Meridian Boxster Rebuild Project '24
 

Well, here we go again, probably the last thing I needed now was to get another Boxster, especially one that needs a new motor. I tried really hard to swipe away on fb marketplace but this thing kept coming back and finally I couldn't resist and went to see it. Not that I wanted to buy it at that point, I was just curious to see a 22 year old Boxster with only 22,000 miles on it and it was nearby. The car was in pristine condition, my daily driver Boxster S Tip seemed like a real s**tbox next to it, even though I put quite a lot of work into that in the past two years. The owner tells me the car was a garage queen in the family throughout its whole life, meticulously maintained with all the receipts and everything since day one. The only tiny blemish is, khm, the engine, which one day, after a loud bang, stopped working. At the shop the owner had been told the engine probably suffered a catastrophic engine failure and needs replacing. Since I have a complete S engine in bits stored in boxes in the shed, I quickly convinced myself (and my wife) that I should not pass on this.. The owner was also super nice and we made a deal.


Not sure at this point how long it is going to take to get it back on the road again, hopefully not as long as the Blue Boxster took http://https://986forum.com/forums/show-tell-gallery/73917-blue-boxster-resurrection-project-10.html, but I thought I'd start a thread about it just to document the progress. Here's a few pictures as a start:

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Looks like now that I own another wrecked Porsche I will have to change my lifestyle accordingly.

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Yep, that's the correct reading.

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Tip got company.

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Oil's clean, that's a good sign. All fluids were replaced shortly before the big bang.

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:cheers: Awesome . I'm really curious to see what you find with the engine. Most 'big bang' failures I've seen make chunks and metal in the oil. Does it turn by hand?

Hopefully you can bring it back to life with manageable effort. Fingers crossed.

Yeah! That's the whole point, curiosity! What an earth could go wrong in a well-maintained Porsche at such low mileage?

The crank moves, but I didn't try turning it a whole revolution just to avoid messing things up even more. Not that it matters, of course.

Also, I got this code below, indicating the cams at one bank are not in sync with the crankshaft.

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Even though the oil was clean, I dropped the sump and found these tiny steel goodies:

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They seem chain roller pieces to me. Luckily, this is a 5-chain engine, so there's 4 more if one's shot.

The internals otherwise are looking great.

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Thanks!! :cheers:

I jacked up the car and fixed the top in service mode.

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Subwoofer. This was an expensive feature back in 2002.

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Lots of dust on the engine, otherwise everything looks great.

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Nice front view also. I haven's seen such a clean head in a long time.

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This mess on the underside is unexpected at this mileage. Looks like a Toyota at 500.000 miles, lol. Most likely we have an RMS leak that has not started recently...

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This is also something you wouldn't want to see when pulling the plugs..

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I wondered a bit what to do at this point. Shall I pull the head cover with the motor in the car on that side where I have the error code and see what's going on with the timing, or just pull the engine and inspect things on the engine stand which is a lot more convenient? I opted for the latter.

I took these guys off just in case someone gets tempted to take a peek under the jacked up car at night. My neighbor's cats got stolen on the driveway last year.

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Two shots of the engine from underneath without cats and driveshafts.

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I see that the engine still has the plastic-cup oil filter thingy. Those sometimes become extremely tight, requiring, I estimate, 250+ ft-lbs to remove. I suggest you remove that from the engine before you remove the engine or transmission from the chassis. Exerting that much force on an engine on a stand only serves to move the stand across your shop. IMHO that plastic cup is the second-worse thing Porsche ever did, after locating the immobilizer module under the driver’s seat.
Oh, also: to remove the oil filter cup, use the aluminum filter wrench branded as Craftsman and sold through Lowe’s, but be aware that you likely won’t be able to remove the cap wrench from the plastic cup once you get it off.
Good luck with project!

The spark plug doesn't look good.

Fingers still crossed. ;)

Yeah, it certainly does not. I don't really get what that spider web-looking dirt might be. Even if the valves stayed open for months no animals should get in there because both the intake and exhaust side is closed.

