2001 Boxster S Engine Noise

[Wilson01S]

Hey everyone- New to the forum but after doing some research this seemed to be the most knowledgeable forum for the 986.

I just purchased a 01 Boxster S with 36,9xx miles on it. I bought this from an extended family member in S. Florida as a project- so I knew going into it that it has an issue.

It has a very loud, very distinct engine rattle/tap during the entire RPM band. I had the car shipped to RD Automotive in Albany, NY for their diagnosis and opinion. Listening to it today on the lift the noise seems to be coming from the Left (DS) cylinder head. The car idles and runs quite smoothly- if you can overlook the noise ha!

Has anyone heard a noise like this or similar? Any ideas as to what it might be coming from inside that little engine?

Here is a quick youtube clip I took of the car inside the shop.

2001 Boxster S engine noise 3.2l - YouTube

[BoxsterSteve]

Crap, that sounds awful!

Look for loose sparkplugs or exhaust manifold bolts, maybe.

[BYprodriver]

Probably a clogged lifter from not changing the oil often enough. You should change the oil & filter & inspect the filter for anything other than oil in it. Adding any sort of engine cleaner will make the problem worse.

Oh, welcome to the best 986 forum!

[Spinnaker]

I'll take a guess - broken valve spring.

[Timco]

Originally Posted by Spinnaker

I'll take a guess - broken valve spring.

This......

[Wilson01S]

A broken valve spring or collapsed lifter was what I thought to myself when I heard the noise and where it was coming from. Have any of you seen valve springs fail on such a low mileage, stock engine? A valve spring generally does not just fail without something causing it to fail. That "something" is what I am fearing ha!

[Wilson01S]

Well I ended up bringing the car home and tearing into it myself. I first changed the oil and inspected the filter to see if there was any major ferrous metallic particles in the oil/filter and if it would change anything. It didn't. Oil looked fairly clean/debris free. Some very, very, very small shimmering specs in the filter, but nothing I would say was major.

I next removed all the coils, and spark plugs to inspect for any obvious cylinder issues, oil/fluid contamination, detonation, damage. All looked ok, and all look like they were the correct color. No oil contamination.

Then I removed the accessory belt to see if that would stop the noise- again no change with engine running/belt off.

So yesterday I took the transmission out (fairly easy job and +1 for the pelican parts guide). Took me about 2 hours to get it out on my back. Anyway- I inspected the (recently new) clutch and flywheel area for any loose/backed out bolts or damage signs back there- all looked ok.

Removed the IMS bearing cover and the bearing looks brand new.

Now I am stuck as to what my next step should be. I guess I should have mentioned that myself, and a good mechanic friend took a second listen with the engine running and the noise seems to be coming from the area on the drivers side chain tensioner, and IMS bearing area. Originally the noise sounded like it was farther out toward the head, but with a good mechanics stethoscope, and a screwdriver to feel for vibrations it definitely seems to be coming from that tensioner/IMS area.

Has anyone ever experienced a bad chain tensioner that would make a noise like that? Mind you this car was checked for cam deviation and that was spot on. I checked the timing marks and it still appears to be in perfect time.

I'd hate to scrap this engine with the thought of it still being something simple, but I guess maybe it's time to look into replacements/reconstruction?

[Wilson01S]

Can the external tensioner (located on the rear of the even bank, near IMS bearing/flyhweel on the left side) be removed without locking the cams if the engine is not rotated?

I want to remove that tensioner to inspect for any obvious clues to the noise. Also it is leaking oil from that tensioner.

[woodsman]

whoa nelly! I'm pretty sure you need to lock those shafts in place. I don't know enough about this but my valves got bent when a 'Porsche trained" indy mech. installed a new LN IMSB. These engines are complex and my 2001S has 5 chains in there!!!

[BYprodriver]

Originally Posted by Wilson01S

A broken valve spring or collapsed lifter was what I thought to myself when I heard the noise and where it was coming from. Have any of you seen valve springs fail on such a low mileage, stock engine? A valve spring generally does not just fail without something causing it to fail. That "something" is what I am fearing ha!

