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Discussion Starter · #1 · (Edited)
I have 2010 Boxster S with PDK.
I have OBD reader so i have constant and true info on the coolant temperatures.
Usually it's rarely over 205F.
Even at the aggressive long uphill mountains driving it's never over 215F.

Recently i see engine temperatures higher than usual - at the uphill runs it reaches 220, which it never did (stock coolant gauge are still at it normal state).
Also to cool down back to 205 now requires much longer drive - 2-3 times longer.

So far i've checked:
1. coolant level stays the same
2. no leaks to be seen
3. water pump area seems to be dry - but there is a gunky area around it - i don't know whether it's dirt or it's coolant seeping. but coolant level is dead on....
4. vents seems to be working OK - they turn ON at usual 203-205 and turn OFF below this.
5. no debris can be seen through radiators opening

So what can cause this unusual behavior?

Also - after hard driving session + short cool down drive + 5 minutes of idling (to cool down), when i turn engine off and than turn it on again after 5 minutes i see 220 but it drops very quickly to 205 - doesn't it mean that radiators + thermostat + coolant pump are all OK?

I'm dazzled and confused and want to fix it before it gets too bad.
Simon



 

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I'm no expert, but maybe a cooling fan(s) issue? Less likely, there could be stuff between the radiators and condenser that you can't see through the bumper opening that could block air flow.
 

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Discussion Starter · #3 ·
1. do you guys see pictures i've attached?

2. fans sound like they're working, and quite loud - so i assume they're probably OK

3. i was thinking too about radiators blocked - from outside they look OK.
of course i can't see if there is a a lot of dirt between the rad and the condenser....
but due to normal temps during normal and high way driving i thought that a sign that radiators are OK - am i right?
 

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1. do you guys see pictures i've attached?

2. fans sound like they're working, and quite loud - so i assume they're probably OK

3. i was thinking too about radiators blocked - from outside they look OK.
of course i can't see if there is a a lot of dirt between the rad and the condenser....
but due to normal temps during normal and high way driving i thought that a sign that radiators are OK - am i right?

Yes, pictures show up for me.

To clarify, a few questions -
A. All three fans (left, right, engine) are working?
B. What is "normal" temp on the highway for you?
C. When is the last time you cleaned your rads?
D. Your car has the center rad, right?
E. Have you looked UNDER the car for the pink crusties that would suggest a coolant leak?
F. When was the last coolant flush?
G. Does your heater work well? It probably wouldn't if you weren't getting good coolant flow.

For my 2011 BS with 6spd, highway temp runs 186 usually, but up to 195 in traffic. Climbing the long hill to my house (at 7000 ft elevation) it was getting up to 210, which is about when my low speed fans kick on. I installed the third rad and it lowered the temp on that hill to 195 when ambient temps are below 70, but it still approaches 210 if it's 90 outside.

I've never seen a temp over 210, but I don't drive very hard. The one time I took it to the track for an HPDE, I never saw a temp over 200. Ambient temps that day were 60-70.

I've heard PDK cars run hotter than the manual cars, so my temps may not correlate directly with yours.

I found a lot of crud in my rads that I couldn't see from the outside, and it had only been a year since the last time I cleaned them. Yours could be dirtier than you think.
 

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Discussion Starter · #5 ·
First of all thanks for the response and help!

A. All three fans (left, right, engine) are working? - YES
B. What is "normal" temp on the highway for you? - 185 - 190 is a normal
C. When is the last time you cleaned your rads? - never
D. Your car has the center rad, right? - YES
E. Have you looked UNDER the car for the pink crusties that would suggest a coolant leak? - YES, haven't seen any
F. When was the last coolant flush? - never
G. Does your heater work well? It probably wouldn't if you weren't getting good coolant flow. - Yes, seems to be OK

when you cleaning the rads - you mean to separate them from condensers and clean external debris?
 

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I mean take the bumper off, gently separate the rad from condenser to let all the crud fall out, and use hose water or air to get in-between the rad fins. That's how I do it anyway, but there may be a more optimal process.
 

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Yes, condensers under both rads.

AFAIK, the water pump is not lubricated by oil, so you wouldn't see anything black coming from the WP if it failed.

Unless you had a strange noise or leaking coolant, I don't think I'd be concerned about the WP. I'd clean out the rads first.

