Ramifications of a Replaced Engine?

I�m looking at a couple of 1999 996s that have had their engines replaced by Porsche 30 � 50K miles ago and I�m wondering what the pros and cons are. I know one con is that they�ll now have the smaller single row IMS bearing which is not a good thing. On the other hand there are a lot fewer miles on the engine which is good. One thing I�m wondering about is that it might not be considered a �matching numbers� car. I know when people look at �classic� cars, one of the things they look at is if the VIN on the engine matches the car. It�s worth a lot less if they don�t match. I don�t know if Porsche stamps the engine with a VIN. I know they have an engine code but not sure about the VIN. So, would a replacement engine possibly hurt the car�s value if it were to become more collectible in 15-20 years? I know these cars aren�t rare and never will be. But I still see people looking for matching numbers on cars like vintage Mustangs which aren�t rare either. Would you pay more, less or the same for a car with a replaced engine?

For a car with the smaller single row bearing, I would pay less and negotiate in the cost of installing the LN Solution. Really the only way to go. Porsche never kept track of the VIN and engine number matching in the 996. Look at the engine number. If it has an AT in it, it is a replacement engine.

Newer replacement short blocks have the large single row bearing, like the 997.

Could be a good thing if it has the larger bearing (like mine)… When was it replaced (year)?

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Well that's promising. I'm hoping to talk to the guy tomorrow AM to see when the engine was replaced. The new engine has ~30K miles on it so chances are it was replaced after 2005. I have heard that older replacement engines could sit on the shelves for a while so that's no guarantee. So you're saying there are M96 engines out there with the larger single row? Or do they put in an M97? Bill, how did you verify that yours had the larger single row? Visually or were you able to tell by the engine #? (FYI, I spent 11 years living in Hilo)

There is a visual difference you can tell by looking at the bearing cover, particularly the center nut size. the small bearing looks like this: the large bearing looks like this:

I'm driving around in a 02 with a replaced motor (under CPO) in 08. It's the newer style 997 version. I just drive it and don't worry (currently 35k since swap).

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True. But the trick is to figure out which bearing it has without dropping the tranny. That's a little beyond your average PPI. :-)

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The only way to know for sure is to see it. I did a motor swap... I would deal with it when it's time to change the clutch. Also, pulling the oil shield on the bearing is recommended.

I talked to the owner today. He bought the car in 2001 with 25K miles on it. Before that it was the sale's manager's car at a Porsche dealership here in San Diego. He moved to Chicago shortly after he bought the car and both engine replacements were done there. Both replacements were courtesy of Porsche. The first time wasn't too long after he got it and it was due to mixing of oil and water. The second time the engine "just blew" and there was oil on the ground. Would this be the IMS bearing? He's going to check but it sounds like the 2003-2005 timeframe (this lines up with the mileages given in Autocheck). So, it sounds like the replacement would have the smaller single row bearing. There are just under 30K miles on the new engine and 68K miles on the chassis. No problems since then. The car spent 4 years in Chicago. They moved to Phoenix in 2006 and it's been there ever since. He sounds like someone who took decent care of the car but didn't obsess over it. He sounds like a point & pay kind of guy and said he wasn't too mechanical. He says he has the oil changed every 10K miles with the Mobil1 Synthetic. I need to double check that because it's only had 20K miles on it in the last 14 years. Most of his driving he said has been longer trips, not a lot of stop and go. With all this, I would want to replace the IMSB. It's almost certainly a smaller single row. It's been in cold weather for 4 years, oil change intervals are pretty long and it sounds like he probably babied it a lot when driving. He's going to talk to his local indy to see if he can find out what type of bearing it has. It sounds like he'll ask him about what replacement costs are which means he might be willing to make that part of the negotiation. The car is advertised for $25K. So, long story short, the IMSB situation doesn't look good. But getting a 1999 with only 30K on the engine would be great.

As said many times over, low mileage is not good for the very reason you mention. 10K oil changes = 2 oil changes in 14 years?

