Thermostat every timing belt change?

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
My BEW Jetta is at 150,000 miles and is due for another timing belt since I changed the first one at 70,000 with the cam. Recently I did a timing belt for a guy and when he got to the shop, the temperature wasn't even halfway to straight up. I queried him on where he lives and it should have been full hot. I changed his thermostat with the belt and it was full warm I. Just a few miles.

So I got to thinking about my car and how fuel economy was poor so I checked my temperature after driving for awhile and it was only reaching 175 degrees Fahrenheit. This tells me that, like a water pump, a thermostat isn't good for two timing belt changes and should probably be changed with the timing belt.

Remember that even though the temperature gauge is straight up that doesn't mean it has reached 190 degrees.

I am hoping that this will bring my fuel economy up from 38 to 40 MPG.

By the way I love telling people that it sucks only getting 38 MPG.
 

steve6

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Joined
May 25, 2010
Location
Beaverton, ON
TDI
2003 jetta tdi
it is a easy change, and if you have the fluid out anyways.. why not. Using a odbII scanner to see the real temps really helps. The car should be running more around 195-200f when fully warm and moving under load I believe.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
The thermostat is one of the most often overlooked things that can have a negative impact on fuel economy on a diesel. Which is why I listed it in my sticky thread on the subject. :)

However, mileage alone is not necessarily an indicator of its ability to do its job. Age and the number of heat cycles it has endured can also be factors.

My BHW's CTS finally started spazzing out around 170k miles, and I was going to replace the t-stat then, but was out of them.... it wasn't until I drove it a few weeks ago for the first time in a while that I realized just how long it was taking to get up to temp. So it made it about 187k miles and 13 years, but was probably not as good as new for a while before that.
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
Yeah, I figured it was there, I just felt maybe a refresher post just about the stat could help others decide that it's worth changing with the TB. I know that Cascade German sells the u Dr kit with the stat and housing, but I know that people often hear their mechanic say that they should do this other thing as long as we are there and sometimes that's true. This is one of those times.

After I changed out dudes stat, I was thinking about posting this and was talking with an older guy and started in about how thermostats usually don't go bad. Well, in a '69 Chevy, it may not be a problem, but welcome to the new Millennium. Computers control the car and they want everything to be just right. If it's not right, it will throw off so much on today's cars.

It reminds me of the lady with the Murano that would throw a code for CMP because her dad told her that mechanics change the oil too often and t can go alot longer than the manufacturer says. While there is a tiny bit of truth I this, if you double the recommended OCI and it causes troubles... MAYBE you shouldn't go that long on the OCI. Just sayin'
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Well, regarding oil changes, lots of people DO change their oil too often. However, in many cases, for reasons I simply will never understand because it goes against common sense, these people CAN remember to make and appointment and bring their car in for service, and pay for it, but they CANNOT seem to be bothered with opening the hood and checking/adding oil as necessary. And more often than not, these are the same people that do not want to do anything else to their car ever, at all.

So I guess if the manufacturer says 7500 mile intervals, but adding a half quart of oil every 2500 is just too stressful for you, but instead paying someone to change it every 3000 miles is better, then.... ????? I don't get it, but whatever.
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
What her dad meant is that the manufacturer recommendations are too short and mechanics follow along because it makes them money.

What makes money for mechanics is people not changing the oil and having bigger problems later.
 

50harleyrider

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Jun 16, 2007
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charleston,wv
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2005 B5.5 TDI/geared BSM, BV43A turbo,stage 2 TDTUNING. 2005 5sp manual passat tdi stage 2 tdtuning,BSM delete. 2015 Passat TDI 6sp manual.
From personal experience, avoid the garbage IDParts sells and is very uncooperative and suspicious of you when you get a bad thermostat from them.
 

Riflesmith

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Joined
Dec 16, 1999
Location
Lovell, WY
TDI
2003 Jetta Wagon TDI 6M, 2015 Golf TDI 6A
After two OEM thermostats that failed after 20K miles, I only install Stant thermostats. 195 degrees F. They work and stand the test of time.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
What her dad meant is that the manufacturer recommendations are too short and mechanics follow along because it makes them money.

What makes money for mechanics is people not changing the oil and having bigger problems later.
No, not really. Because the vast majority of cars with blown up engines get junked or hauled to the auction lot.
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
No, not really. Because the vast majority of cars with blown up engines get junked or hauled to the auction lot.
If they get blown up, sure. But what of the cam position codes caused by plugged valving? Or early turbo failures, or problems caused by plugged PCV systems or whatever else fails from poor maintenance? Not to mention the unrelated things that fail because no one has even opened the hood for 20,000 miles. Tie rod ends, CV boots, Ujoints, worn wiring, corroded battery, loose nuts and bolts. The list goes on all because daddy told them that mechanics are out to steal your money and you don't need to get your oil changed as often as they suggest.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
I cannot speak for everyone in my field, but I would MUCH rather see a vehicle regularly for PM and normal wear items than see it for a bunch of "repairs".

