Oil switch - shrouds for a temp/press issue question.

[DT-VAIR]

Hi all,

I hope this doesn't sound too stupid for me to ask. I just like knowing exactly what to do. I've been reading some posts here and on CC just want to make sure I'll be going down the right path.

First a little history - I've had the car since July '14 and have put about 1700 miles or so on her. Kind of a Franken-engine (bottom half from an early 60's with everything else seemingly from a 64 or newer (I have another post about it). No issues to speak of. All I've done recently was changed the oil and trans gaskets and fluids in January.

My issue - lately the temp/pressure light has been coming on at random times. First time was coming home from a show and while I was sitting talking to a neighbor in the street with the car running the light came on. I went to the house and shut it off and checked that all seemed good (belt still on, oil was good and car didn't seem really hot). Started it up a week later - no issues and drove it around. Two weeks ago I drove it about 58 miles to a shop to have another issue looked at and on the way home from the shop the light came on about 15 miles into the trip. I stopped again, shut it off checked and all I could visually see looked good. Started it up and the light came on, but then turned off again. While I was waiting I read a bit on what could cause this and they said it could be caused by a faulty oil switch. I continued driving (light was still off) and the light came on again about 10 mile later and about 17 miles from my parents house so I just kept driving and put it in their garage (I'm another 15 miles past their house). All seemed fine while I was driving though. I went and purchased an oil switch and socket (just to be safe) but couldn't replace it at my parents. I went to pick it up last Friday and started her up - no light - and drove home. The light came on just as I was shutting it off in my garage. The lower doors were all open, engine doesn't seem crazy hot, oil looked good... Temps both days were low 70s.

So I'm going to replace the switch this week since I have it at my house with the tools I need - but if that doesn't solve my issue I know I need to look the oil cooler and possibly pop the top shroud off to see if any blockages are there. I've never checked the whole flashing issue really but I had the lower shroud off and tried peaking up there and nothing looked too horrible. I would think that there shouldn't be much in there though in terms of nests or I would have seen the issue earlier with the light. I do have a fresh air tube (wrong kind - but is still hooked up at least to the top shroud). If I take the top shroud off (I do have the shop manual with the process) - do I need to resync carbs, etc when putting everything back? I know it said to adjust upper choke control rods and accelerator rods per the tune up section. In general I know it probably wouldn't hurt to take it off and see what's going on in there I just don't want to mess things up too much.

I hope this made sense and I'm hoping the switch is just bad and I can keep on keeping on - but wanted to get some input from you guys. Thanks in advance!

[cad-kid]

I think you have a faulty cyl head temp switch. The oil pressure and temp senders are wired together so one or the other can turn on the light. As the temp switch ages it can trigger at lower and lower temps giving a false overheat indication. Replace your temp switch-

To verify- when the light is on, quickly shut off the engine and pull the wire off the oil pressure switch. Then restart the car, if the light stays on then the switch is the culprit.

[66vairguy]

If the engine is overheating and you turn it off the temp switch will heat soak briefly - do as cadkid said. Turn off the engine and unplug the oil sender wire and start the engine right up again. If the Temp/press light comes on it's the temp snap switch. If not you've probably got an oil pressure switch problem. The oil pressure switches are notorious for failing, especially the new ones.

You can get an inexpensive thermal scanner to read temperatures around the engine to confirm issues.

During normal driving a Corvair has a very adequate cooling system if the belt is on of course. One problem that can occur is a rag or a rodent nest under the top fan shroud. Amazing what folks find when the take the top shroud off.

One last thing. Don't over look worn out wiring. The insulation on the wire to the temp or oil switch gets brittle and cracks and if a bare wire touches ground then the light comes on.

[DT-VAIR]

Thanks all - I'll hopefully get out there tonight or tomorrow night to see what I can find. I'll report back.

[azdave]

My guess is the oil pressure switch is bad or you really do have low oil pressure when idling hot. Did you ever see the light come on when the engine was running 1000 RPM or above?

I've never had a bad temp limit switch but plenty of oil pressure snap switches have failed me.

[Corventure Dave]

It will still be a good idea the check for debris in the oil cooler, while you are in there. You don't have to remove all the fan tin's. Just the cover over the cooler. 2 sheet metal screws.
I agree you probably have temp or oil switch issue.. Oh... when you change the oil pressure switch, be careful not to over tighten it. I have seen the Delcotron adapter... "sometimes called the generator mount or oil filter mount"... crack from over tightening at the oil sender fitting.

Corventure Dave

[DT-VAIR]

Ok - well finally got around to getting the switch replaced. Took out the alternator and checked the oil cooler - all looked good - blew it out a little just to be sure. Replaced everything and took it out. Top down with a hoodie - didn't want to bother to put up the top and I have no heat - but wasn't too bad 55 degrees. Everything was going smooth until mile 11 when the temp/pressure lights came on again. I was almost home and got her back in the garage and again all looked good. Oil seems fine, thermostats are opening, etc.

On another note - when I first checked the thermostat doors at my parents house i noticed a choke coil (sorry I know that's not right but can't remember the correct name) caught in the drivers side door. This shouldn't have anything to do with this right?

What I think is odd is that the car has gone on several long trips (300+ mile round trip) since I've had it with no issues at all. All I did this year was change the oil and gasket as well as the trans fluid and gasket and replaced the thermostats. The only other thing was the car was at the shop to have the leaks looked at (easier on a lift and I wanted someone with more experience to look at it). The shop was one Larry from the Vair shop recommended. They said they had the engine off the back mount so they could see the rear seal as it ran (back by the rear of the car that is) and took a picture to show that's all they could see leaking (which I do still have a leak in the back right under the HB area. ) Just trying to offer up anything more that may shed light on my issue. This is the EM bottom end and it has an oil temp sensor sticking into the pan - I see a wire coming off it - could they have wired that in maybe and could that be faulty?

