Roger @ CA

Well, my thermostat broke on my 93 90CS with a transplanted 95 90 engine... Was overheating ever 15 miles on a long 4 hour trip (Turned into a 12+ hour ordeal...)

But anyway, I have a new Thermostat for the 90 (Audi part number is 078 121 113 F) and am trying to figure out the best way to replace it. I have my old 12V engine to try out any removal techniques on, but I found a post by <i>DimeADip</i> and <i>BLFaster</i> saying they did the T-stat replacement in 3 hours without removing the timing belt. <b>Does anyone know how they did that???</b> I'd be eternally grateful, as I'd rather do that than rip the whole front end and timing belt off to do a stupid little thermostat.

If anyone has any insight into this... Miktip, etc., please let me know... I'll be going to the garage later today to start work on it...
Roger

SiV6Qcoupe

I've done a thermostat r&amp;r without removing the timing belt - it's hard due to the fact the timing belt goes over the thermostat cover which has to be lifted over the 'stat so things can get VERY tight. Best thing to do is just release the tension in the timing belt but don't remove it, mark up the positions of the cams and crank relative to the belt beforehand just to be sure.
Remove the fans behind the rad to give you more room.

MikTip

it can be done without removing the timeing belt.

mingblue90cs

both of my 90's i was able to do it w/o loosening the tb.its a litlle tricky. after removing the 2 10mm bolts that secure the housing to the block and the upper rad hose iremoved the housing upwards and at a slight angle. in doing so i slightly rotated the tb at the same angle i was removing to get the housing out. do the opposite for installation. make sure the small nipple is top side on the tsat when you reinstall. good luck

4Driver4

Maybe you should do the "full monty".

Roger @ CA

I did the full monty about 6 weeks ago when I swapped in a new engine. :-)

YucatanAudi

and left the old thermostat?

4Driver4

Water pump, tensioner, roller, seals?

Roger @ CA

The new engine has great looking belts... not going to replace the water pump, etc. for a year or 20k or so...

dimeadip

Here are the instuctions I referenced. They're actually for replacing the timing belt, but it gives all the steps needed to get to the thermostat. Skip the t-belt stuff. Thanks to Natwhite for posting it sometime back.

Also check MikTip's site for a picture of the t-stat housing. It is TIGHT between the t-belt and housing, but take your time and it WILL come out. But, just in case, I marked the t-belt and cam pulleys with a silver pen just in case it slipped a tooth.

Chris

=======================================

Awesome Instructions... Someone E-Mailed them to me. Thanks!
User account number (aid): 37457
Posted by natwhite on 2002-10-07 22:00:15
In Reply to: timing belt..... posted by BigRed12V on 2002-10-07 17:09:55
VW / Audi 2.8 V6 Timing belt / water pump How-to Procedure REV=1

Written by ARK (An Audiworld forum contributor)

Readers are advised that this article is for informational purposes only. No liability is assumed by the author for the use of or interpretation of information contained within this article -- all actions and decisions based on the data or information are the responsibility of the individual user.

Parts Needed :

1 cam belt (drives the camshafts and the water pump)

1 cam belt tensioner pulley

1 cam belt idler pulley

1 water pump and gasket

1 water thermostat and O-ring gasket

1 accessory drive belt (drives the alternator, AC compressor, and the power steering pump)

1 accessory belt tensioner pulley
(If your car still has the original, longer access belt, buy the "Serpentine accessory belt Update Kit" from Audi, which contains the new shorter belt, and a new design tensioner pulley. This kit eliminates the 2nd fixed (non-spring loaded) idler pulley located above the AC compressor. The 2nd idler just gets removed and discarded. Look for this 2nd pulley to see if your car was already updated.)

1 radiator cooling fan thermoswitch (three terminal) and seal washer. I would recommend the lower temperature version (85C/93C) available from some of the independent VW / Audi parts vendors. Try AutoTech Sport Tuning, (949) 240 4000. There are two versions of the 3 terminal switch. My 1993 90S used the "early 3 terminal version", p/n 10.954.185. This is a non-USA market item, probably not available from a VW / Audi dealer. This will allow your car to run cooler in stop and go conditions.

1 gallon (maybe 2? : need half the rated coolant capacity of your car, see the owners manual) of genuine VW/Audi antifreeze (the blue green type, NOT the newer pink (G12) stuff).

1 gallon (maybe 2? : need half the rated coolant capacity of your car, see the owners manual) steam distilled water (Grocery store or auto parts store)

1 O-ring seal for the engine block coolant drain bolt (located at the bottom rear center of the block, near the bell-housing, a socket head bolt which is vertically installed.

