The BORA

Very fun weekend at the Celebration Exotic Car Festival. Car show Saturday and 140 mile rally Sunday. The Bora got a "gold" award for category J1. I have no idea what that means. I would guess 1/3 of the cars won something. The next day went on the rally with my buddy as navigator. The car really ran great. But at the end we stopped at a restaurant for lunch and when we came back out - vapor lock. Studying this issue a bit I decided I will wrap the fuel hoses in "Vapor Block" by design engineering and switch to ethanol free fuel which has a higher boiling point. Its an issue I need resolved before summer arrives. I also am certain that the right side fan is dying. It pulls about half as much air as the left and I think it even shuts down at times which raises the water temp about 20 F when that happens. New fans arriving today. PO also wired those Spaal fans into the existing wiring which is a no-no. I will wire in a separate circuit with relays and breakers to relieve the stress on the factory wiring harness.

I videotaped the entire rally. Thats actually too much to watch even for a Bora aficionado, but proof the car can do it. I have a lot of pics and videos on the cars own website: www.1974Bora.com

 

Hey, you are a tall guy!
Or is the room so limited under the roof?

 

6’4”. My dad was same height. He drove his new Bora as his DD for years. There are some cars I simply don’t fit into. But for the Bora it has adequate headroom. Just can’t stretch out my legs.

 

Some pics from the car festival


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Very strange goings on with my fans. I’ve felt like the right fan was going bad for a while. Seemed like it would cut out causing high coolant temps. I decided to get two new fans. Bought perma-cool fans. Claim 2800CFM. Seems generous. Anyway here’s the weird thing. Right fan will come in with aircon but not at temp. The thermoswitch has 12v at the in lead which is always hot with ignition on. The far lead is zero volts unless you put the ac on. Then it’s 10+ volts and the fan will come on. My understanding is that the thermoswitch is a NO switch that connects the two leads together when hot. So if I just put a jumper between the two leads that attach to the thermoswitch the fan should come on right? Wrong. It ONLY come on with the ac triggers very weird. So I wired my new relays so that the right fan comes on with the left but that also means both fans come on with the aircon. Not a big deal but scratching my head why that left fan won’t come on when the leads to its thermoswitch are bridged together.

 

Hello Cepat...

The attached drawing may be of some help to you or maybe not.. On my Ghibli SS when the A/C is turned on the rectifier (bottom left in drawing) grounds one of the radiator thermoswitch relays causing the fan to come on.
Not sure if the Bora has this rectifier or not.. Otherwise, when the correct temp on the same thermoswitch is reached it should cause ground at the relay making the fan come on as well.. This thermoswitch should work with the
A/C on or off.. Do you have good ground and are your radiator thermoswitches closing as they should?

All, if I have any of this wrong, please let me know!!!.. But this is what I seem to have found on my Ghibli SS...

Mike
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Following up on my post above.. When I disassembled the cooling fan system on my Ghibli SS I was a bit surprised to find only 3 wires at each relay.
Typically relays have a minimum of four wires (trigger, ground, 12V, and load).. I was concerned about this until I found that the fans
and radiator thermoswitches were always hot when the key is on! Researching this further, I noted the thermoswitches are acting as the
triggers for the relay and as they close (temperature reached) the fans are grounded and come on.. The Ghibli electrical diagram I was working
with did not show the two relay setup. However, the Indy manual showed this and the rectifier acting on one of the fan relays as well...

Again, if I have this wrong please let me know... I am not sure if the Bora has this same setup...

Mike

 

Mike,

I like to draw relays showing all the connections. Your diagram seems to be missing the 12 volt supply that drives the fans. On the early Ghibli the thermo switch was used to ground the relays and thus triggering it. Later cars, including the Bora, the thermo switch supplies 12 volts to the trigger side of the relay. Thermo switches are normally open and close when a certain temperature is reached.
A rectifier is used to convert AC to DC. Our car do not have AC current therefore the device is used as a diode which permits current to only flow in one direction. The AC compressor is also connected to the AC switch. Without the diode currect would flow to the compressor anytime the thermo switch call for the fans.
This diagram would be appropriate for a Bora

Ivan

 

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Hi Ivan. Agree on the rectifier, but look again at my drawing. It is a bit simplified for my use! But only 3 wires are needed when the thermo switch is the fan ground trigger, and the fans are always hot from the fuse bloc or some other 12v source. The yellow wire I show from fuse bloc to fan to relay is always hot when the key is on. When the thermo switch closes the fans get grounded. This is the way my car was wired!!

