update on overheating- now what? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

jhandy · 05-08-2009, 01:15 PM

Thanks to all the guys that helped out, I cleaned the radiators, they had a lot of junk in there.

I started the car with AC on, Both fans are running. AC off, both fan turn off.
Temp 198.

Then I went for a drive, It is hot outside and I drove max 25 miles an hour around the neighborhood.- AC on the temp went to 205.

Then I turned the AC off, and the temp went to 211!!!!

Stopped the car, let it run, AC off, the engine fan turned on, BOTH FANS UP FRONT ARE OFF, temp went to 217, no light on dash.

I turned it off and now I am worried. I always have the AC on, so the fans where always running, and it never went this high. With no fans, I bet it would overheat.

Whats going on? Are the fans supposed to turn on? At what temp? I guess the sensor may be out....where would that be?

James

jhandy · 05-08-2009, 01:29 PM

Also,
Why is there not a center radiator fan?
What harm would it be to have the fans running all the time? Replacement fans are 150$- engine- 15000$.

james

blinkwatt · 05-08-2009, 02:09 PM

I know this wouldn't be a long term fix but couldn't you install a manual switch for the radiator fans and turn them on when the needle is about to hit the '0' on '180'?

jhandy · 05-08-2009, 02:44 PM

Well that is what i was thinking. i was just going to wire it up to turn in when the car is running.
also i wanted to add another fan the the center. The needle looks fine, It always goes to where it is currently, never has had the light turn in. I think that the only reason i notice this now is due the scangague hooked to the obdII port. I bet a lot of people are hitting 210 and more.

cnavarro · 05-08-2009, 03:16 PM

At speed, the fans don't need to be run. In fact, I'm pretty sure on a spec Boxster, they remove the fans. At low speeds or stopped, having the fans run will help, and in fact, with the a/c on, at least the passenger fan is always on. I made the same observation that the temp would rise when the a/c was shut off at a stand-still because you're eliminating the last bit of airflow over the radiator. Theoretically, setrab does make some very small fan packs that would fit nicely on the 3rd (center) radiator to help with low speed/ low airflow scenarios.

The fans typically don't turn on until 210F, or at least that's what I observed in my car. I agree, this is too late. I would prefer they came on much earlier.

Lil bastard · 05-08-2009, 03:40 PM

Sounds like an electronic issue - Fuses (C8 - Rht, C10 - Lft), a relay (there are 4 Hi/Lo speeds, Lft, Rht - #19, 20, 21 & 22), or the Series Ballast Resistor(s) PN# 996.616.101.00.

The easiest is to check the fuses and relays, though I'm betting on the resistor. If you still haven't removed and cleaned the radiators, here's your chance. The resistor is located in the wiring narness to the fans and you just splice a new one in. The fans will work w/ AC on because that is a high speed operation.

The one thing you need to do is get in there and see what's going on. It's possible that some debris has damamged the wiring or resistor, and they are a known weak point, such as the thermo-switch was on older brit cars.

Charles is right that the fans are moot once the car is going 35mph. At this speed, more air is forced through the radiator vanes than the fans can draw through. In fact, the fan blades actually become restrictive reducing the flow that would otherwise take place, though there remains enough to do the job.

If all else fails, the final component is the DME because this is what actually activates the fans. This failure does not throw a CEL but would be seen with a PIWIS or PST2 tester.

jhandy · 05-08-2009, 03:59 PM

ok, Sounds strait forward. The car stays at 195-198 at highway speeds and shoots up when driving slow.

How do I test/check the relays? Do I have to go buy new ones and see if that works or can I bypass them electrically and take them out of the loop?

as for the resistor, pretty much the same question. How do I know that it is bad? I did a quick code check and nothing came up...I just want to avoid going to the dealer (50 miles away) and start buying things that are not needed.

I just cleaned the radiators, I did not remove them. I will remove them and check behind them to see if there is dirt between them and the oil/thing.
I did notice that a fair amount of fins are bent up. I will carefully fix them and see maybe that helps.

Also I checked the fans with a volt meter, Either they are both going bad or they are fine, they are drawing the same amps and with a volt meter I cant tell anything is wrong.

Again, I bet that this is how it always is because the car is acting fine, and the needle is in the same spot as always, however now that I know the car is getting really hot, I may add a third radiator fan.

