Rattle on Startup

[Wrencher]

Greetings from a Porsche Noob.

I have aquired a '98 Boxster that belonged to an older gentleman that now has Alzheimers, and sat for about a year and a half. I replaced the tires, fueled it up, checked the fluids, replaced the battery and fired it up. At first, I thought I had the rare diesel model, but it did quiet down rather quickly and after bringing it up to temperature, and I drove it 20 miles with no further drama. It ran well for 180K, although the "check engine" light assured me there was "something wrong", and the "brake wear" light (red) pretty much gauranteed my certain demise!

Upon restarting it in the morning, I experienced the same "clatter" for 3-4 seconds, then it ran sweet. Same thing over the next 5-6 starts, after sitting for no more than ten minutes or so.

After searching this forum (I love these things!), I have found a bewildering array of potential problems and I'm wondering where to start. I have wrenched on everything from a Talon F-5000 to a Trans Am Tom Gloy chassis, So technical is no problem. Just want to find a starting point and decide the best direction to proceed. Any advice is well appreciated, thanks in advance!

Hans

[Jake Raby]

Replace the timing chain tensioners.

[Pdwight]

My 01 S rattles ever so slightly for about 1/4 of a second.... but it is so brief I did not give it much concern . The other Boxsters I test drove were much much worse..but mine quiets down super quick even if it has been setting for over a week. Usually what Jack says is dead on and I would take it to heart.

[Timco]

Had same issue. It was water pump impellers rubbing the housing. Always went away shortly after startup. Silent now. At least check this. If no slop in pulley with belt off (remove belt, start car. If no rattle then it's some bolt on component) then tensioners are sticking. Don't just remove them. Some advise special procedure here.

[Pdwight]

I have a water pump job on the books now for the fall....just hit 70K and I would rather catch it before it dies....low temp Tstat at the same time.

Question , how does the underdrive pulley generate more horsepower ?

Is it just greater mechanical advantage or what ??

[amagalla]

Originally Posted by Pdwight

I have a water pump job on the books now for the fall....just hit 70K and I would rather catch it before it dies....low temp Tstat at the same time.

Question , how does the underdrive pulley generate more horsepower ?

Is it just greater mechanical advantage or what ??

Technically speaking, it doesn't generate any HP. The reason that it's call an "underdrive" pulley is that it underdrives the accessories (the water pump, alternator, power steering, etc...). That means that the HP that those accessories steal from the engine, can now be put into the rear wheels.

Hope that helps.

[jpc763]

Originally Posted by Pdwight

I have a water pump job on the books now for the fall....just hit 70K and I would rather catch it before it dies....low temp Tstat at the same time.



Question , how does the underdrive pulley generate more horsepower ?



Is it just greater mechanical advantage or what ??

My 2001 S is in the shop for (I fear) is a water pump. What is this "low temp thermostat you refer to?

Thanks, John

[Coaster]

Originally Posted by jpc763

My 2001 S is in the shop for (I fear) is a water pump. What is this "low temp thermostat you refer to?

Thanks, John

Lot's of threads talking about them if you do a quick search. Here is a link to get you started.

Pelican Technical Article: Boxster Water Pump & Boxster Thermostat Replacement - 986 / 987

[DennisAN]

With a lower miles car you might get away with just cleaning and re-installing your 3 chain tensioners. Check for posts on "boiling" the tensioners in a pan of hot Marvel Mystery Oil. They are about $120 each. But at your mileage....

Is the engine original? Many 1997 and 1998 Boxsters had their engines replaced. Check the engine serial number on the passenger side of the engine - it's pin stamped on a small raised boss. You probably will need to clean it to read it. Replacement engines have an X in the first few letters.

[runjmc2]

How many miles, 180K miles? Do have have the CEL code, if not a $40 acrton scanner will read them? The CEL engine light may be entirely unrelated. My '97 is loud at startup, and louder the longer it has not been started. Depending on the CEL code and mileage, addressing the start up noice may or may not be cost effective in the long term.

[Gelbster]

Wrencher,
If you decide to investigate the chain tensioners ,this may be useful:
http://986forum.com/forums/performance-technical-chat/52043-cam-pre-tensioners-timing.html#post411549
The diagram here may help also:
http://www.pelicanparts.com/techarticles/Boxster_Tech/16-ENGINE-Camshaft_Swap_and_Chain_Tensioner/Gp1800.pdf
But please promise to let us know what the problem was and what fixed it -otherwise it doesn't help us to help others.