Last night the wife came home and pulled the car into the garage (2008 XLR-10/12K). When running at aprox 190 F it was not hot. Turned off motor and coolant started coming out of the 'plastic bottle' at the cap. I understand the 'pressure of the waterpump and the expansion when at rest', but the cap was loose. No service people nor myself have touched that cap, and now it's loose ? My fuel filler cap also 'becomes loose' after driving a few miles. Are these things normal ? I'm sure the motor is not overheating, but why would the 'coolant fill cap, or the fuel filler cap' just BECOME LOOSE ? Thanks.

That's a strange one for sure!!

I am wondering if your water pump is going out. I had that happen on my 2004 XLR. It was leaving spots on the garage floor from being too hot.

I actually waited while they put a new one in. It is fairly easy and doesn't require a lot of teardown to get to it.

Would a quick trip into the dealer show whats being recorded in the way of "fault codes" for the cooling system. Maybe a 1 hour labor charge.

Please let us know how this issue is resolved.

Thanks, I will look for any 'spots' on the floor.

A week later, and no 'spots on the floor'. Drove the car (aprox) 80 miles in 6 driving days. Today the wife calls and tells me: "the low coolant light is on". This has been the coolest day here so far. Always ran below 190 degrees (F) I will purchase some 'red coolant' on Monday and try to FILL the system once again. (cold) Tail pipes look 'black' and show no signs of coolant loss. No wet spots under the car at any stops. If this 'problem' continues, I would think HEAD GASKETS, since I see no leaks and the coolant bottle cap was "loosened" by someone or some kind of pressure. Has anyone had this kind of problem ?

I would agree except that you aren't seeing any moisture coming out of the exhaust when it's idling.

Also is it hard to start???

The coolant has to be going somewhere though.

How about a pressure test to see if any leaks pop up???

Please keep us informed.

Regards

Have you looked at the underside of the car? I recently also had a low coolant message. While there was nothing on the floor, the underside of the car had mostly-evaporated coolant on it under the front of the engine. My dealer found the leak and replaced the water outlet gasket.

Thanks ! I refilled plasic bottle to stop the 'coolant light', and will now test for ANY coolant loss. Warning only came on for a minute or two just after (cold) start up. May have not filled to correct level. I will look under the car on Friday to recheck for any coolant leaks. I've had this car since March and have not had any cooling (temp) problems with it. (3100 miles of use) The summer temps got up to 119 F on some days and she ran cool even with the A/C blasting. Has 'no burnt coolant odor' since refilling. Thank you all !

IF THE COOLAND IS BEING "BURNED" You should be able to run your finger around the inside of the exhaust tips and get a sense of what is comng out besides the usual carbon deposits. The antifreeze would be somewhat greasy to the touch...

Also put a piece of plastic down to see what lands on it. I tried news paper but it gets blown around unless you do it after the car is in the garage and remove it before you start it up.

I also agree with the idea that you can look under the car and see where any leaked material is on the bottom of the motor and transmmission. The pressure test will confirm whether or not it is a hose or loose clamp that is under pressure while the engine is running that is causing the loss or not.

Please let us know how this comes out.

I put the car out on the front porch last night, to get the temps down as far as possable. It was 47 (F) last night and no coolant light this AM. I feel the coolant level is back up to the required amount. There were no coolant 'drip marks' on the garage floor. I just don't know how the cap was loosened. I'll continue to test the coolant question, along with one tire that now has an air pressure loss problem. I'm told the chrome wheel is pleeling and the air is lost in the gap between metal coatings.

No coolant leaks, nor any other coolant problems so far. Night temps are dipping into the low/mid 40's and no 'low coolant lamp' in the AM so far. I park the car under my front porch cover "25' X 25' " and it has not been rained on so far. I just don't understand how the coolant bottle cap became loose, and the original coolant level was lost. Now looking at a 'chromed factory wheel' that is losing air pressure. Discount Tire says the 'chrome is peeling and bubbling' and this is causing the air loss. "Every day is a new day".

I am assuming that the coolant cap is still tight right??
Did you mark the level that you filled the resevor up to?

