Engine Flooding
No Start Condition
Window Regulator
Power Steering Rack
Brake Rebuilding
Fuse Box
Rust Patching
Brake Warning Lights
Basic Wrenching Tips
Low/No Boost
Engine Flooding
No Start Condition
Window Regulator
Power Steering Rack
Brake Rebuilding
Fuse Box
Rust Patching
Brake Warning Lights
Basic Wrenching Tips
A lack of any boost is indicated when the needle on the turbo boost gauge does not move above atmospheric pressure when the gas pedal is floored while driving on the road. Atmospheric is indicated by the needle when the engine is off. The car needs to be driven in order to fully evaluate the boost because it won't boost much at all when engine is in park or neutral; the engine needs to be under load to get full boost.
If the needle doesn't move at all when revving the engine in park or neutral, then either the boost gauge is broken, or more likely, the hose connecting the gauge to the intake system is disconnected. While on the road with your foot firmly planted on the throttle, the engine should get up to full boost in less than a second or so, indicated by the needle reaching the point shown in the owner's manual (usually an an orange/yellow area of the gauge). If it does not get up to this area quickly, then there's either a boost problem or an engine problem.
Begin evaluating the situation by disconnecting the "W" hose from the boost control solenoid in the right rear of the engine compartment. There are three hoses going into this small cylindrical valve, which is about the size of a golfball. The "R" hose goes to the air filter cleaner housing, the "C" hose snakes along the cylinder head and down to the right-side turbocharger, and the "W" hose which also snakes along the cylinder head and goes into a T and goes down to both turbos on either side of the engine. There should be small white clips attached to each hose which identifies it.
After disconnecting the hose, drive the car while flooring the gas pedal and note the position of the turbo boost gauge. (The engine can have "unlimited" boost in this condition. Do not boost the engine beyond the maximum boost limits since you could blow the head gasket). If you now get boost, then there is a problem with the knock sensor, its connection, and/or the MABC. If the boost stays the same, then the problem lies with the turbochargers, or there is a boost leak in the intake system, or there is an engine problem such as incorrect ignition timing, low compression, inadequate fuel pressure/supply, or incorrect valve clearances. Other causes might be a clogged intake air filter, an obstructed exhaust system (particularly a catalytic converter that has disintegrated or melted down), and an exhaust leak before the turbo. Any of these problems will cause a lack of boost or low boost condition.
In the rear of the engine compartment, there's a vacuum hose that
connects between the intake manifold and a T-shaped connector
(see photo right). You can remove this hose and insert an air pressure
hose to check for leaks, put the pressure around 10 psi. The pressure should
hold steady. If it doesn't, use a stethoscope to listen
for the source of
the leak. The smallest leak can cause you to loose a significant
amount of boost pressure.
There is a hose that connects the boost gauge to the intake system. On the 425, this hose runs from the dashboard through the left side of the firewall (seen from the driver' side) to the right rear of the engine compartment and enters a mass of vacuum hoses. It can become disconnected when the hoses in the rear of the engine compartment are disturbed.
Another place to check are the distributor advance pods,
located on the distributor. There are two vacuum hoses which connect
into it, and the front pod should hold pressure (again about 10psi). If any leaks out, then the entire unit has to be
replaced. The front vacuum hose has a small restrictor
piece inside of it. This restrictor piece can corrode
and become blocked, and when it does, it will not allow
boost pressure to advance the ignition timing, leading
to poor performance.
On some cars, there's a solenoid-drive valve and cylindrical vacuum pump mounted on the front of the carburetor plenum. The system is designed to suck gasoline vapors out of the plenum when the car is hot and stuff them into a charcoal canister, in order to improve hot starting. If the solenoid doesn't get power when the ignition is on, then the valve will leak boost pressure into the charcoal canister (the valve closes when power is applied).
One easy way to check the condition of the turbochargers is to reach inside the compressor housing (first remove the compressor hose), feel the compressor wheel and turn it by hand. If the compressor wheel feels bent or damaged, then a foreign object(s) must have entered the system and the turbo will need to be repaired. The turbocharger wheel should turn without uneven resistance, make no noise while turning, and it should not have any play or wobble. These checks won't guarantee that the turbocharger is working properly, but they will tell you when the turbocharger needs to be replaced. Blue smoke from the exhaust or noise from the turbos means there's a chance they might need replacing. Blue smoke can also be caused by internal engine problems such as worn piston rings or valve guides, or leaking valve seals.
A general purpose trouble-shooting guide for turbochargers may be found at the Garrett site and the Turbo Spares web site.
