Oil Pressure Switch wire install

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Walt
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Oil Pressure Switch wire install

Post by Walt »

Hello... I recently purchased a 1964 Corvair, and it came with several oil leaks which is fine. The worst was at the oil pressure switch which I replaced and that oil leak disappeared. Then I had the engine steam cleaned - has no lower shrouds so I could see how grimy the motor was - and when I got it back from being cleaned, suddenly the light was coming on on the dash. I came to the forum, found several items of info that were very helpful - when I disconnect the wire from the switch, the light does not come on. But in this process, I noticed that the wire going to the switch was horribly frayed... the braided insulation is totally pulled away from the wire and not just at the oil switch, but also at its other end at the connection to the temp switch. I saw that this Y wire was available as a stand-alone purchase from Clark's so I ordered one up. The wire should get here some time this week, but today I took a look to see what I'm going to need to do to install it. It's an easy clip-in to the main harness and easily will slip onto both switches... but I noticed that the lower part of the wire feeds through a grommet that seems almost impossible to reach!

So all of that lead-up to the question: How do you replace this wire? Do I have to reach up from below with a long screwdriver and pop the grommet out? Any advice would be appreciated... I couldn't find anything listed in the shop manual...

Walt
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bbodie52
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Re: Oil Pressure Switch wire install

Post by bbodie52 »

The easiest thing to do: Install the new wire, connecting the one end to the oil pressure switch next to the generator, and connect the other end directly to the main perimeter wiring harness (so that the oil pressure warning switch is connected to the instrument panel warning light). Don't bother with the connection to the right cylinder head temperature warning light switch. Just leave the temperature switch portion of the wire disconnected and tuck in out of the way with a tie wrap or some electrical tape.

Over the decades I have never seen this cylinder head overheat warning switch actually do anything anyway! The only thing that would make your engine overheat is a cooling fan belt failure, which would be indicated by the GEN/FAN warning light long before the engine overheat light would come on. If you get a GEN/FAN warning light and decide to keep driving until the PRES/TEMP light comes on, you deserve the damage from a cooked engine! In the real world, your main concern is knowing that the cooling fan is spinning and blowing air through your air cooled engine's cooling fins, and that there is oil pressure lubricating your engine.


You could also remove sheet metal item 9 to give you better access to the grommet hole in item 14 (shown below), and maybe install a fresh grommet along with the portion of the new wire that connects to the temperature switch on the right cylinder head. Engine sheet metal removal and installation is described in the attached 1964 Supplement - Chevrolet Corvair Shop Manual - Section 6a - Engine, and in the attached 1961 Chevrolet Corvair Shop Manual - Section 6a - Engine.

Right Rear Sheet Metal Shroud.jpg
Right Rear Sheet Metal Shroud.jpg (39.8 KiB) Viewed 1337 times
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:link: http://www.corvair.com/user-cgi/catalog ... w_page=234
Part number C1278R: EXACT REPRO GROMMET-(TO HEAD TEMP & THERMISTER)

Weight: 0 lbs 2 oz
Catalog Page(s): 7A,234
Price:
1 - 3 $ 3.50

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:link: http://www.corvair.com/user-cgi/catalog ... ow_page=97
Part number C7872: BRAIDED HEAT-OIL WIRE(USUALLY ON ALL * EXC SPYDER & CORSA)

Weight: 0 lbs 4 oz
Catalog Page(s): 97
Price: $ 15.95

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:chevy: :wrench:
Attachments
1964 Supplement - Chevrolet Corvair Shop Manual - Section 6a - Engine.pdf
1964 Supplement - Chevrolet Corvair Shop Manual - Section 6a - Engine
(1.6 MiB) Downloaded 43 times
1961 Chevrolet Corvair Shop Manual - Section 6a - Engine.pdf
1961 Chevrolet Corvair Shop Manual - Section 6a - Engine
(3.53 MiB) Downloaded 40 times
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
Walt
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Re: Oil Pressure Switch wire install

Post by Walt »

Once again very thorough and helpful information thank you so much!
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terribleted
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Re: Oil Pressure Switch wire install

Post by terribleted »

I have had the temp light come on and stop me when I threw a belt and did not realize it right away. The light might have saved my engine! You need a new grommet for the shroud most likely. they tend to get brittle, There is access from underneath for some pushing once the lower shroud is off. It can be done. It is difficult access. A new or supple grommet is key for easiest re-installation. I would not leave the temp sensor disconnected.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
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bbodie52
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Re: Oil Pressure Switch wire install

Post by bbodie52 »

:goodpost:

I guess I am somewhat spoiled in that many of my Corvairs have been Early Model Turbocharged Spyders or Late Model Corsas, and they were all fitted with the Spyder or Corsa instrument panel that included a cylinder head temperature gauge. So between the GEN/FAN warning light and the temperature gauge I never had much reason to depend on the overheat warning light switch in the right cylinder head.

There is another possible cause for a Corvair engine to overheat — even if the fan belt is intact and the cooling fan is spinning...

Image CRITTERS MAY INVADE YOUR CORVAIR!

