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Recommended Posts

MY99 C2 85k miles.

When I start my car there is a vibration coming from the engine compartment. RPM are steady, no leaks,no noises, no errors recorded with the PST2. The car has been driven and everything is like normal but the vibration is a concern.Any ideas?

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If they are leaking or stretched (your exhaust tips sit lower than normal), then they are shot. If original, I would bet they are very weak if not shot already. For DIY, I guess it's so simple that no one bothered to write a full one. Check here for instruction http://www.renntech.org/forums/topic/42353-to-remove-the-engine-mounts-i-remove-the-bottom-bolt-first-right/?hl=%2Bengine+%2Bmount#entry226237

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I just replaced my mounts yesterday. I was really surprised how much they were sagging! My 99' only has 43k miles, but I think it may be a result of age more than wear. My passenger seat would vibrate while at idle at stop lights and it was driving me crazy. It really made a HUGE difference! I even think it shifts smoother now.

I'll try to get a picture on here of the difference of the old and new one next to each other.

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Mine were weak already at 28k miles/5yr. Replaced under extended warranty. Felt like I got new rear suspension and shifting became better too. Vibration was much less with the new mounts like you said. I can only imagine the diff they make to higher mileage/older cars.

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Checked the mounts but did not see any leakage although that does not means the mounts are OK. Read some posts where there was no leakage and the mounts were still bad.

Will be getting the mounts next week. Already copied the DIY steps in order to replace them. Will update.

Edited by hi8ha
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Well it was not the mounts. My wife was driving the car, yes she did but I had no choice, she calls me, the red light by the water temperature gauge flashing, She also mentioned smoke. Other than that all ok . Temp within normal, etc. Water expansion tank lower than minimum. Had refill the coolant 2 or 3 days before. She refilled the water expansion tank. When I checked the car the tank was lower than minimum. Refilled the tank, started the car, the red light by the temp gauge not blinking any more. Checked the rear bottom of the car....water dripping from the water pump area and a noise like a bad ball bearing. I'm sure it is the water pump. Order it today.

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God the water pump. Some questions though, Should I put silicone sealant on the gasket? On the Pedro's Garage website there is a technical article where he mentions that any OAT (Organic Additive Technology) coolant can be used on the Porsche.

He named the following coolants as good to be used: Peak Global Life Time, Pennzoil Dex-Cool Extended Life, Prestone Extended life, Zerex Dex-Cool Formula. Any opinions?

From the Pedro's Garage technical article: "The recommended antifreeze for our Porsche vehicles is the OAT type.

Many of the famous, over-the-counter brands offer OAT coolant with an aluminum-protecting inhibitor package and contain no silicates, borates or phosphates and will be stated as such on their labels. Generally these are called “Extended Life Antifreeze Coolant”."

It is an aftermarket pump so it has the metal impeller, how bad could that be?

Edited by hi8ha
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IMHO Any phosphate free coolant that gets changed regularly wont be an issue...

Metal impeller = good, aftermarket, fine. i stay away from white box made in china el cheapo brands.

make sure the new pump spins freely by hand on and off the engine. you don't want it grinding the block.

A search should reveal lots of info on replacing the pump if there isn't already a tutorial.

That pump would have to be really really bad to cause a vibration in the cabin so dont freak out if that idle vibration is still there afterwards.



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It is an aftermarket pump so it has the metal impeller, how bad could that be?

Very. Porsche uses a composite impeller rather than a metal one for a very simple reason: When the water pump shaft bearing wears and begins to wobble (and they all do), the composite impeller will break up but not do any damage; a metal one on the other hand will do severe damage to the engine case in the rear of the water pump housing.

There is also nothing wrong with Porsche's OEM coolant; mixed with distilled water, it will last for many, many years

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Thanks JFP

Sending the part back on Monday and getting the one with the composite impeller. Better safe than sorry.

How about the coolants I mentioned above?

We do not use anything except the OEM Porsche coolant; it has proven to have a very long life (we have seen it go 8 years without issue) and do an excellent job. It is also not all that expensive, and readily available. It is also well known to have compatibility issues with some aftermarket products, which can lead to a gelatinous mess. Most shops are aware of this and stay with what is known to work, and like us will only add distilled water to any car that they do not know for a fact has the OEM coolant in it.

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Good point on the impeller.

Most of our clientele come in demanding metal impellers because they don't want the impeller failing. The flip side is the bearing failure being more damaging.

Im an advocate of selling OEM as much as possible but you can only lead a horse to water.

Believe me; they will feel a whole lot different when the metal impeller starts boring a hole in the engine cases, filling the cooling system with fine metal filings that are nearly impossible to get out of the system. Even if you could clean up the mess, and the cases aren’t totally destroyed, the new water pump will not be able to move the coolant effectively due to the damage (the gap behind the impeller is now too large), and the car will want to run hotter than it already does.

It is not about OEM vs. aftermarket, but it is about not killing things unnecessarily…….

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