V6 Mechanical Tensioner : question by Joel Lewis | Milano
I recently changed out my Milano timing belt and tensioner. After hours of putting on and taking off the new tensioner, we determined that it was defective ! Scary thought, I am glad we caught it on the "turning the engine over by hand phase" instead of the "test drive" phase ! So, we put the old tensioner back on. It has 30 K miles on it. Do you think one needs to replace the tensioner every 30K miles? or do you think mechanical tensioners can go for 60K?
| | Answer : Aha yes, the mechanical V-6 Alfa tensioner. A perfect example of an engineer’s best intentions gone awry. To answer your question, I would change the belt and tensioner at 30K mile intervals, period. I have seen many a mechanical tensioner prematurely fail and cause thousands of dollars of damage. These mechanical marvels are produced with, what I believe to be, woefully inadequate tension springs. Take a look at the mechanical tensioner on a 308 Ferrari, it’s spring has to be at least 20 times thicker than that on the Alfa. When the Alfa tensioner springs fracture , the tensioner then fails to keep proper tension on the timing belt, the belt skips, the cam timing then goes very wrong and the next sound you will hear is that of valves hitting pistons. A few installation pointers:
1. Apply a light film of grease to the back of the tensioner.
2. Set the tensioner pre-load at T.D.C. #1
3. Adjust the pre-load to the center mark on the tensioner (I know some technicians who believe in adjusting to the high side and those who believe in adjusting to the low side, I have seen nothing that shows me that adjusting to the center is not the best way to go).
4. Turn the engine over by hand, in direction of rotation, stop at T.D.C. #1, and re-check the pre-load mark. If it is not on center, release the tension slowly with an extension and ratchet in the square drive of the tensioner; DO NOT let the tensioner "snap back". Now re-index the pre-load to the center mark and rotate the engine 360 again, and re-check. Repeat the process until you get it right. Remember, it is most important that you handle the tensioner gently. It does not like being snapped back and forth. I have actually seen the springs break when the tensioner was released and allowed to snap to the unloaded position. Good luck and remember a new belt and tensioner every 30K mi. are cheap insurance against catastrophic mechanical failure.
| Smelly Spider : question by Mike Devereaux | ’86 Spider Veloce
We recently purchased a used (55K miles) Spider Veloce and have a problem with exhaust fumes (not gas fumes) being sucked back into the cockpit when we drive the car above 45 mph with the top up and windows rolled up or partially rolled up. We have replaced the entire exhaust system, tried a down-turned exhaust tip, replaced the rubber trunk seal and replaced both the rubber door seals. There have been no holes cut in the area behind the front seats for speakers or anyting else. The car is completely stock and unmolested. It has gotten a little bit better since replacing all those items, but you still can't drive the car for very long (15 or 20 minutes) without feeling "gassed". If the top is up, we have to drive with both windows down. Any ideas? One book I read mentioned that this is simply a characteristic defect of the square tailed Spider body design. We have also put a factory hard top on the car for the winter, yet the problem still persists; we can't drive it with the windows rolled up. Thanks for any help you can give.
| | Answer : Your problem is not an uncommon one for all Alfa spiders. Before getting into mechanical causes, you need to check the uniformity of the trunk seal. Cut a 3" strip of paper, close the trunk on it. You should be able to pull it out but with quite a bit of drag, not enough to tear the paper, but definite resistance. Try this all the way around the seal. If the drag on the paper is fairly uniform, you can be fairly certain that the mechanical seal of the trunk is good. (I know one body shop in Hollywood that pumps smoke into the trunk to check the quality of the trunk seal). If you are certain that the trunk seal is good, the exhaust is sound, and you are certain that there is no other place for exhaust gas to enter you vehicle, it’s time to look for a mechanical cause for your concern. If you take the time to do a leak down test, emissions test, an oil consumption and a fuel mileage test, I suspect that you will find that one or all tests will be failed by your vehicle. I have seen many Alfa’s with this problem, the vast majority of the time the problem is caused by poor maintenance, infrequent oil changes, rich mixture and subsequent oil consumption. I suspect that what you are smelling is a combination of burning oil and unburnt fuel. If you think about it, the Spider Veloce has a converter and a modern FI and engine management system. It should never be producing gas fumes of the magnitude that you are describing, except possibly during warm up. You may have any or all of these problems:
1. Worn valve guides
2. worn piston rings
3. Bad engine management sensor, out of spec. Air flow meter, improper fuel pressure, or some other component failure causing rich fuel mixture. I know that this was not the answer that you were hoping for, however, not all Spiders have this problem and some GTV’s and Berlina’s do, it stands to reason that it is not a problem with the kamm tail design.