 

thanks guys, but I don't think Mikes wiring diagram is correct for Bora. As Ivan pointed out, when the thermoswitch reaches a certain temperature, it closes sending 12v positive from blue/ black wire which is always hot with ignition on to the fan relay. On the right fan thermoswitch therefore if I short the two leads together the right fan should come on if the ignition is on, but it does not. It does however come on when the a/c is switched on and I read 10v on the lead going to the right fan relay at that time ( likely less than 12v due to the diode between the a/c switch and the thermoswitch so that the thermoswitch doesn't turn on the compressor). So somewhere my wiring is buggered somehow. Because if I short those leads together that fan should come on, same as the left fan does when short the two leads on its thermoswtich together.

For the new fans I'm using my own two relays connected directly to the battery cutoff switch. The right fan relay is triggered by the positive power lead to the fan from the factory wiring. The left fan relay is triggered by the positive power lead to the fan from the factory wiring. Now the load on the factory wire is minimal not 10amp per fan. I think OEM fans were 5 amps. I found my plastic bullet fuse (which is only 15 amps in the cars wiring) was actually melting a bit and getting physically shorter which may have caused the the fans to misbehave. Now that theres almost no load on that fuse (which I changed to an self resetting 15 amp breaker anyway) that weirdness should end.

But the only way I can now get the right fan to trigger without turning on the ac is to send the 12v positive (when hot) from the left thermoswitch to the positive trigger of the relay I installed for my right fan. And now the right fan comes on with the left when its at the temperature setting for the left thermoswitch BUT now the left fan comes on with the a/c also so I ordered a diode from vintage air that will let the left thermoswitch trigger the right relay without the right fan powering the left fan when the ac is on. In theory. I hope. Its like voodoo. I remember my Pantera one fan was always on and one fan came on at temperature. It had an idiot light in the speedo or tach I can't remember. That temp dependent fan would cycle on and off depending upon how fast I was driving and how much air was going over the radiator. I'm almost tempted to have the right fan always on, a/c or not and just have the left fan cycle on and off with heat, but I'll try the diode thingy first and see if it works as expected.

 

I love these discussions... Maserati wiring can be perplexing...

I know this is NOT Bora related but might be of some interest somewhere ...

In this drawing, what normally is supplied from a 12v source, is now coming from the fan which was supplied 12v directly from
the fuse bloc (so always hot)... The thermo switch closes triggering the relay which now grounds the fans. This should theoretically work,
correct? But it is still 4 wires! How did the relays I found on my Ghibli SS get away with 3! When Ivan and I discussed this, he suggested perhaps my relays were not
typical.. I didn't think so, but I can't be sure now - as it has been a while!

But anyway - always a good discussion...

Mike
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Hi Mike,
After we spoke on the phone I kept thinking about your diagram and those three wire relays. Looking at your diagram, all the current going to the fans is going through the thermo switches. These switches are not designed to take that heavy load. Also, the thermo switches are typical on a be on a switched circuit.

Ivan

 

Hi Mike,

I was wrong in my previous post. The way your car is wired, although not the conventional way, will definitively work. Those three wire relays must internally connect two of the connections found on a 4 wire relay. By grounding this common connection both the trigger and the load would be grounded. I do not know if the green wire in your diagram, which supplies current to the thermo switches, is always hot (unswitched) or only when the ignition is on (switched). Normally the thermo switches have power only when the ignition is on.

Ivan

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Hi Ivan. From what I found the thermo switches are hot only with ignition on. What was also strange is the thermo switches were wired to the same fuse as the fuel pumps (if I recall correctly). I guess it might be ok if the fuse blows, no fuel, no cooling, car stops. Is this typical in other models? The fuse box cover plate does not show thermo switches on that fuse.

I apologize if these electrical discussions are hijacking this thread! If we need to move it to a separate thread we can!

Mike

 

I'm not surprised if they wired a car completely differently because they had a different component in hand that day like a self-grounding relay. Or it was a friday after a heavy lunch of pasta with a liter of vino.

 

Typically the fuel pump(s) are on a fuse by themselves. The thermo switches do not draw any current and the trigger side of the fan relays very little. You can wire the thermo switches to any switched fuse. I sometimes wire them to an unswitched fuse so that the fans continue to cool down the radiator after the engine is turned off.

