overheat, coolant overflow full = thermostat or water pump?

alex_tdi

Veteran Member
Joined
May 15, 2001
Location
Los Angeles, CA
TDI
TDI GLS, 2001, Blue
hi all,

today while i was driving on the freeway i noticed the temperature go up up up.

my first thought was a bad water pump, so i turned up the heat hoping it would help dissipate some heat. curiously the air turned from hot to cool fairly quickly.

i also tried turning on the A/C, that helped, but only slowed down the temperature rise.

after i pulled over, i popped the hood and noticed that the coolant overflow container was way full. i had a water pump fail before in a Nissan Maxima and that didn't happen, so I'm confused.

Could the thermostat be stuck closed? or is this a common water pump failure? I had it replaced at around 50k when I did my timing belt, but I do have 118k on the car.

Has anyone experienced something similar?

Thanks.

Alex
 

greengeeker

Vendor
Joined
Feb 8, 2006
Location
Cambridge, MN
TDI
2002 Jetta GLS
alex_tdi said:
today while i was driving on the freeway i noticed the temperature go up up up.

my first thought was a bad water pump, so i turned up the heat hoping it would help dissipate some heat. curiously the air turned from hot to cool fairly quickly.
This points towards a shot water pump. The fact that your was overheating combined with a cool heater core says you were not circulating coolant. If you want, you can pull your thermostat and reach through the back of the hole and touch the water pump impeller. IF it spins, it is bad.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
GG is right, however once an engine has heated up too much, you will get the same result whether the original problem was due to a bad water pump or a stuck thermostat. If the heater blows cool air from cool startup with plenty of fluid, through the overheating event, then that points to the water pump.

Once it has heated enough to form a steam bubble in the engine, the water pump has a hard time pumping steam...

The investigation is the same though. Do what GG says, and replace the thermostat with a good one - one you have seen open in a pan of boiling water.

The high temperature in the engine will form a steam bubble, steam is much less dense than water, so a lot of mass is displaced out of the engine. It goes to the reservoir, then out the overflow if pressure gets high enough.

Be warned - the temperature gauge is controlled by a computer. It will display steady at 190 F from 167F to 225F. So from the first time you see it move off of 190, it is overheated already.
 
Last edited:

alex_tdi

Veteran Member
Joined
May 15, 2001
Location
Los Angeles, CA
TDI
TDI GLS, 2001, Blue
How long do water pumps last? I had mine replaced with the timing belt change by Harvieux at around 60k. He's got a good rep here, so I figured he should have changed the original water pump with a new one that does not have the plastic impeller.
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
Any water pump can fail - make that any component. Resin impeller pumps can be of high quality; some people prefer them.

Using high quality components minimizes the number of premature failures, but does not eliminate them.

Why ask this question before inspecting the pump and the thermostat? It is quick and easy, and costs about $20 for coolant and thermostat.
 

alex_tdi

Veteran Member
Joined
May 15, 2001
Location
Los Angeles, CA
TDI
TDI GLS, 2001, Blue
So I went to the dealer. Thermostat, coolant, gasket = $110!

Took off the thermostat, reached it and felt the impeller spinning freely.

So I guess I need a new water pump.

How much do you think I should be looking at to get it replaced?

Also, the water was replaced 4 years (1/7/06) ago @ 60k (now 118k) with my timing belt change, shouldn't these things last a little longer? What's the average life expectancy of these water pumps?

Thanks.

Alex
 

Powder Hound

Top Post Dawg
Joined
Oct 25, 1999
Location
Under a Bridge, Crestview, FL, USA
TDI
'00 Golf 4dr White 5sp, '02 Jettachero 5sp, Wife's '03 NB Platinum Gray auto(!)
alex_tdi said:
... What's the average life expectancy of these water pumps?...
IDK. Not near long enough. I've had a metal impeller one fail at 39k miles. Not a horrid failure, mind you, but a leaky shaft that signals impending failure is still a failure.
 

alex_tdi

Veteran Member
Joined
May 15, 2001
Location
Los Angeles, CA
TDI
TDI GLS, 2001, Blue
Got the water pump replaced. Temperatures are back where they should be.

As it turns out, the old water pump had a plastic / composite impeller which appeared to have worked itself loose from the impeller. The new pump is made by Graf and has a metallic impeller.
 

PDJetta

Top Post Dawg
Joined
Nov 6, 2003
Location
Northern Virginia
TDI
'04 Jetta GLS TDI Pumpe Duce Platinum Grey w/ Leather
You hear about this problem sometimes on this list. Glad you got it fixed.

--Nate
 

alex_tdi

Veteran Member
Joined
May 15, 2001
Location
Los Angeles, CA
TDI
TDI GLS, 2001, Blue
I've also noticed a significant reduction in vibration when I'm in drive, but not moving (i.e. at a stop light).

I don't know if the original vibration was caused by the water pump going bonkers or if it was the IPT valve body that I'd put in, but I'm just glad the car's not vibrating as much anymore.
 

greengeeker

Vendor
Joined
Feb 8, 2006
Location
Cambridge, MN
TDI
2002 Jetta GLS
The vibration was probably due to misaligned motor mounts from your last timing belt change. Now that the motor mounts is bolted up correctly your vibration is gone. I bet they threw in a reman'd WP that finally gave up.
 

2004STARWARSTDI

Top Post Dawg
Joined
Oct 19, 2004
Location
LAKELAND, FL
TDI
2004 Platinum Gray GLS Jetta / 2006 Silver Jetta with DSG
Vibration

I would also check repair bill to see if they replaced the TTY bolts are just reused them when you had the TB job done. Don't want the engine dropping.
 
Last edited:

HoleshotHolset

Well-known member
Joined
Oct 1, 2002
Location
Columbia County, WI
TDI
'00 Jetta TDI
Add my wife's '00 Jedi to the list of failed water pumps. She said it overheated on the way into work yesterday AM (and again this AM...5/25). When I checked the overflow tank last night - there was no visible flow coming into the tank. Bummer.

We were hoping the car would make it until this Fall - but it looks like we won't be so lucky. It has just over 371,000 on it - original clutch, all original engine, original IP (never ran biodiesel or WVO). Engine is tired, has a lot of blowby and eats a little coolant between oil changes. Other than that, it still nets 50mpg and my wife goes real easy on it.

Based on what I'm seeing - it sounds like it needs a water pump. It is also getting close to needing a TB swap - but I really don't want to put a TB in this thing - it really isn't worth putting that much bread into.

Anyone want to buy a fixer upper TDI? :)
 
Top