to create a vaccuum to suck the coolant into the radiator to allow more drainage and have gotten up to over 3/4 gallon of coolant out of the system before losing the remainder by removing the t-stat. I don´t have any vacuum systems to hook to the unit and I don´t think pressurizing the system would do any good, and might even do damage.

any suggestions?

Thank you.

whitedog said:

Where is your hovel located? There may be someone nearby that is looking for a home made meal in exchange for helping.

Click to expand...

[edited] I'd be surprised if any one was within calling distance, much less driving.

To make it worse I don´t have a covered area with electricity to work on it. So I have to do things when the weather permits. It was raining this morning but this afternoon is dry enough to do the 2nd check on the pump movement.

I've already gotten the t-stat removal and replacement down to 30 minutes including drainage and fluid replacement so that is helpful and I still have the jacks and tools out there covered with a tarp so set up time is usually 10 minutes but the pump and timing will take a while. I haven't replaced a timing belt in 8 years so I am in the process of looking up the instructions on that to have on top of the haynes manual.

This will be interesting to say the least. But we do what we have to and this forum has been a major blessing with the wealth of information and guides.

sorry to keep posting but a 3rd point, With the recent replacement of the t-stat the fluid is relatively new. While I don´t trust the fluid that runs over the engine when coming out of the tstat mounting point I do wonder if it would be ok to reuse the aprox 3/4 gallon I will get out of the drain valve. It is a clean jug. Will this be safe or should I break down and ask my friend to order another gallon of c-12? I have aprox 1/2 gallon of 50/50 left (mixed myself so probably slightly more coolant than distilled water).

Reusing G12 is fine if normal in color. As long as it isn't rusty or oily, strain/decant and reuse. I've used disposable coffee filters, backed up by a cone of vinyl window screen to speed it up in the funnel.

Good call on distilled water.

emptly the block by removing the hoses from the oil cooler , then empty the radiator.
when you refill it , use the top radiator hose to fill the engine and radiator with coolant. this will put coolant on both sides of the thermostat and make purging the system easier. then top off the coolant expansion tank half way and start the engine. keep on adding coolant in the expansion tank as the level drops. you might have to drive it for the thermostat to open and get rid of trapped air

This is just my 2 cents . When I first replaced my timing belt and water pump ( plastic impeller ) everything was fine. About a month later I started to have a problem with no heat sometimes. Then I had no heat at all . I did have a little bit of flow in the overflow tank when first started. I took the timing belt and water pump out. The pump was good. I could not turn the impeller freely when I was holding the other side. This did not make and sense. I still had the old pump in the work shop. I took both pumps into the house and put each in a pot of boiling water. Then the funny part was the wife came home and said what is cooking for din. I just laugh and said Nothing at all! The look on her face when she saw the water pumps was priceless. I removed the old pump with metal impeller it would not free spin when holding one side and turning the other. Then the new pump with plastic impeller was pulled out of the hot water held one side and other side would turn freely. Because of this I don’t think you can always check pump in the engine. I need my car for work and had to reinstall the old pump. On the second timing belt change I installed a new pump with a metal impeller. My parts guy was good took the old part back gave me a credit . He also only sells pumps with metal impellers now.

Side note I did replace all the rollers, bolts and tensioner each time. Do it right the first time and it will be less of a head ace. 1999.5 has over 260,000 miles SWEET

wanted to wait a bit before posting the results to give it time to test out.

don't have all the lockdown gear to keep it in time so I had to borrow the money to have the work done.

Took it to [edited] (towed it with my van. listed as protocol auto on the list here). Took all my parts. pump with metal impeller, timing belt, and components.

They had it done in a couple of days. Picked it up Thursday evening. everything worked well for the drive home. It's been running fine since.

now I just need to collect the parts to convert it to a manual trans.

Setting up a stall in the barn for working on the cars. I will eventually run 110 electricity out to it but for now just having a level, dry place to work will help tremendously.

Thanks for all the info and advise.

jetta over heating

fans only come on when A/C is turned on, well i jumped them so the fans stayed on whole time while driving , well the dam jetta over heated again

i test the water pump is working
new cooling fan switch senor
and both of the fans wook so what can i test or do now?
,