The knock sensor is located in the "V" of the
engine and the intake manifold needs to be removed in order
to access it. There is a cable which runs from the knock
sensor to the MABC, which is located inside the passenger compartment next to the glove box. It is a black box
about the size of a cigar case and is partially hidden
behind the carpet. The knock sensor puts out a very
small voltage which the MABC detects. If the sensor
is disconnected, the MABC will go into a failsafe mode
and it will not allow full boost. More information about the
MABC can be found at
Einar's Maserati Pages.
You can also
try here, although that site looks like it deals
with a somewhat different kind of control unit.
It is really easy to install the plenum housing such that the carburetor fuel line will lay on top of the carburetor and effectively hold the automatic choke closed (on the '86 USA carbed cars).
The previous owner of my car had evidently changed the needle valve and seat in an attempt to fix a flooding problem, as I found a spare in the glove box. But before opening up the carb, inspect the choke linkage and the spark plugs for definite signs of rich running.
Also check the choke pull-off mechanism for proper operation if your carb is so equipped. It's designed to slightly open the choke when the engine starts to prevent flooding. Remove the pull-off diaphragm cover and check the diaphragm for damage, and pull the diaphragm out carefully to see that the attaching rod and tab acts consistently on the choke linkage. You can bend back the metal tab with needle nose pliers if it's not engaging.
A malfunctioning idle cut-off solenoid may also cause flooding problems. It shuts off fuel to the carb to prevent engine run-on. A wire that goes into the plenum and to the cut-off valve can become disconnected.
Perhaps the best place to begin diagnosing a starting problem is with the starter relay, located in the engine compartment on the passenger side (425). See the owner's manual for the exact location. You can insert wires into the relay socket with the relay installed and check for battery power when the ignition switch is turned. If there's no power applied to the relay, then the problem lies before the relay, either with the ignition switch, fuse box, or the battery/battery connections/ground strap. If there's power applied to the relay, but no power appearing on the output side of the relay, then the relay is bad. If there's power appearing on the output of the relay, then the problem lies after the relay, such as with the starter motor, the power to the starter, or the fuse box.
Another place to check is the starter interlock safety switch, on the automatic transmission. It is located directly on the transmission and has 4 wires going to it, with a rubber boot covering the connections. Two wires go to the interlock switch, and the other two wires are for the reverse lights. The switch is designed to prevent the starter from being activated if the car is not in Neutral or Park. It can be jumpered if it goes bad.
When the power windows won't go up in a particular position and the window makes a "grinding" sound while attempting to go up, then most likely the window regulator inside the door needs to be replaced. The regulator has a threaded cable and the window motor cog engages with the thread. When the thread on this cable strips, the motor cog won't engage properly against the cable.
The procedure for replacing the window regulator requires removing the door panel and then the regulator from the door. Once removed, the window regulator can be disassembled or replaced entirely.
The window regulator is available only as a complete unit, however the cable inside the regulator can be replaced with a used cable. There are two pop rivets at the bottom window stop which need to be drilled out in order to remove the cable from the window regulator frame. The cable in the regulator of the coupe can be put into the window regulator frame of the sedan, however the frames are not interchangeable between the coupe and the sedan.
Assembly is the reverse of removal. When putting the door lock button back on, guide the door lock handle from underneath the door panel with one hand while driving the screw with the other.
The power steering rack in the Biturbo can develop leaks near the boots, which will require replacement with a rebuilt rack. I've heard that you can replace the early PS rack with a manual rack from an '84 or '85 car, which will give you higher steering effort, but then you won't have to worry about leaks.
The coupling inside the passenger compartment will attach to the steering rack in any orientation, but the bolt which holds the coupling can only be fully inserted in one particular orientation of the coupler and rack. Mark that orientation before removing the coupling.
One of the automatic transmission hydraulic lines might interfere with the rack during installation. I removed one of the hydraulic lines on the steering rack and carefully moved it out of the way during the install. Then I reconnected the line and replaced the copper washers on the rack. Always replace the copper washers on the hydraulic lines after removal. They will leak if you try to re-use them.
Carefully inspect any fluid that comes out of the system for signs of debris that might indicate a failed power steering pump. Any lingering debris in the system will destroy the rack. A flush of the system is recommended in any case.
I found it helpful to use a 13mm swivel socket to remove the bolts on the brackets which hold the rack in place. Inspect the brackets for signs of damage (cracks, bending) and the rubbers for signs of deterioration. These are available at a very reasonable price, so replace them if there's any doubt as to their condition. Replace the lock washers on the bolts go into the bracket.
Inspect the bushing that holds the steering column at its base for signs of damage. It's easy to replace when the rack has been removed. You have to buy a new bracket if you buy the bushing.