Stuff is going to break on every kind of car, sooner or later. Given that the age and mileage on the cars, especially around these parts, is averaging higher and higher all the time, the likelihood of something needing attention is much greater. Couple that with more complexity, shorter tire life, etc. it pretty much guarantees the car will need a professional's eyes or a competent DIYr to remain in proper order for the long haul.

If people would just find someone who is good and stick with them, and stay regular, the car will remain in better condition. That is a fact I have seen proven time and time again over the years. People that bounce around to different shops, or their brother-in-law who has a toolbox because "he is handy", lose the grasp of a good comprehensive vehicle care program.

Our shop, like most shops, keep a nice track record of everything on the vehicle. We have a computer system, but paper records work fine in smaller applications too. There is never going to be a case of overselling something that you don't need because some other shop just did it if you only take your vehicle to one shop anyway. For example: If your car is supposed to get a new air filter every 30k miles, for instance, and we put one in at 30k miles, then we all know that you will need a new filter again at 60k miles. Isn't that simpler than "Well, I checked your air filter, and it is kinda dirty, we should replace it" :rolleyes:

I am doing a 240k mile service on a 2005 Passat this morning. I have serviced this car regularly since it was brand new. I did its 5k, 10k, 20k, 30k,....etc. all the way up until its 240k today. The owner of this car can motor along worry free because she knows EXACTLY what has been done to this car from the day she drove it off the dealer's lot. Every filter, every tire rotation, every brake pad, everything. One thing she does not need to wory about is being concerned that I am going to try and sell some mystery service she doesn't need. And I've done (and will continue to do) my very best to make sure I needn't have to do any repairs to this car.:)
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
I cannot speak for everyone in my field, but I would MUCH rather see a vehicle regularly for PM and normal wear items than see it for a bunch of "repairs".
Stuff is going to break on every kind of car, sooner or later. Given that the age and mileage on the cars, especially around these parts, is averaging higher and higher all the time, the likelihood of something needing attention is much greater. Couple that with more complexity, shorter tire life, etc. it pretty much guarantees the car will need a professional's eyes or a competent DIYr to remain in proper order for the long haul.
If people would just find someone who is good and stick with them, and stay regular, the car will remain in better condition. That is a fact I have seen proven time and time again over the years. People that bounce around to different shops, or their brother-in-law who has a toolbox because "he is handy", lose the grasp of a good comprehensive vehicle care program.
Our shop, like most shops, keep a nice track record of everything on the vehicle. We have a computer system, but paper records work fine in smaller applications too. There is never going to be a case of overselling something that you don't need because some other shop just did it if you only take your vehicle to one shop anyway. For example: If your car is supposed to get a new air filter every 30k miles, for instance, and we put one in at 30k miles, then we all know that you will need a new filter again at 60k miles. Isn't that simpler than "Well, I checked your air filter, and it is kinda dirty, we should replace it" :rolleyes:
I am doing a 240k mile service on a 2005 Passat this morning. I have serviced this car regularly since it was brand new. I did its 5k, 10k, 20k, 30k,....etc. all the way up until its 240k today. The owner of this car can motor along worry free because she knows EXACTLY what has been done to this car from the day she drove it off the dealer's lot. Every filter, every tire rotation, every brake pad, everything. One thing she does not need to wory about is being concerned that I am going to try and sell some mystery service she doesn't need. And I've done (and will continue to do) my very best to make sure I needn't have to do any repairs to this car.:)
Yep..
 

leicaman

Top Post Dawg
Joined
Dec 24, 2004
Location
Sheboygan, Wisconsin
TDI
2015 Golf TDI SE, 2005 TDI GLS, RIP
The thermostat is one of the most often overlooked things that can have a negative impact on fuel economy on a diesel. Which is why I listed it in my sticky thread on the subject. :)
However, mileage alone is not necessarily an indicator of its ability to do its job. Age and the number of heat cycles it has endured can also be factors.
My BHW's CTS finally started spazzing out around 170k miles, and I was going to replace the t-stat then, but was out of them.... it wasn't until I drove it a few weeks ago for the first time in a while that I realized just how long it was taking to get up to temp. So it made it about 187k miles and 13 years, but was probably not as good as new for a while before that.
I myself am due a timing belt in 11k and a thermostat is on the replace list. I am going to demand an OEM one along with the housing. I think anything that has lasted 200k, should be replaced with an identical unit. I have already replaced my CTS when I did the dual pump gasket replacement.
 

Tdijarhead

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Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
Speaking of neglected maintenance I know a woman who years ago bought a brand new van. She drove it for 25k miles and the engine failed. She was so upset. How could this happen there's only 25k miles on this thing? Turns out she put gas in it and nothing else. No oil changes, nothing. The garage determined the engine had run out of oil. I call people like her gas and do drivers.
 
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