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MY NAME IS CHRIS AND I'M A MECHANIC. i JUST REPLACED THE UPPER AND LOWER INTAKE MANIFOLD GASKETS IN A 1998 BONNEVILLE 3.8L ENGINE. AFTER THE REPAIR I STARTED TO ENGINE. IT STARTED FUN BUT IT RUNS ROUGH INTERMITTENTLY AND MAKES A LOUD INTERMITTENT TICKING OR KNOCKING NOISE. PLEASE HELP!!! I'M AFRAID ITS DEBRIS IN THE ENGINE AND THE ENGINE IS NOW DAMAGED???
I have a 99 olds 88 3.8 76k miles. I just had the intake plenum and lower intake gaskets replaced because they were leaking coolant into the cylinders and burning it. I have heard it is a common problem with these engines. Picked the car up from the shop and it ran just fine. 60 miles later, the motor is ticking and I was out of town. Had no option but to drive it home. A couple minutes on the highway and the ticking goes away. 1 hour stop for lunch, then it's ticking again. Back home, 3 hours go by, start the engine again... no ticking. I have the feeling when I start it in the morning, it will be ticking again. I am not sure what to do. I am going to change out the spark plugs and change the oil in the morning. If that doesn't cure it, I guess it will go back to the shop with a lot of questions. I really don't want to pay for a top end rebuild. Has anyone had any luck with Slick50 or similar products?I have a 99 olds 88 3.8 76k miles. I just had the intake plenum and lower intake gaskets replaced because they were leaking coolant into the cylinders and burning it. I have heard it is a common problem with these engines. Picked the car up from the shop and it ran just fine. 60 miles later, the motor is ticking and I was out of town. Had no option but to drive it home. A couple minutes on the highway and the ticking goes away. 1 hour stop for lunch, then it's ticking again. Back home, 3 hours go by, start the engine again... no ticking. I have the feeling when I start it in the morning, it will be ticking again. I am not sure what to do. I am going to change out the spark plugs and change the oil in the morning. If that doesn't cure it, I guess it will go back to the shop with a lot of questions. I really don't want to pay for a top end rebuild. Has anyone had any luck with Slick50 or similar products?
Re: LOUD TICKING NOISE IN ENGINE AFTER INTAKE REPAIR
A Vacuum Leak at Manifold would show up as the Roughness Also its getting a Diff reading at MAF and MAP give it a while to get Friendly with itself, then Freak out LoL Hoping this Little Bit Helps I have had A Bunch of Scarry Startup Initional runs in my years and Run Time Took Care of them.
Good Wrenchin!!!! Please dont forget to Rate Me!!
Re: LOUD TICKING NOISE IN ENGINE AFTER INTAKE REPAIR
How long have you ran the engine ? I know that they will run rough and sometimes make strange noises for a few secounds or a little bit untill everything get oiled up again. I would make sure all the push rods are back in the right place and that all the lifters are tight.
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I found a forum post on Jeep Enthusiast Forums that provides the tightening sequence for the 3.8L upper intake plenum of a 2007 Chrysler TWC. Here are the steps:
Remove covering on lower intake manifold and clean surfaces.
Inspect manifold gasket condition. Gaskets can be re-used, if not damaged. Position new gasket in seal channel and press lightly in-place. Repeat procedure for each gasket position.
Position upper manifold on lower manifold.
Apply Mopar® Lock & Seal Adhesive (Medium Strength Threadlocker) to each upper intake manifold bolt.
Install and tighten bolts to 12 N·m (105 in. lbs.) using torque sequence.
Here is the torque sequence for the 3.8L upper intake plenum:
6 2 4
5 1 3
Please note that this information is provided as-is and I recommend consulting a professional mechanic for any further assistance.
The plastic piece is the upper intake manifold. The metal part is the lower intake manifold. Sometimes the gaskets go bad between the upper and lower intake manifolds. But usually the upper intake manifold is cracked and needs replaced.
Ha, you tried to fool me with the bit about a 3.5 L motor--I could find that one...here is the complete procedure from AutoZone.com:
Installation
To install:
Clean the gasket mounting surfaces. Be sure to inspect the manifold for warpage and/or cracks. If necessary, replace it.
