Block Heater Selection and Installation- 96-97 Passat TDI & A3's, by Jim Dolan.
Since block heater information has been frequently requested on the site, and Spring is perhaps the perfect time to do it when coolant is changed, I have prepared the following to provide others with information needed to successfully select and install block heaters. My TDI is a 1996 Passat, so the information I provide may have to be modified for those who own Jetta and Golf A3’s equipped with the TDI engine. If you have an A4, these instructions will likely be useless. An entrepreneur from Minnesota has designed a recirculating coolant heater which installs into a radiator hose for the A4’s. Information is posted elsewhere on www.tdiclub.com .
A Disclaimer: Car Maintenance And Repair May Be Dangerous! Should you follow the instructions below, you elect to do so with the knowledge that their author is not a professionally trained, licensed, or certified mechanic by any private or governmental regulatory body. You also understand that the author provided these instructions for distribution on www.tdiclub.com without expectation of compensation and such distribution was motivated only by and for educational purposes. In short, what you do with the information is your own call to make and thus entirely at your own risk!
I. Selecting a Block Heater
Of the various companies producing aftermarket VW block heaters, certain constants may be observed which should be noted when selecting a unit.
Size of Block Heater
The frost plug holes measure 36.5 millimeters, and as such you must obtain a heater having this outside diameter to seal the hole properly.
A. Part Numbers
Two manufacturers seem to be the most popular, Zerostart and Kats. Both of these units appear to be widely available. I used a Zerostart product purchased at a local NAPA store. The NAPA part number on this block heater was 605-3230, and it measured exactly 36.5 millimeters in diameter. It is a Zerostart product according to the instructions, and because it fits the same VW and Audi vehicles listed in Zerostart’s 2000 catalogue, one can safely assume it is also Zerostart part number 3100034. As will be seen below, I had absolutely no problems getting this unit to fit securely into the 36.5mm Left Rear (LR) frost plug hole.
B. Pick a Hole, Any Hole. . .Well Almost!
The primary difficulty with installing a block heater in the TDI concerns where the frost plugs are located. The side of the engine closest to the radiator has absolutely no frost plugs whatsoever. A quick removal of the engine compartment under cover (if so equipped) and under-engine examination will reveal that the engine has three frost plugs, all located on the backside of the engine about 6 to 8 inches from the firewall (rear of the engine compartment). Assuming you will be on your back staring up at the rear of the engine block (with your feet protruding from under the front bumper), you will see three frost plugs. All of these are somewhat obstructed.
The plug on the far right is not a candidate for removal, as it is located behind the turbocharger and would be impossible to remove. The Zerostart Installation Guide recommends removing either the center or left hand frost plugs. While the center plug could be used, it is located quite close to the vacuum actuator control rod for the GT-15 turbocharger on this car and as such, might be a bit too close to either the intense heat of the turbocharger, the vacuum actuator control rod’s movement, or both. Furthermore, removal of this center plug is made difficult by having the right hand CV drive shaft obstructing the use of any tools to remove the plug. It is alleged that the right hand CV drive shaft must be removed to install the block heater in this center hole, although I read of one person on www.tdiclub.com who was able to do so without removing the shaft. Thus, the appropriate candidate for removal was the Left hand plug, based on its relative ease of removal.
II. Preparing for Installation
A. Securely Support Front of Car on Jackstands or Ramps!
Everybody is aware how low these TDI’s sit to the ground, although I believe the 96-97 Passat has a bit more ground clearance than the Golf or Jetta. It goes without saying that you should use ramps or jack stands to support the car and give you some quality working room. Of course, if you have access to a vehicle hydraulic lift you would certainly find this beneficial. I placed two jackstands at the rear of the “H” cradle that suspends the suspension and engine compartment. Whatever you do, make sure the vehicle is securely supported on a firm surface (i.e. cement pad), and if you have any doubt, DO NOT crawl underneath it! Last time I checked the statute, improper vehicle support was not a defense against enforcement of the laws of gravity.
B. Remove Engine Under Cover
If this hasn’t been done already, undoing the three bolts at the rear of the cover and two on each side (or whatever configuration your car has) and swinging the cover down from the front tab mounts will remove the cover.
