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Warm-Up Regulator Repair Kit Instructions

Warm-Up Regulator Repair Kit Instructions

Where do i get the kit

The Warm-Up Regulator kit is now available for pre-order at the 2002 FAQ Store. We expect the new batch to be shipped later this summer

What is a Warm Up Regulator, and how does it work?

The Warm Up Regulator (WUR), Warm Up Runner, or Warm Up Transmitter (depending on which BMW document you read) is an add-on device mounted to the back of the Kugelfischer petrol injection pump. Its purpose is to control the enrichment of injection pulses and supply additional ‘fast idle’ air into the plenum chamber during the warm-up phase after engine start. It progressively does this, slowly reducing enrichment and additional airflow in response to rising coolant temperature.


The WUR is based around a wax actuator, a capsule of paraffin wax sealed by a rubber diaphragm - this pushes a steel rod, the ‘moving end’ of the actuator. The actuator is mounted in a coolant loop to react to engine temperature. As the wax warms & melts, there is a volume change, pushing the diaphragm & steel rod with quite a significant force (80+ Newtons). This movement is somewhat linear in the range of -20C to +100C, about 15mm in total.


Warm-Up Regulator


Above is a cross-sectional diagram of the WUR. The wax actuator is on the lower left, immersed in the coolant that flows through one end of the WUR. The WUR Rod pushes a spring-loaded rod…the central body of the WUR is part of the air circuit for the ‘fast-idle’ with the Air Cone and Collar to meter the air, and on the top of the WUR is a ‘top-hat’ nut which pushes the Kugelfischer pump enrichment lever (dotted line section) to adjust the fuel injection volume.


Wax actuator


Cone/Collar arrangement


Checking the Correct Operation of WUR

To check the correct function of the WUR, warm the engine to full operating temperature. Then check:

  • X: Distance ‘A’ should be 9-10mm minimum.
  • Y: Distance ‘B’ should be 4mm
  • Z: ‘Verboten screw’ (1) should be in contact with stop (2)

Warm-Up Regulator Adjustments

If X cannot be obtained, the WUR is either mechanically jammed or the wax element is defective (WUR needs repair). If X is OK and Y is not reached, WUR is likely good and needs top-hat washer adjustment. If X & Y are OK, but Z is not obtained, check if the enrichment lever return spring is in place and the lubrication of the lever pivot point.


Preparing for Repair of WUR


In addition to this info sheet, ensure you have access to the BMW North America Service Training Guide for the Kugelfischer mechanical fuel injection system, published in February 1980. 

What's in the kit?

The Kit is available at the 2002 FAQ Store. It contains FIVE parts:


  1. A New Wax Actuator
  2. A New Water Seal ‘O’Ring
  3. An Air Regulating Cone Retainer Plate
  4. A Pin Wrench
  5. A 2mm Allen key


The wrench is included because removing the collar without damage is critical to rebuilding. The inner diameter must not get deformed or damaged. Because the collar is steel and the WUR body is Aluminium, the parts are highly likely to be corroded together. The wrench is there to ease the collar from the alloy housing gently.


The Air Regulating Cone Retainer Plate is needed to calibrate the WUR (cone height at reference temperature) before the restored unit is re-fitted to the pump & engine. It can also be used to set the top-hat washer position (enrichment) once the WUR is installed.


The other tools needed to perform the repair are your standard screwdrivers, sockets, and spanners - the only slightly special tool you'll need is a 2mm Allen key - now included in the kit, which is used to release the grub screw in the Air regulating Cone.

WUR Differences Over the Years.

To the best of my knowledge, all tii WURs are functionally identical, but there were some differences at the start & end of the tii production. Early WURs have a large locknut helping to secure the collar, as can be seen in this photo from the BMW WSM:


Early Warm-Up Regulator


Then, late in the production run, there was a change in the Kugelfischer pump lever, and a spring was added on top of the cone.