Position the gaskets on the cylinder head with the port blocking plates to the rear and the This Side Up stamps facing upward. Then apply a 3 / 16 in. (5mm) bead of RTV sealant on the front and rear of the engine block at the block-to-manifold mating surface. Extend the bead 1 / 2 in. (13mm) up each cylinder head to seal and retain the gaskets.
Install the lower intake manifold. Tighten the bolts in sequence and in 3 steps, as follows:
Step 1: 26 inch lbs. (3 Nm).
Step 2: 106 inch lbs. (12 Nm).
Step 3: 133 inch. lbs. (15 Nm).
Install or connect the following:
Power steering pumpAlternator bracket bolt near the thermostat housingWiring harness to the lower manifold components, including the injector, EGR valve and ECT sensorAir conditioning compressor bracket-to-the lower intake manifold pencil braces
Install transmission oil dipstick tube, if necessary.
Fuel supply and return lines to the rear of the lower intake
Temporarily reattach the negative battery cable, then pressurize the fuel system (by cycling the ignition without starting the engine) and check for leaks.
Disconnect the negative battery cable.
Install or connect the following:
Heater hose to the lower intakeUpper radiator hose to the thermostat housingDistributor assembly and engage the wiringIgnition coilConnect vacuum hoses to the upper and lower intake manifold.New upper intake manifold gasket, making sure the green sealing lines are facing upwardUpper intake manifoldManifold retainers. Tighten them to 88 inch lbs. (10 Nm) using two passes.Purge solenoid and bracketBrake booster vacuum hose at the upper intake manifoldPCV hose to the rear of the upper intake manifoldVacuum hoses to both the front and rear of the manifold assemblyThrottle bodyThrottle linkage to the upper intakeWiring to the upper intake components including the TP sensor, IAC motor, MAP sensor and the fuel meterEngine coverAir intake assembly
If the manifold was replaced, install or connect the following:
Vacuum source manifold.
Positive Crankcase Ventilation (PCV) valve.
Manifold Absolute Pressure (MAP) sensor.
Throttle body assembly.
Upper-to-lower intake manifold carrier gasket to the upper intake manifold.
Carefully place the upper intake manifold onto the lower intake manifold. Ensure that the alignment pins in the upper intake manifold align with the holes in the lower intake manifold.
NOTE: Apply thread lock compound, to the bolt threads before assembly.
Install or connect the following:
Upper intake manifold. Tighten the upper intake manifold bolts in sequence to 89 in lbs (10 Nm)
Accelerator and the cruise control cables with the bracket to the throttle body.
EVAP purge solenoid vacuum line to the throttle body.
Connect the electrical connectors to the following:
Mass Air Flow (MAF) sensor
Manifold Absolute Pressure (MAP) sensor
Idle Air Control (IAC) valve
Throttle Position (T/P) sensor
EVAP purge solenoid
Install or connect the following:
Throttle body upper support bracket bolt. Tighten the bolt to 89 in lbs (10 Nm)
EGR valve wiring harness heat shield, nut and the bolt. Tighten the nut and the bolt to 89 in lbs (10 Nm)
Both of the engine that came in your vehicle have this issue. The upper and lower intake manifold gaskets, and the 3.8L valve cover gasket need to be replaced. DO YOURSELF A FAVOR, and if you do the work or have it done, have the Thermostat replaced at the same time. Book time is about 6 hours to do this repair plus parts.
Parts stores carry a kit including a manifold and gaskets. When I do the job I always replace the lower intake gaskets because they leak too. Make sure the lower manifold is not warped around the rubber gaskets towards the throttle body side, a new or used loewr manifold might be needed to ensure a correct repair.
NOTE
The 3.8L (VIN K) non-supercharged engine uses a two-piece intake
manifold consisting of an upper air plenum which mounts the throttle
body and a lower intake manifold assembly which houses the fuel
injectors. The 3.8L (VIN 1) supercharged engine uses a similar lower
intake manifold. The supercharger serves as the upper manifold. Lower Manifold
NOTE
Two bolts which fasten the lower intake manifold to the cylinder
head are accessible only after the upper intake manifold is removed.
