What is a 'rebuilt engine'

[Mysterytrain]

After wading thru the thread in the classified on this issue I began to wonder what is the true definition of a rebuilt engine? A top end and reseal? Just Re-ringed or new P & C's? Is it a top end with new valves, rockers, guides, new P/C's, cams, oil pump, chains, sprockets in hopes of building another engine that will go another 100k miles plus.

[john walker's workshop]

runs the gamut from clean and paint, rings and bearings, to a perfect $20K job with every single wear item replaced and all proper machining done. pig in a poke without paperwork, and sometimes with. rebuilt should probably be written "rebuilt".

[Steve@Rennsport]

Ron:

Thats REALLY a great question. The term "rebuilt" as used in the context of automobiles has many different interpretations in the automobile industry and almost all of them are clear as mud.

I wrote something on this subject, http://www.rennsportsystems.com/1.html that addressed this problem.

The aviation business has clearly defined such terminology as: "rebuilt", "overhauled", "new", "zero-time" and such things, but our industry has left that to the service providers, vendors, and the general public to define these terms as whatever is convenient depending on circumstance.

John is right and one MUST get the paperwork for all services & parts when evaluating any engine that claims to have been "rebuilt". In some cases, that very record is suspect (MM) so ultimately it depends on the integrity and competence of the shop & personnel that did the work.

[Mysterytrain]

Steve / John ..thanks for your valued input on this subject. We always see claims of ' you can rebuild your engine for XXX dollars'. After actually having a respected and honest shop rebuild my engine I was way into XXX dollars in new parts alone. No doubt the key factor is a paper trail of exactly what went into the motor and who did the work. A rebuild in a home workshop won't be as prized as one from a Pro shop like those that you guys operate.

[azasadny]

I think the two most overused/variable meaning words used in connection with Porsches are "rebuilt" and "original". "Rust free" could probably also be added to this list...

[lindemans]

One thing for sure:
Regardless of the actual definition, it will often be misused terminology

[svandamme]

and if not documented with pics, bills and/or a reference check of the re-builder... pretty much worthless...

[Mysterytrain]

So a 'home rebuilt' motor is worth slightly more then a MM engine. In the end, the additional cost for a reputable shop's labor may pay dividends when its time to sell.

[304065]

I respectfully must disagree with that statement, Ron.

Let's take my own case, because I know it the best. It's ultimately irrelevant because I'm NEVER selling this car or its engine so a valuation will never come into play, but humor me.

I have receipts for $8,000 in replacement parts and labor by the finest Porsche-specific machine shops in the country.

I have a detailed log of the part number and condition, in many cases to the thousandth of a millimeter, of every nut, bolt, seal and part in the engine, along with detailed disassembly, cleaning and plating, reconditioning and reassembly photos. Many of which have been posted here. That will all be accompanied by a dyno sheet from the engine's break-in.

Contrast that with the shoddy work performed by certain professional shops, including the one that rebuilt my engine 25 years ago with black RTV sealer on the case parting line and cam boxes, mismatched rocker shafts and with a ring gap so wide that I found five broken compression rings on the teardown. "Professional" in name only.

"Slightly more than a MM engine" implies slightly more than zero. In my own case, and in the case of many, many other "home rebuilders" here, I think a credible case can be made that there should be absolutely no discount whatsoever associated with a PROPERLY done and DOCUMENTED rebuild.

[Henry Schmidt]

Well John so goes the question.
It is true that a home builder can do a job comparable to a professional and in many cases the attention to detail is even better. That said, experience is something you can't get from a book or forum.
There are things you learn on your second engine that you didn't know on your first. Imagine how that changes on your 200th or 400th engine.
The professional with a track record offers a peace of mind (for the consumer) that you don't get from a DIY home builder.
I would suggest that you may even spend more as a DIYer than a reasonable professional would charge.
While I admire your attention to detail, it is easy to go over board. Measuring to the nearest "thousandth of a millimeter" takes time and adds no value. It is similar to balancing a flat six to tenth of a gram. It seems better than 1 gram but the engine will never know the difference. We balance to a 1/2 a gram but that is actually a waste of time. The factory calls for 4 grams and at 4 grams you could argue that is close enough.
It is true that a DIYer's passion for a job well done adds value, It is also true an engine built by a passionate, experienced professional adds infinitely more value.