Regulator with top spring


To the best of my knowledge, these changes do not alter the basic function & features of the WUR and the compatibility of this kit. It is suitable for all 2002tii injection pumps:

  • 1969-1971 BMW 2000 tii : PLO4-124.01 (A-1 & A-2) #92 004 010
  • 1971 BMW 2002 tii  :  PLO4-124.01 (B-1) #92 004 011
  • 1972-1973 2002 tii : PLO4-124.01 (C-1) #92 004 012
  • 1974 2002 tii (USA) : PLO4-124.02 (A-1) #94 004 020


Additional Parts Required

Depending on the condition of your system, there are two parts NOT included in this kit that you may wish to exchange during the WUR overhaul. They are the ‘ball cup’ and ‘covering cap’ that locate & protect the intermediate shaft at its pivot-point on the WUR:


‘Ball Cup’- part 9



  ‘Covering Cap’ - part 11



These parts are available from normal ‘02 specialists:


  • Ball Cup BMW 13511256078
  • Covering Cap  BMW 13511257374 [It now seems this part NLA. Many cars have been operating for years without this part, so you may ignore it... or you could DIY a small rubber cup of around 13 mm/half-inch internal diameter from a hardware store - chair leg foot, etc]


The cap & cover don’t affect the WUR’s primary cold-start function. Still, as a secondary function, the body of the WUR is used as the pivot point for the intermediate throttle shaft, and there should be no play in that pivot - the cup is a critical bearing for the shaft, and the cover protects this pivot from debris. Maybe your current cup & cover are in good condition, or maybe it’s time to replace them. You decide.


Preparation for Removing the WUR.

Since the WUR performs that additional mechanical function in the tii setup (the pivot point for the intermediate shaft that actuates both the Kugelfischer throttle lever and the throttle body), when the WUR is removed, the intermediate shaft must be moved, and this risks disturbance of all the settings of your tii. The BMW North America Service Training Guide (Blue Book, link above) provides a thorough guide for resetting this linkage to factory specs - that's one way to proceed. However, if you are concerned about the unknown territory of a full factory reset, then below I suggest some checks & measurements to take before starting disassembly that will enable you to reassemble the linkage ‘back like it was’ even if that's different from what the ‘Blue Book’ says.


  1. Use a 5mm rod/hook to lock the Kugelfischer Pump throttle lever in its idle position.
    • This lever is on the side of the pump closest to the engine, not easy to see
  2. Open the top of the ‘tuna can’ on the throttle body, & observe the position of the ‘D Cam’ relative to the 4mm hole:
    •     D Cam
  3. If the idle screw (1) is touching the ‘D cam’, count the turns to unscrew it until its not touching the ‘D cam’ (Write down how many turns).
  4. Photograph the position of the ‘D Cam’  from a point looking straight down at the 4mm hole (B)
  5. After reassembly, we will try to set the “D Cam’ in the same position and set the idle screw in the same place.


Removing the WUR

  1. Disconnect & remove the battery.
  2. Remove the whole air cleaner assembly.
  3. Drain the coolant.
  4. Prepare a catch-tray, disconnect both coolant hoses from the WUR (3&4 below), and expect some coolant to be lost into the tray.
    • Coolant Hoses
  5. Disconnect the auxiliary air hose (6, above), take care not to damage this critical hose.
  6. Disconnect the return spring (1, below) and unscrew bolts 2,3,4 & 5:
    • Return Spring and Bolts
  7. Bolt No. 3 has a nut on the back that will spin easily, use a long screwdriver to jam the nut so that the bolt can be loosened, and catch the nut with a magnet.
  8. Insert a flat-bladed screwdriver between the WUR body & the back of the Kugelfischer Pump, lever the WUR backward off a locating sleeve, and then downwards to separate the throttle linkage pivot.
  9. Manipulate the WUR to separate the threaded rod/tophat washer from the Kugelfischer pump enrichment lever, and withdraw the WUR from the car.
  10. Locate the plastic ball cup from the pivot point of the WUR. Keep it safe if you plan to reuse it. (it may be in the pivot or at the end of the throttle shaft). Check the rubber ‘Covering Cap’ that should be dangling on the throttle intermediate shaft. Keep it safe if you plan to reuse it.


Dismantling the WUR

  1. Remove the locknut and top-hat washer.
  2. Engage the supplied pin wrench fully into the collar, unscrew, and remove the collar. The spring and threaded rod will pop out as the collar is freed. If the collar is stuck, use heat & penetrating oil to persuade it to break free from the alloy body. Be careful not to damage/deform the collar (e.g., do not use a hammer & punch), as the inner diameter of the collar is critical to the WUR function.
  3. Withdraw the spacer tube - this slides in a simple keyway on all but the earliest examples of the WUR (on early cars, this spacer is free to rotate).
  4. Next, there is a flat washer and an ‘O’Ring that retain the brass actuator, the ‘O’Ring may have solidified, and you will need to scrape it out with a screwdriver. Don’t pull the rod straight up, as it will come out of the old actuator, making it more difficult to remove the brass body. Instead, push the rod side to side to break the brass body away from the alloy tube.
  5. Finally, withdraw the brass actuator.


