Under the Shroud

[jcannon44]

Just pulled off Shroud, trying to diagnose problem with overheating and engine cutoff after 15 minutes of driving




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[azdave]

Doesn't look too bad in that pic. Many people that area filled with mouse nests, deck lid insulation, old shop rags and walnuts.

[JasonL]

You engine looks clean.
What gauge is telling you that you are overheating. I had the same problem last summer it was a bad oil pressure switch turning on the temp\pressure light. It acted the same way.

Have you checked the condition of the thermostat wire? Sometimes they ground out and cause the gauge to look like it is over heating.

[jcannon44]

You engine looks clean.
What gauge is telling you that you are overheating. I had the same problem last summer it was a bad oil pressure switch turning on the temp\pressure light. It acted the same way.

Have you checked the condition of the thermostat wire? Sometimes they ground out and cause the gauge to look like it is over heating.

Gauge isn't showing anything, just my best guess as to why engine is dying. Plus engine very hot to touch!


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[64powerglide]

He said it shuts off after running about 15 minutes!!!!!!!!!!!! Corvair engines are HOT!! Check all your tuneup specs!! Especially timing & valves. How well does if run before it quits??? How much compression does it have in all 6 cylinders??

[JasonL]

You car probably is not over heating.
You may have several problems causing the stalling.

I would start the diagnosis by checking for spark once it stalls. If you have spark then move to fuel. If you spray some fuel into each cylinder does it run? Again do your diagnostics when it is acting up.

If you have spark and fuel then it may be a cylinder pressure issue. A compression test on your engine would tell you if it is timing or cylinder pressure related. Look carefully at each spark plug as you remove them see if any of the tips are white or black, that could indicate a problem. They should be a tan or brown color.

Another question is does the engine completely die or does it only die at high speeds or low speeds?

[jcannon44]

Dies at light, but will start again, but if i give it too much gas will stall, have to slowly nurse it to keep going.


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[bbodie52]

Welcome to the Corvair Forum!

Your problem might be a weak spark from the ignition coil. If the ignition coil is beginning to break down and fail, heat buildup could potentially increase the failure and weaken the spark voltage output.

If you suspect a failing ignition coil, and you decide to replace it, is not a bad idea to relocate the coil mount position at the same time. The standard installation of the ignition coil was always mounting it directly on the right cylinder head. The cylinder head on an air cooled engine gets very hot, and a significant portion of that heat can be transferred via the coil mounting bracket to the coil itself. If you decide to replace your coil, I would recommend relocating it as shown in the pictures below at the same time.





Another possibility may not be heat-related at all. If you're still running standard ignition points, the wire that connects between the points and the negative terminal of the ignition coil can deteriorate over time. That wire is subject to continuous flexing as the vacuum advance moves the breaker plate in the normal course of engine operation. The metal strands of wire inside the outer insulation can begin to break down over the years. Clark's Corvair parts sells a replacement wire for this reason. If the connection between the points and the ignition coil has become intermittent and/or unreliable, you might check this wire using a multimeter to check continuity and internal resistance while you manually wiggle the wire to see if internal breakdown is a problem.

Part number C530: 60-69 DISTRIBUTOR POINT LEAD

Weight: 0 lbs 2 oz
Catalog Pages(s): 75,77(11«),77(19)
Price: $ 8.00


Another possible source of an intermittent ignition problem might be a poor connection in the electrical multi connector in the left front portion of the engine compartment. You did not mention your Corvair model year, but the picture makes it look like a 140 hp engine that would normally be found in a 1965 or later Corvair. The electrical multi connector in the engine compartment is subject to corrosion internally due to age, moisture, heat and vibration. Even though the two halves of the connector may look to be solidly attached to each other, the internal metal connections may have degraded. Vibration and internal resistance may have increased to the point where the voltage provided to the ignition coil positive terminal may be low or intermittent. There is also a ballast resistor wire in the wiring harness that is designed to reduce voltage to the ignition coil to a nominal 7 V DC to help prolong the life of the ignition points and to help reduce ignition coil operating heat buildup. The ignition voltage is temporarily increased when the engine is being cranked to a full 12 V DC that is supplied by the starter solenoid to the ignition coil. This higher voltage from an alternate source is discontinued when the key is released and it returns to the ON position. This would help the engine to start when it is being cranked, but the spark voltage could be degraded when the key is released and the power source for the coil returns to the normal circuit via the ballast resistor wire and the multi connector. A failing resistor wire can tend to overheat during operation, and internal resistance may increase with heat buildup. A poor connection inside the multi connector can also produce intermittent engine operation.

