996 mixing coolant and oil

These cars were notorious for having bad engines. Porsche was aware of the problem and issued a "seat belt recall" where they replaced the motor. Long story short, the 996s are extremely cheap to purchase. Look at a 2001 or newer

 

There is actually a possibility of cracked head. Its somewhat common when you see your symptoms. I have them welded when we find them cracked. They form a crack right at the water jacket.

Sorry.


The M96 Engine and Cracked Cylinder Heads

The cylinder head(s) on any water cooled engine has the potential to crack, and Porsche’s M96 engine in the 986’s & 996’s is no exception. The most common reason for this to happen is when an engine significantly overheats, usually due to the loss of coolant. Overheating can be caused by something as simple as a faulty coolant hose, a cracked or broken radiator or coolant reservoir, or a water pump failure. If the driver is not periodically checking the instrument cluster, they might miss a warning light or a dramatic change in the reading on the temperature gauge (if your vehicle has a temperature gauge). When the coolant flow is lost, it doesn’t take much time for the engine to get really hot.

When the engine overheats a great deal, the aluminum head material can actually distort in shape due to the combination of the extreme heat and pressure (or torque) being applied to the head by the fasteners that hold it in place. If the head material distorts, even a small amount, cracks in the metal can occur.

With regards to the M96 engine, another issue that can cause cracks in the head is based in the coolant water pump. As the water pump ages, pieces of the internal plastic impeller can break off and these plastic bits will circulate within the cooling system. If these plastic pieces become lodged in the many small coolant passages within the head they could partially to fully obstruct the flow of coolant at that location. The combination of debris and loss of coolant flow can create localized hot spots in the head but can yield the same result, cracks in the head.

Also unique to the M96 engine is the fact that the heads can be cracked by improperly attaching components to them. Incorrect tightening of the valve lifter cradle or the camshaft cover (also known as the valve cover) can cause cracks in the head. The use of a torque wrench and the knowledge of the correct tightening procedure are critical to the repair of this engine.

When cracks develop in the head, a number of symptoms can result depending on where the crack is located. Keep in mind that oil and coolant both circulate inside the head. If cracks develop between oil and coolant passages, the result can be the proverbial “chocolate milkshake” in the coolant, oiling system, or both. This is the result of oil and coolant intermixing together. Additionally, cracks can develop in the cylinder head combustion chamber unnoticeably causing a loss of coolant or oil. It is important that the technician think through all the symptoms to insure a proper diagnosis.

Generally speaking, another problem area can be the head gasket. The head gasket fits between the head and the cylinders. A failed head gasket can also exhibit the same symptoms as a cracked head. The good news here is that head gasket problems on the M96 engine are very rare. That is because Porsche uses a multi-layer steel (also called an MLS) head gasket. This type of gasket is very robust when installed properly.

Keeping the cooling system in top operating condition is critical to the M96 as it is to all water cooled engines. Have the hoses and other cooling system components, including the coolant reservoir and pressure cap, carefully checked at every service. It is important to maintain the proper pH level of the coolant, as with age and exposure to aluminum, the coolant can become more acidic which in turn hastens the demise of the rubber hoses. Flushing and replacing the coolant every 2 to 3 years is recommended as the best way to maintain the correct Ph balance. As for the coolant water pump, replacing it every 5 years or 50,000 miles may be the best defense against these components failing when you are enjoying a nice drive.

 

Don't rule out the real possibility that the "foam" is simply condensation, which does not indicate engine damage. These engines have a tendency to build up a lot of gunk in the oil filler tube if the car is used repeatedly for short trips thus not allowing the engine to warm-up enough to burn off built up condensation. An easy test would be to check the oil dipstick, if the engine has experienced intermix issues it will be very apparent on the dipstick.

Yes, and this notoriety is mainly undeserved internet hype IMO.

Do you know any of this as fact or are you simply regurgitating internet hype? I've owned a 2000 996 for about 8 or 9 years and it's the most reliable car that I have ever owned.

Also, your advice to buy a 2001 or newer model may be a bit misleading. Evidence suggests the double row int. med. shaft bearings in the 1999-2000 cars are more robust than the single row bearings that were used in the 2001+ model years.

 

The timing of this thread is perfect (bitter sweet) given I was going to ask a very similar question.

A good friend’s 2000 996 has significant water in the oil. Mechanic states that one of the cylinder sleeves “shifted” and this is a common problem with these motors. I figure there are two options: 1) replace the sleeve, 2) replace the motor. A refurbished motor is about $7K + core so they say. I have yet to do any research on this, thought I’d ask you guys first. Has anyone replaced a sleeve, is it a viable option?

Thanks in advance, Larry

 

Whoever said they could do that for $7K is either lying to get you to commit to the job or has simply never done it before. 996 motors are an absolute PITA to build. Very few shops have the ability to do it correctly. The best option is buy a complete engine from the dealership but it costs way too much IMHO. When my customers' boxster or 996 motors fail I tell them the hard truth to walk away from the car.

 

Thanks for the reality check Bill. Just saw this this morning.:
Hard To Find Good Used 2000 996 Carrera Motor Outright
Is there simply too much risk with these engines?

Larry
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Not worth the risk IMHO. $7500 for the engine, $1500 for "might as well do it while the engine is out" components, $1500 labor. Close enough to call it $11k for a car worth maybe $20k? And to risk it all on an unknown used component with 82k miles on it? Doesn't make sense to me.

Sell the car as a parts car/project to someone who can't do math. Sorry.

I've been working on Porsche cars for 25 years and lusting after them since I was 8. The 996/boxster cars are possibly the worst cars porsche produced excluding the 924, lol.

It hurts, but take the financial hit just once instead of multiple times. Put that 11k towards an earlier or later variant and be much happier in the long run.