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I need to verify the oil changes. If that's the case it would be a deal breaker but I doubt that's what's really going on. If he's not getting it changed at least once a year I'll have serious reservations. I wanted to ask about the low miles on the 996. I want to avoid cars that have been sitting for a long time but that's not the case with this one. According to the reported mileage over the years it's been driven pretty consistently at 1K - 3.5K miles per year. I know Jake Raby says that those are the ones that seem to have more IMSB failures but does it cause any other known issues? I did a search for "low mileage" but didn't find anything concrete. My sweet spot is 50 - 80K. This one is 68K with 30K on a 16-17 year old engine. Should I be looking for higher mileage cars?

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I wouldn't focus so much on the mileage to be honest. I got my 99 with 50k miles, I would not have paid more for one with 30k. I would actually rather have one with more mileage that has the IMS done or pay less and just have it done myself which is what I did.

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I agree there isn't much difference between 30K and 50K miles. Still, when buying a car mileage can make a difference. Both too much and too little. I notice there's a price drop for cars over 100K miles. I wouldn't buy a 95K mile car just because it has the IMS done. I'd rather get one in the 50-80K range and have it done myself. I totally agree that some of these seriously low mile cars are to be avoided especially if they've sat a long time. I notice people want way more $$ for them too! I'm just trying to get a handle on how little is too little. Maybe I am being too tempted by these low mile engines. That's why I'm here. To get these questions answered.

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What ever you decide on, make sure to get a proper PPI scoping the cylinders from the bottom. Good luck!

Buying a 996 with a "replacement engine" requires extra precaution and extra due diligence. First of all, not all replacements. are equal. Was it a "junk yard" special or was it competently re-built prior to installation. Both circumstances qualify as "replacements" but may differ significantly in terms of reliability. Engine history or proof of history is paramount. If it was re-built, who performed the re-build? The term "re-built" is not an industry standard term. The reputation of the re-builder here is paramount. Many Porsche indy's "re-build" 996 engines, but few have the tools and experience to do it well. The lack of such "exactness" in terminology and complexity of all Porsche engines explains why many buyers shy away from 996s (especially) with an engine other than the original...Sad but true. The example you are citing is over-priced. Used 996s are plentiful and $20K will buy a nice "no stories" example. My advice: keep shopping...better examples are available for less money. relinuca

Buying a 996 with a "replacement engine" requires extra precaution and extra due diligence. First of all, not all replacements. are equal. Was it a "junk yard" special or was it competently re-built prior to installation. Both circumstances qualify as "replacements" but may differ significantly in terms of reliability. Engine history or proof of history is paramount. If it was re-built, who performed the re-build? The term "re-built" is not an industry standard term. The reputation of the re-builder here is paramount. Many Porsche indy's "re-build" 996 engines, but few have the tools and experience to do it well. The lack of such "exactness" in terminology and complexity of all Porsche engines explains why many buyers shy away from 996s (especially) with an engine other than the original...Sad but true. The example you are citing is over-priced. Used 996s are plentiful and $20K will buy a nice "no stories" example. My advice: keep shopping...better examples are available for less money. relinuca Porsches Forever

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Man, I hope you're right about the price being too high. So far, everything decent I've found has been around $25K. Anything around $20K has been in rougher shape or has well over 100K miles. I've only been looking since around Xmas. I'm hoping it's because there aren't a lot of people selling right now. However, I'm starting to think prices may have gone up from a year ago. If you've been keeping your eye out and have seen something good for less, let me know. The engine replacement was under warranty by Porsche so there are no problems there. The main questions are, what kind of IMS bearing does it have, Is it more susceptible to bore scoring than the original '99 engine, since many people like the '99 for the engine, is it really a "99" anymore? etc...

Where are you searching for these cars you're seeing? There are 100's of them for sale right now. Don't forget, asking prices are rarely what cars actually sell for. Make an offer share your concerns and negotiate so both parties are happy!

I'm curious about Porsche replacement engines as well. I've found a '99 that had it's engine replaced sometime in the 2010-12 timeframe by Porsche. So it should have the bigger bearing. This thread mentions a engine number cutoff: https://rennlist.com/forums/996-foru...ability-2.html Curious if anyone knows what typically is included in a Porsche factory replacement motor? Does it include all new injectors, coils? Would variocam chain guides be improved material less likely to wear and cause camshaft deviation? Maybe the sparkplug tubes would better too? I would expect stuff like A/C, P/S, alternator would be re-used. As far as scoring, I've seen it mentioned the 3.4 is less likely than the 3.6, but certainly it's a risk based on some recent threads with failures. The skirts would be the newer material that's more likely to score than the inital piston design. I doubt I'll spring for a scope PPI unless another symptom is present (ticking, excess oil consumption, extra sooty tailpipe on one side - usually drivers).