When installing the rack, tilt the passenger side of the rack (LHD) back towards the rear of the car, and tilt the driver's side forward, then push the driver's side up into position. It's helpful to have a second person guide the rack while inside the car as you push up on the rack from below. Make sure that the plastic bushing in the rubber bellows doesn't pop out when you do this.
You can do a simple alignment that's good enough to drive the car to the alignment shop afterwards, by placing some boards flat against the tires. Then measure the distance between the boards on the front and rear using a tape measure, and get them equal by turning the tie rods appropriately. Try to get the steering wheel in the correct straight-ahead position.
The early Biturbo features 4-piston fixed caliper brakes in the front which are easily rebuilt with readily available parts. I sourced most parts from Auto Italia for my repair job, except for the caliper seals which I got from MIE. They offered the OEM ATE caliper seals, and the difference in price between those and aftermarket seals was negligible. Most prices were actually pretty reasonable except for the brake lines. The rotors were brand new and came in a Brembo box.
Removing the old parts is perhaps the hardest part of the job. While trying to remove the hard brake lines from the caliper using a flare nut wrench, I noticed the bolt was starting to round, so I removed the brake lines from the other end with a 15mm flare nut wrench. I left the hard brake lines attached to the caliper during the entire process. The driver's side brake lines took a lot of effort to remove; I was sure I was going to round off the bolt but they eventually came off with sustained pressure and some liquid wrench.
You have to catch the brake fluid with a rag as it can damage the paint and the suspension bushings. After removing the brake lines and the brake pads, the calipers are easily removed with 2 bolts.
The factory shop manual gives measurements for the wear specification of the rotors. Mine were just under spec so I had to replace them.
The rotor on the passenger side was held on with an allen-head screw which was partly rounded by the previous owner. It came off after I hammered the screw face using the edge of a chisel, to get it to turn some. Then I finished it off with a hand-impact wrench.
The passenger side rotor seemed to be welded on to the hub. No matter how hard I hammered on the backside of the rotor, it wouldn't come loose. Squirting some liquid wrench into the bolt threads for the wheels didn't help any. Then I got the idea to insert the the caliper retaining bolts into the spindle and use them to push the rotor off the hub. After turning the 2 bolts slowly together against the rotor there was a loud crack and the rotor was partly free. I turned the rotor 90 degrees and repeated the process and finally removed the old rotor.
The new rotors will have a film of oil on them to prevent them from rusting, which has to be removed since otherwise it will contaminate the brake pads.
Once the calipers are removed, the 4 pistons have to be removed, cleaned, and inspected. I was told by MIE that splitting the caliper halves by removing the 4 bolts which hold them together might cause them to leak, however I did split one caliper and it did not leak afterwards. If you do split the calipers, look for a small round seal inside. It looks difficult to remove and re-install the pistons with the calipers held together but in my experience it wasn't that hard.
With the dust shields and retaining rings removed, the pistons can be blown out with compressed air (about 40 psi does nicely), while stuffing rags against the pistons so the pistons don't go flying across the room. I blew them out one at a time, using the hard brake lines. It seemed like one would pop out first, and then the next, even though one brake line feeds 2 pistons.
The pistons must be kept in order as you will want to reinstall them in the same bore as you removed them from. If they're stubborn, you can sometimes wiggle them out with your hands or with a crescent wrench on the very top of the piston where it's not a machined surface.
After removing the pistons, the seals inside the bores need to be removed. I took these out with some wooden skewers/toothpicks so as not to scratch the machined surface in the bore.
The new seals didn't seem to fit quite right on the pistons as can be seen from the photo. The bottom seal is the original that was in the caliper and the top is the new OEM ATE seal. I found similar fitment concerns using aftermarket seals. However I was pleased to find that the OEM seals do the job very well.
Before re-installing the pistons, it helps to first attach the dust seals to the pistons. With the pistons installed it is difficult to attach the dust seals.
Getting the pistons into the bore can be tricky and may take repeated tries. Be sure that everything is lubricated with brake fluid and very clean. Any dirt on the piston or inside the bore will make it very difficult to get the piston installed. I found that firm, even pressure using both thumbs on top of the piston worked the best, followed by placing the palm of my hand on the piston and forcing it in using all of my weight on top of it. Hammering should not be necessary and will cause the piston to get cocked in the bore and it will not go in. Be sure to push the piston all the way down into the bore.