These bolts are located in the right front and left rear corners of the
lower intake manifold. Remove the upper intake manifold to service the
lower intake. The 3.8L (VIN 1) supercharged engine uses a manifold
similar to the 3.8L (VIN K), but the supercharger serves as the upper
manifold.
Disconnect the negative battery cable.
On 3.8L (VIN 1) engines, remove the supercharger assembly. Please see the procedure in this section.
Remove the upper intake manifold using the procedure above.
Remove the EGR outlet pipe from the intake manifold.
Detach the engine coolant temperature sensor wiring harness from the sensor.
Remove the lower intake manifold bolts and carefully lift off the manifold.
Clean all parts well with degreaser, especially the gasket seal
surfaces on the upper and lower manifold pieces and between the lower
manifold and the cylinder heads..
Install new gaskets to the cylinder heads and new seals to the
engine block. Carefully lower the manifold into place. Apply
thread-locking compound to the bolt threads. Make sure to install the
two hidden bolts in the lower intake manifold. Hand start all bolts,
then torque evenly to 11 ft. lbs. (15 Nm). Follow the toque sequence,
starting in the center, then working outwards in a circle.
Install the remaining components in the reverse order of the removal process.
Upper Intake Manifold (Plenum)
Disconnect the negative battery cable.
On 3.8L (VIN 1) engines, remove the supercharger assembly. Please see the procedure in this section.
Tag for identification, then remove the right side spark plug wires.
Disconnect the ignition wires from the fuel rail.
Remove the fuel rail. Please see Section 5.
Remove the cable bracket from the intake manifold.
Remove the throttle body.
NOTE
Two bolts which fasten the lower intake manifold to the cylinder
head are accessible are accessible only after the upper intake manifold
is removed. These bolts are located in the right front and left rear
corners of the lower intake manifold.
Remove the upper intake manifold bolts and carefully lift the upper intake manifold from the engine.
Fig. Upper intake manifold and bolt torque sequence-3.8L (VIN K) engine To install:
Clean all parts well with degreaser, especially the gasket seal surfaces on the upper and lower manifold pieces.
Install new gaskets to the cylinder heads and new seals to the
engine block. Carefully lower the manifold into place. Make sure to
install the two hidden bolts in the lower intake manifold. Hand start
all bolts, then torque evenly to 89 inch lbs. (10 Nm). Follow the
torque sequence, starting in the center, then working outwards in a
circle.
Install the remaining components in the reverse order of the removal process.
if you have the 3.8 liter its more than likely bad intake manifold gaskets or a cracked manifold. Ford has had several TSBs on this issue. O2 sensors do not go bad as often as mechanics say they do. I have a 1999 that after 100 dollars at the parts store solved all lean conditions on the top end. The manifold has three parts to it. A lower aluminum that houses the butterfly blades for the variable intake runners( known vacuum leak were rods protrude at passenger side of lower bad bushings likely cause). Middle riser which uses oring seals which dry out and cause major vacuum leaks. upper is more or less the top cover which uses one large oring to seal. Hope this helps!
It is the head gasket. Have that replaced and you will be fine. You have an air leak. I was told by the mechanic at mazda that the anti freeze eats away at the gaskets. CRAZY, but it works. I still have an issue with my 2001 Tribute revving while in park. Its always something.
If you are talking about 3.4L engine there are only two manifold gaskets. But there are Four Intake gaskets two for the upper intake and two for the lower intake.
Fig. Lower intake manifold tightening sequence-4.3L engines 
I have a 99 olds 88 3.8 76k miles. I just had the intake plenum and lower intake gaskets replaced because they were leaking coolant into the cylinders and burning it. I have heard it is a common problem with these engines. Picked the car up from the shop and it ran just fine. 60 miles later, the motor is ticking and I was out of town. Had no option but to drive it home. A couple minutes on the highway and the ticking goes away. 1 hour stop for lunch, then it's ticking again. Back home, 3 hours go by, start the engine again... no ticking. I have the feeling when I start it in the morning, it will be ticking again. I am not sure what to do. I am going to change out the spark plugs and change the oil in the morning. If that doesn't cure it, I guess it will go back to the shop with a lot of questions. I really don't want to pay for a top end rebuild. Has anyone had any luck with Slick50 or similar products?
Is it a high pitch or low pitch?
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