8 new socket head bolts which hold the accessory belt drive pulley to the nose of the crankshaft. (VW / Audi Parts Dept)

1 tube of Permatex Blue Silicone RTV gasket goop (for the waterpump gasket)

1 container of Naptha solvent, or Brake-Clean

1 spray can of WD-40

1 toothbrush

1 roll of paper towels

Tools : (above and beyond the normal basic tools)

1 set Metric socket head bits (6 sided "allen key") for your ratchet driver handle, 6mm to 17mm (guess)

1 strap wrench, must accommodate an 8-inch diameter object. (to hold the crank pulley or PS pulley from turning as you loosen the attachment bolts)

1 breaker bar, or a 1.5 foot pipe which fits over your ratchet handle.

1 bottle of "White-Out" (to make some painted alignment marks. I don't know if regular paint will attack the rubber belt)

1 silver or gold permanent ink fine point marker pen. (Stationary or Art Supply store)

*1 Cam sprocket alignment tool (see Blaufergnugen web site, tool # 3242)

*1 crankshaft TDC holder tool (see Blaufergnugen web site, tool # 3243)

*1 gear / sprocket puller, 3 arm jaws, accommodates a 5 or 6 inch diameter sprocket

A copy of the Audi Factory Service manual (Bentley Publishers or Dyment Distribution) The 1 page cambelt procedure that Mike Tip has posted on Audiworld is essentially the same info. A copy of the factory service manual (up to model year 1997?) is also available on CD ROM, sold under the "Popular Mechanics" brand name, available from K-Mart ($20) or JC Whitney. This is actually an Alldata product.


How -to :

There are two ways to do this job. One is slightly easier, less risky, idiot-proof, but more expensive. This easier way is to buy or rent the special tools for the job (marked with a *). This method is bulletproof as far as getting the cams aligned properly. Follow the Factory Procedure EXACTLY. The Audi Cam belt alignment procedure is unlike typical set-ups, as there are NO traditional cam sprocket timing marks! If you are replacing the camshaft oil seals, you MUST use the factory procedure and special tools, as the cam sprockets must be removed to gain access to the seals. I am not sure if the special TDC locking tool is needed if you are replacing only the crankshaft oil seal. I will look into this.

If however you are more confident of your mechanical abilities, you can work meticulously, and are POSITIVE that the cam timing alignment of the old belt is correct (Either it is the original belt installed at the factory, and hasn't lost any teeth or slipped yet, or the previous mechanic did the last belt replacement correctly), these special * tools are not needed. The cam belt timing alignment must be accurate to +/- 0 teeth, there is NO room for error. Then the procedure is as follows : (You cannot replace the cam oil seals if you follow this procedure.)

Note : These instructions are my recollection of this procedure I did on a 1993 Audi 90S. Other 2.8 V6 (NOT VR6) models (Audi 100, A6, A4, VW Passat) are probably similar), but may use a different cam belt tensioner (self adjusting in later production).

1) Put the car on ramps, parking brake ON, and remove the bellypan. Manual tranny in 1st gear. Auto in Park. Put safety chucks on the rear wheels.

2) AFTER the engine has cooled down (ideally to room temp), drain the coolant by loosening the overflow tank cap, and the heater hose bleed screw (black plastic, knurled, about the size of a dime, located near the firewall at the high-point of the hose), then remove the engine block drain screw. This screw is located on the bottom of the engine, about in the center, right near the end of the block where the transmission bell housing starts. This is a hex socket head bolt, threaded straight up into the block.

3) To gain some working room on a 90/Cabrio follow steps 4 thru 5. The radiator does not get removed. For 100 (or A6 up to 1997) models, the radiator fans do not need removal, there appears to be enough working room. For Passats, A4s, or 1998 or newer A6, the front bumper comes off, and the radiator and AC condenser is moved aside to allow access to the front of the engine. Refer to the service manual for "Moving the radiator carrier to the Service Lock position"

4) Remove the 2 (or 3) radiator fan motor wires at the fan resistor, a flat aluminum plate, located on the underside of the forward frame-rail tube, on the drivers side, about 8 inches behind the bumper.

5) Pull off the rubber weatherstrip that runs along the top of the radiator fan assembly. Remove the 2 or 3 bolts at the top of the fan assembly, holding it to the top of the radiator. Remove the fan assembly by tilting the top back towards the engine about 1/2 inch, then pull straight up. The bottom will slide out of a spring clamp.