C. Drain Engine Coolant
This is an unpleasant job, made more difficult by the fact that the car has no radiator drain or block drain to make removal of the coolant easy. Before beginning, remove the cap from the expansion tank, turn the heater controls on high, and obtain a plastic drain pan of about 2-2.5 gallon capacity (8-9 liters). Find the water pump. There is an elbow-shaped plastic fitting that returns coolant to the radiator. Remove the little spring clip that holds the elbow to the water pump and slowly pull the elbow from the pump fitting. You may need to wiggle this fitting or use a screwdriver or similar tool to separate it from the pump. Take care that you do not break the plastic. When it is pulled off of the pump, a torrent of red antifreeze will pour into the drain pan. I found that removing the upper heater core hose on the firewall of the engine helped relieve any air locking to drain more coolant and made refilling the block and head easier.
D. Familiarize Yourself with the Engine Compartment Layout
As discussed above under Roman numeral I, section C, infra have a good look around your engine from the rear, and decide which of the two holes would be easiest to remove with the least amount of hassle. For my money and time (and yours, I would strongly argue), removal of the LR (left rear) plug is easiest. Visualize how you would go about removing the frost plug, installing the block heater into the hole, and routing of the power cord, etc. Think before you swing that hammer!
III. Installation Procedure
A. Removal of Frost Plug
This is undoubtedly the most unpleasant part of this job. With my full permission to laugh, it took about three hours for this shade-tree mechanic to remove the plug based on the tools I had available and the obstructions needed to work around. I imagine there is a perfect combination of tools available, but as this is generally a one-time job I am unable to provide any advice as to what the exact combination might be. Take a good long look at the obstructions that exist while you are under the car and you will understand what I’m saying.
You will have to have something sufficiently long enough and angled enough to exert enough force on the frost plug to cause it to pop out of the hole and remove it from the block with pliers. The following is what I used to accomplish this:
1. One Sears Craftsman Mechanics Prybar, with a 10 degree angled bend
2. One 10” long 3/8” drive socket extension coupled with a deepwall socket over the conical end of the prybar.
3. One 24 Ounce (1.5 pound/3.3 kilogram) maul or hammer.
Of course, you could probably find something else to finagle the obstructions better than what I have described above. Use whatever works when applying reasonable force with the maul/hammer. Make sure that the tools selected allow you to remove the frost plug without knocking it into the engine as removal from the water jacket would be extremely difficult due to the holes obstructed location. I used the prybar by working it back and forth among the obstructions and applying direct force to the plug by striking the end of the prybar/socket extension with the maul. It took a great deal of effort but as I said, it does pop out eventually. During the course of this work you will likely put a hole into the frost plug. When this happens, be prepared for a small torrent of G-12 antifreeze to come out of the hole, and have a small plastic pail to catch as much of this as possible. Once you have bent the plug enough it will not fit securely within the circumference of the hole and will start to move. Do not knock this into the engine block, just gently pry on it a bit with a drift and see if you can wiggle part of it out of the hole. I used a really small channel lock pliers to pull/pry it from the block.
Take care to wash off any splashed antifreeze/coolant from your body- it’s neither particularly pleasant nor healthy to have on you.
B. Install Block Heater Into Engine Block
Use a small magnet on a string or a telescoping magnet antenna tool for removing all metal chips and or flashing from the inside of the hole. I had several small chips, which were all removed from beneath the hole inside of the block water passages. It helps if you wrap the telescoping magnet in plastic wrap as you can easily take the plastic off and throw the plastic and metal chips away without re-introducing these in the engine. Use the magnet inside the block two times to remove the chips.
Next, take a clean shop towel or paper towel and put some lacquer thinner or other similar solvent and wipe the inside of the hole surface completely out. Take the block heater, remove the O-ring supplied with it and place a bead of silicone spark plug boot grease on the groove the O-ring fits around. Do not use a petroleum-based grease, as it will eat the rubber. Put a bit of this grease on your finger and place a coating of it inside the empty frost plug hole. Place the block heater securely inside of the hole with the element facing upwards at the 6 O’clock position. It should fit a little snugly into the block, you will feel a bit of resistance at first but it will “pop” into place.
Take a 5/16” or 7mm socket and begin tightening the screw securing the heater in place. The accompanying literature supplied with the block heater suggests that this bolt should be tightened to a torque of 2.5-3 Newton-Meters or 20-25 inch-pounds, but I defy anybody to use a torque wrench in such tight quarters. When I felt resistance different from that I originally felt after awhile, I simply put another 1.5 to 2 additional turns on this bolt. If you cannot move the metal block heater housing from the engine block, you have it just right.
