Speedo cruise on the audi 100 does not work

Could be a faulty cruise control servo activator. The power to move the cruise control Actuator is most likely coming from the Brake power hydraulic booster vacuum pipe and if the cruise control vacuum servo is failing and leaking in air you lose the brakes power hydraulics.
check the vacuum pipe coming off the power booster brake master cylinder vacuum pipe you may find a tee connector in the vacuum main pipe and follow it to see where it goes to. Could be a break in the cruise control vacuum hose but if it is only happening when the cruise control is activated a fault or leak in the cruise control servo device is the main suspect. Which you should find at the other end of the cruise control vacuum hose.

which engine,there are many , state displacement and cylinder count.
DID YOU OVERHEAT IT?
this is covered in the FSM, get one.
or use Alldata.com
lots of steps.
well over 100..... counting adjustements, etc.....
i guess you never done a head job before?

do not just replace it. (gasket) check for head AND engine
deck warpage. ( a $2 tool , )
here is my wild guess,

Except Accord V-6 The cylinder head temperature must be below 100F (38C); allow the engine to cool several hours if the car has been recently driven. Turn the crankshaft pulley so that the number one piston is at Top Dead Center (TDC) of the compression stroke.

1. Disconnect the battery ground cable.
2. Drain the cooling system.
3. Remove the air cleaner and intake duct assembly.
4. Label and remove the brake booster, PCV and charcoal canister vacuum hoses from the intake manifold.
5. Remove the engine ground cable from the cylinder head or valve cover.
6. Relieve the fuel pressure using the proper procedure. Disconnect the fuel lines.
7. Disconnect the accelerator cable at the throttle body or carburetor. On automatic transaxle vehicles, also disconnect the throttle control cable.
8. Disconnect and tag all the wire harnesses and vacuum hoses from the cylinder head, intake manifold and throttle body/carburetor. Disconnect the spark plug wires, then position them aside.
9. Disconnect the upper radiator hose. Remove the heater hoses from the cylinder head.
10. If equipped, remove the cruise control actuator. Do not disconnect the cable; move the actuator out of the work area with the cable attached.
11. Remove accessory drive belts.
12. Disconnect the inlet hose from the power steering pump and plug the hose immediately to prevent fluid leakage. Remove the power steering pump from the cylinder head and position it aside.

When the power steering hose is disconnected, the fluid will flow out. Cover the alternator with a shop towel to prevent the fluid from leaking into it.

1. If the alternator is mounted to the cylinder head, remove it.
2. Remove the power steering and alternator brackets if they are mounted on the cylinder head.
3. Remove the distributor. Be sure to scribe a line relating the position of the distributor to the engine for easy installation.
4. If equipped, remove the cylinder sensor next to the distributor.
5. Remove the valve cover.
6. Remove the timing belt.

Do not crimp or bend the timing belt.

1. Remove the exhaust header pipe nuts and the header pipe bracket (if equipped). Pull the pipe away from the exhaust manifold.
2. If equipped, remove the EGR crossover and air suction pipes.
3. On Accords through 1989 and Preludes through 1991, the cylinder head can be removed with the intake and exhaust manifolds either still attached or removed. On other models, the manifolds should be removed first.
4. On some engines, it will be necessary to remove the camshaft holders, camshafts and rocker arms to access the cylinder head bolts. If so, refer to the proper procedures in this section.
5. Remove the cylinder head bolts in sequence (take notice of any bolt holes occupied by longer bolts). Failure to follow this procedure may cause the head to warp.
   1. On 1984-89 Accords and 1984-91 Preludes, work from the ends toward the center. Loosen each bolt about 1/2 turn each time and make several passes to release the tension evenly.
   2. On 1990-95 Accords and 1992-95 Preludes, follow the loosening sequence shown in the illustrations. Loosen each bolt about 1/3 turn each time. Repeat the sequence until all bolts are loosened.

Remove the cylinder head. The head may resist removal, even with the bolts out. Tap the edge of the head with a plastic or rubber mallet; lift the head straight up to remove it.
Remove the cylinder head gasket and clean the mating surfaces.
(do not use wire brush or metal scrapers on alum, heads)
use a plastic scraper.
then check for warping, (ask)
If applicable, remove the intake and exhaust manifolds from the cylinder head. (lol, is listed last, gotta love non FSM real online data)


i post this to dissuade you, its not complete.
there are many factors,checks and issues, TTY, and others.....
graphics missing above, head sequence rules. on and off !

if the head was overheated, you need to get it pressure tested
and warp checked.
the top to reasons for new gaskets , put on to fail in first 10k milles
is , not warp checked, pressure checked)
or 2: surfaces were not good. (might need to be milled a tad)
3: not using new head bolts, some are TTY and if not ,should not be used 3 times.