6) Remove the black plastic top engine cover (4 fasteners

7) Remove the top center front plastic cover (2 ? fasteners)

8) Using a small mirror and flashlight, locate the square hole and the smaller round "holding" hole on the access belt tensioner arm. Using a breaker bar, inserted into the square hole, rotate the arm against the spring until the small round hole lines-up with a matching hole behind it. Insert a metal pin, or large nail, into this holding hole. Remove the breaker bar. Remove the access belt, noting its routing.

9) If updating the access belt, pop the black plastic front cover off the fixed idler pulley located above the AC compressor. Remove the center-bolt, and pull the pulley off and discard. (There are instructions and a belt routing diagram included with the Update Kit.)

10) Remove the spring-loaded tensioner pulley, by removing the center bolt.

11) Use the strap wrench to hold the power steering pump pulley (top front center of engine), loosen and remove the 3 (4?) socket head bolts. Remove the pulley.

12) Remove the left and right black plastic cam belt covers (some spring clip fasteners), noting how this jigsaw puzzle fits together. (Remember what tab fits in what slot......which piece fits in front of the other..........)

13) Note the camshaft ends have a "2 holed wing-thing" (for lack of a better word) at the sprocket centers. One hole is larger than the other. NEVER loosen the center bolts of the cam sprockets, if you are following this "No Special Tool" procedure.

14) For manual transmission cars, put the gearshift selector in 5th. This will hold the crankshaft from rotating as the 8 socket head crankshaft pulley bolts are loosened. Do not remove the bolts at this time, just break free the holding torque, and loosen ¼ turn each.

15) For automatic tranny cars, use the strap wrench to prevent the rotation of the crankshaft as the 8 socket head crankshaft pulley bolts are loosened. Do not remove the bolts at this time, just break free the holding torque, and loosen ¼ turn each.

16) Put Manual transmission cars in neutral.

17) Using the strap wrench (or a breaker bar and socket on the large center bolt) rotate the CRANKSHAFT pulley CLOCKWISE (Do not rotate CCW!) until the two large holes on the camshaft wing-things are closest to each other. Ideally a straight horizontal line can then be drawn between the two camshaft center bolts, which must also pass through the centers of the 4 holes of the two wing-things.

18) Check if the TDC notch on the crankshaft pulley lines up with the mark on the black plastic bottom cover. (I think it is located at about "1 O'clock" position). If it does not, return to step 17 and continue to rotate the crankshaft clockwise until the camshaft wing-thing holes line up again as described in step 17.

19) Remove the 8 socket head crankshaft pulley bolts, (Do not rotate the pulley), and then remove the pulley.

20) Remove the bottom black plastic crankshaft sprocket cover. (Not sure of the number of fasteners)

21) Use a clean paper towel wetted with Naptha solvent (or Brake-Clean), wipe the metal front surfaces of the crankshaft sprocket and the 2 camshaft sprockets where the belt teeth meet the metal teeth.

22) Using WhiteOut, make a pair of small adjacent white dots, one on the metal crankshaft sprocket "valley" and one on the mating cam belt tooth (on the `edge' of the belt). Pick a valley/tooth pair that is roughly in the center of the series of engaged teeth. As back-up marks, use a silver permanent ink marker pen to draw a line across the wide part of the belt, at the white marked tooth.

23) Repeat step 22 for each of the camshaft sprockets.

24) For future reference, note the tension of the old cam belt, by twisting the belt with your thumb and fingers, at the center of the belt section between the tensioner and the passenger side cam sprocket. Note the amount of force needed to twist the belt 90 degrees. This will help to learn how much to tighten the new belt.

25) For future reference, note carefully which direction the cam belt tensioner eccentric rotates as it is loosened in the next step. (It will have to rotated and tightened in the opposite direction when the new belt is tensioned)

26) Loosen the tensioner attachment bolt, relieving the cam belt tension.

27) Remove the old cam belt, noting its routing. Put it on the floor, in an area it will not be disturbed, with the white paint marks facing up. The crank paint mark should be closest to you (the "bottom").

28) DO NOT ROTATE either cam sprockets OR the crankshaft sprocket !!!!

29) Using a pen as a pointer, carefully count the number of teeth, (#1 starting is the bottom crank mark), moving counterclockwise around the belt, until you reach the next (2nd) paint dot at the driver side cam location (Include this painted tooth in your count). Write down this tooth #. Recount as many times as necessary, until you are sure that this number is correct.

30) Continue counting teeth counterclockwise until you reach the next (3rd) white paint mark at the passenger side cam location (Include this painted tooth in your count). Write down this tooth #. Recount as many times as necessary, until you are sure that this number is correct.

31) Lay the new cam belt next to the old, and make the first WhiteOut mark on any belt tooth edge near the bottom. This is now the new crank mark.