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Coopduc did a very nice right up on his shortblock purchase, search and read. Porschetech3 can share his experience and answer your specific questions regarding what Porsche reuses when they replaced motors.

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Why would people want the '99 engine, the most problematic M96 engine due to the thinnest cylinder walls. The only reason to want a 98-99 is to have a real throttle CABLE.

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I actually wanted to ask about where else to look. Mostly it�s been Auto Trader and Craigslist. I look on Rennlist and Bring a Trailer but the cars there tend to be overpriced. I�ve looked on eBay but so far when I have, it�s been dealers and there were no private party cars. Just started looking at Facebook marketplace. Where else is good? Also, it might seem like there are a lot out there, but when you start filtering down to what you want, it gets sparse. I�ve been filtering for <$30K, <100K miles, private party only. I also am not interested in a C4, C4S or a cab.

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Well, according to Wikipedia, the auricle of all things 996: Feeling pretty good about my Feb 1998 build, though I have yet to scope the cylinders, so stay tuned...

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This is the first I've heard about them being the most problematic engine and the first I've heard of them having thinner cylinder walls. If you like Jake Raby, his favorite is the 1999. The big deal is that it has the dual row IMSB (1% failure rate vs 8% for 2001+) and they seem to have less of a problem with bore scoring than the 3.6.

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I like using CarGurus.com

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What I've gained from these forums over the years is that both the Mk1 and Mk2 have Lokasil cylinder coatings that ARE susceptible to scoring. The 3.4L had it's own unique sins such as D-chunk and Y2K. Seems to me that Porsche should have stuck with nikasil bores like what was found in the Mezger 996 engines. If it were me, even with the low failure rate, would be to install the IMS Solution at clutch service.

I know of someone selling a brand new the "Solution" for $1100. if anyone is interested.

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I do like Jake, I was one of the 1st 10 people in his 1st M96 engine rebuild class 20 years ago. Being a ex-Marine we understand each other very well I think. I would guess Jake likes the simplicity of the early 996's like I do & it's cylinder deficiencies are not a issue for him.

"I would guess Jake likes the simplicity of the early 996's like I do & it's cylinder deficiencies are not a issue for him." The reason the cylinder deficiencies aren't an issue for Jake, is that he sends the cases out to LNE/Charles Navarro and has them machined away and replaced with "Nickies"... In fact, I'd say he probably LOVES Lokasil/Alusil cylinders as they drive a good part of his engine building business!

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What is the difference in the cylinders between the earlier 996.1 3.4L and later 996.2 3.6L engines? AFAIK they're the same and they both have the locasil coating rather than the better coating that the Turbos and GTs have. I read every once in a while that the 996.1 engines are less susceptible to bore scoring but to be honest, I've watched several hours of Jake Raby's videos about it and he doesn't mention it. All the things he mentions that contribute to it have nothing to do with any difference between those two engines. Wives' tale?

Smaller bores, have marginally less side load,, But at the end of the day, its how well the engine is maintained,, and I'm in the change injectors = longer engine life camp.. Already had two rigs ,, other makes with scoring issues and both times it was a cylinder with a leaky injector..

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The GT cars, and Turbos don't use a "cylinder coating". These engines utilize Nikisil PLATING. Plating, and coating are dramatically different processes. The earlier 996.1 engines used ferrostan piston processes, where the later 996.2 used ferroprint. we see just as many 996.1 engines fail from bore scoring as 996.2

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I got that impression from Charles here: https://rennlist.com/forums/996-foru...l#post15737923 But I think the amount Lokasil I is "better" is not quantifiable. The experience of JR at F6I is probably more relevant - they can all score.

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The 1st 3.4 M96 engines have the thinnest,weakest cylinders. The 3.6 engines have much thicker cylinder walls.

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Thanks for the clarification. I've watched 5 or 6 of your bore scoring videos and they help a lot. I took notes. I knew about the different coating/plating from the videos but couldn't figure out why the 996.2 seemed to be more susceptible to scoring as some people had said. Maybe that information is outdated.