C. Routing of Block Heater Cord
I routed the heater cord by threading the smaller plug for the block heater through the grille first, up and around the side and back of the battery in the engine compartment, across the expansion tank to engine antifreeze return line, and then plugging the cord into the block heater. Secure the cord to the coolant return line with a zip tie where it connects with the metal support bracket and union for the heater core return lines, taking care to ensure sufficient tautness. Use another zip tie to secure the cord to the battery bracket before the cord goes around the rear of the battery. In any event, make sure that the power cord is adequately suspended above and away from the various cables and levers for actuating the gearshift, which are directly below the cord.
IV. Post Installation
A. Reconnect Opened Coolant Fittings
B. Refill Block
C. Refill Expansion Tank
D. Start Engine
E. Add Coolant Via Expansion Tank
F. Check For Leaks
V. Advantages
Upon October 2000 installation here in Northern Minnesota, I tested the block heater by plugging in the heater on an evening when the mercury reached 15 degrees below zero Fahrenheit (-26 Centigrade). The yellow preheat light came on for about 1 second if that, and the car started right up without the usual puff of smoke. The car also warms up a great deal quicker than normal, thus making a block heater an prime candidate for winter days where your car is only driven on short distance errands that ordinarily do not sufficiently warm the engine to operating temperature. I also hazard to guess that use of the block heater also prolongs the life of your TDI’s glow plugs, since these are used only when absolutely necessary during the winter. Lastly, because these cars have an oil cooler/heat exchanger which uses the coolant to regulate the temperature of the oil, it follows that the use of the block heater should assist in warming up that synthetic 5W-30 or 5W-40 in the crankcase.
In my experience, the car may be plugged in 3-4 hours before startup before the upper radiator hose will be warm to the touch (about 70-80 degrees Fahrenheit, 21-26 degrees Centigrade). At home, I placed my block heater on a timer such that it comes on for three hours before the morning commute and three hours in the late evening at the end of the workday. You can select timers which allow you to increase the number of on/off periods throughout the day to take into account your own schedule.
That’s all folks. . . best wishes!
Since block heater information has been frequently requested on the site, and Spring is perhaps the perfect time to do it when coolant is changed, I have prepared the following to provide others with information needed to successfully select and install block heaters. My TDI is a 1996 Passat, so the information I provide may have to be modified for those who own Jetta and Golf A3’s equipped with the TDI engine. If you have an A4, these instructions will likely be useless. An entrepreneur from Minnesota has designed a recirculating coolant heater which installs into a radiator hose for the A4’s. Information is posted elsewhere on www.tdiclub.com .
A Disclaimer: Car Maintenance And Repair May Be Dangerous! Should you follow the instructions below, you elect to do so with the knowledge that their author is not a professionally trained, licensed, or certified mechanic by any private or governmental regulatory body. You also understand that the author provided these instructions for distribution on www.tdiclub.com without expectation of compensation and such distribution was motivated only by and for educational purposes. In short, what you do with the information is your own call to make and thus entirely at your own risk!
I. Selecting a Block Heater
Of the various companies producing aftermarket VW block heaters, certain constants may be observed which should be noted when selecting a unit.
Size of Block Heater
The frost plug holes measure 36.5 millimeters, and as such you must obtain a heater having this outside diameter to seal the hole properly.
A. Part Numbers
Two manufacturers seem to be the most popular, Zerostart and Kats. Both of these units appear to be widely available. I used a Zerostart product purchased at a local NAPA store. The NAPA part number on this block heater was 605-3230, and it measured exactly 36.5 millimeters in diameter. It is a Zerostart product according to the instructions, and because it fits the same VW and Audi vehicles listed in Zerostart’s 2000 catalogue, one can safely assume it is also Zerostart part number 3100034. As will be seen below, I had absolutely no problems getting this unit to fit securely into the 36.5mm Left Rear (LR) frost plug hole.
B. Pick a Hole, Any Hole. . .Well Almost!
The primary difficulty with installing a block heater in the TDI concerns where the frost plugs are located. The side of the engine closest to the radiator has absolutely no frost plugs whatsoever. A quick removal of the engine compartment under cover (if so equipped) and under-engine examination will reveal that the engine has three frost plugs, all located on the backside of the engine about 6 to 8 inches from the firewall (rear of the engine compartment). Assuming you will be on your back staring up at the rear of the engine block (with your feet protruding from under the front bumper), you will see three frost plugs. All of these are somewhat obstructed.