32) Counting counterclockwise along the new belt, make a white paint mark at the tooth # recorded in step 29. Recount as many times as necessary, until you are sure that the tooth selected is correct. This is the driver side cam location.

33) Continue counting counterclockwise along the new belt, make a white paint mark at the tooth # recorded in step 30. Recount as many times as necessary, until you are sure that the tooth selected is correct. This is the passenger side cam location.

34) Perform one last check : On the old belt, count the # of teeth BETWEEN each set of paint marks (now NOT counting the marked teeth). Compare these three count numbers with the corresponding segments of the new belt.

35) Set the new and old reference belt aside in a safe location, maintaining the orientation of the crank mark location.

36) Remove the water pump. Make sure all traces of the old gasket are scraped away from the engine block mating surface. Do not scratch/gouge the mating surface. Dry up any wetness due to antifreeze. Use a shop-vac to suck out any gasket debris that may have gotten into the threaded mounting bolt holes. Clean the mating surface on the engine and the new pump with a clean paper towel and Naptha solvent. Clean the threads of the water pump bolts with a toothbrush and some WD-40 spray. Apply a THIN layer of Blue RTV to both sides of the gasket and them assemble the pump and gasket to the block. Tighten the bolts evenly, in a multi-stepped criss-cross pattern, until the factory torque spec is achieved.

37) Loosen the bottom radiator hose clamp. Remove the 2 bolts which attach the thermostat housing / pipe. Remove the rubber hose / metal pipe / thermostat housing from the engine and radiator. Note the orientation of the old thermostat ! (The longer protrusion goes into the engine, the bleed "jiggle pin" should be at the top.) Using a small flat-blade screwdriver, carefully scrape clean the O-ring seal area of the housing and the block. Do not gouge the soft aluminum!

38) From underneath the car, unplug and remove and replace the radiator fan thermoswitch, which is screwed into the passenger side radiator end tank. Working room for a wrench is very tight, but it can be done! (at least on a 1993 90S automatic!) The removed radiator hose helps access. Make sure the old fiber gasket seal washer comes off with the old switch.

39) Use a shop-vac to suck out any gasket debris that may have gotten into the threaded mounting bolt holes where the thermostat housing bolts onto the engine. Clean the threads of the thermostat housing bolts with a toothbrush and some WD-40 spray.

40) Using a new O-ring gasket, assemble the new water thermostat into the housing/pipe, and attach to the engine block. The O-ring goes between the thermostat and the housing/pipe. The thermostat must be correctly orientated into the engine block hole. (The longer protrusion goes into the engine, the bleed "jiggle pin" should be at the top.) Evenly tighten the 2 housing bolts to the factory torque spec. Re-attach the radiator hose to the radiator, tightening the clamp.

41) Remove and replace the old cam belt tensioner pulley. Tighten the attachment bolt only slightly snug, so that the tensioner eccentric can still be rotated.

42) Remove and replace the old cam belt fixed pulley.

43) Install the new cam belt : Start at the passenger side cam sprocket, line up the paint marks. While holding the belt on this first sprocket (or temporarily use a nylon tie-wrap thru a sprocket hole to hold the belt on), route the belt around (smooth side of belt) the waterpump pulley, then to the drivers side cam sprocket. The drivers side cam belt and sprocket marks should line up. There should be no belt slack between sprockets/pulleys. Use another tie-wrap to fasten the belt to the drivers side cam sprocket.

44) Route the belt down, around the fixed pulley (smooth side of the belt), down towards the crankshaft sprocket. The crank cam belt and sprocket marks should line up. There should be no slack between sprockets/pulleys.

45) Pop the belt around (smooth side of belt) the tensioner pulley, rotating the eccentric for the most clearance.

46) With a ratchet/socket on the fastening bolt, and an allen key in the tension adjusting hole of the cam tensioner pulley, rotate the eccentric in the correct direction (see step 25) until the cam belt slack is removed, then tighten (to the spec'ed torque) the fastening bolt to hold the eccentric position. Check the belt tension per step 24. You should make the belt a little tighter than what was noted for the old belt. It should take a fairly substantial finger force to twist the belt 90 degrees, but resist the temptation to overtension it.

47) Double check that all the timing marks on all three sprockets line up.

48) Temporarily replace the bottom black plastic crankshaft sprocket cover.

49) Temporarily replace the crankshaft pulley (aligning the key to the crankshaft), using 4 of the 8 new socket head bolts. Just tighten the bolts finger tight.