Anyways, upon closer inspection through the spark plug hole with a borescope, this is what I can see:

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That curvy line on the piston top looks like a valve-contact.

Could also be some kind of scratch. But a photo of a not so good screen is often misleading.

Valve seems more likely. Is that the cylinder the spark plug shown above came from?

Well, unfortunately this means engine out - needs to be investigated further. :(

I already passed that point...

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Here's a couple pics along the way:

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The friction disc is not too bad, but worn asymmetrically, so probably I'll just get a new one. Hopefully it's sold separately.

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Leaks..

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Look at that mess around the AOS. Probably the O-rings got brittle in the past 22 years. Or it was just a crappy design in the first place.

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Crappy design?

Designed for a car lifetime of 10 years - and still kind of functional after 22 years. So what do you mean? :D ;)

BTW: jealous of your neighbours. My neighbours would kill me if i would do an engine out on the driveway. ;)

True. A little oil leak won't affect functionality. Also, one bank is still totally fine. Not too bad for a 22 year old car. ;) Downsizing engines to 3 cylinders is kind of popular nowadays anyway. :)

Yeah, they don't see much of this, I park the family minivan in between his car and the Porsche (we share the driveway). He's nice, he comes by every now and then just to express his genuine surprise of seeing what's going on there. Once he even offered his help :D. I don't make a mess that would affect them anyhow.

Further insights into the engine.

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Stripping the top.

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Something seems off here.

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Yep.

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Everything looks clean and nice inside though, no sludge, deposit. etc. This was indeed a well maintained car.

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Ouch...

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Well, i think you found the problem. ;)

Hope there is no excessive damage to the engine casing. Sometimes these chains can do ugly things

How does the IMS look?

How do pistons, rods and valves look?

The casings seem fine, I haven't discovered any damage on them so far, which is great.

IMS looks great too. Rods look fine, pistons have slight damage but seem reusable, I'll have to do measurements though. Several valves are bent. I'll upload pictures later.

The question is, why did the chain snap? Tearing a dual row chain apart like this requires quite a bit of force. However, I think I found the answer for that.

Inside the scavanging pump, that's a crack right there:


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Yep, the rotor is broken.

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It clearly picked up something which seized up the pump and hence the camshaft, that's why the chain snapped. I can make out the piece that's now melted in the pump housing.

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But I have no idea what it may have been and where it came from. So far I haven't found anything that came loose, missing bolt, etc. So I'm puzzled. Anyways, the engine obviously needs to be taken apart to the last bolt.

Hm, looks like something hard did get sucked through the scavenger pump. Doesn't look like a normal wear pattern. That could have blocked the pump and things happened. The question is what got sucked into the pump? In my opinion, it must have been something hard like metal.

The IMS bearing is completely intact? No single bearing ball is missing?

Were you able to identify where the metal parts in post #4 came from?

Exactly, something got jammed in between the rotor and the pump housing. It's kind of visible if you look at the picture carefully. It's not there anymore. But clearly, that's what seized up the camshaft and consequenly snapped the chain.

IMSB is in perfect condition. A ball couldn't just escape without ripping the whole thing apart. Those metal parts in the sump are remnants of the chain rollers.

Here's a picture of the IMS bearing. No sign of damage or even wear.

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The sprocket also looks fine looking down from the head. The bottom sprocket is the mirror image :)

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Head off.

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Tiny marks from the intake valves.

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Or, in this cylinder, from the exhaust valves.

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All valves should be closed with the camshafts being off. The reason why they are open is they are bent. It's not very much of a damage after a timing chain failure.

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On its way onto the engine stand. The other bank was all right.

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The oil pump rotors also have some slight chips..

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Further pieces from the chain in the bottom of the case. I'm glad I decided to tear it down totally.

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A chain shrapnel melted into the crank-to-IMS chain guide..

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Hope you'll find all metal pieces.

Would be bad if you rebuild the engine and something is left in there that causes future damages.

The chain guides look pretty good. Seems the mileage of the car is correct.

For sure, that would be an absolute disaster.

Yeah, most parts show really low wear representing the low mileage, while others are kind of puzzling and I just don't get it. Look at the main bearings for instance.

