I have a 2004 R53 Monte Carlo Edition that I will most likely be putting up for sale very soon. It has 63K miles and of course the standard features of the MC edition (wheels, seats, etc.). The previous owner hit a dog late one night and it went under the car, busted a radiator hose and she ran it hot. She got the insurance company to buy it as a loss. There was almost no other damage. I have a clean TN title for it. A guy who specializes in Coopers locally bought it, replaced the head with a new one, new water pump (with an electric one), new radiator, new expansion tank, etc. I bought the car and put about 2000 miles on it when it started having some issues - temporary spikes in temperature but never truly overheats as the 2nd stage fan cuts on and brings temp back down. There is no coolant in oil, no white smoke but the system tends to push coolant out the expansion tank. After bleeding the system, replacing radiator cap, etc - the issue still exists.


I've decided to just sell it instead of fixing it - I know I will lose a ton of money but I don't want to spend any more on it. My question is -what should I ask for the car? I want to be fair to both me and the seller.


Thanks


Bob

 

When you say it's pushing coolant out of the expansion tank, is it coming out through the cap? Those caps eventually go bad and if its not holding pressure and letting coolant out that might account for your temperature spikes. Autohausaz.com has OEM caps for a good price. You might give that a shot before writing off the car.

 

Sorry - its pushing out the overflow tube right under the cap. Just put a new cap on to see if it made a difference and it didn't.


One thing I did notice is that this only happens at highway speeds. I can drive it and let it sit idling for 5-10 minutes and it will never spike at all.

 

Hey Bob, welcome to NAM! Don't lose faith!!!!!!

^^ That tube is the overflow return. It's supposed to come out of the tube, back into the overflow tank. Unless you mean it's leaking out of the tank in that area. Then just replace the expansion tank. $50 and 20 minutes of your time, plus another bleed.

The differences in temperature is likely because of a bad radiator fan resistor. Happens all the time. Pelican sells just the resistor on their website for ~$50. Or Rockauto has a lower-quality-but-very-affordable after radiator fan. A good mechanic should be able to replace either in an hour and a half. Highly recommend getting a good water temperature gauge so you can watch coolant temps!

TL;DR--please don't sell your car just because you're starting to run into a few issues. If it's getting too expensive to maintain, find a good mechanic who will charge a fair price and buy the parts yourself to avoid markup. There's a few hundred people on here that would give their left kidney (or unborn child) to have your car. Aren't you one of like, 2000 people on Earth with an MC40 (minus the few that have been crashed)?

Edit: Not sure if I trust aftermarket water pumps though...that's the next thing to replace, if the resistor doesn't fix it.

 

Actually 1 of 1000 LOL.


Both stages of the cooling fan are coming on so would a bad resistor still allow that to happen? I actually have a replacement resistor and was going to do it but since both stages are working I wasn't sure whether I wanted to pull the front off to replace the resistor


The expansion tank is a new aluminum one. One thought is that I am running the 15 PSI cap but some folks were saying I should be running a larger PSI (possibly as high as 28 PSI) on it instead?

 

Okay I'm going to offer my $.02 which may not necessarily be worth $.02. It sounds like something is blocking your flow. I would pull your thermostat and check operation. It could be a soft failure there. If it's not that, I'd follow Sarom's advice and look into the water pump. Both are easy fixes.

I'm also typically against taking to a mechanic due to cost, but if you have a good one he/she is probably well worth it.

 

Electric water pump you say? Maybe that is your issue. Why not a stock pump? I concur on the thermostat potentially being an issue.

Sarom058, if you can replace a fan in 1.5 hours you have mad MINI skills dude. I did it 2 weeks ago and it was no fun dismantling the front end and putting it all back together. 3 hours is more like it.

 

What brand of Electric Water pump did they use...same one that comes with the Sprintex Superchargers ?? Also, it's a pressurized system. Any leaks or lack of proper bleeding of coolant system after this type of repair will result in frequent heat spikes....

 

Why do you ask about the Sprintex pump?

 

Last I knew no issues with that one...at least not anything I have heard. Always wondered about the benefits of going electrical. Takes a load off the supercharger, same as going electrical for the PS pump. Boost may spool up faster...

 

It's forcing the tube off the nipple and blowing coolant out despite a hose clamp, which should be in place?

If you're getting low and high-speed operation, then the fan/resistor is good...

If it's failing from the hose and not the cap, then I'd certainly not want to put an even higher tolerance cap on the tank.

 

I thought you knew something I didn't... Was gonna say I have no issues with my pump - that's about the only thing so knock on wood!

Probably about the same as other cars who go with underdrive pulleys - less parasitic loss of power. That's about all I can surmise.

 

Installed a new thermostat so know that isn't issue. The water pump is a Davis Craig EWP80 - it was on the car when I bought it. I would replace it with a mechanical but not sure how much work that will be since I am sure things were modified to get this one fitted.

 

Was the coolant system fully bled after work was performed ? There are two places to bleed the system. And sometimes folks think they have, but air pockets were still an issue sometimes for weeks after work was performed.

 

Yes

 

My WP diagnostic panel is saying I have a "temperature sensor short circuit" and "low temperature " which I believe (1) means sensor is bad and (2) water pump is not running because it thinks the temperature is below,140 which is the bottom threshold

 

I'm about to the point if so,wine showed up at my house tomorrow with $4000 cash they would probably own it !!!!

 

Aww shucks, thanks dude. But I'm really not a good wrench..I've just had to deal with enough cooling issues over owning two shoddy pre-facelift R53's in Arizona. Plus I've spent way too much time grooming NAM's DIY's while my cars have sat and picked up a few tricks along the way (ie long bolts that are the same thread/pitch as some of the front end service mode bolts to support the radiator shroud in place without having to remove it to access the stuff behind it, only disconnect top hose and tilt the radiator forward to remove fan as to not lose coolant, etc).

And harley, bahahaha I'd buy an MC40 in a heartbeat for that price if I had that kind of money. Want to trade with cash on top from my end? You'll lose a cooling issue and gain a nice case of transmission whine

 

Hey, just to add a thought to your situation, it sounds like you a
Have a air pocket. You just need some patience and a little coolant to fix it.

 

Just because something is new doesn't mean it functions correctly. You have SOMETHING in your cooling system that's preventing flow. There's really only 4 things that can do this short of a foreign object:
1. air pocket
2. thermostat
3. water pump
4. radiator

Radiators very rarely go bad, though it's not unheard of. Due to the temp coming back down, I'd say your radiator is fine. It's one of the first 3. In all honesty, I'd take it to a mechanic and say fix it. Otherwise I'll show up on your door with $4k and some champagne and wine if you send me your address.

 

^^ +1. If there's enough pressure in the tank to pop the return line off of the nozzle, something's clogged.

 

If you installed the thermostat, just double check your work. It's easy to put in backwards. It'll take an hour, and then while it's out toss it in some boiling water just to eliminate that entire possibility.

I thought EWP ran 100% of the time? Seems needlessly complicated to put a controller and sensor in there, especially when the thermostat will prevent circulation when the coolant isn't warm enough. I'd double check the wiring and sensor on this though. Sounds like a likely culprit.