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Lotus Elise SC: Anyone Changed the Thermostat?

9K views 62 replies 11 participants last post by  Sean K. 
#1 ·
2008 Lotus Elise SC (factory supercharger). Searched and all I'm finding is N/A Elise info. As other threads suggested: pulled passenger tire, fenderliner, serpentine belt, disconnected the battery, alternator bolts (only 2 though on the SC model).....can't see how I can get to the electrical connector/wiring on the Alternator or if I manage to get it pulled out somehow that I will actually have room to get to the thermostat housing.

I'm wondering if anyone with the factory SC has changed the T-stat and if so, did you have to remove the A/C compressor as well? There's a strut/support brace running from the SC down to the A/C bracket that looks like it's in the way of removing the T-stat housing.

Any advice appreciated.

TIA,
Sean
 
#3 ·
JFYI....the alternator wiring on the SC is different than the YouTube video I watched for the NA Elise. There are only 2 bolts holding it to the block/SC bracket, not 3. There isn't the traditional lug under the boot near the alternator; instead, it branches into another wiring loom that is near the oil filter location but more towards the center of the car.......then, that wiring loom snakes over by the driver side firewall into a little plastic box afixed to the firewall that is open on the bottom but apparently had two looms in one side of the box and two more in the other. The box is filled with what appears to be dielectric grease. You have to unbolt the lug at this end to disconnect the alternator loom.

I got the alternator loose....it's just floating in the car right now. I can't tell if it's supposed to come out through the engine cover hatch or snake out through the passenger fender well. Neither option is working well. I'm about ready to yank the clam (I have the Radium Engineering Clam Shell kit, but as I recall it's a helluva lot more involved than the "10 minutes" they claim on their website).
 
#5 ·
Ya, it's definitely not an easy car to work on just due to accessability issues. I've pretty much decided I'm going to give it one more shot at getting the alternator out. If I can't do that, I'm pulling the clam. Then it should be easy.
 
#7 ·
PHP:
Appears to be sticking.....running into overheating issues even with the ProRad all-aluminum radiator. Replacing it with the Duralast 4077 (made by Motorad, all metal, 170ºF) and new gasket 35445. Most people here have the opposite problem.....center plastic piece breaks out and you have no t-stat and the car won't get over 150º. I'm in AZ, so that might be fine. Unfortunately, this is my 6th vehicle so I don't drive it as often as I should (I try to run it for 15 minutes at least once a week) so I wonder if that didn't cause the problem.
 
#8 ·
I'm not having such an issue. I would also like to lower my temperature. The temperature usually fluctuate between 184F to 186F while driving. In bumper to bumper traffic it fluctuates from 196f to 206f. Once in a while it goes up to 210f and then it drops to 206f while stuck in traffic and not moving. Once I get back moving the temperature goes down to 184-186F. I have an aluminum radiator. I live in hot South Florida. Is this normal?
 
#10 ·
Any advice appreciated.
The opening and closing of the thermostat should be undetectable. When the fan comes on, the temps should go down, but while driving at cruise above 45 mph, you should not see a temperature fluctuation. Are you seeing jumps up or down while at cruise?

Have you already pressure-tested the cooling system to find leaks? Leaks can be above or below the water line. A leak below the water line will drip, but a leak above the water line will cause the system not to pressurize and can cause localized boiling so you won't see the leak. What you'll sometimes see is that the car will stay pretty normal until you go up a hill or get on the SC and then the temp will come up fast. That is likely a case where pressure is being held until a certain point and then lets go. If you can't find a leak using the pressure-tester, you can try draining the system and using an air-lift. The vacuum on the system will often cause a hiss that you can track down.

Finally, if the cooling system heats up really fast (in seconds), then you probably have a blown head gasket.
 
#13 ·
Not sure I'm following you....when the temp reaches a certain point, the t-stat opens and temp drops. Not sure why you're saying that's undetectable, but I'm probably just not understanding you.

In this particular case with my car.....it's been sitting in the garage idling or I'm varying the RPMs slightly with throttle modulation.....and the temp slowly climbs....I usually shut it off once it hits 212ºF, but will occassionally let it get up to 220 or so. For a few weeks recently, it acted normally.....with the t-stat opening and temps dropping to normal here in Phoenix (190-205º is pretty normal).....but it's been getting worse with the sticking and overheating issue.

I have not pressure tested the system. AFAIK, there are no leaks. I'm never low on coolant, nor do I seem to be losing any.

I do have an Airlift for bleeding the system....I'll give your recommendation a shot. Question though....do I drain the system completely and then try to find the hissing noise?

No chocolate milk shake in the oil, so I'm reasonably certain the head gasket is fine.

