[BRM] Replace thermostat while doing timing belt?

[beowulf_lives]

Greetings

I've purchased a timing belt kit that includes the belt, tensioner, water pump, and roller. I'm also replacing the serpentine belt. Should I replace the thermostat?
The timing belt is about 8,000 miles over due, 300,000 miles on the engine. I'm the bazillionth owner and it runs like a top *.

Edit: I don't know the age of the thermostat but I've owned the car for 20,000 miles without any signs of overheating issues.

* Edit 2: Poor word choice. 'I'm the bazillionth owner, and it now runs like a top. The previous owner was an animal.'

 

[325_Guy]

You might as well, since you already have coolant drained.

Recommend using OEM VW only. The aftermarket ones (even from our vendor list) are hit-or-miss on quality.

 

[beowulf_lives]

Is Mahle the oem supplier? Does that count as OEM VW w/o paying VW price?

MAHLE BEHR 044 121 113 / 044121113 | German Auto Parts

MAHLE BEHR Thermostat 044 121 113 / 044121113

www.germanautoparts.com

 

[Nuje]

FWIW, I've had a couple OE thermostats that were WAY too slow to open - got overheating going up the local ski hill.
Brand new OE with VW/Audi logos on the left; Mahle on the right. This was right on the cusp of full boil (water ~97°C).

I've used Mahle in the past and haven't had an issue with them; I'd just suggest that whichever you get, throw it in a pot of water on the cooktop with a infrared heat gun in hand and make sure it starts moving at 87°C.

 

[P2B]

Edit: I don't know the age of the thermostat but I've owned the car for 20,000 miles without any signs of overheating issues.

If it ain't broke...

 

[beowulf_lives]

If it ain't broke...

He had me at boil a thermostat. For science.

 

[Rx7145]

If it’s working I wouldn’t worry about it.

 

[privateTDIjet]

Save money live better

 

[oilhammer]

Slowly failing thermostats not allowing the engine to get up to temp and/or maintain it are probably one of the most common overlooked things on these cars, and cause for some hits in fuel economy that may not have any other explanation.

No 200k mile 19 year old Volkswagen has its original thermostat in "perfect" working order, but they have to be pretty bad to ever flag a DTC for it.

I only use OEM ones.

Never, ever, seen one fail the other way.

 

[d24tdi]

Slowly failing thermostats not allowing the engine to get up to temp and/or maintain it are probably one of the most common overlooked things on these cars, and cause for some hits in fuel economy that may not have any other explanation.

In addition to agreeing on that, I would argue that it's just about the most overlooked and neglected item on virtually EVERY vehicle, not just TDIs. Especially considering its near-zero cost of both purchase and labor to replace.

I don't think I have virtually ever bought a car or truck that didn't need a thermostat. One of those parts that fails gradually over time (usually) and almost never truly "breaks" in a way that disables the vehicle. As a result, people just keep running with the temp gauge sitting at 1/4 until the end of time.

All the more so on vehicles like VWs (and Fords, and Volvos, and many others, I'm just naming the ones I have dealt with most) that use a temp gauge with a big dead spot in the middle that can hide a tstat that is starting to fail.

I like to pretty much put in a new one anytime I am going to touch anything near it, particularly on engines like most of VW's where the tstat is located low in the system and requires dumping the coolant to replace it. Less of a big deal on other vehicles (most commonly domestics) where the tstat is up top and can be changed on its own without emptying the system. The drain and fill is the biggest part of the job on a TDI (or Subaru or Toyota or whatever)..... For the $5-$50 it costs, always should change it if the coolant is out.

 

[Rx7145]

Using VCDS or any other scanner, you can watch the engine temperature to see if it gets up to the actual set temperature. My BRM runs from 190° up to about 207° when fully warmed up.

 

[turbodieseldyke]

Especially considering its near-zero cost of both purchase and labor to replace.

I noticed you have no CJAA listed in your TDI stable

 

[d24tdi]

Lol, yeah never for me.

The V6 gas (and diesel) belt driven engines hid the tstat in a bad spot too. But to me I say the same logic applies, do it whenever you have anything resembling a good opportunity that gets you at least part way there.

Most definitely makes sense on a BRM belt job IMHO, to the OP's question.

On a CJAA I don't have a clue but I'm assuming having the coolant dropped for a water pump exchange still creates more of a chance than doing it on its own. Maybe you're gonna tell me it's difficult enough on those, or the part is expensive enough, that there's no moment when it makes sense as a proactive job and you are better to wait till it quits and really needs it. I suppose there must be some engine out there where that is true.

 

[turbodieseldyke]

The part is around $40. Not a killer. Stupid that it's fully enclosed in the housing with no way to change out the actual tstat, but much worse is the location.

 

[oilhammer]

Yep, CJAA and CKRA t-stats are fun...

 

[d24tdi]

That's nuts.

 

[oilhammer]

And what's worse is, a faulty thermostat on these will keep things from regenerating properly, yet it will never set a P0128 DTC for thermostat below operating range. You just have to figure it out by monitoring the ECU data.

I do a crap ton of thermostats on CJAAs for this:

TT 01-19-07 DTC P1A58 NOx Catalytic Converter Regeneration Required

 

[d24tdi]

Yet another reason I can't understand why folks live with the CR cars and tolerate this kind of unnecessarily difficulty, as long as there are still VE and PD models out there that are viable and legal to operate, but I guess they must have their own kind of charm.

 

[Rx7145]

Yet another reason I can't understand why folks live with the CR cars and tolerate this kind of unnecessarily difficulty, as long as there are still VE and PD models out there that are viable and legal to operate, but I guess they must have their own kind of charm.

it’s not that bad, plus the engines are much more refined and more powerful. That being said I do own three BRM cars.

 

[oilhammer]

I've tried over the years, with mixed success, to push people who have good working VE or PD TDIs than needed some work to keep them instead of "upgrading". The failed attempts often end up being taken on by me, and I have a bunch of good working cars as a result of it. Some of which have already lasted longer with less fuss than the newer cars the owners replaced them with. But no takesies-backsies.

Right now, I have a CR in my stable that was one such car, and may be acquiring another..... a Sportwagon with a third pedal and NO STUPID PANO ROOF!!!

 

[privateTDIjet]

Yet another reason I can't understand why folks live with the CR cars and tolerate this kind of unnecessarily difficulty, as long as there are still VE and PD models out there that are viable and legal to operate, but I guess they must have their own kind of charm.

Nothing difficult as long as you're willing to learn.

 

[oilhammer]

Learning your car needs a thermostat that takes four hours to replace to keep a three thousand dollar deNOx cat from failing is a tough lesson that most people are not at all happy about.

 

[privateTDIjet]

Learning your car needs a thermostat that takes four hours to replace to keep a three thousand dollar deNOx cat from failing is a tough lesson that most people are not at all happy about.

Wait till they hear about the flywheel

 

[oilhammer]

The [DSG] DMFs are far less troublesome on CR cars than PD cars. But yes, eventually they'll need that, but I'd place that pretty far down the list of wallet crushing things on the CR engines. And those are easy to replace, anyway. They're no more difficult than on a BRM or one of the FWD gassers that use them.