The coolant temp behavior on these cars seems to be a lot different than other (non-Porsche) cars where I've monitored the temp closely, with a much wider swing during normal driving. It has been very difficult to find other data points to see what is considered normal for street driving. However, there is a lot of discussion on other forum and threads about PDK cars running very hot on the track, especially if equipped with an LSD. I've seem people mention temps of 250 during track events.

When did your temps start going higher, and when did you start monitoring them? Since the needle on the OEM gauge has not moved, perhaps 220 is still "normal" for a PDK and this is just because of the higher ambient temps of summer?

Anyone else monitor temps via OBD?
 

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You don't list your location or how long you've been monitoring OBDII temps, but could this just be normal for your location in the summer? Hotter air temperatures mean the radiators can't dump heat from the coolant as quickly which mean higher coolant temps at high engine loads, which mean higher engine temps as well.

The dash gauge is a sort of damped/dumbed-down display and while it displays temperature, it's not a linear response; it's calibrated to stick pretty much right on 180 whevenever temps are in the normal operating range. If it's near 180 for you, it means the ECU is content with your engine temps.
 

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Since the problem seems to be higher than normal temps on uphills and aggressive driving, but not at idle or low speed commuter traffic, you can focus on dirty radiators (inside the cores, not external), a thermostat that is not opening fully, and the water pump. I would guess the water pump impeller is worn and you are not getting enough coolant flow during the spirited driving sessons. A worn impeller can still push enough flow at lower RPMs which would account for it cooling down eventually. Slightly dirty radiator internals can cause the same issue. The seepage around the water pump is a warning sign of imminant failure coming, so replace the water pump sooner than later and see if you still have the problem. Be sure to replace the thermostat when changing the water pump as part of normal PM. BTW, seepage from the water pump is generally a small enough amount that you wouldn't notice a change in coolant level in many cases. An experienced tech would know that any gunk build-up is a sign of leakage/seepage; that area should be dry and clean.
 

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On my 2001BS, it was possible to build up lots of crud between condenser and radiator. Worth some disassembly IMO.


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Discussion Starter · #13 ·
Thank you all for your input - really really appreciate it !!!!

I'm leaving is southern Spain - it's pretty hot here.
but I do my driving at the early morning - so the temps are in 70-90 range.

I own the car for 4 years and have OBD since day one - so i can see that what i see now hasn't happen before.
i'm really glad for my habit from Miata days to use OBD - it enables to catch the issue before it becomes costly disaster.

So tomorrow i have a date in the shop.
Following your suggestions i will ask them to pay close attention on water pump and external radiators cleaning.
Of course if they decide that water pump should be replaced, the thermostat will be replaced too.

It's an indy shop - a lot of times they use TWR, Textar , Mann and other oem like products - i don't know what they have in stock for the water pump and the thermostat - should i insist on 100% Porsche original part?
 

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It appears your belt tensioner may be leaking fluid. It is that "mini shock absorber" thing in your picture near the water pump pulley. As it fails it will allow the belt to slip. I would chnage both the tensioner and the belt. Also realize when you shut down the engine the coolant flow stops and the temperature of the engine coolant will rise without the circulation of the water pump. Good luck.
 

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Discussion Starter · #15 ·
Update - went to the workshop today.
They said that water pump looks normal and they don't think that eroded impeller is a thing.
The soot in the WP area is, like Rob said, is form the belt tensioner - they said very little chance would affect coolant temperature.

They removed the bumper and gave good clean to the rads - i wouldn't say they were crazy dirty or blocked but obviously they were far from being clean. Some leafs and a bird were removed.

The next thing they said is a vents' speed - they said that vents should have 3 speeds and the 3rd speed can't be tested.
And at 80 miles they say the vents give more air flow than the natural air speed - sound weird to me but i don't know....
So next thing from their point of view is vents control unit (~200$ and located under front right headlamp).
 

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Was your shop able to control your fans with a Porsche tester? With that they can test the fans. If they don't have this type of tester find another shop otherwise they are randomly replacing parts at your expense. Did they separate the AC condenser from the radiator to get in between?
 

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Discussion Starter · #17 ·
They don't have tools to actuate fans.
I have Durametric basic and tried to do it - it didn't work as i would expect, but this might be not 100% correct sign.
When the engine temp is high the is working and pretty loud...

When cleaning - indeed they separated condensers from the radiators.
 

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This doesn't sound like an actual problem. These temperatures will vary with environmental and driving conditions. Temperatures in the low 200's are so far from an issue I suspect you're wasting time and money. Let's talk if you hit 250 and the temperatures are still climbing...


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