Alfa GTV6 Idle Speed O-ring

 

The Alfa Romeo GTV6 is filled with unusual and interesting engineering features and solutions. One of the unique features is this simple O-ring. This humble O-ring plays a big part in how your car runs because it regulates the amount of air that bypasses the throttle valve, setting the idle speed on your GTV6. If it is worn out, it will make for the most frustrating driving experience. If you are unfamiliar with the GTV6 Idle Speed O-ring, stick around —we'll tell you everything you need to know.

The Alfa GTV6 uses the above fittings to control your idle speed (minus the extra O-ring shown).  The various fittings are put together and screwed into the side of the throttle body. Over the years, the rubber O-ring can harden and become brittle, and when that happens, your car can develop idle issues. This tiny O-ring is often overlooked, and if you or your mechanic don't know about it, you can end up chasing all sorts of false solutions trying to fix your problem. 

If you have an idle issue or can't adjust your idle and don't have a vacuum leak, look into replacing this O-ring. The good news is the o-ring is inexpensive and can usually be had at your favorite Alfa Romeo vendor. It is also easy to change. 

  

Alfa Romeo GTV6 Idle O-Ring part number 60523368 size:

• 14 mm outer diameter 
• 7 mm inside diameter 
• 3.5 mm thickness

When you inspect your Idle O-ring, it should be soft, flexible, not oil-soaked, and not cracked. If it can't pass the inspection, you need to replace it. If you can't find a replacement O-ring, you can use the above dimensions to source one in an emergency.  Because of the heat and fumes in the intake tract, look for an O-ring made from a material like Viton rather than the more common Nitrile. 

This is the GTV6 idle bypass adjuster assembly.

The O-ring goes in first. Push it all the way into the hole. The O-ring bottoms out against a tapered flare shape.

The idle bypass assembly is then inserted into the hole in the throttle body. For clarity, I placed the O-ring at the entrance so you can see where it goes. Make sure you push the O-ring in first, as was mentioned above.

A close-up shot of the idle bypass assembly.  You should use a new copper washer at some point, but a little grease on the threads and washer will help it seal.

It is called an idle bypass because idle air bypasses the throttle valve.  The throttle valve on a GTV6 is nearly fully closed at idle. Idle speed is controlled by the amount of air passing through the above hose and bypass assembly. 

This air is drawn from the intake boot after passing through the airflow meter. This ensures the change in engine air intake, as controlled by the idle bypass screw, is sensed by the airflow sensor, which also proportionally adjusts the injected fuel rate. 

Note: the above image is from an early (1981-1983) North American spec GTV6.  Later GTV6 models with the EZ-L Ignition System (1984 and up, North American GTV6) and cars sold in other markets have their idle speed adjuster mounted on the side of the plenum assembly, as shown below.

How to Adjust the Alfa GTV6 Idle Speed

NOTE: To adjust the idle on a GTV6, DO NOT touch the throttle valve stop screw.  Use the idle bypass adjuster ring (red arrow).  The engine must be at operating temperature with no accessories engaged and the gearbox in neutral.

1. First, loosen the idle speed bypass adjuster lock nut. This is the nut to the right of the adjuster ring in the image above. You should hold the adjuster ring with another wrench while loosening the locknut.
2. Turn the idle speed bypass adjuster ring in or out until you have the correct idle speed. You will feel the rubber squish as you tighten the adjuster. When you have the idle speed set, tighten the lock nut while holding the adjuster ring to keep it from moving.  GTV6 idle speeds are listed below for your convenience.

1981-1983 Alfa GTV6 Idle Speed North American Specs

• 800-1000 rpm

1984-1986 Alfa GTV6 Idle Speed North American Specs

• 950 +/- 50 rpm up to 4,000 ft. elevations
• Above 4,000 ft, 800-900 rpm acceptable

How the Alfa GTV6 Idle Speed O-ring Works

This is the view of the GTV6 O-ring looking through the bypass adjuster. Notice the size of the opening through which the intake air flows.

 

A close-up of the idle O-ring opening at its maximum size. The more air flowing through this opening, the faster the car will idle. Remember, the airflow sensor meters the air, ensuring the correct air/fuel ratio. Idle-speed adjustments do not affect CO measurements.