I am curious if driving around without the bumper off would make a difference,

I worry that if I take it to the dealer and they mess with it, It will be documented that the car was running hot and if the motor ever blows because of the IMS, the warrenty direct people will use that to not pay for anything. That is how it is in medicine at least.

Sounds like I have something to do this weekend!!

Thanks for all the help

Lil bastard · 05-08-2009, 04:21 PM

Quote:

Originally Posted by jhandy

ok, Sounds strait forward. The car stays at 195-198 at highway speeds and shoots up when driving slow.

How do I test/check the relays? Do I have to go buy new ones and see if that works or can I bypass them electrically and take them out of the loop?

as for the resistor, pretty much the same question. How do I know that it is bad? I did a quick code check and nothing came up...I just want to avoid going to the dealer (50 miles away) and start buying things that are not needed.

I just cleaned the radiators, I did not remove them. I will remove them and check behind them to see if there is dirt between them and the oil/thing.
I did notice that a fair amount of fins are bent up. I will carefully fix them and see maybe that helps.

Also I checked the fans with a volt meter, Either they are both going bad or they are fine, they are drawing the same amps and with a volt meter I cant tell anything is wrong.

Again, I bet that this is how it always is because the car is acting fine, and the needle is in the same spot as always, however now that I know the car is getting really hot, I may add a third radiator fan.

I am curious if driving around without the bumper on would make a difference,

I worry that if I take it to the dealer and they mess with it, It will be documented that the car was running hot and if the motor ever blows because of the IMS, the warrenty direct people will use that to not pay for anything. That is how it is in medicine at least.

Sounds like I have something to do this weekend!!

Thanks for all the help

You need to check the circuit for resistance - Ohms. What you do not want to see is infinite resistance, probably some value less than 1. A code reader will not tell you anything. The DME can store faults which aren't readable with an OBDII reader, nor can you reset it, this is why a PIWIS or PST2 is needed. For checking relays, see my post: http://www.986forum.com/forums/showthread.php?t=20195&highlight=relays

If you have radiator vanes which are bent, this can be quite an issue, depending on the number and severity. You can buy a vane comb from an auto supply store to straighten them, usually a couple bucks. If attempting manually, take care as they are fragile - take your time.

You need to remove the bumper cover and separate the AC condenser to properly clean them. All sort of junk can collect between them and the radiators. Flush from the backside so you push the debris out the way it came in - don't inadvertently force it deeper between the vanes by spraying into them and don't risk damaging them by using a power washer.

Dar01 · 05-08-2009, 05:45 PM

It seems to me your "fan" arguments are just a band aid....something else is going on. My temp is always between the 8 and the 0 (180), driving around the fans do not come on and the temp stays right there. If I am in stop and go it rises slightly (still no fans)......if I am sitting for a train lets say for 5 minutes or so, the temp rises slightly still and the front fans come on. I have only heard the engine compartment fans 2 or 3 times.....sitting long periods, hot summer day. I still don't remember my temp gauge ever leaving the "0" (180) it could have, just not sure.

If you are constantly over 200 something is going on.....thermostat going bad, but usually when those go bad they stick open and the car never reaches correct operating temp because it is wide open.

I cleaned my radiators as you did, and did not notice any "lowering" of the engine temp (I had a LOT of crap between the radiators!).

I remember reading a post where someone had said the biggest temp drop they saw in their car was a coolant flush and fill. You might want to try that and a new thermostat. Again, just my opinion if somebody wants to chime in.....I just don't think it's a fan issue....sounds like they are working like they should.

2000, base 2.7, no third radiator.

Keep us posted!

jhandy · 05-08-2009, 10:39 PM

Yes i agree with you. something is not right. however my temp gauge says only a little above 180. I bet you if you buy a "scangauge" device you will see exactly how hot it gets. The car is running normal, never has a light turned on, and if I did not have the scan device thing I would not even notice.

i will check everything tomorrow. If i need a new thermostat, I will buy the 160 from Mr. Navrro. If it is the same great, if it lowers the temp, even better.