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The crank seems fine, but the bearings show quite a bit of wear. However, the thrust bearing washers have no wear, underlining the low mileage.

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Especially around the small windows where the oil gets in there's a lot of wear, suggesting there was something in the oil and made most of the damage here. What I don't understand is, how can the debris get through the filter?

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Also, it seems most of the damage can't be accounted for the chain snap, I think this wear had happened before... Just in comparison, in the other engine I rebuilt there was literally no wear on the bearing shells, at 100.000 miles. This engine had 22.000 in it...

This car was a garage queen. Since it is 22 years old, on average it ran 1000 miles/year, meaning probably there were several month-long gaps when it was not running at all, which is not really healthy for the bearings for obvious reasons. Still, hard to believe that this alone could have caused this much wear.

That is pretty easy to answer. The oil filter has a valve / bypass. The valve is actuated by a spring. If the oil pressure is too high – especially when the oil is cold – the bypass opens and unfiltered oil runs through the engine. Sometimes these springs also get old. And in the 9x6 oil system the spring loaded bypass is not part of the oil filter itself, but of the oil filter housing - so potentially never gets replaced.

The rod bearing wear doesn't look evenly to me. That should be investigated further.

Thanks for the tip, I never had a problem with loosening that cap. A kit is available to convert it to a spin-on type filter and then you can choose different filter materials with different filtering pore diameters.

Yeah, that's a possibility, but the bypass valve should only open when the filter gets completely clogged up. This was not the case in this engine. I think the wear on the bearings would look different also. I opened up the filter and it looks like this:

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Hundreds of these tiny metal chips. I also found one or two on the back side but I'm not sure if they made it through the filter material or I just contaminated it when I cut the filter apart. Anyways, I think if these pieces went through the main bearing clearances they would have left a lot of scratch marks on the bearing surfaces and even on the journals. Instead, the wear on the bearings looks smooth to me. So it's more like a wear caused by oil starvation. I'll look into the spin-on filter conversion though, that adds some extra protection against the old bypass valve failure also. Thanks for the tip :cheers:

I didn't post pictures of the rod bearings. If you meant the main bearings, there is indeed some unevennness. One side must have undergone a lot of impact when the pistons were hammering on the valves, that force went down all the way to the main bearings. This could cause some asymmetry in the wear pattern...

Sorry, but you're wrong on that. It will also open if the oil pressure exceeds a specified pressure level. And this can also happen when the oil is cold and thick.

That explains the main bearings (i meant main bearings, sorry. English is not my mother language).

Because of the metal chip contamination, all bearings should be checked.

Yes, you are right. I'm not sure though if at this climate the oil can get that thick.

Mine neither :)

Any news? Any new findings?

Not much, really. I did some measurements on the crank journals, they are all uniform and don't show any wear, so I dropped the crankshaft off at a machine shop for polishing. I ordered new bearings, once they arrive I'll assemble the bearing carrier, so there's that. Regarding the wear on the main bearings, I contacted the original owner to get to know more details about the circumstances of the failure. He says the engine was running for about half a minute after the bang and it was running pretty rough. So, it's surprising that the engine did not just stall, with only 3 functional cylinders. It's also interesting to consider that it was running without oil returning from the head to the sump, potentially resulting oil starvation at the main bearings at idle..

I've been busy with lots of other stuff but now I'm back at this project. Weather is getting awesome here and my kids also keep asking when we'll have a working convertible again, so I better keep up the pace.

I got the crank back from the machine shop (months ago...). The machinist (it's a one man shop) polished the journals, mic'd them and said it's good to go. Now they (the journals) are smooth and shiny.

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I cleaned and tested the squirters and put them back in.

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Fresh set of bearings.

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I checked the clearances all around with platigauge, just in case. Everything is within specs.

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I replaced one thrust bearing also as it showed some minor wear.

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Torqued down.

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The bearing carrier is now ready for the conrods. I'll throw them in once I received the new rod bolts from Pelican.

