Never a straight line

[BDA]

I have to admit that I was unaware of the "bounce back effect". I guess you could construct a duct with a fan that starts behind the grill. The car would get warm in traffic and I just didn't feel comfortable with the cooling capacity. Hopefully this aluminum radiator and the stronger fan (~900 cfm vs 2000 cfm) will keep the engine cool.

Thanks for the kind words about my bracket. It took a long time to make it but it will be fine. My CV joint is different from yours so I only have three places to put magnets. It will be in acceptable range of pulses/mile. I plan on using safety wire to make sure the magnets don't come off.

Your set up looks really nice! Have you tested it out yet? When I bought my speedo, the only GPS speedo I saw was not very similar to the other gauges. Since then, I've seen some that look much closer to stock and I wish I could use one of them. It seems that it should be a lot easier!

[Grumblebuns]

My observation of the bounce back effect is all unscientific, just an observation after I installed my new radiator. It felt as if there was more air being bounced back than going through the core. However, I still believe that the OEM radiator is more than capable of keeping the stock Europa cool in all street conditions provided there is design coolant flow going through the radiator and sufficient air flow across the fins. It may or may not apply under race conditions. You have to admit though that an aluminum radiator looks good up front. As I stated before this bounce back may be a factor only for a marginal cooling system in hot stop and go traffic. If you can't get air through a radiator, it ain't gonna cool.

I can't take credit for the first rate fab job done with the speedo bracket, done by the PO. This was done before GPS speedos came on the market. The speedometer used with the sensor is a Stewart Warner design, looking not even remotely close to a Smiths and ugly as hell. I bought the Speedhut GPS speedometer on sale a while back. I will probably use that instead.

Joji Tokumoto
Fallbrook, Ca 

[BDA]

I think you're right about the stock radiator & fan. I don't think it was at all optimal but serviceable under most conditions. When I lived in New Orleans, I don't remember mine ever getting really hot. I do think I remember some "official" suggestion (I don't remember where I heard this) to rev the motor if it got hot to put more coolant through the radiator so at least among some had some concerns about keeping the engine cool.

The radiator looks so good, it ought to cool really well, too! 

I think the GPS speedo is the way to go. I imagine it is a lot easier to set up. I don't know how many satellites it needs to acquire. I hope it's quicker to acquire them than our Garmin. Even if it takes a while, I don't see that as a substantial negative.

[BDA]

Ok, I got my aluminum radiator plumbed up and got the thermostat wired in. I went to burp the cooling system and it wouldn't turn the fan on (I know the fan works). I fiddled around with it and finally decided to see if the thermostat switch ever closed so I hooked a volt-ohm meter to register resistance and let the car idle. The temp gauge finally got way hotter than I would want (over 120C) and the meter still showed infinite resistance. The radiator was very hot to the touch but unfortunately, I don't have a thermometer to measure it. ?

I took the thermostat out and used a candy thermometer to measure the water in a pan and held the thermostat in the water. It finally registered no resistance at about 180F!!! No I'm really confused!

I had seen this before with my last radiator but I didn't investigate so deeply then. I just assumed that since it was a custom radiator that maybe there was a place that just didn't get as hot for some reason or that the thermostat switch didn't work but this switch works and the radiator gets really hot!

Does anybody have any ideas?

[EuropaTC]

What's the wiring circuit like ?  If you had similar problems before then maybe it's not the new radiator/thermostatic switch, but the car's wiring.

Unfortunately my car is set up with no thermostatic switching, it's just a manual "on/off" thing that I use in heavy traffic so I'm limited help. I guess my first thoughts would be

1. check earth wiring on the fan
2. directly wire the fan to the battery to make sure it works - you've done this already I guess if you know it works ?
3. look for any bullet connectors in the section of the wiring circuit involved. Pull apart/clean.
4. Are you getting power to one side of the thermostat switch ?
5. By-pass the thermostat and see if the fan runs then. I assume the switch is just a circuit break when cool ?  If that doesn't work when out of the circuit then it's back to wiring ?

I'm not good on electrics. I'm still at the level where I shake wires and tap things to get them working....

Brian
 

[StephenH]

Just wondering if anyone has fabricated a working front shroud for the radiator in gaining greater cooling efficiency by forcing more out.

Another thought I had was to replace the OEM style pusher fan with a puller fan. Putting it behind the radiator in the wheel well exposes it to road debris and possible tire interference.