[Steve@Rennsport]

Just MHO here, but Henry really makes some excellent points and I must wholeheartedly concur,....

Its especially important when it comes to racing engines that spend the majority of their time above 7000 RPM.

"Professor" Cramer is a VERY careful, detail-oriented and methodical individual and with all respect, might be the exception not the rule about homebuilt engines, at least from what I've seen to date.

[304065]

LOL, if I had my engine rebuilt by either of you gentlemen I would certainly demand a premium when the time came to sell. Ditto the other "excellent" shops: the confidence inspired by reputation goes a long way toward being able to strongly support the seller's valuation.

Henry, the reason I measure to the thousandth of a millimeter in many cases is because that's what the factory spec calls for. That and the fact that as an amateur, my measurment technique will undoubtedly have errors-- but I figure that by shooting for the center of the bullseye I'm more likely to get it on the paper. You're definitely right about the additional time and money involved, but economics of time and cost aren't priority #1, it's a fun learning experience for me.

Steve, you're really on to something with your second paragraph. From my own research I've learned that there are literally dozens of items that if improperly done, can prove catastrophic, and that's for a stock rebuild.

Factor in the more precise tolerances required for a high-rpm race setup and the professional's experience is even more differentiated from the knowledgable amateur. One area that occurs to me (you both may think of others) is piston-to-head clearance. A pro that's done it hundreds of times probably has no trouble confidently running a very tight clearance: for an amateur, this is inviting very expensive noise.

That being said, all professionals are not created equal: Henry, you don't say whether it was an amateur or a pro, only a "mechanic familiar to the Porsche community" that perpetrated the RTV nightmare illustrated in this thread:

Holy RTV Batman!!

[Henry Schmidt]

Originally posted by john_cramer
---edit---That being said, all professionals are not created equal: Henry, you don't say whether it was an amateur or a pro, only a "mechanic familiar to the Porsche community" that perpetrated the RTV nightmare illustrated in this thread:
Holy RTV Batman!!

The RTV nightmare was the product of a DIY home builder who has been known to rebuild engines for Pelicans and the unaware public at large.
This mechanic was actually consulted on proper engine building techniques by our host for his 911 engine rebuilding book.

[304065]

Egad. Score one against the "amateurs."

[svandamme]

but i'm sure it didn't leak, right?

[Mysterytrain]

John, sorry I was painting with the ol' broad brush. I've seen some amazing examples of talent on Pelican but I would guess that pelicans with your talent and attention to detail only account for a fraction of the membership. The term rebuilt is tossed around almost as much as low ball dollar amount for getting the job done. I for one wasn't shocked by the 20K figure that B.A. quoted. If you think about it there is no way MM could 'rebuild' an engine for $3800. I doubt a home grown 'rebuild' can be done for that amount. Andial wants that for a set of mahle p and c's.

[Henry Schmidt]

You have hit the nail on the head with price. MM quotes $3800 or so for a rebuild and BA's quote has $7800 labor. Both extremes are ludicrous, although I must say if you know the real cost going in a shop should be able to charge what they want. Around the high performance world there seems to be a "perception of excellence " attached to a high price.
There are way to reduce the cost of a 911 engine rebuild (low overhead, in house machine work, reduce build time do to experience and the most important & least appreciated, knowing what parts need to be replaced and what parts don't). The last item can only be learned through experience. Either yours or some that is borrowed. That is where this forum works it's best. The freely shared experience of experts willing to help.

