engine temperature raising

[alexmd]

Hey everyone,

I'm new to this forum and just got my first porsche. It's a 2000 Boxter.

I bought it from a dealer and two weeks into driving the engine temperature went to about 3/4 and there was a knocking sound under that felt like it's coming from under the seats. I stopped the car right away and found that all of the coolant leaked out, by the rear passenger side wheel.

Took the car back top the dealer where they said that the thermostat got busted and there were air pockets in the coolant system. They said they fixed everything, but when I got the car back I noticed the engine temperature is still higher than half way (see the picture) and that's after about 15 minutes of driving.

If you guys could give ne sine advice on the following, I would really appreciate it:

1. Is this an actual problem our that's a normal Porsche engine temperature.

2. Could this be because they didn't fill up the system with a good quality coolant?

3. What could be wrong and how to fix it?

Thanks!!

[alexmd]

Forgot to say it has around 73k now, 2,7 engine, 5 speed manual and it's in the US.

[White987S]

That seems high. Should be on about the "8" in "180". Check your coolant cap (very tight, new, blue, part number ending in "04") and reservoir level. Maybe it needs to burp, and top-off. Make sure air intakes in front bumper are clean. And the front radiators. Do fans kick on? How old is water pump? How old is serpentine belt?

[Loren]

The need straight up (12 o'clock position) is perfectly normal.

[alexmd]

12 o'clock position is what I thought is perfect.

Cap is tight, coolant level is high.

Fans kick on, not sure about water pump and serpentine belt, should probably take it in for service, right?

It just kills me that I got it from the dealer after they did the repairs and there are problems right away.

[alexmd]

Small update.

Temperature goes up only when driving on traffic.

Took it to the dealer, they said the water pump is new, they have just replaced the thermostat, radiators look clean, no coolant leak.

They said they even wonder if there is a problem... which is bs.

[Hilux2400]

The coolant reservoir cap would be a good start. It's a cheap fix.  Mine looked Ok but it was leaking when under pressure. . 

 

If it's leaking even slightly the car will run at a higher temperature as a result of pressure loss in the system. 

 

H

[alexmd]

Thanks for this, any cap in particular you can recommend?

So another small update on this:

Took the car to an independent mechanic. He inspected everything and said the car is in great shape. At this point all I can think of is changing the reservoir cap, Hilux2400 suggested and stitching to Porsche branded coolant..

Will keep this thread updated once I have any news.

Edited February 12, 2015 by alexmd

[JFP in PA]

Thanks for this, any cap in particular you can recommend?

So another small update on this:

Took the car to an independent mechanic. He inspected everything and said the car is in great shape. At this point all I can think of is changing the reservoir cap, Hilux2400 suggested and stitching to Porsche branded coolant..

Will keep this thread updated once I have any news.

 

You want an OEM cap whose part number ends in -04 or higher.

[wvicary]

It's best to read the engine temp via a scan tool as sometimes the gauge can be off. If the fans are operating at all speeds and the engine isn't over heating then just keep an eye on things as it might be normal for your vehicle.

[alexmd]

Thanks guys!

[Firosche]

I had what I thought was a simular problem and I noticed that cleaning the radiators kept it closer to the "8" than before. They are in a bad spot as far as collecting leaves and debris between them and the condensers.

[Boxstah986]

Assuming the 2 front radiators have been cleared of road debris (must remove front bumper to gain good access), assuming the thermostat is new and system's new coolant fluid has been cleared of any air, and the coolant fans are working, then I would be suspicious about the "good" water pump.  The only way to know about the state of the water pump is to remove and inspect.  Quite possibly the impeller on the pump is not sufficiently tight on the pump shaft - if loose or damaged the impeller will not pump enough coolant to keep engine cool.   For my car 98 boxster I ignored recommendations about replacing the water pump with a fibered impeller.  Instead I ordered a Gates metal impeller water pump ($65) and that fixed my overheating problem.  This is a common problem with the BMW's - on the bimmerforum most writers recommend a metal impeller for the water pump replacement.   Also, by opening the coolant lid with car engine running and applying some short revving bursts one can see/hear the coolant fluid being pumped if the impeller is working.   Another test - with the car warmed up, crawl under the engine and with your hand compress the inlet and outlet sides of the water pump hoses - they both should be warm/hot about the same temperature.  If one hose is much cooler than the other then you have a bad impeller.

[wizard]

"Took it to the dealer, they said the water pump is new"

 

Porsche original ...... or something off e-Bay?

 

In the case of critical things like the water pump, it's always best to pay the Porsche price!

[wizard]

Oops. February 2015 post resurrected !!!

[Boxstah986]

If a Porsche brand pump is so great then why do they break?  Are they using better bearings than everyone else.  I do know that their fibered impeller approach is flawed.

[JFP in PA]

1 hour ago, Boxstah986 said:

If a Porsche brand pump is so great then why do they break?  Are they using better bearings than everyone else.  I do know that their fibered impeller approach is flawed.

 

Run a metal pump for a while and you will completely understand.  Porsche uses a composite impeller pump because there are only a couple of thousandths clearance between the front of the engine case and the rear of the impeller.  When the pump wears, and the shaft begins to wobble (which the all do, regardless of what type of impeller is involved), the composite pump will start to break up.  The metal impeller pump will start machining metal off the front of the engine cases, both filling the cooling system with fine metal particles that are both difficult to get out, and clog off some of the many small diameter cooling passages, both reducing the pump flow, and creating hot spots in the engine which leads to things like cylinder head cracks.  Once the metal impeller pump is removed, and all of the metal filings that can be removed are extracted using an arduous (read expensive) flushing process, a new pump, regardless of the impeller type, will not flow as much coolant, leading to a permanently hotter running engine.

