Overheating issues

Mperry

Member
Joined
Mar 20, 2019
Location
PGH pa
TDI
04 golf 1.9. 06 Jetta 1.9
I recently bought an 06 Jetta TDI and I'm having some overheating issues I can't wrap my head around. I found the last owners receipt from a garage that replaced the egr cooler and still had issues when they returned the car. I checked the thermostat and water pump and both appear to function as normal. I did a few coolant flushes since there was an empty bottle of bars leak in the trunk and green coolant. Car will run normal temps till I get to a hill and then rocket to 250°. Pull over and check but the rad is ice cold and both hoses are hot. Reservoir appeared empty after I cracked it it filled to the top and then settle back down to the minimum mark. I pulled the radiator and tested it with the garden hoes and flows just fine. I bought a junk thermostat and took the guts out of it so flow wide open, this brings normal operating temperature down to 170 degrees but still pulls up to the to 230 to 240 on the same Hill. Fresh oil and air filter change. Does anyone have an idea where to start looking next.
 

tactdi

Veteran Member
Joined
Jun 21, 2010
Location
North Carolina
TDI
2005.5 Jetta
Water pump not turning to move the coolant.

If you pull the timing belt to check the pump,
you should just perform a complete timing
belt service while replacing the water pump.

Also, flush the coolant out and replace with VW
Brand coolant.



Sent from my iPhone using Tapatalk
 

Mperry

Member
Joined
Mar 20, 2019
Location
PGH pa
TDI
04 golf 1.9. 06 Jetta 1.9
I checked the water pump when I had the thermostat out it does not move or spin freely and I had my dad bump the engine and it spins with the engine running. During my testing sometimes I have cabin air heat sometimes I do not. I pressurized the tank and bled air out everywhere I could until it was all water. I can reach back and feel that the coolant lines going in and out of the heater core are not very hot most of the time.
 

Metal Man

Vendor
Joined
Sep 29, 2001
Location
Sunbury,PA 17801
TDI
1998 NB TDI, 2006 Jetta TDI, 2014 Tiguan gas, , 2019 E Golf X2
Is there coolant flowing to the top of the coolant bottle? It sounds like either a water pump or a head gasket.
 

iluvmydiesels

Veteran Member
Joined
Nov 21, 2015
Location
phila area
TDI
AHU
I checked the water pump
it does not move or spin freely and I had my dad bump the engine and it spins with the engine running.
During my testing sometimes I have cabin air heat sometimes I do not.
I can reach back and feel that the coolant lines going in and out of the heater core are not very hot most of the time.
yup i ve had a similar problem on an older model. i think that time i had put a plastic water pump in(impeller), the plastic impeller separated from the shaft, almost the same symptoms, lack of heater working, hoses not feeling hot or right temp, over-heating.
of course esp a toothed timing will turn a pump your hand cannt. replace before it blows fully, and you lose your timing belt.
does it happen to be a plastic impeller water pump?? if so find a metal one.
 

Mperry

Member
Joined
Mar 20, 2019
Location
PGH pa
TDI
04 golf 1.9. 06 Jetta 1.9
It is a metal impeller and I have coolant returning to the bottle. I made a clear vinyl tubing bypass for the rad and could see water flowing. The shop did a pressure test and some other test and ruled out head gasket but it is starting to look that way. May only be leaking under boost?
 

JB05

Top Post Dawg
Joined
Oct 20, 2005
Location
Il.USA
TDI
Golf,2005,anthracite blue
What coolant is presently in the system, green or the VW specified G13 pink?
 

Matt-98AHU

Loose Nut Behind the Wheel Vendor
Joined
Apr 23, 2006
Location
Gresham, OR
TDI
2001 Golf TDI, 2005 Passat wagon, 2004 Touareg V10.
Open the reservoir cap to relieve pressure, re-tighten it, literally just go for a drive up your street, put your foot to the floor even for just a couple seconds. Remove the reservoir cap again and see if there's a significant pressure build up.

There will be almost zero thermal expansion from such a short trip after relieving pressure from the system, so any significant pressure build up from just a quick stab of the throttle under load would definitely point towards a compromised headgasket that's allowing exhaust to pressurize the cooling system. Some are just weak enough that they only do it under high loads/high boost levels.
 

Mperry

Member
Joined
Mar 20, 2019
Location
PGH pa
TDI
04 golf 1.9. 06 Jetta 1.9
At the moment I'm running 100% distilled water during my testing. The shop that did the egr cooler also did a combustion has test and showed nothing. Guess I'll be pulling the head this weekend and seeing what it looks like in there. Thanks for the info!
 

Matt-98AHU

Loose Nut Behind the Wheel Vendor
Joined
Apr 23, 2006
Location
Gresham, OR
TDI
2001 Golf TDI, 2005 Passat wagon, 2004 Touareg V10.
Most chemical "block testers" only change color significantly with a significant amount of carbon monoxide in the exhaust gases that are being forced into the cooling system. Diesels produce exceptionally small amounts of CO compared to a gas engine.

Sure, those block testers say they're good for gas and diesel, but they rarely are conclusive when used on a diesel. Which is why I've learned to pay closer attention to cooling system pressure to determine headgasket issues.
 

Mperry

Member
Joined
Mar 20, 2019
Location
PGH pa
TDI
04 golf 1.9. 06 Jetta 1.9
Yes the head gasket was blown out on #4 cylinder. So while it is opened up time for cam lifters and a belt since it's off. Thanks for the help!!!
 
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