Resean for jaguar xj6 3.6l idles rough when cold all works perfect when temp reaches 90 deg c

First time you might check the thermostat operating.

Heed of antifreeze coolant temperature!!!

The thermostat location for 2000 VW Beetle 2.0L is on back of the alternator at the bottom side of the bracket.

IMPORTANT NOTE: It is NOT necessary to replace the alternator if you want to change the thermostat !!!

Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.

Thermostat location, Part number: 050 121 113 C, in german - "Kuehlregle".
Remark: 87 ... 102 Celsius deg.
Price around $35:



Important note: Always replace the thermostat seal, position 7 in the above picture.

First time you might check the thermostat operating.

Heed of antifreeze coolant temperature!!!

The thermostat location for a 2000 Audi A4 1.9 TDI is on back of the alternator at the bottom side of the bracket.

IMPORTANT NOTE: It is NOT necessary to replace the alternator if you want to change the thermostat !!!

Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.

Thermostat location, Part number: 044121113, in german - "Kuehlregle" (Price around $25):


Important note: Always replace the thermostat round seal, position 7 in the above picture.

Check & replace the engine thermostat if necessary.

Heed of antifreeze coolant temperature!!!
First time you might check the thermostat operating.
The thermostat location for 2005 Audi A4 1.9 TDI, is on back of the alternator at the bottom side of the bracket.
IMPORTANT: It is NOT necessary to replace the alternator if you want to change the thermostat !!!
Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.

Thermostat location, Part number: 044121113, in german - "Kuehlregle" (Price around $25):



Important note: Always replace the round thermostat seal, position 7 in the above picture.

Please do rate my response. Thanks!

Heed of antifreeze coolant temperature!!!
First time you might check the thermostat operating.
The thermostat location for VW Golf 1.6 is inside of coolant thermostat housing placed on back side of the cylinder head. See pictures below.
Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.

Thermostat location, Part number: 032121110B, in german - "Kuehlregle" (Price around $20):




Important note: Always replace the thermostat round seal, position 6 in the above picture.


Please do rate my response. Thanks!

Heed of antifreeze coolant temperature!!!
First time you might check the thermostat operating.
The thermostat location for VW Jetta 1.9 TDI - AJM engine, is on back of the alternator at the bottom side of the bracket.
IMPORTANT: It is NOT necessary to replace the alternator if you want to change the thermostat !!!
Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.

Thermostat location, Part number: 044121113, in german - "Kuehlregle" (Price around $25):



Important note: Always replace the thermostat seal, position 7 in the above picture.

Please do rate my response. Thanks!

Heed of antifreeze solution temperature!!!
You must check the thermostat operating. The thermostat location for 1997 Audi A4 1.9 TDI is on back of alternator at the bottom side of the bracket.
IMPORTANT NOTE: It is NOT necessary to replace the alternator if you want to change the thermostat !!!
Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.
5. If the thermostat and the temp sender are OK the last piece out of order will be the instrument cluster.

Heed of antifreeze solution temperature!!!
You must check the thermostat operating. The thermostat location is on back of alternator at the bottom side of the bracket. IMPORTANT: It is NOT necessary to replace the alternator if you want to change the thermostat !!!
Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.

HAVE THE COOLANT TEMP SENSOR CHECKED TO SEE IF IT IS FUNCTIONING PROPERLY.HOPE THIS HELPS. BEST OF LUCK. LET ME KNOW?