When the engine is anywhere besides TDC there are valvesprings fully compressed. If the car sits for long periods of time (months) this can cause premature failure of the valvesprings.

I just posted on your thread in Pelican Parts with photo re: your next step.

[BYprodriver]

Originally Posted by Wilson01S

Can the external tensioner (located on the rear of the even bank, near IMS bearing/flyhweel on the left side) be removed without locking the cams if the engine is not rotated?

I want to remove that tensioner to inspect for any obvious clues to the noise. Also it is leaking oil from that tensioner.

You will need a new crush washer & O-ring to fix the leak.

See your post on Pelican forum.

[Wilson01S]

Originally Posted by BYprodriver

You will need a new crush washer & O-ring to fix the leak.

See your post on Pelican forum.

Thanks! I will check it now

[Wilson01S]

On a side note: How much free play is tolerable for the DM flywheel? When I was disassembling I noticed it probably had a 1/8-1/4" play left to right. Is this within spec for some movement? I know my measurment isn't exactly precise, but a rough guess.

[Wilson01S]

How much should the chain tensioner (nearest the oil pump) be able to collapse? It barely moves 1/4" and becomes rock hard. Doesn't appear to be any cracks on the contact pad inside the engine case, and the wear pattern is central on the end of the tensioner.

[BYprodriver]

Originally Posted by Wilson01S

On a side note: How much free play is tolerable for the DM flywheel? When I was disassembling I noticed it probably had a 1/8-1/4" play left to right. Is this within spec for some movement? I know my measurment isn't exactly precise, but a rough guess.

Your flywheel is great, tolerance is about 1/2"

[BYprodriver]

Originally Posted by Wilson01S

How much should the chain tensioner (nearest the oil pump) be able to collapse? It barely moves 1/4" and becomes rock hard. Doesn't appear to be any cracks on the contact pad inside the engine case, and the wear pattern is central on the end of the tensioner.

Is this the tensioner with the spring preload plunger? You should be able to compress it 1/2" - 3/4". To properly test it, place in hot clean engine oil 2" deep & pump the plunger. You should see dirty oil coming out making room for clean oil to go in.
Easiest to do this in a electric cooking pan @ 250 degrees.

[Wilson01S]

Originally Posted by BYprodriver

Is this the tensioner with the spring preload plunger? You should be able to compress it 1/2" - 3/4". To properly test it, place in hot clean engine oil 2" deep & pump the plunger. You should see dirty oil coming out making room for clean oil to go in.
Easiest to do this in a electric cooking pan @ 250 degrees.

Ok great. I pumped it in a container of clean, ambient oil for about 10 mins and it loosened up. I will do again with hot oil to make sure its all the way cleaned out.

I am afraid that the ~15k mi oil changes my uncle followed with this car sludged this engine. According to his service records it has had 3 oil changes in 36,975 miles over the course of 12 years HA!

I think some dirt and sludged oil may have partially or fully collapsed a lifter since everything else in the area seems to be in good working order.

Is it ok to run this engine with the trans out and the flywheel on? The engine is well supported, and I can easily put the exhaust on and support that without the trans in. I would like to listen for this noise again and be able to get closer.

**note I won't touch the flywheel

[Homeboy981]

Originally Posted by Wilson01S

Is it ok to run this engine with the trans out and the flywheel on? The engine is well supported, and I can easily put the exhaust on and support that without the trans in. I would like to listen for this noise again and be able to get closer.

**note I won't touch the flywheel

I had the same question too! We need a voice of experience here. Who has done it, please step forward!

[Wilson01S]

Originally Posted by Homeboy981

I had the same question too! We need a voice of experience here. Who has done it, please step forward!

Well I ran it for over an hour tonight with the trans out. Had the flywheel on and torqued, all went well! Had a slight drip from slave cylinder...that was the only real issue with it running with the trans out

[BYprodriver]

Originally Posted by Homeboy981

I had the same question too! We need a voice of experience here. Who has done it, please step forward!

Yeah you can, you just have to compensate for the missing transmission mounts.