Chromed Wheel Loosing Air--Not a possibility that I am aware of unless the wheel casting is very pourus. Have Discount Tire fill it up with nitrogen since the molecules are larger and see what happens.

Also the valve/TPM assembely may just have a bad "O" ring on it.

Please let us know how these issues are progressing and resolved.

Actually 'overfilled' the plastic bottle and it has shown no problems so far (almost 500 miles) The factory chrome wheels have been inspected by my local Discount Tire. One of them (that shows no signs of curb contact) is still leaking. It drops to (aprox) 20 lbs and then just remains. DT says "the chrome is peeling and causing the leak" The info panel indicates different tire pressures in the other three every day, but the "bad one" remains the same number. Now the fuel cap seems to be impossable to install into operational position. It just clicks, but does not retain. I put 15 gallons in (fill it up) every three weeks, and just now the cap starts to act up. I've had girlfriends in the past whom acted just like this car: beautifull, sexy, everything I desired, except for the minor BIPOLAR PROBLEM ! Thank you all for your help.

Gas Cap--It can be fixed by replacing it with a new one. It's not expensive and will correct the condition.

Wheel-"I'm calling BS on the chrome peeling causing the leak". Ask Discount to fill it up with nitrogen and see what happens. If that fails then I would discuss a replacement wheel with Cadillac since the casting is faulty (safety issue). Is the car still under any Cadillac Warranty???

Also there are wheels for the car on the Internet. You may be able to pick up one, two or a set fairly inexpensively.

WE'LL GET IT ALL CORRECTED!!! There are a lot of good members here.

Regards

Jerry

OK, I am just back from my local GM dealer. My "overheating at idle without AC on" problem was NOT FOUND. But I had it puke fluid on my driveway that same day before taking it in. The "engine light on" was the fuel cap leaking. Even though the DIC never read 'check fuel cap'. (it has in the past) The right front wheel "shows signs of curb damage" (as my car was a demo) so no warranty. Engine coolant temps seem more stable since oil change, so I will wait out any cooling system problems. Seems to run smoother since oil change. It only went to 25%, so I think I'll just change oil at 2500 miles instead of 5K. I really love this car, and I'm just now getting comfortable with it's "personality traits". (this is why I didn't buy a BMW or MB !) I think I'll look for a new set of wheels and just drive the car as much as I can. "First the wife, then the pets, now the CAR all have me IN LINE for their needs !" HA HA!

I hope they were using Mobile 1 as they are supposed to. The 25% remaining is the correct point to do a oil service.

Gas Cap if it acts up again just get one of the new caps and all of those problems should go away.

Overheating--Yea it will be nice to just watch all of the levels and see what happens over time.

Wheel--There have been some deals on wheels on EBAY. You may be able to get a used one at a good price there. Is the damage real bad???

I ask becauseyou may be able to pay a repair fee and switch the wheels out with one of the wheel companys that do chroming. They will fill and correct the spot and charge a small amount. LA Wheel and Tire is one of the best vendors out there.

Everybody here will help in any way they can to reslove your problems.

Regards

Thank you. My ESV has 3K intervals for oil change, so I assumed this car was the same. I finally read about the 5K interval (while seeking info on the check lamp) and never intended to go that far. I'll do oil @ 50% from now on. I checked with 'wheel chroming web sites' and they all DON'T WANT wheels that have been already chromed, only non-chromed wheels are used as trade in's. I'll check with "LA Wheel and Tire" in hopes that they can help. I would just opt for all 4 when doing wheels/repairs/replacements. I do like some of the new Vette wheels, like the 'Super Sport' style, in chrome. I'm open to look at anything chrome, and I know they are out there. I was offered some wheels and tires a few months ago, fitment was a problem (my front is 1' lowered) and I let that deal go away. My "cooling/overheat problem still haunts me". I'll let you know what we find. PS, dealer installed a new fuel cap durring this past visit, all OK for now. (light is off)

LA Wheel will sell you replacements for a little more than exchanges but you need to buy a whole set.

Cooling problem. I am thinking water pump. See if they are willing to do a pressure test on the whole cooling system.

We'll get it resolved sooner or later.