The contents of the WUR (with exception of actuator body, only the actuator shaft is shown)


Clean the alloy body, and check for leaks in the bottom chamber. It can be welded or even epoxied to effect a repair (its only purpose is to circulate coolant around the brass actuator). De-rust the cone, collar, and threaded rod. Loosen the 2mm grub screw that clamps the cone to the threaded central rod, leave the grub screw in the cone with its head flush with the cone surface (so it will still slide thru the collar), and check the cone will turn on the threaded rod - screw the cone ‘up’ the threaded rod by about 10mm - this cone/rod adjustment will be used in calibration later.


Rebuilding the WUR

Once the WUR body is clean, the reassembly with the new parts is straightforward:

  1. Insert the new wax actuator into the WUR body.
  2. Drop the supplied ‘O’Ring over the actuator shaft (if there's any corrosion inside the WUR body, some sealant on the ‘O’Ring may help ensure a watertight seal)
  3. Drop the plain washer over the actuator shaft.
  4. With the ‘key’ indentation at the top, guide the spacer into the WUR body. (on early cars, there is no ‘key’ to orientate the spacer - in this case, align the hole in the spacer with the air outlet on the side of the WUR - then use a wooden dowel pushed into the air outlet to stop the spacer rotating during rest of this assembly sequence)
  5. Place the cup end of the threaded rod over the head of the actuator shaft.
  6. Locate the spring on the rim of the cup on the threaded rod.
  7. Lightly grease the collar - both externally threaded and inner plain surfaces.
  8. Push the collar against spring pressure to engage in the WUR body thread, and tighten the collar using a pin wrench until it is solid against the internal spacer. (remove the wooden alignment dowel if fitted in 4, above)
  9. Perform calibration of cone height (see below)
  10. Loosely install top-hat washer & locknut.


Calibration of the WUR

To calibrate the WUR we must set the height of the cone at the reference temperature of 30°C.


  1. Prepare a bowl of water at 30°C, it should be big enough for the lower ~50mm of WUR body to be immersed. Check and correct the temperature regularly.
  2. Immerse the lower part of the WUR, expelling air from the WUR chamber as best you can. [Don't dump the whole thing in the water, only the bottom half]
  3. Allow the WUR to stabilize at this temperature.
  4. To calibrate, the cone must be raised/lowered on the threaded shaft so that the Air Regulating Cone Retainer Plate can be inserted flush with the surface of the collar. Hold the flats on the top of the threaded rod & turn the cone to adjust the cone height.
  5. It should be possible to remove & re-insert the Air Regulating Cone Retainer Plate (ARCRP) without force on either the plate or the cone - In other words, the ARCRP is not holding the cone against the spring pressure - the cone's 'natural height' should mean the ARCRP slips in and out easily)
  6. Once this is achieved, add hot water to the bowl to raise the temperature to ~60°C so that the cone extends to reveal the cone grub screw - tighten the 2mm grub screw to lock the cone on the threaded shaft & fix the calibration.


Installing the WUR

  1. Refit the plastic ‘Ball Cup’ to the pivot & apply some grease to the plastic cup.
  2. Push the Covering Cap (if fitted) onto the intermediate throttle shaft.
  3. Manipulate the WUR to engage the threaded shaft/tophat with the Kugelfischer pump enrichment lever, then the throttle shaft into the ball cup pivot & finally to locate on the back of the pump.
  4. Replace four bolts that secure the WUR.
  5. Refit the auxiliary air hose.
  6. Refit coolant pipes
  7. Ensure the enrichment lever return spring is in-place (either on a bracket close to the verboten screw or between the cone and the lever on later cars). 
  8. Adjust Top-Hat Washer:
    • Pull/lever the threaded shaft up against spring pressure until the Air Regulating Cone Retainer Plate can be inserted.
      • Cone Retainer Plate
    • Adjust the height of the top-hat washer until the gap A is 2.6 +/- 0.3mm. (DO NOT adjust the ‘verboten screw’ to set this gap!)
      • Height Adjustment
    • Lock the position of the top hat with the locknut.
  9. Refit the air cleaner, refit and connect the battery, and refill the coolant.
  10. Go through the full adjustment procedure in the “Blue Book’ (page 12 onwards)
  11. -or- 
  12. Repeat/review items 1-4 above, loosening the clamp bolts on the intermediate shaft to move the D cam position to be the same as before, and then reset the idle screw. You’ll probably need to fine-tune idle and mixture using the ‘tuna can’ adjustments.
  13. Start the engine & go through the warm-up cycle. Check X,Y,Z at the start of this document.