The plug on the far right is not a candidate for removal, as it is located behind the turbocharger and would be impossible to remove. The Zerostart Installation Guide recommends removing either the center or left hand frost plugs. While the center plug could be used, it is located quite close to the vacuum actuator control rod for the GT-15 turbocharger on this car and as such, might be a bit too close to either the intense heat of the turbocharger, the vacuum actuator control rod’s movement, or both. Furthermore, removal of this center plug is made difficult by having the right hand CV drive shaft obstructing the use of any tools to remove the plug. It is alleged that the right hand CV drive shaft must be removed to install the block heater in this center hole, although I read of one person on www.tdiclub.com who was able to do so without removing the shaft. Thus, the appropriate candidate for removal was the Left hand plug, based on its relative ease of removal.
II. Preparing for Installation
A. Securely Support Front of Car on Jackstands or Ramps!
Everybody is aware how low these TDI’s sit to the ground, although I believe the 96-97 Passat has a bit more ground clearance than the Golf or Jetta. It goes without saying that you should use ramps or jack stands to support the car and give you some quality working room. Of course, if you have access to a vehicle hydraulic lift you would certainly find this beneficial. I placed two jackstands at the rear of the “H” cradle that suspends the suspension and engine compartment. Whatever you do, make sure the vehicle is securely supported on a firm surface (i.e. cement pad), and if you have any doubt, DO NOT crawl underneath it! Last time I checked the statute, improper vehicle support was not a defense against enforcement of the laws of gravity.
B. Remove Engine Under Cover
If this hasn’t been done already, undoing the three bolts at the rear of the cover and two on each side (or whatever configuration your car has) and swinging the cover down from the front tab mounts will remove the cover.
C. Drain Engine Coolant
This is an unpleasant job, made more difficult by the fact that the car has no radiator drain or block drain to make removal of the coolant easy. Before beginning, remove the cap from the expansion tank, turn the heater controls on high, and obtain a plastic drain pan of about 2-2.5 gallon capacity (8-9 liters). Find the water pump. There is an elbow-shaped plastic fitting that returns coolant to the radiator. Remove the little spring clip that holds the elbow to the water pump and slowly pull the elbow from the pump fitting. You may need to wiggle this fitting or use a screwdriver or similar tool to separate it from the pump. Take care that you do not break the plastic. When it is pulled off of the pump, a torrent of red antifreeze will pour into the drain pan. I found that removing the upper heater core hose on the firewall of the engine helped relieve any air locking to drain more coolant and made refilling the block and head easier.
D. Familiarize Yourself with the Engine Compartment Layout
As discussed above under Roman numeral I, section C, infra have a good look around your engine from the rear, and decide which of the two holes would be easiest to remove with the least amount of hassle. For my money and time (and yours, I would strongly argue), removal of the LR (left rear) plug is easiest. Visualize how you would go about removing the frost plug, installing the block heater into the hole, and routing of the power cord, etc. Think before you swing that hammer!
III. Installation Procedure
A. Removal of Frost Plug
This is undoubtedly the most unpleasant part of this job. With my full permission to laugh, it took about three hours for this shade-tree mechanic to remove the plug based on the tools I had available and the obstructions needed to work around. I imagine there is a perfect combination of tools available, but as this is generally a one-time job I am unable to provide any advice as to what the exact combination might be. Take a good long look at the obstructions that exist while you are under the car and you will understand what I’m saying.
You will have to have something sufficiently long enough and angled enough to exert enough force on the frost plug to cause it to pop out of the hole and remove it from the block with pliers. The following is what I used to accomplish this:
1. One Sears Craftsman Mechanics Prybar, with a 10 degree angled bend
2. One 10” long 3/8” drive socket extension coupled with a deepwall socket over the conical end of the prybar.
3. One 24 Ounce (1.5 pound/3.3 kilogram) maul or hammer.
Of course, you could probably find something else to finagle the obstructions better than what I have described above. Use whatever works when applying reasonable force with the maul/hammer. Make sure that the tools selected allow you to remove the frost plug without knocking it into the engine as removal from the water jacket would be extremely difficult due to the holes obstructed location. I used the prybar by working it back and forth among the obstructions and applying direct force to the plug by striking the end of the prybar/socket extension with the maul. It took a great deal of effort but as I said, it does pop out eventually. During the course of this work you will likely put a hole into the frost plug. When this happens, be prepared for a small torrent of G-12 antifreeze to come out of the hole, and have a small plastic pail to catch as much of this as possible. Once you have bent the plug enough it will not fit securely within the circumference of the hole and will start to move. Do not knock this into the engine block, just gently pry on it a bit with a drift and see if you can wiggle part of it out of the hole. I used a really small channel lock pliers to pull/pry it from the block.
Take care to wash off any splashed antifreeze/coolant from your body- it’s neither particularly pleasant nor healthy to have on you.
B. Install Block Heater Into Engine Block
Use a small magnet on a string or a telescoping magnet antenna tool for removing all metal chips and or flashing from the inside of the hole. I had several small chips, which were all removed from beneath the hole inside of the block water passages. It helps if you wrap the telescoping magnet in plastic wrap as you can easily take the plastic off and throw the plastic and metal chips away without re-introducing these in the engine. Use the magnet inside the block two times to remove the chips.
Next, take a clean shop towel or paper towel and put some lacquer thinner or other similar solvent and wipe the inside of the hole surface completely out. Take the block heater, remove the O-ring supplied with it and place a bead of silicone spark plug boot grease on the groove the O-ring fits around. Do not use a petroleum-based grease, as it will eat the rubber. Put a bit of this grease on your finger and place a coating of it inside the empty frost plug hole. Place the block heater securely inside of the hole with the element facing upwards at the 6 O’clock position. It should fit a little snugly into the block, you will feel a bit of resistance at first but it will “pop” into place.
Take a 5/16” or 7mm socket and begin tightening the screw securing the heater in place. The accompanying literature supplied with the block heater suggests that this bolt should be tightened to a torque of 2.5-3 Newton-Meters or 20-25 inch-pounds, but I defy anybody to use a torque wrench in such tight quarters. When I felt resistance different from that I originally felt after awhile, I simply put another 1.5 to 2 additional turns on this bolt. If you cannot move the metal block heater housing from the engine block, you have it just right.
C. Routing of Block Heater Cord
I routed the heater cord by threading the smaller plug for the block heater through the grille first, up and around the side and back of the battery in the engine compartment, across the expansion tank to engine antifreeze return line, and then plugging the cord into the block heater. Secure the cord to the coolant return line with a zip tie where it connects with the metal support bracket and union for the heater core return lines, taking care to ensure sufficient tautness. Use another zip tie to secure the cord to the battery bracket before the cord goes around the rear of the battery. In any event, make sure that the power cord is adequately suspended above and away from the various cables and levers for actuating the gearshift, which are directly below the cord.
IV. Post Installation
A. Reconnect Opened Coolant Fittings
B. Refill Block
C. Refill Expansion Tank
D. Start Engine
E. Add Coolant Via Expansion Tank
F. Check For Leaks
V. Advantages
Upon October 2000 installation here in Northern Minnesota, I tested the block heater by plugging in the heater on an evening when the mercury reached 15 degrees below zero Fahrenheit (-26 Centigrade). The yellow preheat light came on for about 1 second if that, and the car started right up without the usual puff of smoke. The car also warms up a great deal quicker than normal, thus making a block heater an prime candidate for winter days where your car is only driven on short distance errands that ordinarily do not sufficiently warm the engine to operating temperature. I also hazard to guess that use of the block heater also prolongs the life of your TDI’s glow plugs, since these are used only when absolutely necessary during the winter. Lastly, because these cars have an oil cooler/heat exchanger which uses the coolant to regulate the temperature of the oil, it follows that the use of the block heater should assist in warming up that synthetic 5W-30 or 5W-40 in the crankcase.
In my experience, the car may be plugged in 3-4 hours before startup before the upper radiator hose will be warm to the touch (about 70-80 degrees Fahrenheit, 21-26 degrees Centigrade). At home, I placed my block heater on a timer such that it comes on for three hours before the morning commute and three hours in the late evening at the end of the workday. You can select timers which allow you to increase the number of on/off periods throughout the day to take into account your own schedule.
That’s all folks. . . best wishes!