The Biturbo fuse box is located behind the glove box compartment and is bolted to the firewall. Many kinds of electrical problems can be traced to the fuse box, which routes and interconnects many of the car's electrical functions. (The other leading cause of electrical problems are the chassis grounds). There is a multi-layer printed circuit board inside the box, which tends to delaminate with age, leading to intermittent connections. Replacement of the box is the best option (IMO), although the box can be disassembled and the connectors re-soldered.
To replace the fuse box, disconnect the battery, and remove the glove box compartment from its lower hinges by prying with a large screwdriver. Start pulling out the connectors from inside the passenger compartment. It helps to mark the connectors before removal to facilitate re-assembly, however each connector can only go in one spot, so don't worry if you forget to mark a few of them. Squeeze the connectors on each side to remove them. Use a small screwdriver to reach difficult spots and press down on the side of the connector with the screwdriver.
On the engine compartment side, remove any hoses which are blocking access to the plastic cover over the fuse box. Remove the plastic cover using a 1/4" drive socket wrench with an extension and a swivel adapter. It helps to use a deep socket to remove the 10mm nuts. The relay sockets might block access to the fuse box connectors; they can be removed by pressing in on their retaining clip.
Pull out the connectors on the engine compartment side. Inspect all of the electrical connectors for signs of damage or corrosion. Remove the fuse box from inside the passenger compartment. Install the new fuse box. The new box should come with all of the correct fuses already installed. It uses the same printed circuit board construction as the old box. Replacement is the reverse of removal.
When I got my car, I discovered some rust in the cowl area, on the driver's side. The rust had perforated through the metal, and it allowed water to leak into the passenger compartment and stain the carpets. I cleaned out all of the leaves and debris which had allowed moisture to accumulate in that area. (There are some water drains located in the cowl area. Make sure these are clear and don't allow debris to build up in the cowl).
The optimal solution is to remove the rust entirely by cutting it out and welding in a replacement panel, but that was beyond my ability and that kind of repair can be expensive when done professionally. So I decided the patch the rust using a product called POR-15 (for "paint over rust"). There is a POR-15 starter kit, sold by Automobile Atlanta, that is just the right size to deal with this problem.
I wire-brushed the area to remove as much rust as possible, and to remove any paint before applying POR-15. It is a two-step process; you first apply a product called "Metal Ready" which removes rust and prepares the surface, and then apply the POR-15 black paint. After finishing with POR-15, I laid some fiberglass over the area to fill the rust hole perforations. Total cost was about $40 to patch the area.
Maserati has provided no less than 5 dashboard warning lights associated with the braking system. Reference the following diagram which illustrates the position of each light on the dashboard. The lights are as follows:
It is important NOT to rely on the warning lights as a substitute for proper maintenance, which includes regularly checking the brake fluid level, the operation of the brake lights, the brake pad wear, and the proper functioning of the parking brake on a steep incline. If there is any question about the proper operation of the braking system, do not drive the car!
Use hose clamps with a hex head drive. Then use a 1/4" drive socket wrench and appropriate extensions and swivels to access the clamps, instead of using a screwdriver. The 1/4" ratchet is smaller and lighter than a standard 3/8" ratchet, making it easier to maneuver with one hand in the tight Biturbo engine compartment. It also fits tight spots better than a screwdriver.
Some tasks require removal of the radiator. Removal is simplified if you leave the lower radiator hose connected to the radiator. Then you don't have to jack up the car to remove and re-install the hose.
Don't jack up the rear of the car using the suspension or the differential. The suspension pieces locate the struts in the horizontal plane; they weren't designed to support half the weight of the car. Jack up the front of the car using the jack receptacles behind the front wheels. You will find that you can raise the car enough to place jackstands underneath the jack receptacles in the rear, just ahead of the rear wheels. For simple tasks, you can usually get enough clearance underneath the car by driving it up on stacked wooden boards.
Always disconnect the negative cable to the battery before beginning any repair work on the car.
A Mity-Vac vacuum pump is a handy device for diagnosing vacuum leaks, and is much cheaper than an air compressor. They are sold at K-Mart.
Check fluid levels often -- brake fluid, power steering, coolant, transmission, differential, and engine oil. A dropping fluid level indicates a probable leak. Try to park your car in the same spot everyday so that leaks are easier to discover.
Buy a factory repair manual and an electrical diagram. They can be found at the usual parts sources, and sometimes they can be seen on EBay. They are essential for doing any kind of serious repair on the car.
When servicing the brakes or wheel bearings, do one side first, and then the other. If you forget how something is put together, then you will have a reference on the other side.
When installing the spark plugs, put a section of heater hose onto the plugs to use as a tool to guide them into the holes, and screw them in. If the hose is loose enough, it will help prevent you from cross-threading the plugs in the holes.