1965-1969 Corvair Engine Compartment Wiring Harness

1965-1969 Corvair Engine Compartment Wiring Harness Multi-pin Connector

1965-1969 Corvair Engine Compartment Wiring Harness Multi-pin Connector.jpg (33.79 KiB) Viewed 853 times

The wiring harness schematic for many different Corvair model years can be seen using the following viewtopic.php?f=225&t=12968

[JasonL]

See if you can simulate the driving conditions in your neighborhood then check the strength of the spark and pop the intake off and see if you have fuel flooding the carbs or if the squirters are pumping jets of fuel into the carbs when you press the accelerator. Try do do it near where you can open the hood and look things over.

It may be a bad coil like mentioned above or plugged ports in the carbs, stuck float, weak fuel pump, or several other things.

[skipvair]

Or vapor locking


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[jcannon44]

Thank You! So many good ideas! Troubleshooting now.


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[Bard Beach]

I'm curious if you're getting a lot of blow by or smoke as the engine overheats?
I'm getting a lot of the same symptoms as you but accompanied by white smoke. Maybe because of the overheating in combination with other conditions that are causing blow by?
I've had the ignition recently replaced with an electric at the corvair ranch in PA I but was told to look into replacing the coil


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[bbodie52]

Tue Aug 29, 2017 3:44 pm

I'm curious if you're getting a lot of blow by or smoke as the engine overheats?
I'm getting a lot of the same symptoms as you but accompanied by white smoke. Maybe because of the overheating in combination with other conditions that are causing blow by?
I've had the ignition recently replaced with an electric at the Corvair ranch in PA I but was told to look into replacing the coil.

I want to encourage you to try to carefully determine why the engine is cutting out after 15 minutes or so of operation. The problem may or may not be heat related. The engine should continue operating in less either the ignition system or the fuel system is disrupted. One of your first steps and troubleshooting your problem will be to determine if the engine dies because of fuel starvation, or if the engine dies because of an ignition fault. I mentioned earlier that heat can cause an ignition coil to begin to fail. However, deterioration or a loss of power to the coil can make it look like the coil has failed. If the engine will not restart right after it dies, does the problem seem to clear after a period of time has elapsed? If the engine is not running, is there an indication that a spark is present? (Try unplugging one of the spark plugs and insert a screwdriver into the spark plug boot to make contact with the metal connector inside. If you hold the screwdriver shaft near a point that is grounded to the chassis and have someone crank the engine, you should be able to see a spark jump from the screwdriver to the grounding point while the engine is being cranked. If the spark seems to be absent and you have access to a multimeter, you should be able to check for the presence of voltage at the ignition coil positive terminal when the ignition key is on. If voltage appears to be present at the coil positive terminal, but you are unable to get a good spark from the coil when the engine is being cranked, a faulty coil may be considered. If you cannot find input voltage at the coil positive terminal, there may be a problem with the wiring harness or ballast resistor.

If you're not familiar with fault isolation and troubleshooting procedures on your Corvair, you might try contacting one of the CORSA club chapters in discussing your problem with them. You might find some volunteers were experienced Corvair mechanics who can help you to determine whether the fault lies in your Corvair. On the other hand, if you do some troubleshooting on your car and tell us on the Corvair Forum the results of your testing, we may be able to help you with proceeding to the next step in correcting the fault.

You should be able to do a lot of troubleshooting before you actually start buying replacement parts. It is possible to waste a lot of money buying replacement components that are not really bad. It is much better to gain a full understanding of what you are looking at and to do effective troubleshooting before you spend money on replacement components.