My S2 has a 'duct' fabricated to feed the radiator plenty of air, not completely sealed and in my opinion doesn't need to be.
Built by the previous owner and after correcting two small issues (fan relay incorrectly wired to thermo switch and fan blade mounted backwards) I am now confident to drive in higher temperatures (40C+) without engine overheating. Impressive amount of heat comes out of the wheel well when the fan is running.

I have the radiator fan wired (in what I think was standard practice for Australia) with the 2nd position of the cabin ventilation fan turning the radiator fan 'on'.
This lets me better control engine temperatures for the short sprint and hillclimb events where I might be sitting stationary for a long time before the start.

As to the thermal comfort of anyone in the cabin, well that is another story.....

[BDA]

What's the wiring circuit like ?  If you had similar problems before then maybe it's not the new radiator/thermostatic switch, but the car's wiring.

Unfortunately my car is set up with no thermostatic switching, it's just a manual "on/off" thing that I use in heavy traffic so I'm limited help. I guess my first thoughts would be

1. check earth wiring on the fan
2. directly wire the fan to the battery to make sure it works - you've done this already I guess if you know it works ?
3. look for any bullet connectors in the section of the wiring circuit involved. Pull apart/clean.
4. Are you getting power to one side of the thermostat switch ?
5. By-pass the thermostat and see if the fan runs then. I assume the switch is just a circuit break when cool ?  If that doesn't work when out of the circuit then it's back to wiring ?

I'm not good on electrics. I'm still at the level where I shake wires and tap things to get them working....

Brian

Thanks, Brin. This is not a wiring problem. The most simple set up was an ohm meter connected to the leads of the thermostat switch. Resistance was always infinite even with a very hot radiator.

[4129R]

Get a new thermostatic switch. It sounds like it is only working intermittently. I have the same problem on my VW Golf R32. Sometimes the thermostat just does not click in, and the engine temperature soars. After turning the ignition off and on a few times, the thermostat seems to start working properly.

OR. Why not put in parallel a switch which earths the fan (just as the thermostat does), and put it near the ignition switch, so you can put the fan on at the flick of a switch when the temperature starts climbing.

[jbcollier]

"fan blade mounted backwards"

You would not believe how often I come across this, including many later MGB's which had them installed backwards from the factory!  A well designed fan blade has a curved cross section forming a "cup" to catch and direct the air.  The difference in airflow between the proper and reversed rotation is very, very large.

As posted on the yahoo list:

"Sounds like the switch is fine.  I’d have to second that there must be air in the system.  Every high spot higher than the radiator must be bled as air will collect there and will not shift.  On my alloy rad, they use a drain petcock as an air bleed point.  This is not a good idea as the internal opening on standard drain petcock will not be at the very top.  I am going to remove mine and fabricate an air bleed using a brass fitting and a valve.  The other critical point is at the water pump where the heater hoses attach.

Also remember that alloy transfers heat much more effectively than steel or copper so the rad may feel hotter than it actually is.  Get a cheap contact thermometer and calibrate it in boiling water."

[Grumblebuns]

Just wondering if anyone has fabricated a working front shroud for the radiator in gaining greater cooling efficiency by forcing more out.

Another thought I had was to replace the OEM style pusher fan with a puller fan. Putting it behind the radiator in the wheel well exposes it to road debris and possible tire interference.

My S2 has a 'duct' fabricated to feed the radiator plenty of air, not completely sealed and in my opinion doesn't need to be.
Built by the previous owner and after correcting two small issues (fan relay incorrectly wired to thermo switch and fan blade mounted backwards) I am now confident to drive in higher temperatures (40C+) without engine overheating. Impressive amount of heat comes out of the wheel well when the fan is running.

I have the radiator fan wired (in what I think was standard practice for Australia) with the 2nd position of the cabin ventilation fan turning the radiator fan 'on'.
This lets me better control engine temperatures for the short sprint and hillclimb events where I might be sitting stationary for a long time before the start.

As to the thermal comfort of anyone in the cabin, well that is another story.....

It appears that this design requires the elimination of the spare tire. Not an issue for competition but can be for road use. I have a spare front half shell to play around with and come with a design.

Jim, I posted in the Yahoo list this morning about your issue. My Macs aluminum radiator came with a screw in temperature switch for the fan. If I remember correctly, the switch was a single terminal switch and was grounded to the radiator. Since the radiator was electrically isolated to the body, I had to run a separate ground wire for the switch.
I don't know how your switch is set up.