Ivan

 

I asked earlier what the green box behind the little door on the drivers side did. I’m back to post the answer. It’s a “centrifugal relay” and it is somehow concerned with the air pump pollution control device which was amputated long ago. I have no idea how it works. But interestingly it has two power leads associated with it. One is hot with the engine running and one is hot with the engine off. Was thinking to putting a 3” inline fan and a duct to blow air over the fuel rail on the right (and the carbs in general) powered by that hot when off wire and computer controlled with a countdown timer so it ventilates that area for 15 minutes or so after stopping. Really not sure where the fuel is boiling. I’ve seen bubbles in that glass fuel filter bowls when it vapor locked after the 140 mile rally. But the gas tank could be boiling as far as I know. Other thoughts are ethanol free gas with a higher boiling point and insulated fuel line wrap for as much of the fuel lines as I can get to.

The computer control gadget max temperature is 185F but I don't think inside that little compartment it will exceed that. But who knows.
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Where would the cool air come from?

Live with the car for a full set of seasons before attempting anything like this. Translation ... The Bora's engine compartment is a pretty much a closed to air flow hot box and getting fresher, cooler air into it in an effective and reliable manner requires the addition of ugly ass external scoops that can have unfortunate side effects like the ingestion of water.

 

its a concept. I've been waiting for some octane booster to arrive so I can fill the tank with ethanol free gas (which locally is 89 octane). That will have a slightly higher boiling point. Its also a bit cooler than usual this week so not a good week to torture test the car vis a vis vapor lock. The hottest it will get to is 83F tomorrow then its cooler than that for a week. There's an intersection nearby that is under construction and totally fubar for months now. They are changing it to the type where the right hand lanes move to the left and vice versa. Its a total cluster and it takes 3 or 4 cycles of the traffic lights to get through there. I figured wait until its in the 90s and go through that then U-turn and do it again. Then park for a cup of coffee and see what happens. If it can survive that without vapor lock I will be happy. I did apply some fuel line insulation for what its worth. So called "vapor block". But like you said, its more or less a closed oven once the car is parked so not sure insulating the fuel lines will do all that much.

 

Bob,
I have read with interest your numerous contributions wrt the "closed box" and overheating in the engine compartment of the Bora.
Compared to a front engine car like the Indy or the Khamsin, what makes this situtation worse and more prone to overheating: is it the fact that the fans (absent in the Bora) are pushing/extracting air around the engine in the front engine cars?

 

It's much worse than that. I've proven empirically that even at high speed say 140MPH air does not flow though the engine compartment and out. In point of pack fact the air flowing under the car at best stalls inside the engine compartment. This may get even worse at higher speed but I don't know that part empirically.

I learned this at the very tragic Nevada Silver State open road race in 1989. The was the second year it was run. One of the early lead cars went off early, rolled and burned. This induced an enormous delay of more than 3 hours with car a silver Bora I was co-pilot in baking in the sun. Everything got very hot. So when we quickly reached 140 MPH all the temperature gauges got way too hot. In an effort to get more cooling I suggested opening the heater valve and putting the fan on high. When that wasn't making a dent in the temperatures I cracked the passenger window open and the interior was immediately flooded with dark oily smoke. That cause quite the WTF moment but I immediately closed the window and eventually the smoke dissipated. But we were driving at high speed with impaired vision for a while!

The postmortem: After finishing with a paltry average of 125MPH we looked things over. The AC compressor's idler arm had come loose where it bolts directly into the crankcase and that bolt was completely gone. This allowed oil to leak out and spray onto the LH header and cause the smoke. You would have thought that the smoke would have just rolled backwards under the car and out. But instead it flowed up the central tunnel where the shift linkage is located and then into the cabin where it was drawn out that passenger window. So the conclusion I came to is that at high speed there's an enormous high pressure condition in the engine compartment.

If you look at later mid engine design cars they have much better provisions for air to exit the engine compartment. Many went to a rear radiators arrangement. Without chopping up the exterior design I don't believe that there is a solution for this car. The closet I can think of is the as seen on later Ferraris with a black round hole mesh grill on the rear back of the engine compartment. That wouldn't look so bad.

I've posted about this many time on here so I'm not going to repeat all of it it all over again.

 

did your car have the european exhaust and rear bumper or US with the extra weird shaped resonators in place?

 

Thank you, Bob.
Yes I was aware of your misfortunes...
So basically, it's not that much the fans presence (or not) in the engine compartment but more the fact that air cannot escape from it in the Bora while it can through the various grills in the Indy, Khamsin et al.
Such air exits were built in the Bora Gr. IV and some "tuned" Boras. As you say, a discrete rear grill would be the most elegant and effective modification!

 

It wasn't my car it was one converted to Euro exhaust and bumpers. Those aren't the cause of a lack of air flow anyway. Hot air rises and has no place to go. There is also zero cool air input to engine compartment just the hot air flowing under the car some of which dead ends into the engine compartment.