 

Note the size of the O-ring opening when the adjuster is tightened down. Tightening the adjuster squishes the rubber O-ring and reduces the opening size, and decreases the idle speed.  This is why the O-ring needs to be soft and flexible.  Old school engineering. Simple and effective.

So the next time you place an order for Alfa parts, have them throw in a replacement O-ring.  And when it's tune-up time, replace it.  Having one handy can save you a hassle and keep your car singing its happy tune.

Smooth sailing!

Alfa GTV6 Rear Coolant Hose

 

There’s nothing like the mesmerizing sound of an Alfa Romeo GTV6 on the open road. When you’re behind the wheel, you never want to stop—especially for that dreaded "B" word: Breakdown! I’ve owned my GTV6 for 39 years, and it has been impressively reliable. 

Still, I've had a couple of close calls that almost left me stranded. One was an alternator failure. Fortunately, I made it to a friend's house and avoided being stuck. The first incident, though, was the rear coolant hose coming out of the left cylinder head, leading to the "T" fitting and feeding the heater core.  This burst, spewing coolant and a huge cloud of steam and ended an enjoyable drive. Luckily, I was able to splice the hose together and make it home, avoiding a huge tow bill or overheating and damaging my engine.

My advice to anyone who owns a GTV6 is to inspect and replace this hose before it leaves you stranded.

Alfa Romeo GTV6 Rear Coolant Hose

Can you see the rear coolant hose? In the picture, it is the hose located just to the right of the fuel inlet hose.  This rear coolant hose feeds the heater core and comes out of the left cylinder head and is buried in the valley between the two heads.  As you see, this hose is obscured by the intake plenum, the fuel inlet hose, and wires.

This hose is buried behind the engine and pressed against the firewall. It’s easily overlooked when inspecting your engine. As a result, it often becomes old, neglected, and frequently soaked in oil—making it prone to failure, possibly on your next drive.  

This hose is difficult to reach with the intake plenum installed; removing it may help. Once the plenum is off, you might as well inspect your intake pipe couplings. Note: A lot of coolant will leak out when removing this hose, so have plenty of rags around.  Ideally, you should drain a good portion of your anti-freeze out before removing this hose.  Don't forget to bleed your cooling system. The link at the end of this post on replacing the thermostat has tips on bleeding your cooling system.

The Alfa part number for this hose is 60701345. It’s a hard-to-find part, so check your preferred Alfa vendor, eBay, or bring the hose to match at a local parts store. The GTV6 alloy engine does not like overheating, so while you're at it, consider replacing all your hoses. The worst things you can do to a Busso engine are to not change the timing belt, run low on oil, or overheat it.

Alfa Romeo GTV6 Coolant Hose T Fitting

Inspect your "T" fitting. Mine had some corrosion.

So I soaked it in Evaporust.

Rust removed and ready for paint.

If you can't salvage your "T" fitting, the part number is 60533669.  Note that these fittings are subject to deterioration, and because they have two different hose sizes, they are not easy to find locally.  So it is a good idea to get one and have it in your spare parts stash before you need it.

Don’t forget the two thermostat bypass hoses up front behind the thermostat housing. These are also out of sight and frequently neglected. Read more about them here:

Alfa Romeo GTV6 Thermostat Replacement

Smooth sailing and happy motoring!

Disclaimer: 

This post is provided for informational and entertainment purposes. If you have any doubts about your ability to perform this work or have any issues, I recommend having it done by a professional. I am not responsible for any issues arising from your reading this post. Use at your own risk.

Alfa GTV6 Recommended Lubricants Guide

 

Alfa Romeo GTV6 recommended lubrication decal part number 116.00.80.400.00 - 10050.

The Alfa Romeo GTV6 came with a recommended lubricants guide decal stuck under the hood to the top of the windshield washer reservoir.  Many of these decals are no longer readable. so I've posted one for your reference.  Many, if not most of these fluids are no longer available, so I've posted the generic specifications for your convenience.  The Alfa Romeo part number for this decal is 116.00.80.400.00 -  10050.