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The engine I'm assembling had oil starvation since the previous idi--owner drove it after the cam tensioners had disintegrated. There was debris blocking the oil pickup pretty much completely. The only effect was one main bearing toasted and the others had a little heat. The crank needed only a polish on the one journal.
I reassembled the bottom end and found a tight spot. Looking at it again, there were high spots in one shell. I'm going to follow professional advice and just try smoothing with some grey Scotchbrite.
Otherwise, I'll just get another shell.
Did you use the ARP bolts for the crankcase? I found it helpful since they are reusable and I have definitely used that feature!

Yep, worn cam tensioners is a typical failure, one of my previous Porsches had to be rebuilt for the same reason, the tensioner wore off, fell apart, then the chain jumped over one or more teeth.

These high spots are surprising because the whole unit is pretty robust and should survive some extra heat without being damaged. Did you tighten the bolts down to the secified torque in the correct order? The bearing carrier halves have to be perfectly and evenly bolted to each other so the clearances will be the same all around.

I used genuine bolts.

Replacement IMS and fitting new bearing
 

This car had the single-row, small bearing, which is the weakest of them all. Although it's still perfect and shows no wear, I didn't want to just leave it as is.

Luckily I have a few more IMSs lying around that I can pick from.

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The right most is the original. On its left is the newer IMS with the non-servicable bearing (not in place). To one more on the left is a similar one, with a flange. I found this on ebay a few months ago for a good price. This is the one I'll go with.

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Deflanged.

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Extracting the old bearing.

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Side by side is a small bearing and the larger kind (6305).

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This is new replacement bearing chilling in the freezer to accompany some ice creams. The next morning I heated up the IMS in the oven. If you do this installing the bearing does not require any force, it just slides right in.
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Spins nicely with negligible runout.

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I added a Hartech-flange to the assembly instead of the original for increased lubrication by the splashed oil.

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Since that post I have been fortunate to work with an experienced mechanic close to one of the major M96 sources (and worked there.)
He was worried the crank was bad so we had it checked. It's good so we are going with new bearings. He doesn't like the coated bearings and thinks that is the problem or there is an issue with the carrier.
I had really aimed for getting this on the road this summer, but as these things go, that is looking less likely.

Yeah, it takes a lot longer than one would think.. Especially if you get lost in the details. What are those coated bearings like?

They look like bearings to me, but I'm not remotely an expert! All I know is they are substantially more expensive than your basic Clivites!
Yes, it has taken longer than I thought. I've been amassing parts for a while, and in fact, noticed a box dated 2020 just yesterday. But there are a couple of factors like a 1000-mile move and a second bad engine, but we'll skip over that.

Joining the cases
 

I had some progress with the engine in the past weeks (months?), starting with some clean-up. Case halves drying in the sun.

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Ready for the crank assembly.

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Here it goes.

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Chains...

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Gapping the new rings.

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Torquing down the rod bolts.

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Case halves rejoined. :cool:

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Home made tool to make sure the casings are perfectly aligned. There's a factory mandrel that fits into the bore of the IMS bearing (not the imfamous one, but on the other side, by the oil pump) and holds the case halves aligned.

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Pulling out the tool.

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The newer Boxsters differ from the base model regarding this circlip. The base model has a simple circlip, while the newer version has a lug that needs to be installed in a specific position making the whole proces a bit more difficult.


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Borescope-view of piston pin #6.

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Amazing clarity with that boescope! When we assembled mine, I could barely make it out. On that topic, Jake says in the video he just clips that lug. My mechanic friend who has LN ties, doesn’t, but it would seem to complicate assembly.
As far as the rings, the Mahles were pretty much right in the ballpark, not needing any filing, except one was slightly looser but still acceptable.

Yeah, I tried a couple borescopes, I got lucky with this one, it stays in focus even when it is really close to the object, while the others became blurry,.

Actually it doesn't take longer to install the circlip with the lug, you can clearly feel where exactly it is by gently rotating the tool in the piston pin bore. I don't think it's a smart idea to clip it off, but unnecessary at the very least.

I used Mahles too, but they were all tighter than Mahle specs so I needed to file off a little bit of each.