There are some real good minds here. (not mine. I'm old)

HAPPY HOLIDAYS!!!!!

My "cooling/overheat problem still haunts me". I'll let you know what we find. PS, dealer installed a new fuel cap during this past visit, all OK for now. (light is off)

Can I check a really basic question with you about the coolant filler cap?

On my XLR the cap is seriously difficult to refit. Once it has been refitted, I cannot imagine coolant puking out of it, it has an 'O' ring seal inside it and seals off. Though sure, a small amount might weep out of the pressure relief valve system (little pipe to the rear of the filler bottle).

So two questions arise:

1/ Basic question. Is the cap on properly? To fit mine, I have to get it 100% square on the thread and then press down pretty firmly (don't break the bottle) to get the threads to engage. It then takes a good few full rotations (about 3) to screw it down until it is properly in place. This design is entirely different from any coolant cap I have met on any other vehicle. I am guessing it has to pull down a good 1/4inch on the threaded section. It is pretty firm all the way down and has a click torque relief when fully fitted (like the gas cap). Pretty stiff coming off too.

2/ If the cap is on right and coolant is blowing past the pressure relief valve, is the valve faulty?

Thanks. When I had coolant leaking out of the bottle, the cap was loose. No one had touched the cap in 6 days (me). I originally asked if the caps had a problem of coming loose (on their own) as I knew at the time mine was installed correctly for almost a week (aprox 150 miles) Since the service check up and oil change the motor does not 'overheat' at idle, it only goes up to 220 and then back down as the car starts moving thru the air. I have never heard any cooling fans come on while driving this car, at any speeds. It did leak a little coolant and run at 220 + idling in my driveway just before I took it in to the dealer, but no coolant leaks since out of the shop.

[snip] It did leak a little coolant and run at 220 + idling in my driveway just before I took it in to the dealer [snip].

What? That it leaked at all is a fault, period. 220 is within normal limits before the thermostat opens, I would have to check the exact figures but around 260 is typical max high before being properly overheated, with a typical first alarm at 235. You do have 50/50 genuine Dexcool mix right? There are very few causes of the symptoms you describe:

1/ Cap/cap fitting faulty (I have seen the thread on header bottles damaged, resulting in failure to build pressure)
2/ Cylinder-head gasket failed (easy chemical test)
3/ Improper coolant mixture (replace it).

Also
4/ Pressure leaks (e.g. loose hose, damaged radiator) (you are not reporting drips though and usually it would not blow through the cap) (a pressurized system is required for proper function)


If you were reporting much higher temperatures then faulty water pump, blocked radiator (both fins and internal waterways) and thermostat get added to the list.

Dexcool is replaced every 5 years so the 2004 cars should all have been done as should the early 2005 cars.

I would replace the cap and if that doesn't fix it, replace the header bottle and the cap, especially since the cap came loose, that is wrong.

Changing the oil will not fix a cooling problem. You are not measuring oil temperatures, one major function of oil is to transfer heat away from the pistons and bearings into the block and hence to the water jacket, however, you are measuring block/water jacket temperatures so the oil has already done its job. Sure, the right grade oil will make a tiny difference, but not worth talking about at idle.

Well you make good points but this car is still under factory warranty and I can not TELL the dealer how to check out my questions. I fully understand how gasoline fueled internal combustion engines work. I am a former GM Proving Grounds Engineer and I have been building and racing powerboats for the past 40 + years. Being a 2007 inductee of the West Coast Boat Racers Museum, right along side of/with Stuart Hillborn, (and others) I have a 'small clue' as to what my Northstar engine is (or is not) doing. I just feel I need to educate my local dealer as to "what is correct and what is not" . If the car were not 'under warranty' I would do the work myself, (after purchasing a TECH 2) but it is and I will continue to "walk the line" as far as dealer services go. I'm just posting this here to "BITCH, CONVERSE, and EDUCATE" myself. Many of you here have more 'miles' logged as far as dealer services and their short commings, I just come here to "exchange information" and I thank all of you for your input.