If you do find any vintage fluids, be careful using them. Fluids and lubricants do go bad after a while. Oils that are five years old or older are generally considered past their use by date. They would have to be examined for separation and other deteriorations before using and it is likely not worth the bother.

ALFA GTV6 ENGINE OIL*

• AGIP SINT 2000 SAE 10W 50
• IP SUPER MOTOR OIL 10 W/50
• SHELL SUPER PLUS 15W/50

*SE Oil Specification

Note: Many modern motor oils, designated for fuel economy and emissions standards, do not contain enough zinc (ZDDP, or zinc dialkyldithiophosphate) to adequately protect a flat-tappet engine like used in the GTV6.  You should look for oils specifically designed for flat-tappet engines.  Using a ZDDP additive may be an option, but it is possible to have too much ZDDP.  Do your research carefully.

ALFA GTV6 ENGINE OIL CAPACITY (Sump and Filter)

• Full - 7.1 qts**  
• Danger Level -  4.75 qts

** Quantity needed for a regular oil change.  Total amount of oil in oil circuit (pan, filter and passages) - 7.65 qts

Original Alfa Romeo GTV6 North American Underhood Lubrication Decal.  The Shell Super Plus oil listed was an add on sticker 

ALFA GTV6 GEARBOX and DIFFERENTIAL*

• AGIP F 1 ROTRA MP SAE 80W90
• IP PONTIAX HD SAE 80W90
• SHELL SPIRAX 80W/90 HD

*SAE 80 W/90 API GL-5 specification

ALFA GTV6 GEARBOX OIL CAPACITY

•  3 qts

ALFA GTV6 FRONT WHEEL BEARINGS*

• AGIP F1GREASE 33FD
• IP AUTOGREASE FD

*SAE NLGI 2/3 specification

ALFA GTV6 SPICA STEERING RACK*

• AGIP F1 ROTRA MP SAE 80W90
• IP PONTIAX HD SAE 80W90
• SHELL SPIRAX 80W/90 HD

*SAE 80W90 API GL-5  specification

ALFA GTV6 ZF STEERING RACK*

• ALFA ROMEO NORMALE 3671 69328

*Note: Right Hand Drive

ALFA GTV6 BRAKE FLUID*

• ALFA ROMEO NORMALE 3681-69905
• AGIP BRAKE FLUID SUPER HD
• ATE Blue S

*Dot 3 specification

ALFA GTV6 BRAKE FLUID CAPACITY

• Sufficient Quantity (yes, that is the Alfa spec listed in the manual. LOL)

ALFA GTV6 RADIATOR AND EXPANSION TANK*

• ALFA ROMEO NORMALE 3681 69958 COOLANT

*conventional antifreeze

ALFA GTV6 COOLING SYSTEM CAPACITY

•  3.2 gallons

Alfa Romeo GTV6 Underhood lubrication Sticker, Alfa Romeo GTV6 Recommended Fluids

Alfa Romeo GTV6 Fluid Capacities from Owner and Workshop Manuals.

Alfa GTV6 Fuel Tank Strainer Servicing

The Alfa Romeo GTV6 fuel pump is fed with gasoline that passes through a fuel strainer at the bottom of the fuel tank. It can be unscrewed from the tank with a large 32mm socket after you remove the banjo fitting for the hose on the bottom. The banjo fitting bolt is 13mm. When you remove the banjo bolt, you should hold the base of the filter with a 32mm open wrench. 

The base of the filter is a soft metal and has likely been screwed into the tank for decades. Make sure you clean and around the threads and use a good penetrating fluid to give yourself every chance of getting this filter to unscrew. Hopefully, yours will come free. 

Before you do all this, you must figure out how to drain the fuel from the tank. Don't cut the feed hose unless you have a replacement, as it is not the easiest to find. The size of this hose was originally 12 mm and could have been replaced with the easier-to-find 1/2 inch size. Ensure you get a fuel hose and not the more common heater hose. The hose should also be ethanol-compatible if that's what is used in our area.