All done, good for another 50 years!



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Definitely going to pick this up. My warmup crapped the bed a couple of years ago. Been a smelly warmup for a while. Need to change plugs and oil more often.


When will we be able to purchase this kit? March?



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4 hours ago, roman.lysiak said:

Definitely going to pick this up. My warmup crapped the bed a couple of years ago. Been a smelly warmup for a while. Need to change plugs and oil more often.


When will we be able to purchase this kit? March?



It is available for Pre Order now.  They should be shipped in March.


steve K.

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Excellent, thanks for the hard work!


I ordered a kit, and look forward to no longer needing to keep my foot on the throttle when the engine is cold.


I had begun to rig up a hand throttle cable to control a ball valve for the extra air passage, but this is a much better solution.

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I want to order one kit but several additional wax motors.


Any chance I can do that, is there a difference in price, and how can I order in that way?





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Just checked. Mine comes up when warm but not even 6mm and there is not contact at the verboten screw. Guess I need one!

Edited by Highnote1
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4 hours ago, Einspritz said:

Any chance I can do that, is there a difference in price, and how can I order in that way?

Hi Ted,

To start and and to keep things simple, we just plan to sell the kits. Most of the cost is the engineering investment for the actuator, so there wouldn't be a huge price difference without the tools and it would complicate ordering and inventory managment (I am a simple guy, new to this kitting/shipping/coordinating).


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On 1/6/2023 at 9:00 PM, dlacey said:

Covering Cap  BMW 13511257374

It's been pointed-out that this part is NLA, sorry to dash your hopes (i am sure i purchased one a few years back...)... Only chance is to do your best to save the one you have, or craft something from a small rubber cap (pipe cap, stool foot etc) found at local hardware store... or just forget it...I am sure thousands of tii are running fine without this cap...

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11 hours ago, dlacey said:

It's been pointed-out that this part is NLA, sorry to dash your hopes (i am sure i purchased one a few years back...)... Only chance is to do your best to save the one you have, or craft something from a small rubber cap (pipe cap, stool foot etc) found at local hardware store... or just forget it...I am sure thousands of tii are running fine without this cap...

I'm sure almost all are running without this cap.  I have never seen one.

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I would like to thank everyone fro the preorders as that gives us a better idea of the initial numbers that we need.


steve k. 

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Hello All,


After having completed a full rebuild of the WUR using Dave's kit and instructions (I was a guinea pig tester) - I wanted to share my thoughts here in support. First off, Dave did a great job on the initial instructions and I know in consideration of feedback provided from some of us - he'll be making some small tweaks, so I will leave the details of those to him :). What I can say is rest assured if your WUR needs a rebuild this is the way to go and you'll be very pleased with the outcome. 


With respect to the cone grub screw and setup, I set mine and validated the rise using temps in Fahrenheit (a little different than the instructions. After a cold check at 35-40F (recessed cone) and standard temp check 60F (at 85F no measured change as well when compared to 60F) I then set it at flush, mine was two downward turns then perfect. I then rechecked it a 35F and 60F and it was gold. I then used 160F hot water and checked/confirmed the full 10mm extension and locked the grub screw. 


Upon completion, my Tii started significantly better to say the least on a couple really cold mornings here a week or so ago - 21F and 23F respectively. Not only that, but in my opinion the new actuator opens up a bit smoother as well or at least it seems to transition/sound better to me as it warms up. So A+ all around to Dave for all his efforts here. 


Thanks again Dave - I and our wonderful community appreciate you!


A few images from along the way!











Edited by Rodolfo Lasparri
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Those who know me well know how bad my memory is - it there a way to confirm that as intended, that I actually did pre-order the WUR rebuild kit? I tried the chat function on the FAQ store but no one replied. Given I may have paid with PayPal or CC I'm not seeing an entry that appears to match, but who knows what it's listed under.

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