| Milano No Re-Start : question by Michael Jones| ’87 Milano
The car sporadically dies and won't restart. A few hours later it fires up and drives for a short while. There is spark, the fuel filter seems clear, we have disconnected the fuel line just after the pressure regulator (?) and before the fuel rail going to the injectors and we get a gusher. Any suggestions? | | Answer : The no re-start is a not uncommon problem that seems to plague a few V-6 Alfas. Unfortunately I have seen a number of failures that can cause this symptom. The sporadic idle is not nearly as common, so let’s look at possible causes for that first. The first place I would look for an idle problem would be the auxiliary air valve. It will not, however, cause a no-start condition. This may sound basic, but I have seen people tow their vehicles for miles, only to find that the plenum hose was not connected. Make sure you don’t just have a huge vacuum leak. I suspect that the fuel injectors may not be getting a signal to open. You can purchase a test light designed to plug into the injector harness that will easily check for voltage. First, check all the connectors involved with the FI system. Check all input sensors involved in the L-jet injection system for proper resistances; check all the connections at the sensors as well. Make absolutely certain that the black wires that attach to the back of the right cam cover are sound and well connected. I have seen several no starts caused by these wires being attached to a bolt in a hole that the threads were stripped out and were consequently not making a good ground for the FI system. An out of specification air flow meter will cause this problem and could easily cause a no-start condition as well. Since I don’t have the time to write a test manual on air flow meters, I would suggest you get your hands on a known functioning unit and install it in your Milano. (This can be done in about 60 seconds for test purposes). If that doesn’t cure the problem, next borrow a working L-jet processor and plug that in after checking all connection in that impressive connector. Check for wires that could be backing out of the connector as well as corroded or loose fitting connections. If this doesn’t cure the problem, I would verify fuel pressure and delivery rate, test the injection temperature sensor, I could go on for pages about the possible causes of a no start condition. If none of this helps, Email us back with more particulars and we will try again.
| Built GTV Misfire : question by John Hoffmann| ’71 GTV
Engine-Sperry stage 4, Shankle 7L cams and HP Ingram pump. Car runs fine when first started up, but as it warms up, it starts to "misfire". Can't tell whether it's fuel delivery or electrical problem. When completely up to temperature, RPMs will not exceed 3500. Timing and ignition set properly. I'm being told that the stock ingnition is not suitable for a modified engine. I appreciate any help. | | Answer : First of all, although the stock ignition (I assume you mean a stock Marelli points and condenser system) is not an optimal set-up for your modified engine, it can perform adequately. Before there was electronic ignition, points and condenser systems were all that was available at a reasonable price. In any case, if your ignition system is in good working order, I doubt that it is the cause of your problem. Assuming that this configuration ran well and that this is a new problem for your GTV, we can rule out FI pump timing as the cause. With your vehicle up to temperature, make these diagnostic checks:
1. Check the fuel pressure and delivery rate
2. Check that the thermostatic actuator has proper rod length
3. Check that the ignition is advancing correctly and achieving max. advance
4. Try another set of plug wires, I know that this problem only occurs when the engine is hot, but bad plug wires can produce this symptom.
5. Inspect the plugs for insulator overheating or improper gap and fouling.
6. Visually inspect the cap and rotor for carbon tracking and/or cracks.
7. Have your car hooked up to a 5 gas analyzer and check the mixture Without more details, it is difficult to give an actual diagnosis of your problem. Rule out ignition as the cause. Then I would look to fuel delivery, either not enough pressure or volume to the FI pump or a problem with the FI pump itself.
| Building a Hi-Performance 3.0 : question by David Alexander | Alfetta GT
I am in the process of rebuilding a 3.0 for my street/track Alfetta GT. Of course, I want to build in some extra power. The plan is to balance the pistons and rods, lighten the flywheel, high compression pistons, 164 "S" cams (or something more radical) and modified heads. I want to finish off with a Simple Digital Fuel Injection System with direct ignition using sensors off the front pulley. Additionally, a free flowing exhuast system is planned. The plan is to keep the stock headers as the aftermarket (Ansa's and Shankle's) don't seem to have a great reputation. What do you advise (besides checking in to the to the nearest mental hospital)? | | Answer : Interesting project. First thing I would do is the one thing that you are not planning on doing: headers. An internal combustion engine is an air pump, to optimize it’s performance you must be able to get the air out as well as getting it in. It is all well and good to raise compression, modify the heads and manifold for increased airflow, and toss in some cams with increased lift and duration. If you can’t get the exhaust gasses out of the engine at lease as quickly as you get the fuel mixture in, you are loosing HP. I have seen both Shankle’s and Ansa’s headers and the only problem I see with either of them is that they occasionally blow collector gaskets. I have had luck overcoming this problem by making a 1/16" asbestos gasket and sandwiching it between two copper gaskets and putting the flange together with self locking copper exhaust nuts. 164 S cams are a good compromise. If you are planning on going over 10.5:1 CR, I would look for a more radical cam to make full use of the increased compression. Definately go for big valve heads, and I would look to Sperry Valve Works for their large intake runners and modified plenum. A programmable crankfire ignition/injection system would top the whole project very nicely. Good luck, and let me know how it works out. | Click Here To Return to This Month's Tech Q & A |