Alfa Romeo GTV6 Fuel Tank Strainer Parts

 

 Alfa Romeo GTV6 Fuel Tank Strainer Part Numbers

• Fuel Filter Strainer Alfa part number: 0060523420 / old Alfa part number: 11911320260200
• Oring Alfa part number:  0010298460
• Washer Alfa part number: 0060523440 

Alfa Romeo GTV6 Fuel Tank Strainer and sealing washer and Oring.  The GTV6 fuel tank strainer has long been discontinued. The Alfa Romeo part number for this was 0060523420. The filter was made by FISPA*, and the part number is 3160.02.  

Hopefully, yours is still serviceable, but if not, the only way I have seen to get one is to scour eBay or other "for sale" sites. 

Alfa Romeo GTV6 Fuel Strainer Specs

The outside thread size of the Alfa GTV6 Fuel Tank Strainer is 40x1.5mm.  The inner thread where the banjo bolt is screwed into is 22mm.

Other car companies like Porsche and Mercedes-Benz use similar in-tank fuel strainers. However, I have not found a substitute filter with the same thread size.

Alfa 6 Fuel Tank Strainer

The Alfa Romeo Alfa6 sedan uses a similar 40mm outside thread filter. However, the inner thread size is only 18mm, not the larger 22mm used on the GTV6.  Using that filter will limit fuel flow going to your fuel pump.

The Alfa Romeo Alfa 6 Fuel Filter part number that is not recommended is FISPA 316003 or Alfa Romeo part number 119203202600.  This old part number was superseded by the new Alfa Romeo part number  60737161.

Alfa Romeo GTV6 Fuel Tank Strainer Sealing Washer

The Alfa Romeo GTV6 Fuel Strainer sealing washer is a copper washer with an inner diameter of 41.95mm.  The outer diameter measures 48.77mm. The thickness of the used washer was 1.51mm.  Unsurprising, this M42 washer is not the easiest thing to find. 

After much searching, The closest I found was this 42mm inner and 49mm outer, 2mm thick, DIN 7603 Copper Sealing Washer at the Misumi USA. Misumi is the world's largest supplier of fixed and configurable components for the manufacturing industry.

Part Number: 7603-CU-42-49-A

DIN 7603 Sealing Washers, Copper.

Alfa GTV6 Fuel Strainer Washer Outside Diameter is 48.77mm

The Alfa GTV6 fuel strainer washer thickness measured 1.51mm.

Alfa Romeo GTV6 Fuel Tanks Strainer Oring

A replacement for the Alfa Romeo GTV6 fuel tank strainer Oring is no longer available. And even if you did find one, it may not be ethanol-fuel compatible. One of the more significant hurdles is finding one that is compatible, and measuring a used shriveled-up Oring is difficult.   After much research,  I decided on Buna-N 70 Duro Orings, which are ethanol-fuel-rated.

I'll confess that I ordered dozens of Orings trying to find a size that would fit like the original. These Orings were often only available in bulk, and I spent over $100 never to come up with a definitive size. 

I  settled for a 34 x2.5 mm Oring that seems to fit well. This is a decision you'll have to make for yourself. To ensure no leaks, I used an ethanol-fuel-safe thread sealant.   This would normally not be necessary if all these parts were available from Alfa. Again, it is up to you.

The Oring Store 

Fuel Thread Sealant For Ethanol Applications

Because I had a hard time finding the exact size of the ring for the fuel strainer and to make sure I didn't have an issue, I used this thread sealant made specifically for sealing gas fittings for ethanol applications. This sealant is also compatible with Buna-N Nitrile O-Rings (NBR) .  I would not use this on the banjo fittings.  The copper washers will be fine.   

Gasoila PTFE Thread Sealant for Ethanol E10 & E85 Applications**

Alfa Romeo GTV6 Fuel Tanks Banjo Fittings

 

The Alfa GTV6 uses banjo fittings to connect the fuel hoses to the fuel tank.  The larger banjo fitting is the fuel feed from the fuel strainer.  The smaller fitting is for the fuel return hose coming from the fuel pressure regulator on the engine.  You need to change the sealing washers whenever you remove these fittings.  Here are the sizes for your convenience.

Alfa Romeo GTV6 Fuel Feed Banjo Fitting Sealing Washer Size

For the GTV6 fuel feed banjo fittings you will need to order two 20mm inside x 26mm outside diameter, 1.5mm thick washers.