 

We have seen the scenario play out multiple times on customers cars; there is an important reason Porsche used a composite impeller pump.......

[Boxstah986]

JFP in PA

 

If there are only a 2 thousandths of an inch space between the engine face and impeller rear (I think you meant "impeller front") as you attest then the  Porsche engineered pump is designed to fail and thus destroy the engine, regardless of the impeller's material substance.   Instead, I believe the plastic impeller would loosen from the shaft long before the bearing wears enough to be torqued by the serpentine pulley to cause the abrasion you described.

 

A more probable scenario would be:  the plastic impeller will get lodged and stop turning, thus won't pump.  The expensive engine will overheat and crack the heads, score the rings, etc.   Also, both plastic and metal impellers have a slope to their design, so the bulk of the material geometry would not erode away due to abrasion as you suggest because the slope emanates away from the engine face.   

 

 A metal shaft with a metal impeller is a much better design:  it  equates to similar material with the same thermal expansion coefficient.  Also,  plastic parts can break off in chunks to stop up a coolant block whereas metal parts will be tiny flakes .  A coolant flush every now and then would wash away the metal flake risk and help lubricate the water pump bearing.   I doubt if a flush would wash away any chunks of plastic.

 

More likely, if the bearing wears enough to allow the shaft to wobble then the seal will leak, and you will notice the coolant fluid leaking from the water pump housing long before significant impeller parts are scattered throughout the coolant jacket.  One can hear the rubbing noise if the impeller were metal.  A plastic impeller would probably remain silent to the unsuspecting driver.  This is why a well designed metal water pump had a hole in the housing so the fluid would leak out slowly to alert the unsuspecting driver/mechanic.  Also,   the impeller on the water pump would push the coolant outward thus thrusting the impeller away from direction of water flow (Newton's third law of motion - for every force action there is an equal and opposite force reaction.     So, I can not buy into your abrasion theory.

 

I'll stick to my fully metal water pump design on both my Boxster and M3!

    

[JFP in PA]

1 hour ago, Boxstah986 said:

JFP in PA

 

If there are only a 2 thousandths of an inch space between the engine face and impeller rear (I think you meant "impeller front") as you attest then the  Porsche engineered pump is designed to fail and thus destroy the engine, regardless of the impeller's material substance.   Instead, I believe the plastic impeller would loosen from the shaft long before the bearing wears enough to be torqued by the serpentine pulley to cause the abrasion you described.

 

A more probable scenario would be:  the plastic impeller will get lodged and stop turning, thus won't pump.  The expensive engine will overheat and crack the heads, score the rings, etc.   Also, both plastic and metal impellers have a slope to their design, so the bulk of the material geometry would not erode away due to abrasion as you suggest because the slope emanates away from the engine face.   

 

 A metal shaft with a metal impeller is a much better design:  it  equates to similar material with the same thermal expansion coefficient.  Also,  plastic parts can break off in chunks to stop up a coolant block whereas metal parts will be tiny flakes .  A coolant flush every now and then would wash away the metal flake risk and help lubricate the water pump bearing.   I doubt if a flush would wash away any chunks of plastic.

 

More likely, if the bearing wears enough to allow the shaft to wobble then the seal will leak, and you will notice the coolant fluid leaking from the water pump housing long before significant impeller parts are scattered throughout the coolant jacket.  One can hear the rubbing noise if the impeller were metal.  A plastic impeller would probably remain silent to the unsuspecting driver.  This is why a well designed metal water pump had a hole in the housing so the fluid would leak out slowly to alert the unsuspecting driver/mechanic.  Also,   the impeller on the water pump would push the coolant outward thus thrusting the impeller away from direction of water flow (Newton's third law of motion - for every force action there is an equal and opposite force reaction.     So, I can not buy into your abrasion theory.

 

I'll stick to my fully metal water pump design on both my Boxster and M3!

    

 

To disprove your logic, we have never seen a composite impeller that slipped on the shaft from the jamming you propose, but have removed a mountain of them with blade tips worn away from contact with the engine cases after the shaft bearings  wore loose and the impeller began to wobble.  Porsche acutally tested and evaluated both composite and metal impeller pumps, and went with the composite design as a scraficial componet to prevent permanent case damage.

 

 

But by all means, feel free to use what ever you please; after all, it is your car, and your money; and you will the one that has to deal with the consequences.

[Boxstah986]

Referring to your picture I see that Porsche finally put a metal ring to connect the fibre to the shaft.  So even they believe that part of the impeller assembly should contain metal.

[Yong Kim]

What's the normal operating temps for a boxster.  I am getting worried about my temps as well. I am constantly seeing temps in the 215s.  Also once temps get up to that temperature I feel a bit of vibration in the steering wheel, but it does not vibrate when its in the lower temps when the car is still warming up.

[White987S]

Young Kim, mid 180s (highway cruising) would be better. Make sure your front fans are properly working, both low and high speed. May also be a good time to pull the front bumper, and do a thorough cleaning of your 2 front radiators.  Check coolant level. Be prepared for a new water pump (including coolant flush and new thermostat) of all else checks out.