replace thermostat without replacing waterpump - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Hi Guys, So recently I bought the LN low temp thermostat almost as an impulse buy while purchasing my spin on filter kit. I checked Wayne's instruction on replacing this item here ( http://www.pelicanparts.com/techarticles/Boxster_Tech/34-WATER-Thermostat_and_Pump/34-WATER-Thermostat_and_Pump.htm ), but it seems to be more geared toward replacing water pump. Thermostat instruction is added in almost as an after thought. So my questions is if I only want to remove the thermos, will I need to follow the entire tutorial and remove the tension belt, remove the water pump, ect? Can I take this step by step short cut ? PS. Please keep in mind that this is a technical question so lets keep the answer technical. I realize that some on this forum are very opinionated about this mod, but since its already here sitting on the shelf, kinda moot to argue the validity of the item here. Thanks for all your advice !

I replaced my t-stat with the LN low temp unit a year/half ago, without replacing the water pump. Wish I'd known of Raby's recommendation to replace the pump every three years, because now I have to do the coolant project again this spring when I do the replacement. To answer your question, you can R&R just the t-stat, but if your pump is original (like mine) or older than three years, do them both. And don't use brandX coolant...the Porsche OEM stuff is cheap insurance.

But why? Ok. The water pump isn't cheap, but it is cheaper than the damage you will sustain if your existing pump fails. You have to drain the coolant anyway. Why not update all of your parts?

Yes you can install the T'stat as per your step by step instructions. If you're filling the system without a vacuum pump, I would flip the pressure release clip and drive for a couple of days with it open, topping up the coolant as required. I mirror jmatta's comments exactly - replaced my T'stat 18 months ago but only changed my water pump in January this year. Its no biggie, but most of the time is spent jacking up the car, draining and (especially) refilling the system.... If I had to do it again, I would replace all 4 componants (pump. T'stat, polyrib belt & Porsche coolant) at the same time - then I'm good for the next 3-4 years.

Thanks for all the great advice guys. I guess I just didn't want to replace the water pump. Being a novice garage tech, I was just a bit intimidated by the belt replacement. I never knew our OEM water pump with its plastic blade degrade over time and sends bits and pieces flying into the engine. I'll be looking to order a metal fan pump now though. Does this look like the correct one I should order ( http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=996-106-011-55-M59&catalog_description=Water%20Pump%20%28requires%20o ne%20996-106-340-54-M30%20gasket%29%2C%20Boxster%2FBoxster%20S%20%2819 97-04%29%2C%20Each ) ? Oh, and by BrandX coolant, I didnt mean cheapest flavor of the week at Kragen. I just didn't do enough research yet to know whats the best brand to use.

There was talk a while ago about steering clear of the metal bladed water pumps. If I remember correctly, its possible that if the pump bearings collapse it allows the metal blades to drop & wear through the alloy crankcase wall - you can guess the outcome of that. My pump which was 10 years and 48,000 miles old when I removed it had no damage to the pump vanes and visually looked the same dimensions as the new pump. But costing only a couple of hundred dollars, I strongly believe that this type of preventative maintenance is a no brainer, considering the damage (not to mention the considerable inconvenience) of a failed water pump....

I didn't know that any of the water pumps were available with metal vanes. That confused me because American car makers have had metal vaned water pumps forever, and don't have any problems with the vanes breaking or bearings collapsing. I'd just replace it every few years. The belt is super easy. Put a piece of masking tape on it indicating which way it goes before you remove it though. You will likely have to trim the water pump gasket though. The Bentley manual tells you exactly how to do that.