OT: 2003 Boxster S engine replacement Options

[jesiv]

Jake

Thank you for your response! A wealth of information. Funny you mention water pump. My water pump blew in my driveway about six months ago. Gunter/dealership was initially concern about possible fragments in the system. However upon replacement didn't feel it was an issue. This evening I was wondering if a fragment finally made it to the head and then... Localized heat build up and poof!!

I am trying to decide what to do. What would be your recommendations?

Thank you for the help

Regards

James

[Woody]

You need someone with a clue about M96 engines to really diagnose this.. You won't find that at the dealer level, we pluck cars out of dealer lots all over the country and save them weekly after being deemed junk.

Pretty broad statement there buddy.

[Jake Raby]

Now.. Wonder how I guess about your failed water pump in the past? Thats right, because that is what led to your current issue.

What has taught us that? Nothing more than extracting pieces of broken impeller blades from the depths of the cylinder head after milling cracks open so they can be repaired.

Failed water pumps create collateral damage like this. That judgment call that was made has put you where you are today. See the August 2012 volume of the Excellence Magazine Tech Forum for an article that Tony Callas and I put together on this very topic. That article stemmed from seeing this over, and over and over again and to the point where I can tell the customer the story that unfolded (almost verbatim) as soon as they tell me "I have a blown head gasket".

"What to do" is entirely dependent upon how much you love the car. The thing you don't want to do is continuing on the path you have been on. You probably just need to pop off the heads and have the one repaired, then have both ultrasonically cleaned and pressured tested. Then clean the internal passages within the block to clean the other debris from it and go back together with it.

I have instructed two of my M96 engine mechanical classes in your area in the last two years. Those who have attended have been instructed on the proper method of resurrection for this mode of failure.

That said, the crack that you have WILL NOT show up on a conventional pressure test, the opposite side of the head must be pressurized and thats not easy to do or to evaluate. This crack has bitten me in the ass in the past on one occasion.

Today we had our very first "double whammy" cylinder head crack.. Thats right, one engine with BOTH cylinder heads cracked. It also had recently lost a water pump and someone "wasn't concerned" with the debris that could not be fetched from the cooling system.

Good luck man. I hope what I have told you has saved you a few thousand dollars when someone thinks you have a blown head gasket, pulls off the heads, carries out an incorrect pressure test (for identifying this crack), doesn't find a crack and puts it back together to only have the same exact issue. Do you know how many times thats happened?

[Woody]

Ive done over 100 water pumps on m96 and 97 engines. Never had a problem. I must be doing something wrong. Come to think of it, Ive rarely seen a cracked head. We used to see a few cars with oil mixed in the coolant but all the heads we pressure tested were good. No cracks found. Must not get hot enough in Texas to see these problems. I could see an improper bleed procedure causing some problems though. Most likely caused by an independent shop without the proper equipment.

[Jake Raby]

Ive done over 100 water pumps on m96 and 97 engines. Never had a problem. I must be doing something wrong.

You just haven't done enough yet. Keep going and you will arrive. Thats the same thing I tell people in my classes when they say "I have never had that problem".

The issue is replacing a failed pump that lost a bearing and allowed the impeller blades to contact the crankcase, then break. The tangent of flow will disburse these through the cross flow portion of the system to bank 2 primarily. This is where they tumble around until they wedge into any one of many critical coolant capillaries. The capillaries in these heads are "as cast" and not drilled, so some are more constrictive than others and some more filled with casting flash than others. That casting flash can grab the debris and hold it in place.

Once the capillary is blocked (even partially) a localized hot spot forms. Through thermal cycling a crack begins to form and we have seen evidence that the cracks actually occur on cool down. When the crack forms it will then propagate to the path of least resistance and that can either be to an exhaust valve guide spring seat (like this failure) or to an oil passage within the head. If the oil passage and coolant passages are interconnected the result is intermixed oil and coolant (the typical cracked head resultant symptom but limited to 00-01 MY engines) that can contaminate either or both of the sub-systems.

If any M96 engine comes to my facility with a failed water pump that has shed impeller blades, theres no way I'd risk just replacing that pump without accounting for every bit of debris missing from the old pump. That means invasive procedures.

But we don't have to worry about making that call; because we are always picking up the other guys slack, that didn't know, what he didn't know or didn't care because the directive didn't tell him to engage his brain.