26mm outside diameter,

The washer is 1.5mm thick.

Alfa Romeo GTV6 Fuel Return Banjo Fitting Sealing Washer Size

The smaller fuel return banjo fittings will take two 12mm inside x18mm outside diameter, 1.5mm thickness washers.

The Alfa GTV6 fuel return banjo fitting sealing washer.

The return banjo fitting washer is 1.5mm thick.

I picked up this set of copper sealing washers from Amazon that had all the sizes I needed for the banjo fittings.

180Piece Copper Sealing Washers Box M5 M6 M8 M10 M12 M14 M16 M20**

This is how I serviced my fuel pump strainer on my GTV6.  The information is provided for entertainment and informative purposes. Only you can decide if you feel comfortable doing this kind of work. Use the information at your own risk.  If you have any doubts on you ability to perform this work or have any issues, I recommend having it done by a professional. I am not responsible for any issues arriving from you reading this post. Good luck with your project!

Read about replacing the Alfa GTV6 Fuel Pump Hoses

Check Out the Topics page

**NOTE: I spend hours researching to find products that I can use for my car.  To save you time and the aggravation of finding something that works for your car, I've posted links to the products I've used. 

Do your own due diligence when making purchases.

*Fabbrica Italiana Specialità Parti Auto (FISPA) or Italian Specialty Auto Parts Factory was founded in 1925 and is supplier of OEM and aftermarket car parts.

Alfa GTV6 Fuel Tank Strainer Size, Alfa GTV6 Fuel Tank Fittings, Alfa GTV6 Fuel Strainer Washer 

Alfa GTV6 Fuel Pump Hose Replacement

 

The Alfa Romeo GTV6 fuel pump hoses have a unique routing that have hoses with 180 degree bends.  Naturally, these hoses are no longer available. Even if they were available, there is a very good chance that NOS (New Old Stock) fuel hoses will not be compatible with the ethanol fuel most of us have to use. If you are running original fuel lines, or fuel hoses that have been on for a decade or two, you should change these fuel hoses before a disaster occurs. 

The Alfa Romeo GTV6 uses an electric fuel pump located under the car, tucked besides a chassis reinforcement at the right rear.  Fuel runs from the fuel tank to gravity feed the fuel pump (#10 in the image above) and then is sent to the fuel filter (#9) then makes a 180 degree turn to run towards the front fuel feed (#11) 

Sure, changing old fuel hoses is a good idea, but the problem is because of the convoluted routing of the GTV6's fuel hoses, there aren't many options available to service these GTV6 fuel lines. A couple of Alfa specialists make these special  fuel hoses with the 180 degree bend, but they are expensive, or may be out of stock and those that come from Europe may not be compatible with the fuel blends sold here.  

Ethanol fuel can cause issues in classic cars that were not made for the that type of fuel. Problems can include deteriorated rubber fuel lines, gaskets, and plastic and rubber fuel-system parts.

The work around many people do is try to bend a straight length of hose 180 degrees. This will likely to kink and restrict the fuel flow.  This could result in poor performance and premature fuel pump failure.  No Alfa GTV6 owner wants poor performance, so here's an option.

RetroMotion Innovations' Sidewinder U-Cut Molded Curved Fuel Line part number: RMI-33010 half-inch J30R7 (35 PSI)  fuel hose along with a Bosch fuel pump and stainless steel fuel barb connector.

Retro-Motion Sidewinde 1/2" Molded Fuel Line Rubber Hose

Stainless Steel 1/2" to 1/2" Hose Barb

I found a set of universal ethanol resistant fuel hoses made for custom applications with pre-formed 180 degree bends.  Manufactured by RetroMotion Innovations, their  Sidewinder U-Cut Molded Curved Fuel Line, features universal hose elbows with 45, 90, 135 and 180 degree curves. The company makes fuel lines in 3/16", 1/4", 5/16", 3/8", and 1/2" sizes.  

The Alfa GTV6 uses a 12 mm and 8 mm fuel hose.  Many in the US Alfa community use 1/2" for the 12mm and 5/16" for the 8 mm. 