Thanks for the input.
 
#11 ·
While driving at steady speed, i.e. 45-50 MPH the temperature remains steady at around 184 F. It only fluctuate while at a bumper to bumper traffic. As a matter of fact, the harder I run the car the cooler it gets as long as I keep moving. I have actually being stuck in traffic and the temperature around 200F, as soon as I take off at high RPMs the temperature drops to 184-186f. Thanks for the responses!
 
#15 ·
Once again, completely normal. It jumps around because the Elise shows live coolant data. The temperature fluctuates just as much on normal cars, but most people would be concerned about the needle always moving around. Manufacturers program the gauge to read steady as long as the coolant is within nominal temperature range.

The water pump is belt driven, so it works more efficiently at higher RPMs, hence the temperature drop when you take off.
 
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#12 ·
I just did this a month ago on an 06 exige with an OEM super charger.
I understand your pain. I ended up removing the clam because of the same alternator that needs to be removed. Looking back, I think i could have maneuvered the alternator out thru the wheel well with out removing the clam.

As for the thermostat housing, no clam made it easier. Hardware removal will be mostly by feel.

good luck.
 
#20 · (Edited)
Odd development.....

Got the t-stat out.....it was already changed. I'm the 2nd owner, bought with 3470 miles on the car. I just pulled out the 180º Motorad Duralast t-stat. Guess I'm going to need to try the hot water trick to find out if it was stuck or not. :(


***EDIT****Ya, it's not sticking. Worked fine on the stove. Opened right at 180º. Must mean I have a leak somewhere.....but that's odd, as I wasn't low on coolant and I just changed the oil (while I had everything off) and there wasn't any coolant in the oil.

It is possible with an above water line leak that the system simply can't pressurize so it overheats? Any ideas on how to diagnose? I don't have access to tools to pressure test the system. I do have the air lift....but will that tell me anything if it's the reservoir that's the problem (for example).
 
#31 · (Edited)
There is an electric Bosch pump in the system that thankfully is running when you shut your engine down at 230 deg. It's designed to reduce localized boiling in the system. It is plumbed into some bypass hosing in the engine bay.

It's not a boost pump.

On an unrelated note, since you have the front clam off, there are a bunch of A/C mods that you can perform including the Tony Waa bypass mod: http://www.lotustalk.com/forums/f92/heater-core-bypass-mod-tony-wa-how-26740/
 
#36 ·
Hey Glen, what temp does your car seem to run at normally? Reading over other threads....a lot of guys even in higher temp regions where the ambient air temp is over 100ºF, only get into the upper 190ºs range. Just curious what temps you're seeing.
 
#37 · (Edited)
@Sean K. - My 2011 Elise SC coolant runs at 194° F during steady-state, low-load conditions like cruising at 4,000 rpm. The outside air temperature has no effect on this number. Sitting in stop-and-go traffic at 100° F, the coolant will get up to 208° - 212° F and then cycle a few degrees above and below as the fans turn on and off. Working the engine hard on the track or at high altitude, I’ve seen temperatures as high as 225° F, but only during the high load. The very minute I back off, temps come right down. I do have dual oil coolers, so that is probably relieving some of the load on the water cooling. I’m running a Radium expansion tank and a 1.3 bar radiator cap.

As far as diagnosing your problem, I’d suggest first pursuing a cause that matches your observations regarding temperature. If you haven’t noticed a significant coolant loss, then look elsewhere because a coolant loss so small you can’t detect it is an unlikely cause. @Roundabout has already suggested one theory that would align with the very rapid temperature rise you’re describing: your cooling system may have air trapped in it and needs to be bled. Sorry, but all the talk about a “waterline” in your cooling system is distracting nonsense. If there is any air in your cooling system, it needs to be removed by bleeding it. After that, your (properly functioning) system will stay full of coolant whether it’s pressurized or not, hot or not, or in any other condition representative of a properly functioning cooling system. And with a full cooling system, there’s no “waterline.”

I have an Airlift system, but I’ve never had to use it to fill/bleed the cooling system on my Elise. After draining all the coolant and flushing the radiator, I fill the cooling system from the expansion tank. When it stops accepting coolant, I start the engine and continue adding coolant until it won’t accept anymore. When pouring the coolant in, I pour it in a slow, laminar flow stream that avoids adding any unnecessary air into the fluid. Then I bleed the block and coolant hose points, top off the coolant, drive it up and down a few steep hills, then check the coolant level. It usually takes about 1/2 cup more and I’m done. That’s it ... works every time.