To do a flush and fill is very expensive, even if you buy the 200$ flush kit, the coolent is pricey and should i also do the pump while i am in there is also a question. The price of coolent is almost the cost of a new pump. If i have to flush the system, why not make it the first and last time it needs to be done? I will report back tomorrow after i clean the radiators and test the electricals.
james

jhandy · 05-09-2009, 02:25 PM

ok here is the current situation.

I removed the bumper and cleaned the radiators. I then loosened the AC rads and WOW. How can so much crap get in between the two? So cleaned that out.
Cleaned the center rad by removing the rubber tunnel, LOTS of stuff in there as well.

I checked the fuses, and the relays with the multimeter, all check out fine. I did not know how to check the resistors so I left them alone.

Then with the bumper off I drove around. Temp went to 200 max.

I put it all back together and then drove, The temp went up to 217. Still the needle on the dash is not past the 0 in 180. AND NO FANS!! aside from the engine compartment fan.

So I flushed the system. Incidentally the stuff that came out was not green or red, it was almost pure water with the slightest amount of green. This is the Original fluids from the dealer when I got the car new in 2002, 65000 miles ago.

So on the hunt I go for antifreeze, in my small town, nobody had any of the approved fluids, so I in austin I found only the texaco extended kind, and it is on the list of OK fluids.

I put in 3 gallons of texaco and 1.5 of water for a 60ish/40ish ratio.
Then drove around in 93F sun and the temp still went up, but only to 207.

So I guess that this is it. Aside from a new pump or T-Stat, I am at a loss. Maybe it is normal??? Does anyone else have a OBDII real-time scanner that can report normal operation temps??

One person posted that his needle never goes past the 0 in 180, well neither does mine and the highest temp I have seen lately was 221. The dash gague is horriable.

That is almost to the boiling point of a 50/50 mix antifreeze!!!! and still no fans.

jmatta · 05-09-2009, 02:44 PM

I still contend what you are finding is normal. The dash gauge is inacurate, as you've discovered. The car runs much hotter than we are led to believe and the aftermarket (LN Engineering) offers the 160 T-stat that we dicussed in your earlier post.

I, for one, have already ordered mine and will be installing before the summer heat comes. I want to do everything I can to preserve my engine for the future, but still have fun driving the car.

blinkwatt · 05-09-2009, 04:40 PM

Dude just take a pic of where the temp gauge is when your worried about it and we'll let you know if it's normal or not.

Steve Tinker · 05-09-2009, 05:33 PM

jhandy.... you say you put in 3 gallons of coolant and 1.5 gallons of water in your system - thats 66% coolant which is far too high a percentage.
Water is a far better heat dispersant than coolant so your ratio should be 50/50 max. If you live in a warm climate where there is no fear of freezing, then a 60% water / 40% coolant will also work well.
I'm changing out my coolant next service (9 years & 67,000km old original fluid) and while its empty I will also change out the pump. You only need a pump working at (say) 80% efficiency & there will be overheating no matter what type of driving you do.

jhandy · 05-09-2009, 06:31 PM

As requested, here is a picture.

blinkwatt · 05-09-2009, 11:06 PM

HAHAHA dude that's normal. Drive the **************** out of it.

jhandy · 05-10-2009, 07:40 AM

Ok, I guess all of this talk about premature engine death had me worried about the temp.

I want to thank all of those who helped, this was not a wasted venture, I cleaned the radiators and flushed the coolent, so not bad.

Also I drilled a 1/2 inch hole through the plastic cover so I would not have to remove the cover just to remove the drain plug.

ramo80 · 05-10-2009, 11:04 AM

mine fluctuate around that area too. You might need some gas too

Jaxonalden · 05-10-2009, 11:36 AM

Quote:

Originally Posted by blinkwatt

HAHAHA dude that's normal. Drive the **************** out of it.

My gauge needle reads at the same spot no matter what kind of driving I do.

Blinkwatt...I think he's concerned with the 215 degree fahrenheit WT (water temperature) reading on the scan gauge. Why the disparity?

JFP in PA · 05-10-2009, 11:38 AM

Quote:

Originally Posted by jhandy

Also I drilled a 1/2 inch hole through the plastic cover so I would not have to remove the cover just to remove the drain plug.

Sorry, but putting a hole is the belly pan is somewhat of a waste of time, as you still need to pull it to disconnect the foward hoses and drain the radiatiors as well. No sense in doing half the job once the car is in the air................