 

"The 996/boxster cars are possibly the worst cars porsche produced excluding the 924"? Most of the Porsche magazines are calling it one of the best buys you can make in a Porsche. Tons of performance and fun for minimal dollars. I'll take my 996 and all of the fun/community/thumbs up/Porsche pride any day. Not everyone can afford a new Porsche (or even a 997 in my case) so this car is the only way many of us can even step into something in the Porsche lineup.

If you do your homework, get a PPI, and keep up with the proper care and upkeep, there is no reason not to buy. It's seems every model that's ever been in the Porsche lineup has had it's unique faults/quirks (talk to a 991 GT3 owner and see if they agree).

The white one is $20,000 new and the worst car (mine! ) was also $20,000. I know which one I'm happy with.









We now return to our regularly scheduled thread..........My guess is the frothy buildup inside the oil cap is exactly what a previous poster advised, too many short trips without warming up.
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I wouldn't care if you've been working on Porsches for half a century, after reading this ignorant comment I wouldn't let you touch any of my Pcars.

Great looking car Neil. It looks like my 996's twin except with an aero kit.

 

Geez, people on the internet get so butt hurt defending their choices, lol. I'm sorry I hurt your feelings. Since you know so much, why don't you tell us what you think the biggest loser porsche ever produced? Before you pick on the lowly 914 remember it was a joint effort with VW. The six cylinder cars were the only 914s considered to be a Porsche and they sell now for 10-15 times what they sold for new. Think your 996 will ever sell for more than you paid for it?

 

the 996 chassis is great, especially if you dial the understeer out of it. but I'll never own another M96 equipped porsche though, that engine just isn't up to porsche standards IMO.

as for the worst porsche ever, I'd say 924. too heavy to be a sports car, too slow to be a GT, too VW to be a porsche

 

Where does it say my feelings are hurt??? I was merely stating that the 996 gets a bad rap, however, it's a great car for $20,000. All were my opinions (and we know what they say about those ). Sounds like you might be reading into things a little much. Or you're trolling for a fight via a forum. If the later, with your total of 8 posts, you may not realize this site is more mature than that.

I agree with the 924 being the worst Porsche for the reasons above.

 

Ha... the 924 was ALL VW... no Porsche content... well, a couple badges, maybe.

It was originally supposed to be the next iteration of the VW Karmann Ghia (as was the 914 before it).

 

Well... I have been working on/in/with Porsches for over 35 years... And I have rebuilt quite a few of all types with my two hands. Let me tell you all that the best boon to my group was the 1974-1977 2.7 liter 911S. The thermo reactors (look that up) and the mag case... Ohhhh that engine set many customers back a multitude of times. And guess what?.. They made a fraction of those cars in comparison with the M96 engines that this thread is trying to speak intelligently about. Meaning that the percentage of failures was MUCH higher on a 2.7 mag case than this recent M96 version you speak of. Additionally the Internet has made it so things get blown so out of proportion compared to how news traveled in the seventies. The M96 bashing is unnecessary when educated about it.

Now I like the classic seventies 911S, so don't get me wrong. But nevertheless that platform was probably the most troublesome of all Porsches (coming from an actual expert).

Summarizing: The percentage of failures (all types of failures) on the M96 engine is much less than that 2.7 mag case (again all types of failures). Some M96 engine versions have a failure ratio of near 1% of production. You think that should count as a "worst" of anything? I think not. I own two M96 engine cars right now (one with over 100k miles, the other with under 20k miles), I believe in them as much as any other version.

AND I need to disagree with the valuation of 996 cars as the 996 GT3 (admittedly not the same as the pedestrian M96 engine but still represents the 996) is doing quite well resale wise.

Lastly, the 924 or: slope nose Audi 100LS (again look it up). It served the purpose Porsche intended. Stop there.

 

So are the later 3.6 engines "better" than the earlier 3.4s? I would like to add a 996 or an m3 down the road since I won't need a 4 door anymore.

 

In 2002 the 996 went to a 3.6 liter that gave much more performance and good reliability. I do recommend that when a customer is looking for a 996 that they take the plunge & opt for a 3.6 version. Additionally the Boxster 2.7 engine was upgraded in 2003 to produce more power & gain better drive-ability. Both would still get an upgraded IMS bearing at my place when & if you ever replaced a worn clutch.

With the upgraded IMS bearing any IMS concerns are diminished.

 

Back to 996 mixing coolant and oil.

Has anyone heard of Raby Engine Development? His Intermix Package FAQ (attached) reads well. Still not sure what they do to fix the problem.
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Raby is the "go to" guy for 996 rebuilds...but they are expensive. like, cost of buying another 996 expensive. (he quoted $15k to rebuild my 3.4)

 

I have no experience with the 2.7 mag cases, but I have owned three M96 motors...a 3.4 996, a 3.6 997, and a 3.8 997 S. All 3 saw some track time, the 3.4 and 3.8 saw significant track time. the 3.4 and 3.8 both suffered catastrophic failures (as in, engine replacement).

so in my opinion, the M96 is a decent road use only motor, but the moment you put significant stress on the motors, it becomes a ticking time bomb. which wouldn't be a problem, if Porsche didn't sell sports cars, and market them as the ultimate dual purpose track day weapon.

 

He quoted $11K to fix the intermix problem, replace the IMS bearing, + a new clutch.

 

mine was slightly more involved than that

also at the time he had a long backorder, maybe 4-6 months.

 

Sent the car to Raby. Turns out there was a crack in each cylinder head. She’s all put together, dyno looks great, and on her way home! Thanks Jake and Jud!
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Well what do you know... Heck and I don't even get a "at-a-boy" ?

Tough crowd.