Texas? Yes this happens with Texas cars. I only have 7 Texas cars here at the present, and either 3 or 4 of them were intermix cars. Its pretty conclusive that "improper bleeding" didn't cause the issue when you can physically extract broken impeller blades from the confines of these cracks (just under the cracked area) in almost every instance. Improper bleeding in my experience will lead to cracked cylinders are the 12-2 O clock point of cylinders 1 and 6, the area where the air bleeds last from each respective bank of cylinders. This is indicative by hot spots and how the boring head chops through the OE cylinders when we turn them into chips in the CNC machine to replace them with Nickies. That particular material is heat treated-

This post has been edited by Jake Raby: Dec 4 2013, 10:38 PM

[Woody]

Have had plenty with broken or missing blades and have never had to disassemble an engine because of it. I have also never had cars come back with an overheating problem after a pump replacement. The only way I see this being so common would be an incorrect bleed procedure without the recommended air lift type evacuator. But what would I know.

So your advocating a teardown for a simple failed water pump? That's kind of far reaching all things considered.

[Jake Raby]

Have had plenty with broken or missing blades and have never had to disassemble an engine because of it. I have also never had cars come back with an overheating problem after a pump replacement. The only way I see this being so common would be an incorrect bleed procedure without the recommended air lift type evacuator. But what would I know.

The engines don't overheat when this occurs. One square inch of one head becomes hot and the coolant won't show the issue because the heat isn't carried into the system, because the pathway is constricted. The vast amount of coolant will mask the issue.

I have only had maybe 3 cars that had owners who stated that the engine showed any elevation of coolant temperature on the gauge. Thats what makes the issue so mythical, is that it is basically symptomless until coolant pours out the exhaust or you end up with a milkshake in the coolant tank.

It can take one day or a decade for a piece of impeller blade to end up creating the collateral damage I have stated here. We can tell how long ago the damage occurred by looking at the edges and points of the recovered broken impeller blades. The nice sharp ones always come from the cars with shiny new water pumps, the ones with nice rounded "tumbled" pieces have somewhat older pumps installed. It just took those longer to get to the right place and create the issue.

Hell, I have even seen one water pump fail and shed one color of impeller blade, then a piece of that debris that wasn't recovered then passed through the replacement pump and stripped all the impellers off the replacement pump and the engine had the debris from two water pumps inside of it. The 4-6 head on that engine had 3 cracks and was non-repairable.

I have an entire chapter about this in the M96 Definitive Guide, because its landing more cars here than anything today and it can be avoided by:
- Proactive water pump replacement.
-Ensuring the proper care and concern is taken when replacing water pumps that have failed.

But what would I know

I am always more concerned with what I don't know, rather than what I do know. We learn something new daily and the engine is the instructor and the directive. The engine won't lie and is never wrong.

If we knew what we were doing, what we do wouldn't be called research.

This post has been edited by Jake Raby: Dec 4 2013, 10:54 PM

[rick 918-S]

Very interesting Jake. Thanks for sharing that info. I learned a lot about the M96 engine. Nice photos too. Any way to flush the heads to cause a back flow and dislodge any debris in the heads?

[JeffBowlsby]

Suby time?

[Jake Raby]

Where the debris ends up there's no way to remove it without invasive procedures.
Typically the issue isn't compounded until the new pump
is installed with the broken impellers in the system. The new pump is what distributes the FOD to the places where it doesn't need to be.

[DRPHIL914]

Jake, this brings up the question of when should we replace our water pumps ? I have 84k miles on my 2000s, should I put a new one in now? It has not yet failed but sounds like it will eventually. And should this be oem or a different brand?
Thanks for the advice, I'd like to avoid what this gentle.an is facing!

[jimkelly]

woody, pls tell us more about these engines. my impression is Porsche really dropped the ball in terms of engineering on boxsters within certain years. shame on them for putting such crap on the roads.

what repairs do you do most AFTER waterpump replacements?

[Woody]

woody, pls tell us more about these engines. my impression is Porsche really dropped the ball in terms of engineering on boxsters within certain years. shame on them for putting such crap on the roads.

what repairs do you do most AFTER waterpump replacements?