[BDA]

Thanks for the replies, guys. I'll try to address all the points raised:

4129r: I hope my switch is good - it's brand new. I will be doing some more tests on it today so if I have problems, I'll go back to the Kenlowe thermostat switch I used to use.

jb: "fan running backwards" - that's what I was trying to make sure wouldn't happen - that and make sure the switch did in fact close. A contact thermometer might be a good investment. I'll take a look for one. Infra-red thermometers are not that expensive but it seems silly to spend that money for a single test.

Steven: I really want the fan to come on automatically. I know having a manual switch is not uncommon and maybe at some point I might set up an over-ride to turn the fan on earlier.

I posted my issue to the lotuseuropa yahoo group (if you're not a member of it, you should be) and I got some more good replies. One of the more interesting included some information about the Lotus otter switches:

Europa S1-S2 Otter Switch ... After Sept '68
A036K6026Z    82°/68° C  (180° / 154° F)
....................Close / Open
Note that once switched on, the contacts stay closed longer than typical thermo-switches... all the way down to 68° C.

Europa Twin Cam Otter Switch:
A036K6026ZH  84°/74° C  (183° / 165° F)

Elite-Eclat, Esprit S1-S2 … Federal & Middle East
A075K6007K    80°/70° C  (176° / 158° F)

I tested my switch and it open at above 194F and closes at about 185F. So this is a narrower range than the Lotus switches and it opens at a warmer temp. This person also posted information about the gauge. It appears that I may have been more concerned than I needed to be. I think I would prefer that the fan start at a cooler temp so I might use an adjustable switch.

[jbcollier]

Which temperature range of the fan switch you should use depends on which part of the rad the fan switch is located.  On most vehicles, the hot coolant enters the top of the radiator and exits out the bottom. On the Europa, the hot coolant enters the bottom of the rad and exits, hopefully cooler, out the top.

If your fan switch is located next to the “cold” outlet (top — S1 & S2 are configured this way) then the switch Tim mentioned is correct — S1 & S2s came with a 82°C stat (180ish°F — you can get a 74°C/160°F stat if you dig).  The fan comes on not much more than the thermostat rating and goes off when it is delivering distinctly colder coolant to the engine.

If your fan switch is located next to the hot inlet (bottom — TCs are configured this way) then you need a switch that comes on well above the thermostat rating and goes off above it as well — TC came with a 78°C stat (172ish°F though most are fitted with 160°F now).  Otherwise, the only way the fan will switch off is if you manage to cool the coolant to the point it closes the thermostat!  Difficult and not a good idea for efficiency’s sake.

The alloy rad I have takes the euro-common standard 22 mm x 1.5 thread.  These are available in a wide range of temperature options from VW water cooled aftermarket part’s suppliers.  It has the fan switch on the hot side so I will be running a fan switch in the range of 185 - 190ish on and 175 to 180ish off paired with a 160 stat.

YMMV,

John

[BDA]

Thanks for the analysis, John. Even though I've pretty much decided to go with an adjustable controller, this will help me set it up. From your description, the Sentra switch would be appropriate. I have the 165F thermostat and the open and close temps are both above the thermostat rating. I may put it back in the radiator in case I change my mind. I am concerned about the higher open and close temperatures on the Sentra switch verses the TC otter switch.

I see you're on the lotuseuropa group so you may already know the reason I chose the Sentra switch is it had the correct threads (M16x1.5). There seemed to be so few with those threads.

I ordered an adjustable unit that has a probe that goes into the core. If all else fails, I will go back to the adjustable Kenlowe switch that has the probe in the radiator hose.

[StephenH]

It appears that this design requires the elimination of the spare tire. Not an issue for competition but can be for road use. I have a spare front half shell to play around with and come with a design.

Actually the spare has been relocated and so it is elimination of the rear storage.
I don't load much into the Europa so the remaining storage in the front has been enough for me.

[BDA]

That reminds me of the old prototype cars that ran international long distance races back in the late '60s. The FIA required the cars to be able to store a suitcase of a certain dimension and a spare tire. The suitcase wasn't a big deal but those tires were starting to get pretty big. They had to store them in the engine compartment - sometimes over the headers! The tracks were much longer than they are now and every once in a while, a driver would have to change a tire. Of course, after all that heat, they weren't good for much but I think they usually got him to the pits (slowly). 

Obviously, I don't think you have to worry... It just got me to thinking...