Hi there:Removal and InstallationExcept Accord V-6

The cylinder head temperature must be below 100 degrees F (38 degrees C); allow the engine to cool several hours if the car has been recently driven. Turn the crankshaft pulley so that the number one piston is at Top Dead Center (TDC) of the compression stroke.

1. Disconnect the battery ground cable.
2. Drain the cooling system.
3. Remove the air cleaner and intake duct assembly.
4. Label and remove the brake booster, PCV and charcoal canister vacuum hoses from the intake manifold.
5. Remove the engine ground cable from the cylinder head or valve cover.
6. Relieve the fuel pressure using the proper procedure. Disconnect the fuel lines.
7. Disconnect the accelerator cable at the throttle body or carburetor. On automatic transaxle vehicles, also disconnect the throttle control cable.
8. Disconnect and tag all the wire harnesses and vacuum hoses from the cylinder head, intake manifold and throttle body/carburetor. Disconnect the spark plug wires, then position them aside.
9. Disconnect the upper radiator hose. Remove the heater hoses from the cylinder head.
10. If equipped, remove the cruise control actuator. Do not disconnect the cable; move the actuator out of the work area with the cable attached.
11. Remove accessory drive belts.
12. Disconnect the inlet hose from the power steering pump and plug the hose immediately to prevent fluid leakage. Remove the power steering pump from the cylinder head and position it aside.

When the power steering hose is disconnected, the fluid will flow out. Cover the alternator with a shop towel to prevent the fluid from leaking into it.

1. If the alternator is mounted to the cylinder head, remove it.
2. Remove the power steering and alternator brackets if they are mounted on the cylinder head.
3. Remove the distributor. Be sure to scribe a line relating the position of the distributor to the engine for easy installation.
4. If equipped, remove the cylinder sensor next to the distributor.
5. Remove the valve cover.
6. Remove the timing belt.

Do not crimp or bend the timing belt.

1. Remove the exhaust header pipe nuts and the header pipe bracket (if equipped). Pull the pipe away from the exhaust manifold.
2. If equipped, remove the EGR crossover and air suction pipes.
3. On Accords through 1989 and Preludes through 1991, the cylinder head can be removed with the intake and exhaust manifolds either still attached or removed. On other models, the manifolds should be removed first.
4. On some engines, it will be necessary to remove the camshaft holders, camshafts and rocker arms to access the cylinder head bolts. If so, refer to the proper procedures in this section.
5. Remove the cylinder head bolts in sequence (take notice of any bolt holes occupied by longer bolts). Failure to follow this procedure may cause the head to warp.
   1. On 1984-89 Accords and 1984-91 Preludes, work from the ends toward the center. Loosen each bolt about 1 / 2 turn each time and make several passes to release the tension evenly.
   2. On 1990-95 Accords and 1992-95 Preludes, follow the loosening sequence shown in the illustrations. Loosen each bolt about 1/3 turn each time. Repeat the sequence until all bolts are loosened.
   
   

Fig. 1: Bolt loosening sequence on 1990-93 Accords and 1992-95 Preludes with 2.2L engines

24. Remove the cylinder head. The head may resist removal, even with the bolts out. Tap the edge of the head with a plastic or rubber mallet; lift the head straight up to remove it.

1. Remove the cylinder head gasket and clean the mating surfaces.

1. If applicable, remove the intake and exhaust manifolds from the cylinder head.

To install:

1. Install a new head gasket on the engine, making certain it is positioned correctly. The cylinder head dowel pins and the oil jet must be in place. Refer to the illustrations if necessary.
2. Install the head. Lower it straight down onto the block, aligning it correctly.
3. Apply clean engine oil to the bolt threads and the contact face of the bolt head. Install the head bolts finger-tight.
4. On all models except 1988-89 DOHC Prelude and 1992-95 Preludes with 2.3L and VTEC engines, tighten the head bolts following sequence A. On 1988-89 DOHC Preludes, use sequence B. Use sequence C on 1992-95 Preludes with 2.3L and VTEC engines.
   1. On 1984-89 Accords and 1984-91 Preludes, tighten the bolts in two passes. The first pass should bring the bolts to about 22 ft. lbs. (30 Nm). On the second pass, tighten the bolts to their final torque of 49 ft. lbs. (68 Nm).
   2. On 1990-93 Accords, tighten the bolts to 29 ft. lbs. (40 Nm) on the first pass, 51 ft. lbs. (70 Nm) on the second pass, then tighten the bolts to their final torque of 78 ft. lbs. (108 Nm).
   3. On 1994-95 Accords and 1992-95 Preludes, the bolts are also tightened in three passes. Tighten the bolts to 29 ft. lbs. (40 Nm) on the first pass, 51 ft. lbs. (70 Nm) on the second pass, then tighten the bolts to their final torque of 72 ft. lbs. (100 Nm).
   .
   

Fig. Cylinder head bolt torque sequence B


Fig. Cylinder head bolt torque sequence B


Fig. Cylinder head bolt torque sequence C

1. If applicable, assemble the intake and exhaust manifolds to the head. Use new gaskets.
   
2. If applicable, install the cam, rockers and camshaft holders.
3. If equipped, install the EGR crossover and air suction pipes.
4. Connect the exhaust pipe to the manifold using new nuts.
5. Install the timing belt.
6. Install the valve cover.
7. Install the cylinder sensor (if equipped) and the distributor.
8. If applicable, install the alternator.
9. Install the power steering pump, then connect the inlet hose to the pump.
10. Install the accessory drive belts. Adjust the belt tensions.
11. Install the heater hoses.
12. Install the cruise control actuator if it was removed.
13. Connect the spark plug wires. Connect all the wire harnesses and vacuum hoses to the cylinder head, intake manifold and throttle body/carburetor.
14. Connect the throttle control cable and/or accelerator cable at the throttle body.
15. Connect the fuel lines.
16. Install the brake booster, PCV and charcoal canister vacuum hoses.
17. Install the air cleaner and intake duct.
18. Refill the engine coolant. It is recommended that the engine oil be changed whenever a cylinder head is removed.
19. Connect the negative battery cable.
20. Start the engine, allowing it to idle. Bleed the cooling system. Check the work area carefully for any signs of fluid leakage or any indication of the timing belt rubbing or slapping the covers

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.
Thank you for using FixYa.

Hello Steve , congratulations for driving such a fancy car. I will try to help. My first guess would be to check in the area of the cruise control for vacuum leaks. There are hoses that come from your engine to the cruise control that in some way make it work. Get a piece of 1/4 inch rubber hose and use this as a listening devise , one end to your ear and use the other to listen around the the various hoses. Possibly you may find broken, collapsed, or cracked hoses in this area. Check these things first and please get back to me, GOOD LUCK.

An "easy" fix is only easy depending on your definition of what is easy or difficult repair is as a practical concern..

The variation of the idle speed in Park, is most likely due to a vacuum leak in the crankcase ventilation/positive crankcase ventilation system hoses. Check all the hoses and hose connections for loose attachment to the hose fittings and connections, and carefully examine the hoses for failures like splits and cracks in the hoses. Inspect the crankcase ventilation system hoses and tubing for partial or complete blockage from oily sludge deposits, and clean out the hoses and fittings as required.

If still present, cut off the factory hose clamps using a Dremel metal cut-off tool, and replace the hose clamps with the correct sizes for the hose diameters the clamps are to fit. The spring type Corbin hose clamps are good because they stay tight on the hoses as the hosed relax and dry out with age. Special pliers should be used to easily remove and replace the factory Corbin clamps and any new Corbin clamps that replace the crimped original factory clamps.

The harsh engagement of the transmission is likey associated with the higher than specified idle speed caused by vacuum leaks as I explained above.
Finally, the transmission fluid and fluid filter have probably never been drianed/replaced.. Audi claims the transmission ATF and fluid filter do not require periodic replacement, and is a "Lifetime Fill", with no recommended service specified. This Audi policy really only helps reduce the cost to Audi during the New Car warranty period. Realize that what this policy really means for Audi owners with Audis past the warranty period, is that the "Liifetime Fill, actually means "Until the transmission fails", as a practical situation.