50) Using the strap wrench (or a breaker bar and socket on the large center bolt) rotate the CRANKSHAFT pulley CLOCKWISE (Do not rotate CCW!) a few turns until once again the two large holes on the camshaft wing-things are closest to each other. Ideally a straight horizontal line can then be drawn between the two camshaft center bolts, which must also pass through the centers of the 4 holes of the two wing-things.

51) Check if the TDC notch on the crankshaft pulley lines up with the mark on the black plastic bottom cover. (I think located at about "1 O'clock" position) If it does not, return to step 50 and continue to rotate the crankshaft clockwise until the camshaft wing-thing holes line up again.

52) Check that the 2 pairs of camshaft sprocket / belt tooth paint marks are still aligned.

53) Recheck the belt tension, readjust if necessary.

54) Remove the crankshaft pulley and black plastic cover.

55) Check that the crankshaft sprocket / belt tooth paint marks are still aligned.

56) Re-install the bottom black plastic cover, and the crank pulley, now evenly torqueing the 8 socket head bolts to the specified tightening torque, in an even stepped criss-cross sequence. Use the strap wrench to hold the pulley from rotating as the bolts are tightened. (Or 5th gear with a manual transmission)

57) Replace and tighten the engine block drain bolt. Use a new O-ring gasket !

58) Make a 50%/50% mixture of antifreeze and distilled water. (A third gallon container is needed for this.)

59) Loosen the 2nd bleeder screw, located on the U shaped black metal coolant pipe, which runs around the base of the intake manifold (snakey thing). It is a metal hex socket head bolt, facing up, near the rear right of the engine. Do not remove it, just loosen it 3 turns.

60) Slowly refill the cooling system at the overflow tank, until coolant dribbles out of the 2nd bleeder screw. Close the 2nd bleeder screw. Continue filling until coolant dribbles out of the heater hose bleed screw. Close the bleeder screw. Fill the overflow tank to the full cold line.

61) Make sure all tools are clear of the pulleys, tranny in Park or Neutral, start the engine and allow it to idle for a minute, then raise the RPM to 1200. Listen for unusual cam belt noise. Shut the engine off. If the belt is too tight, you will hear a distinctive howling sound, that rises in pitch if you rev up. If too tight , readjust the belt tension per step 46.

62) Replace the left and right black plastic cam belt covers. They will only fit properly if you observe the correct order of assembly. (Insert curse words here)

63) Clean the threads of the spring-loaded tensioner bolt with a toothbrush and some WD-40 spray. Use a shop-vac to suck out any gasket debris that may have gotten into the threaded mounting bolt hole where the tensioner bolts onto the engine. Install the new updated design serpentine acces belt spring loaded tensioner pulley. Note the locating pin on the back of the pulley base, which fits into an alignment hole on the engine. Tighten the mounting bolt to the specified torque.

64) If necessary (the new spring loaded pulley may be pinned already), use the breaker bar and a pin to set the tensioner arm to the "belt install" position, per step 8.

65) Clean the threads of the power steering pump bolts with a toothbrush and some WD-40 spray. Replace the power steering pump pulley, using the strap wrench to prevent the rotation of the pulley as the bolts are evenly tightened in a criss-cross pattern to the specified torque.

66) Install the new serpentine access belt, following the new revised routing.

67) Using the breaker bar, relieve the spring pressure on the holding pin, and remove the pin. Slowly release the spring tensioner against the belt.

68) Replace the top center front plastic cover (2 ? fasteners)

69) Replace the black plastic top engine cover (4 fasteners)

70) Replace the radiator cooling fan assembly. Re-install the mounting bolts and the weatherstrip. Re-attach the wires at the fan resistor.

71) With the coolant tank cap off, start the engine. Turn OFF the Auto-climate control system (set the fan speed to the lowest setting, then release and push the "-" fan speed button once more) so that the radiator fans don't run (for the AC), and the heater is off. (Manual AC/Heat control : set the fan to OFF, temp to cool, AC OFF.) Let it idle until the engine temp gauge reads normal operating temp. Do not rev the engine as it warms up, as the water pump bearing/seals may not be well lubricated until the thermostat opens and purges out the trapped air that may be in the pump. Once the engine has reached normal operating temp, rev the engine a few times (2500 RPM) to purge any remaining air pockets. Recheck the coolant level, and then tighten the coolant tank cap so the system can pressurize. Let the engine continue to idle until the radiator cooling fan comes ON. Let it idle for a few more minutes, then shut off. Check for leaks. Recheck the coolant level when the engine has cooled back down to room temp. Check underneath for coolant leaks.

72) Replace the bellypan.

73) Remove the car from the ramps.

74) Have a beer and count the +$500 you just saved.

75) Keep an eye on the coolant level for a few days to verify there are no leaks.