Bosch 69412 OE Electric Fuel Pump

The Alfa GTV6 uses an electric fuel pump.  The original Bosch part number was 0 580 464 020, however, it is no longer available.  It has been replaced with this Bosch OEM replacement pump, part number 69412 ( 0 288 517 941 21).  This pump is capable of putting out 100psi, so it is important to use fuel injection pressure rated hose for the output and hoses downstream of the pump. It should also be ethanol compatible. The SAE standard to look for is J30R9 (100psi).  

The inlet to the fuel pump is 12 mm, but a 1/2" (12.7mm) is deemed acceptable by many in the GTV6 community. The inlet or suction side of the fuel pump is gravity fed, so a J30R7 (35 PSI) spec fuel hose is what I used.  Getting a flexible J30R9 (100psi) spec, ethanol safe 1/2" fuel hose is difficult to source, plus the hose has to be flexible enough to be routed around chassis components. That may be difficult to do with a super stiff reinforced hose. 

Above you can see how I trimmed the inlet a little at a time to get the right fitment. There is not a lot of room to fit all these hoses in the fuel pump location, so to help,  I trimmed the inlet hose as tight as possible to the fuel pump. 

I suggest starting off trimming these fuel hoses a little long, so you can fine tune the fitment.  It is a  tight fit under the car, so I wound up trimming the inlet end as close as possible to the pump.  I used a  1/2" barbed fuel line connector and high quality European style clamps. The barbed end was super tight to push in, so a little P-80 Emulsion rubber lubricant made the fitting slide in super easy. 

HIGH PRESSURE J30R9 100PSI Sidewinder 5/16" RMI-33004 Rubber Fuel Hose

Once the fuel pump inlet side was done, I went to work on the fuel filter side. This hose has to be high pressure  J30R9 (100psi) spec hose.  The RetroMotion Innovations' Sidewinder 5/16 molded fuel line comes in J30R7 (35psi) or J30R9 (100psi) specs.  Make sure you get the high pressure 100psi hose! You'll also need a 5/16" barbed fuel hose connector and high pressure fuel injection spec hose clamps. 

Stainless Steel 5/16" to 5/16" Hose Barb

The trimmed fuel hoses. The small tube is the P-80 fuel hose lubricant that helps ease installing the tight fuel hose barbed ends.

The fuel hoses installed on the fuel pump and fuel filter.  

After the fuel pump and filter are clamped into their respected brackets, the large feed coming from the fuel tank (green arrow) is connected to the fuel pump barb.

The fuel pump feed line  (green arrow) come from the bottom of the tank, attached to the fuel tank filter screen. I used a fire and abrasion resistant silicone insulation sleave over the fuel feed hose. The red arrow is the fuel retune line coming from the fuel injection rail.  

Here's the GTV6's fuel tank screen and banjo fitting. The large 12 mm / 1/2" fuel line is attached to this and feeds the fuel pump.

This is how I renewed my fuel hoses on my GTV6.  The information is provided for entertainment and informative purposes. At the very least, you'll get familiar with what's going on under the car.  Only you can decide if you feel comfortable doing this kind of work. Use the information at your own risk.  If you have any doubts on you ability to perform this work or have any issues, I recommend having it done by a professional. I am not responsible for any issues arriving from you reading this post. 

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Parts I Used On My Car For Your Convenience     

Retro-Motion Sidewinde 1/2" Molded Fuel Line Rubber Hose

HIGH PRESSURE J30R9 100PSI Sidewinder 5/16"RMI-33004 Mandrel-Formed Rubber Fuel Hose 90

P-80 Emulsion Temporary Rubber Assembly and Pump Seal Lubricant

I bought the above parts from Amazon (except the RMI-33004, which I couldn't find on Amazon).  

NOTE: I spend hours researching to find products that I can use for my car.  To save you time and the aggravation of finding something that works for your car, I've posted links to the products I've used. 

Do your own due diligence when making purchases.

Alfa Romeo GTV6 Fuel Pump Hoses, Alfa Romeo GTV6 180 Degree Fuel Pump Hoses, Alfa Romeo GTV6 Fuel Pump Hose Routing, Alfa Romeo GTV6 Fuel Pump Hoses Diagram, Alfa Romeo GTV6 Fuel Pump Hose Replacement