Here are a couple of pics of the oil cooler (taken because I think Brad had asked if the barrels were notched or drilled through) and inside passenger shroud. There is the head temp sensor there too right? The pic really doesn't show the other one - but it's there in the upper left.

Oil Cooler

[bbodie52]

Still trying to pull together the clues to figure out what engine you have. The folded fin oil cooler you have was seen on 1960-1962 engines, but in late 1962 the new oil cooler design was phased in. According to the shop manual supplement, the oil pressure switch was relocated to a spot next to the generator. So it would appear that your engine was from 1960-early 1962. If it has an automatic choke on the heads, this was introduced in 1962. The road draft crankcase breather tube was phased out in 1963 and replaced with a PCV system. The drilled cylinder barrels were only seen on the 140 CID 1960 engine. 1961 and later cylinder barrels had cast recesses in the fins to accommodate the studs that extended from the cases to the heads. So if your cylinder barrels are drilled with stud passages you must have a 140 CID engine from 1960.

The oil pressure switch and cylinder head temperature switch produce a ground when a warning condition exists. A ground at either switch will produce a warning light. If the wire insulation is cut or worn by a sheet metal shroud, a false warning light can be produced whenever the wire comes into contact with a metal shroud.

[DT-VAIR]

Thanks Brad! If it were a wire issue wouldn't that create more of a random occurrence where the light would come on and off? This seems to come on and stay on. I will definitely check though for sure next time I can get out there. It probably won't be till next week though as the next two nights are pretty shot and we're out of town this weekend. I also want to get an actual gauge for the oil pressure just to make sure it is OK too. I'll also have to get that choke piece put back on too.

On the oil cooler pic I think you can see the slots in the barrels - am I looking at that right? The part that I found is below. I believe I have the PCV system based on the hoses/tubes under the air filter. But then again I have the oil temp switch sticking into the pan so... I think this thing was cobbled together from whatever the guy had when he rebuilt the engine. Who knows what was the thought process behind it aside from get it back on the road! :) I've been trying to find the owner before the guy I bought it from. I have his name from the title but haven't had luck finding him to ask some questions... but that's another story.

So sorry if this sounds dumb - but I should only have the head temp switch and the oil pressure switch running the dummy lights correct? But since it looks like have the 1960 block I have the oil temp switch too in the pan. If they hooked all three switches up would that cause problems? Should I try just disconnecting the oil temp switch - could it just be bad? I see a few online for about $25 or so so I guess I could just replace it easy enough too.

Sorry - trying to get this all figured out best I can with my experience! Also - sorry if this sounds rambling - trying to respond at work and I get pulled away often!

Thanks again for all the help!

[bbodie52]

The picture below is of a highly modified Corvair engine, but it also clearly shows the cylinder head studs painted in red, and passing through recesses in the cylinder barrel cooling fins...



1960 Cylinder barrels, with holes drilled through the upper (top five) cooling fins...




1961-1969 cylinder barrel cooling fin configuration, with recesses cast for the studs...

So sorry if this sounds dumb - but I should only have the head temp switch and the oil pressure switch running the dummy lights correct? But since it looks like have the 1960 block I have the oil temp switch too in the pan. If they hooked all three switches up would that cause problems? Should I try just disconnecting the oil temp switch - could it just be bad? I see a few online for about $25 or so so I guess I could just replace it easy enough too.

The oil temperature sending unit would not be an on/off switch. It would be a continuous variable resistor designed to control voltage to an analog oil pressure gauge, in a manner similar to a fuel gauge sending unit. The readings would change on this calibrated sending unit to provide accurate and specific voltages to be interpreted and displayed by a temperature gauge in degrees. In a similar manner, an oil pressure gauge uses a complex sending unit to provide the driver with specific pressure readings in PSI, as opposed to the oil pressure warning switch, which simply informs the driver of the presence or absence of oil pressure using an indicator light. So the Corvair can use a single PRESS/TEMP warning light to come on when either warning switch provides a ground. A lamp test is provided when the key is turned on, but before the engine is started. This would always illuminate the PRESS/TEMP warning light to test the bulb before the engine is started. Once the engine starts and oil pressure is present, the ground condition from the oil pressure warning switch goes away. The light would only be illuminated if oil pressure fails, or if the engine temperature is excessive, causing the warning switch to close and provide a ground to illuminate the warning light. Unfortunately, with only one warning light, the driver cannot tell if the engine is without oil pressure or if it is running hot.

Your oil filter adapter may already be tapped for an oil pressure sending unit. If you find a small pipe plug there, it can be unscrewed and the oil pressure warning switch can be transplanted from the present location under the engine to the oil filter adapter, next to the generator/alternator. Then insert the pipe plug in the vacated hole under the engine, and modify the wiring to extend the connector to reach the new oil pressure switch location.

[DT-VAIR]

Thanks Brad - I actually have the switch there in the adapter. The other pics are helpful - again thanks for detailing this so well it really does help me out! Pictures are worth a lot when I'm not entirely sure of the correct location/terminology! Here's a shot of my adapter (thanks to google photo backup I can actually access all my photos pretty easily now from anywhere... thanks Google....)

adapter

[64powerglide]

Look right down behind the oil filler tube & fuel pump & read the engine number so the guys know what they are dealing with.

[DT-VAIR]

Jeff - it's T0329Z. Brad was helping me decipher this in another post earlier this year here: viewtopic.php?f=55&t=9143. Dealing with a little bit of a franken-engine it looks!

[64powerglide]

O. K., now I remember. I was thinking it was probably a 95 HP 64 engine.