If you want to use the Airlift for something, remove the rubber adapter and use it with an air chuck to put 15 psi on your cooling system (that’s about one atmosphere, a little less than your OEM radiator cap). It should easily hold that for as long as you want to hold the rubber cone on the tank. If it leaks down quickly, then you probably have a leak you need to chase down before adding coolant. I just did this the other day to find a (big) leak on another vehicle.

Once you have coolant back in the system and it is bled, you should also verify your electric fans are coming on at the appropriate temperatures ... this is a pretty common failure and would also be consistent with the symptoms you are describing.

Your thread started out with asking about the alternator. Having to remove the clam and wrestle with other parts in the way of a repair sucks. I’ve been there with my Lotus and many other cars. I rehabilitated the cooling system in my VW a few years ago and had to remove the headlights, front grill, bumper assembly, forward cross-member and engine mount, the supercharger, the alternator and probably a half-dozen other things I’ve forgotten just to get the radiator out. That shows a complete disregard for any sort of engineering aimed at maintenance ... it doesn’t have to be that way.

Glen
 
#38 ·
I had this issue once before after a coolant flush and it was air trapped in the system. Had to squeeze the coolant hoses a few times along with bleeders open. Not sure if that's what fixed it exactly, but my car didn't over heat after that. I don't think a coolant air bleeder is necessary as the bleeders on the car should work fine.

I did that with a stock coolant tank, but most recently did it with the radium engineering coolant expansion tank as my OEM one was beginning to rot away. I would recommend upgrading to a metal one if you haven't already. Hope you get this solved soon -.0
 
#40 ·
One question for all you guys saying it's air in the system.....how did it get there after 1.5 years (roughly)? I'd assume (and maybe I'm being naive) that *eventually*, any air in the system is going to work it's way back up to the reservoir and out through the overflow tube. Is that not the case?
 
#41 · (Edited)
The reason there are bleeders in cooling systems at certain points is because air or vapor can get trapped at a local high point (like an upside down U in a line that continues below that point)... the result is that the system may not self-bleed there, so you have to do it manually.

Assuming you started with a properly bled system, one way to get air into the system would be to start the engine, get it very hot, then shut it down and let it heat soak (sit with no further active cooling). Coolant sitting in the very hot head could boil, turn to vapor and push coolant into the overflow tank. If you remove the radiator cap before things cool down sufficiently, atmospheric pressure is insufficient to collapse the area filled with steam back to liquid (it could end up sucking air through the open radiator cap instead of coolant from the expansion tank). On the next startup, you have a void in the cooling system not filled with coolant. This lets the head get even hotter on the next start up, creates more steam, dumps more coolant into the expansion tank and potentially even out an overflow if the expansion is sufficient.

I’m sure there are other ways for this to happen. For example, the constituents of coolant break down into their component gasses (hydrogen, oxygen, etc.) when heated many times. Expansion tanks and swirl pots are usually sufficient to remove the resulting small gas bubbles in the system. But if a cooling system were operated for short periods, it is conceivable the normal course of events - the bubbles get removed - could be circumvented. The bubbles would then migrate to high points in the cooling system and create voids in the coolant. The chemical reaction of coolant with metals can also create gasses. For the record, although this mechanism is possible, it seems less likely to me.

Glen
 
#44 ·
Another question: Anyone know if the oil dipstick tube is simply a push-in with a rubber o-ring or grommet on the engine block?

The way the factory designed this on the SC model is a royal PITA. They have a steel tab welded to the oil dipstick tube that affixes the tube to the block at the uppermost stud/bolt for the t-stat housing. Since the nose cone of the SC effectively encases the dipstick between it and the rest of the engine, you can't wiggle it to get it off the stud. I ended up having to bend it out of the way with pliers. I'd like to remove it from the block and straighten that tab out (wasn't able to just use pliers again to straighten it), but I'm not sure how it's held on at the block/pan junction.

Anyone know for sure? I definitely don't want to just yank on it and risk breaking something that isn't a push-in....

TIA,
Sean
 
#46 ·
Just fired it up after changing the t-stat. A total of just under a gallon of fluid came out due to the T-stat change. Replaced about that amount of fluid before starting up. Ran until temp reached 212ºF, then shut down....fan never came on and the radiator never got hot. Bleeder was open at the front passenger wheel well, hose wasn't hot....small amount of bubbles came out initially, then stopped. Rear bleeder in the engine bay was open....no bubbles, just fluid. Heater was in the "on" position with fan speed at highest setting on the interior.

After shutting it off, I pressure tested system. Under 15 psi, the front bleeder had a steady stream of fluid coming out. Rear bleeder initially didn't leak....but I tightened it a bit more (after noticing earlier that it's not an o-ring, but a flat rubber disc...that may used to have been an o-ring)....and it started leaking. Need to replaced that flat rubber disc with an o-ring before I can check anything else.