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Critter Invasion.jpg

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THEY CAN FIND THEIR WAY INTO THE ENGINE COMPARTMENT AND UNDER THE SHEET METAL SHROUD, AND BUILD A NEST THAT WILL BLOCK AIR CIRCULATION. :angry: :doh:

Maybe you should just take the time to unbolt some sheet metal, replace the rubber grommet, and connect the wire to the cylinder head temperature switch!

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All of this driving during a hot summer, and the old 140 hp Corsa (loaded with me, the wife, two kids and all of our luggage from our return from West Germany) never overheated during 4 solid days of 70 mph driving!
Image
Brad Bodie
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Walt
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Re: Oil Pressure Switch wire install

Post by Walt »

Thank you both for your replies! I think I will attempt getting that grommet out and getting everything wired up. And those are quite a few photos of homesteads! Yikes! Hopefully I won't ever have to deal with that!
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Re: Oil Pressure Switch wire install

Post by bbodie52 »

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THE PREVENTIVE MAINTENANCE SERIES
by: Mike Dawson

Overheating Corvair Engines (Don’t!)

Water cooled cars will generally announce approaching overheating with lights, buzzers, puddles of
coolant and clouds of steam way before they reach a 600 degree head temperature which is where
Corvair engine destruction begins. A Corvair has a single warning light (turbos have a buzzer)
which is in combination with oil pressure warning. The ’60 model (only) also had an oil
temperature switch.

The Corvair “Temp/Press” light warning system contains two switches, both of which will ground
the dashboard light to turn it on while the engine is running if either detects a problem. The oil
pressure switch will also be grounded anytime the engine is not running and this lights the dash
bulb with the key on and engine off. The temperature switch is only grounded when the head
overheats and this varies with the three different switches used over the years. The first switch
grounded at 450 degrees (smooth hex body), the second at 500 (grooves in the body) and the third
(turbo and 140) has fine threads and is set for 575.

If the “Temp/Press” light comes on only at a low idle the problem is either a sticky oil pressure
switch or low oil pressure with thin oil. If the light comes on under a load on the highway then
goes off as you slow down it is definitely an overheat issue. A Corvair will heat and cool just the
opposite of a water cooled car; the faster you drive a Corvair the hotter it gets and the slower you
drive the cooler it gets. They do not overheat in a parade.

If your “Gen/Fan” light comes on, pull over as soon as safely possible and check the belt – if it is
working properly (check a failed balancer also) you should be able to safely drive to a location
where you can check the system. If the “Temp/Press” light comes on, you need to shut off the
engine as soon as safely possible and check the belt and the oil level; if both are good and the lifters
are not rattling, it should be safe to drive to a location to check out the problem. If the “Gen/Fan”
light came on and you keep driving until the “Temp/Press” light came on you are in very real
danger of severe engine damage – shut off the engine and stop as soon as safely possible. A tow
charge is always cheaper than an engine replacement which is the point I wanted to get to.

When you keep running a Corvair with the belt off and/or the temperature light on, the temperature
keeps rising rapidly. Once you cross the 600 degree point some almost irreversible problems start
to happen. The steel valve seats which are heat shrunk into the heads will come out and may
shatter, ruining three pistons and cylinders on the side that looses a seat first. The aluminum alloy
head may soften to the point the seat areas will all have to be welded and may even be unusable.
The aluminum cam gear is heat shrunk onto the steel cam and will expand faster that the steel and
will move out on the cam, making it also unusable. The aluminum around the upper head studs
will soften, allowing some, if not all of the studs to pull out of the head. Again, the aluminum may
be too soft to repair. The cooling fan bearing mounting shaft is steel and is also heat shrunk into
the aluminum top cover. When overheated it will move up in the cover allowing the fan to hit the
shrouding and the aluminum cover may also loose the shrink fit. Late model stock pistons will
crack around the oil ring grove and any piston may have holes burned in the tops or down the side
from severe detonation. In the final analysis, an overheated Corvair engine may be a junk engine;
only the sheet metal is safe to reuse.

Test your warning system every time you drive your Corvair by simply turning the key to the “On”
position for a moment before starting and observe that both dashboard warning lights are bright red
and then go out after the engine starts.

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Brad Bodie
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joelsplace
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Re: Oil Pressure Switch wire install

Post by joelsplace »

On generator equipped Corvairs sometimes the generator will "motor" when the belt comes off so the gen light doesn't come on.
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Re: Oil Pressure Switch wire install

Post by terribleted »

joelsplace wrote: Tue Aug 11, 2020 5:20 am On generator equipped Corvairs sometimes the generator will "motor" when the belt comes off so the gen light doesn't come on.
Or as in my case the unlikely failure of the gen /fan bulb made the temp pressure light more important. I had been self testing previous to that day. Not sure I paid good attention to it that AM, but I did see the temp pressure when it came on and I stopped. Once I saw the light I immediately turned down the radio and pulled over. Once U turned the radio down I could hear the engine detonating from being so hot. That day I was in an 67 A/C 110 Monza. The A/CV belt was close enough to the fan belt to install in it's place and get me down the road. I knew the fan belt was poor (old and getting dry and cracky) I had just not changed it yet:)
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
Currently working full time repairing Corvairs and restoring old cars.
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Walt
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Re: Oil Pressure Switch wire install