We do thermostats with the waterpumps but that's it. Never had a problem with one after a pump replacement. As far as dropping the ball on the M96 engines, I'm amazed at how much the internet can blow things out of proportion. 993s were great cars but no one remembers how every single one had valve guide problems. I was doing them under warranty back in the day. What about broken studs on the 3.0s? Or pulled studs on the mag cases before that? Each one requires engine disassembly, usually well before 100,000 miles. Nobody dares mention the M96 motors we see go past 200k without a problem. Yes some of them will have a bearing issue but its not all of them as someone would have you believe. I have been replacing the IMS bearings as a preventative measure but it is an un-proven repair. We didn't start seeing bearing problems until the cars had some years put on them. The same could go for the L&N bearing since its only been on the market a few years. I would recommend replacing it every clutch job or so, especially on cars that are driven on the track. Now an engine teardown because of a failed water pump? Waterpumps aren't exactly new technology, neither are aluminum engines. If the car didn't overheat which takes a pretty incompetent driver considering all the warnings that will light up, just put a new pump and t-stat on it. Ive had plenty of cars come in with the impeller hub completely gone with only a nub remaining. Remove the broken parts you see and move on. That's it. With the miles of coolant lines under the car it is easy to get air trapped. Porsche uses a device that puts the whole cooling system under a vacuum. After all the air is sucked out the coolant will be drawn into the engine and lines. Pretty simple device but most small shops will not have one. This can cause a problem with the localized hot spots and could even be undetected until something goes pop. I'm sure theres a few boxster or 996/997 owners on here that have had a water pump failure. Ask them how it went.

[ThePaintedMan]

Seems I wasn't as far off base as it might have seemed. That engine is still good, and worth the effort to try and repair it, as both Woody and Jake have described. There is no catastrophic failure, but Porsche would likely rather sell you a used or new engine than repairing the problem and diagnosing the original cause of the problem. Financially it makes sense for them.

With regards to whether it's the head or not, the only way to tell is to pull the offending head, or have someone you trust do it for you. Again, doubtful that Porsche will do that since they're usually under instruction to box up any engine failures and send them back to Stuttgart. I, for one, would make dawn sure it's coolant you're seeing coming out of the exhaust before tearing it all down. If there were a way to check each side of the exhaust independently, even better.

I understand Woody's points here, but if this is a head issue, then there is a reason why the failure occurred in the first place, since the car never actually overheated. Jake's suggestions seem logical and lucid to me. Determining the original reason for the failure is paramount to making sure this doesn't happen again if/when a new head is installed.

Consider asking Woody or Jake for a reputable place to send that engine. You can pull it yourself if need be. All is not lost my friend. (IMG:style_emoticons/default/beerchug.gif)

[Jake Raby]

Ive had plenty of cars come in with the impeller hub completely gone with only a nub remaining.

Do you have the VINs for those cars. If so I'll tell you if you've had a problem thats ended up here.

[Woody]

Again, doubtful that Porsche will do that since they're usually under instruction to box up any engine failures and send them back to Stuttgart.

This is another bit of miss-information. Porsche requires us to do a teardown on every engine and do a cost analysis of replacement vs rebuilding. They have for years. On a vehicle out of warranty we let the customer decide after presenting them with all the facts and how much both options would cost. One of the more common problems we see dealing with coolant/oil mix is a failed water/oil cooler which is mounted on top of the engine, externally. Pretty simple repair and then we have a Porsche supplied coolant flush to clean the cooling system. I am constantly amazed at the amount of miss-information being spread on the internet.

[Woody]

Ive had plenty of cars come in with the impeller hub completely gone with only a nub remaining.

Do you have the VINs for those cars. If so I'll tell you if you've had a problem thats ended up here.

Sure, I'll get right on that.

[ThePaintedMan]

This is another bit of miss-information. Porsche requires us to do a teardown on every engine and do a cost analysis of replacement vs rebuilding.

My mistake. Obviously we're talking about a Boxster, but this does hold true for GT3s, though correct?

[Jake Raby]

I am constantly amazed at the amount of miss-information being spread on the internet.

Thats why I am writing the book on it. Full documentation in print, for the record and this isn't an "E-Book".

I am constantly amazed that anyone can feel its acceptable to leave debris within the sub-system of any engine or machine following a failure without their being negative effects.

I guess they think its kind of like space junk that'll just float around and never cause an issue. Perhaps because Porsche never created a TSB for this it hasn't existed. Yeah, that way of thinking and application found them in a Class Action suit on IMSB issues that were also "Hyped up BS on the Internet" until the discovery documents proved the issues and the case was settled.

After that, all of a sudden everything changed.

[DRPHIL914]

Jake, this brings up the question of when should we replace our water pumps ? I have 84k miles on my 2000s, should I put a new one in now? It has not yet failed but sounds like it will eventually. And should this be oem or a different brand?
Thanks for the advice, I'd like to avoid what this gentle.an is facing!