[snip] I can not TELL the dealer how to check out my questions. [snip]

There is nothing I can add to that.
To recap,
1/ My XLR has an effective coolant tank (header tank) cap, it requires a firm grip to remove it, I can't see any way it will just unscrew
2/ Any (modern, sealed system) car that is blowing coolant out of the header tank has a fault.

Wheel Specialists in Tempe swapped out my brushed OEM's for chrome OEM's for $850 installed. They provide wheels to all the high end dealers in the Phoenix area. Have used them fo rother cars as well.
www.wsiwholesale.com

Thank you for the 'wheel connection', near my 'hood. I went thru the bank 'auto ATM' today and have a cooling system question. I was 3rd in line and waited (aprox) 10 minutes for my turn and then another 3 minutes for my business. I idled 'out of gear' 90% of the time, and yet my coolant temp went from it's 'normal 10.30' (clock position) to almost straight up (220F) on the gauge. I never heard any fans turn on while idling in line. I had no A/C on, and when I first noticed indicator level moving up I opened the window to listen for fans. No sounds, no fluid leaks. Done with my business, I drove UP the street at 35/38 MPH and within a block the temp needle started going down. 1.5 miles later the coolant temp level was back to normal. My questions are: does this car have 'cooling fans operational when the A/C is off? Also, IF there are fans, what temp is required for them to operate? What if I am stuck in 'stop and not go traffic' ? Then lastly, is MY PROBLEM common or normal, or terminal ? Thank you for any and all replies.

Questions to the answers you posted:

1) Yes, the XLR does have an engine cooling fan.

2) Yes, the engine cooling fan can operate with the A/C off if the engine coolant, engine oil or transmission fluid temperatures are high enough.

3) Fan operating parameters are:

Low –speed fan operation begins @ 204 degrees (engine coolant temp.) or A/C pressure of 160 psi.

High-speed operation begins @235 degrees (engine coolant temp), 302 degrees (engine oil temp), 270 degrees (transmission oil temp.) or A/C pressure of 360 psi.

If the engine is shut off and the engine coolant temp is >235 degrees, or A/C pressure is >249 psi, the cooling fan is commanded to low speed. After shut-off if the coolant temp drops below 230, or A/C pressure <241 psi, the fan will shut down. The fan will turn off after two minutes has elapsed, regardless of temperature.

The Engine Control Module controls the cooling fan speed via the Fan Control module.

The COOLANT OVER TEMP indicator will illuminate if the engine coolant exceeds 256 degrees. The optional ejection seat should deploy if the cabin interior temperature sensor (located adjacent to the ignition switch) exceeds 190 degrees. (Just wanted to see if anyone was still awake after reading this.)

---Quite a cooling system on this car. Did you know even the generator has engine coolant lines running through it? (A major job to replace too.)

4) Your system is probably working nominally, but if you're concerned about the coolant system, have it checked/flushed if necessary. The fan duty cycle can also be tested with a Tech 2 in 10% increments.

Hope this helps,
CC :cheers

Those are the parameters I was asking about. I now understand that my car SHOULD start cooling itself when the dash needle gets 'just over 1 o'clock' and then I should also have no coolant loss. I read my 'owner's manual' and it did not indicate how the 'dash gauge' should react to 'stopped in traffic' conditions. Even though it has lost coolant a number of times, it has never shown coolant (indicated) temps above the needle reading of straight up. Thank you !

The car has been parked for aprox 6 weeks, due to city sewer install and torn up streets. Rolled her out on Saturday (have been using battery charger every 5 days) and everything was fine UNTIL.... We got in stopped traffic. The dash gauge never got to 210 (F) indicated, but we could smell the odor of HOT/BURNT COOLANT while driving the car and while it's parked. I still feel that there is a coolant leak somewhere, but there are no DRIPS under the car. This car always runs hotter when the A/C is off, but it has never gotten above 210 (F) indicated, at any time. In stopped traffic I can turn on the A/C and it takes about 3-5 minutes to cool the motor down to "10 o'clock" on the temp gauge. If I don't run the A/C the temp gets up to aprox. 195 and we smell the ODOR. ?????? Am I losing a head gasket ? Do 2008's also have radiator 'tank/leak' problems ? This is not the kind of question I should be asking about a well maintained 34K mileage car. ????