1. Therefore, I recommend you have the ATF drained and a new fluid filter installed, then the transmission refilled using ONLY Pentosin ATF-1 100% Synthetic auto transmission fluid. Then after driving for another ~5000 miles, drain and refill the ATF again, without replacing the filter. Perform ATF replacement thereafter every 40,000 miles or more often if mostly city driving.

After servicing the AFT fluid, drive the car normally for a few hundred miles and note if the symptoms with the harsh gear engagement is improved or not. If not, seek additional advise here as needed.

If you change the head bolts that's the safest bet for trouble free operation. But, I've changed head bolts on Hondas for years and they never stretched. I know this is for a Kia. My best guess is that it's not necessary since the Chilton based manuals don't say to do this.

If the head is torqued down to specifications and it leaks, then I would say, otherwise. Even torque is more important than bolt stretch, especially if the bolts don't stretch so much that the head gasket can't be tight against the head and block.

Cylinder Head Removal & Installation SOHC To Remove:

1. Relieve fuel system pressure.
2. Remove timing belt cover. Camshaft timing marks
   
   
3. Turn crankshaft until timing mark on front housing and the arrow "2" on the camshaft pulley align.
4. Loosen lock bolt on tensioner.
5. Pry tensioner away from timing belt and tighten lock bolt to relieve tension on the timing belt.
6. Remove timing belt from camshaft pulley.
7. Disconnect battery negative cable.
8. Remove 3 bolts that secure accelerator cable and air intake hose to cylinder head cover.
9. Detach accelerator cable and place off to side.
10. Remove the following;
    • Air hose
    • Air ISC air hose
    • Breather hose
    • Vacuum hose from air intake hose
11. Disconnect mass air flow sensor electrical connector.
12. Remove air intake hose.
13. Remove PCV valve from cylinder head cover.
14. Remove ISC air hose from idle speed actuator.
15. Remove air hose from behind intake manifold.
16. Remove 2 screws from high tension wire protectors.
17. Detach wire loom from holder at rear of cylinder head cover.
18. Detach vacuum tube at rear of cylinder head cover.
19. Remove vacuum pipe. Cylinder Head Cover
    
    
20. Remove 7 cylinder head cover bolts.
21. Remove cylinder head cover and gasket.
22. Disconnect 2 ignition coil electrical connectors.
23. Disconnect 2 fuel injection electrical connectors at rear of cylinder head.
24. Disconnect the following electrical connectors;
    • Oxygen sensor
    • Throttle position sensor
    • Idle speed actuator
    • Oil pressure switch
    • EGR vacuum solenoid valve at intake manifold
25. Disconnect heater hose from elbow.
26. Disconnect brake booster vacuum hose and cruise control vacuum hose from surge tank.
27. Detach wire harness from rear of cylinder head.
28. Disconnect purge control solenoid vacuum hose from intake manifold.
29. Disconnect fuel hose from fuel connector assembly.
30. Remove grounding bracket.
31. Remove 4 bolts and intake manifold bracket.
32. Remove starter.
33. Detach water bypass hose from bypass pipe.
34. Disconnect water hoses from oil cooler.
35. Disconnect fuel hose from fuel pipe.
36. Remove exhaust manifold heat shield.
37. Remove exhaust flange nuts and front exhaust bracket bolt.
38. Lower exhaust system. Cylinder head bolt loosening sequence
    
    
39. Loosen cylinder head bolts in 3 steps in proper sequence.
40. Remove cylinder head bolts and washers.
41. Remove cylinder head, intake manifold and exhaust manifold as an assembly.

To Install:

1. Install NEW cylinder head gasket.
2. Install cylinder head, intake manifold and exhaust manifold as an assembly.
3. Tighten cylinder head bolts in 3 steps in reverse sequence that was used during removal. Tighten bolts to 62 ft lb (84 Nm).
4. Install front exhaust bracket bolt. Tighten bolt to 20 ft lb (27 Nm).
5. Install NEW lower exhaust flange gasket and 3 nuts. Tighten nuts to 24 ft lb (31 Nm).
6. Install exhaust manifold heat shield. Tighten nuts to 35 in lb (4 Nm).
7. Connect fuel hose to pipe.
8. Connect 2 hoses to oil cooler.
9. Attach water bypass hose to bypass pipe.
10. Install starter and bolts. Tighten bolts to 34 ft lb (46 Nm).
11. Install intake manifolds bracket and 4 bolts. Tighten bolts to 32 ft lb (45 Nm).
12. Install grounding bracket.
13. Connect fuel hose to fuel connector assembly.
14. Connect the following electrical connectors;
    • Oxygen sensor
    • Throttle position sensor
    • Idle speed actuator
    • Oil pressure switch
    • EGR vacuum solenoid valve at intake manifold
15. Connect purge control solenoid vacuum hose to intake manifold.
16. Attach wire harness from rear of cylinder head.
17. Connect brake booster vacuum hose and cruise control vacuum hose to surge tank.
18. Connect heater hose to elbow.
19. Connect 2 fuel injection electrical connectors at rear of cylinder head.
20. Connect 2 ignition coil electrical connectors.
21. Install cylinder head cover.
22. Install 7 cylinder head cover bolts. Tighten bolts to 60 in lb (7 Nm).
23. Install vacuum pipe and 2 bolts at rear of cylinder head cover. Tighten bolts to 60 in lb (7 Nm).
24. Connect vacuum tube to pipe.
25. Connect loom holder to rear of cylinder head cover.
26. Install 2 screws to high tension wire protectors.
27. Install air hose to behind intake manifold.
28. Install ISC air hose to idle speed actuator.
29. Install PCV valve to cylinder head cover.
30. Install air intake hose.
31. Connect mass air flow sensor electrical connector.
32. Install the following;
    • Air hose
    • Air ISC air hose
    • Breather hose
    • Vacuum hose from air intake hose
33. Attach accelerator cable.
34. Install 3 bolts that secure accelerator cable and air intake hose to cylinder head cover. Timing belt pulley timing marks
    
    NOTE: Timing belt pulley timing mark and timing mark must be aligned.
    Camshaft timing marks
    
    NOTE: The arrow at "2" on camshaft pulley must be aligned with timing mark on front housing.
    
35. Install timing belt.
36. Install timing belt cover.
37. Pressurize fuel system.
38. Start engine and check ignition timing.

CHECK CRUISE CONTROL FUSE. IF FUSE GOOD PROBLEM IS IN THE SERVO MOTOR THE CRUISE CONTROL MODULE VACUUM PUMP AND CLUTCH VENT VALVE THE BRAKE VENT VALVE AND VACUUM SIGNAL AMPLIFIER.YOU HAVE TO TAKE CAR TO DEALERSHIP THEY HAVE EQUIPMENT TO FIX IT.

REMOVAL & INSTALLATION

1C-LTC and 2CL-TC Engines
(see Figures 1 and 2)

1. Disconnect the negative battery cable. Remove and label all electrical wiring, connectors and vacuum hoses necessary to gain removal clearance.

Fig. 1: Loosen and remove the cylinder head cover retaining nuts

1. Disconnect the PCV hose.
2. Remove the six nuts and seal washers from the cylinder head cover. Loosen them in a crisscross pattern.
3. Remove the cylinder head cover and the cover gasket from the cylinder head. Discard the gasket and replace with a new one.
   

To install:

1. With a wire brush or gasket scraper, remove all the old gasket material from the cylinder head and the cylinder head cover gasket surfaces.
2. When the cylinder head surfaces are free and clean, apply beads of sealant to the cylinder head in the locations shown in the accompanying illustration.

Fig. 2: Be sure to apply sealant on the cylinder head prior to cover installation

1. Install the new gasket in the cover. Make sure that the gasket seats evenly.
2. Place the cover with the gasket onto the cylinder head.
3. Install the six nuts and seal washers. Tighten the nuts to 65 inch lbs. (8 Nm).
4. Connect the PCV hose. Connect all removed vacuum hoses, connectors and electrical wiring. Connect the negative battery cable.
5. Start the engine and inspect for oil leaks. Repair any leaks as necessary.

Hope this help (remember comment and rated this).

If you see fluid at the rear of the master where it attaches to the power booster then the cylinder itself is leaking. It's not often that the container leaks.
The hissing noise is very likely coming from the power booster. This must be replaced. If cruise has a vacuum hose that connects to hose to booster it's possible that vacuum loss at booster is causing the cruise problem.If you are going to do the booster, have a good tech take a look at it first. they are expensive and you don't want to change it on my advice alone...I'm not there and can't hear it!