Is the reservoir tank supposed to be capped while attempting to bleed the system with the car running? I've never had to do that before on a regular radiator with a normal overflow tank. What about that little bleeder on the reservoir itself....supposed to be cracked or tight?
 
#53 ·
Ran for 50 minutes....got to 208ºF, fan kicked on (low speed)....dropped temp to 201º. It's only 52º ambient here tonight. Doesn't seem like it should be running that hot....not confidence inspiring when the temps hit 110-115ºF. FYI....these notes are mainly for me. If anyone has advice, feel free to chime in though.
 
#54 · (Edited)
@Sean K. - I think you are trying to infer how the cooling system in your Lotus will perform during normal use from how it performs at an extended idle. The amount of heat generated and the amount of airflow across the radiator are massively different under these two conditions.

The design intent of the cooling system in your Lotus is to get the engine up to operating temperature as quickly as possible, then keep the temperature in an acceptable range under the expected operating conditions. The engineers only intend that your vehicle will survive an extended idle with no airflow generated by vehicle motion . . . they did not intend that it would achieve and maintain an optimal temperature.

Have you ever seen a vehicle on a dynamometer and wondered why they had big fans pointed at the radiator? It’s because the built-in radiator fans alone can’t move enough air to maintain an acceptable operating temperature. Your vehicle is designed to be in motion and that’s the environment for which the cooling system is designed. So if you want to conduct a meaningful test of your cooling system, you need to go drive your vehicle and subject it to the conditions you want to survive. A properly operating thermostat will largely negate the effect ambient air temperature has on coolant temperature. Yes, even in Arizona.

Glen
 
#55 ·
I understand that....however, at this point, I'm just trying to ensure all the air is out of the system and that there are no leaks....

The pressure tester is not holding pressure though...indicating there is a leak somewhere, but I'm not losing fluid....which makes me wonder if it's the tank or the tester itself not sealing (or the seals in the tester, etc).

The other problem is though....with traffic being what it is here, extended idling where you don't move at all or not above 1st gear is all too common. It is that type of scenario that's seen the temp spike up above that 226 point in the past and keeps me from taking the car out much due to the possibility of overheating. In short, I don't trust it and in it's current state of repair, I'd say it's still not ready for that type of use.

My work schedule is currently such that I don't have time to dedicate to it the way I'd like so I'm working in spurts. I'll likely try the airlift on it next as something still seems off.
 
#57 ·
If the coolant is being circulated, the fans at low speed are enough to keep idle cool on the hottest of days. You shouldn't see above 208F unless there is a problem. You are almost guaranteed to see 207 though unless you are running AC, at which point the temp should be lower since the fans are always at least low speed.
 
#58 · (Edited)
So tonight I went to pressure test it....and couldn't build any pressure at all. The pressure just vents out of the overflow tube on the reservoir. Not sure what's going on at this point.


***EDIT*** System apparently just had too much fluid in the res. Once I drained some out, I could pressurize the system***
 
#59 ·
So it looks like the air entering my cooling system was doing it through the bleeder valve near the engine (the one with the flattened o-ring that looked like a flat rubber washer).

Everything seems to be fine now.....though this car just seems to run hotter than others.

As for bleeding the system....what worked best was opening the bleeders partially (including the engine breather) and filling the tank without the engine running until the reservoir was full. I pressurized the system with a pressure tester and watched for solid laminar stream from the bleeder screws and tightened them up once I didn't see any bubbles for a while. Turned on the engine with the cap off the reservoir and a small vinyl hose attached to the overflow tube.......let it get hot and puke bubbles and fluid into a catch can under the car until it "burped" a couple of times and dropped the coolant level in the reservoir down to almost the bottom (careful not to actually let it get empty thereby letting air back into the system)....and just kept topping off. Put the cap on once I felt it had burped out most of the trapped air and let it idle for awhile. Got up to 210ºF before dropping back down to 201 (fans came on half speed at 206-208 and dropped the temp). Left the little white plastic wing nut bleeder on the reservoir alone completely. Pressure tested system and while it doesn't hold 16 psi for long....it drops down to 14 psi or so and stabilizes for hours at a time. No leaks anywhere at this point.
 
#61 ·
Pressure tested system and while it doesn't hold 16 psi for long....it drops down to 14 psi or so and stabilizes for hours at a time. No leaks anywhere at this point.
While you could fix the remaining leak(s) that are bleeding off above 14 psi, I usually don't try. It rarely gets above 110*F here and I haven't run into any issues - even driving on track at 106*F days.
 
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