Post by Walt »

Ok... so a follow-up! I installed the new wire just into the harness and onto the oil pressure switch and left the other end of the wire for the head temp switch tucked away at first... just to see if the temp light on the dash would now work properly i.e. come one just before starting the engine but then go off and say off once the engine was on. And it worked great! I drove it for a couple of days like this to make sure the light stayed off while driving... and it did. So I figured cool! Problem fixed! And I would wind the other end of the wire down to the head temp switch soon. However after about two days, I went to turn my car on and still watching for the dash light to go on as I turned the key... the temp light did not light suddenly, only the gen light. Ugh! What? I tried it a few times, and it remained consistent, the temp light was not turning on now when I turned the key on prior to starting the engine. So I thought, maybe it does need the head temp connected. So this weekend, I connected the head temp switch as well with the new wire... but no. So... what are the odds that the bulb on the dash burnt out? And if so how to check & replace? Or what else should I check here... with the stories I hear about these lights saving engines from overheating, I want to make sure they are working correctly! Thanks in advance for any insights!
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joelsplace
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Re: Oil Pressure Switch wire install

Post by joelsplace »

It is just a regular 12V bulb. Ground the oil pressure wire and see if the light comes on. If it does then the oil pressure sender is bad. If it doesn't either the bulb or the wiring is bad.
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Walt
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Re: Oil Pressure Switch wire install

Post by Walt »

Thank you for your response... both the wire and the oil press switch are brand new... obviously that doesn't mean they aren't bad, but I'd say the odds are low. I will try to test the circuit and change the bulb. Just wanted to inquire with those who know these cars better than I if there is anything else that may be going on.

Thanks!
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Re: Oil Pressure Switch wire install

Post by bbodie52 »

The wiring harness TEMP/PRES warning light ground circuit is labeled 20 DBL. In the diagram it is marked with a RED line all the way from the oil pressure warning switch to the indicator bulb (which shows the GROUND portion of the circuit). The BLUE line portion of the circuit shows where power is applied to the bulb whenever the KEY is in the ON position. (This provides a warning light bulb test with the key ON but the engine not running — NO OIL PRESSURE). Otherwise you may have to inspect or replace the bulb.

Your intermittent bulb function may indicate a faulty bulb, but another possibility is the electrical multi-connector in the engine compartment. This multi-connector is subjected to age, heat, moisture, and vibration and could conceivably be a point of interruption for this circuit if the bulb ground connection is not making it through the multi-connector. It is possible that if you simply separate the two halves of the connector, inspect the metal pins inside for dirt, damage or corrosion, and then re-seat the two halves of the connector shell the bulb may light again if this reestablishes the ground connection.

Image
1964 Corvair Engine Compartment Wiring Diagram (Rev. A).jpg
1964 Corvair TEMP-PRES Warning Light Circuit
1964 Corvair TEMP-PRES Warning Light Circuit
1964 Corvair Generator Charging Circuit.png
Brad Bodie
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Walt
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Re: Oil Pressure Switch wire install

Post by Walt »

Fantastic Brad, thank you very much, I will check it out!
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Re: Oil Pressure Switch wire install

Post by Walt »

ok... update and question... So I check at the connector coming out of the wire harness... it has power… I plugged the new wire into the harness and check at the end that connects to the oil pressure switch and it has power... I connect the wire back up to the oil pressure switch. I reach around under the dash to see if I can pull the bulb out from behind... it actually comes out very easily. I put in a new bulb even though the bulb that is in there doesn't look bad then I turn the key on and it lights up! So all is looking good however as I am trying to reach my hand in to put the bulb back where it lives behind the dash, behind the temp/press dash face, I find it very difficult to get the bulb socket assembly to go in to where it should live and while I am doing that I drop the bulb down a little bit and so it's not showing through the dash it actually looks like it's not lit. The point I am making is that I'm thinking that I did all of this work to discover that it looks like maybe it was just the light and bulb socket assembly that was not seated well in the dash and had just fallen down a little bit so it looked like it wasn't turning on but it really was! And as I am trying to reach in behind the dash to push the light and socket into the place where it lives I'm finding it very difficult to do so... So that is the story and here comes the question: Does that bulb and socket assembly just push in to where it lives or does it twist in or is there some other trick? I would like to make sure it is in there securely so that it doesn't look like it is off when it is on as I'm driving some time. Thank you in advance for reading my story and giving me some insight to my question!
Walt
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Re: Oil Pressure Switch wire install

Post by Walt »

Ok scratch that whole last post... turned the key to 'on' today and temp/press light did not light. Pulled it out of where it lives in the dash and it still didn't light. Ugh. Put it back in the dash... tried turning the key on and off several times... and after about 5 times... it lights up! Could it be possible that there is an issue either with the ignition switch or the wire going to it?
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