The definition of rebuild varies from builder to builder.
As I see it you have many layers of repair.
Reseal = disassemble and reassemble to repair leaks (mainly gaskets, seals and gluing technique)
freshen up = add bearing, rings, rod bolts, valve inspection to an engine of know quantity. IE: 10hrs on a race engine
rebuild = return engine to factory specs. Valve job, new pistons as needed (at this point up grades make sense)
remanufactured = restore engine to as new condition (within reason, reusing main components)
Remanufactered 2.2 911"S" engine.

[Grady Clay]

An important aspect Henry alludes to is the “how much is too much” situation. “Almost” anyone can build a really nice engine using all new parts. The art of engine rebuilding in knowing what needs replacing, what needs reconditioning and what is still OK to use. Part of that is experience, part is measurement skills, part is the willingness to research and ask questions. Updating is an important aspect.

Thirty+ years ago a bunch of us (pre-internet) single-handed kept AT&T long lines in business discussing these issues, sometimes daily. Today you have this Forum.

An advantage of Pelican is you get a combination of experienced pros (Steve, Henry, John W and more) plus some very skilled DIY builders (John C and more). This Forum also has many “amateur pros” who do professional level work but aren’t in the full-time business. Some become the best shops. Add to the mix the first-timers who ask great basic questions and you get a good combination of skills and information.

A good shop has (in addition to experience) the advantage of technical information, parts availability, specialized tools and more, including an engine dyno in many cases.

An advantage a DIY build has is time. When you DIY, you can stop (or even go back) and deal with any issue that comes up. Out of necessity a shop must be efficient building engines or no one could afford them. This is done with experience, parts & services availability, dovetailing projects (having more than one in process at a time) and efficiencies of scale.

Of course there are shops and DIYers who are incompetent, misdirected or just plane crooks. Chris’ Rant: Hack mechanics (and possible lesson?) is a good example and the above mentioned shop … well. Often bad results happen when someone runs out of time or money and “cheep-shots” the reassembly. This one reason a through PPI is so important.

A very important aspect of DIY is the satisfaction of having done it yourself. Henry may be able to build a 901/05 as well as John, and even in a fraction of time but that isn’t the reason why John is DIY. John may even spend additional money out of choice or abundance of caution. There is nothing wrong with that.

Steve brings up a good point. DIY shouldn’t be considered as a cost savings project. In fact it often becomes more expensive. Too often this is from not recognizing a problem or underlying cause, not replacing something that should be replaced, or error. This is the experience Henry is talking about.

If someone DIY gets into an engine and finds the challenge too great (sometime just the time available factor), a good shop is an ideal safety net. It wasn’t infrequent that we got an engine in boxes. It is a little more difficult because you don’t get to see the condition on disassembly first-hand.

Steve’s point about race engines is right on. As soon as you try to exceed “normal” limits, the care and experience necessary goes up exponentially. Even more so as you start to mix-and-match parts, use custom configurations and parts. This forum is full of discussions about deck height, compression ratio and more.



Back to Ron’s original question, probably the best examples are in Wayne Dempsey’s Engine book and Bruce Anderson’s book. Both have great check lists and examples. Many more engine projects are well documented on this Forum. As I have said many times, a first-timer benefits greatly from having ALL possible information sources. That includes the FWM, Spec books, Technik books, Bentley, Cramer’s, Haynes and more. Finding and editing information from the forums is very important. This can just be excerpt copies of the portions relevant to your project. This is where making your own personal loose-leaf manual is beneficial.

Ron, I think John & Steve (and you) are right on; every rebuild (DIY or Pro) should have documentation of every minute detail. With convincing documentation, a good DIY can be every much as good and valuable as a professionally built engine. With the ease of digital imaging and burning a CD, every rebuild should have accompanying documentation. This should include the disassembly and diagnosis, all the processes, the measurements prior to assembly, the assembly process and the resulting dyno run-in and testing. Even though John C isn’t intending to ever part with his 901/05, his is well documented here for everyone’s benefit.

What is a proper rebuild is highly dependent on age, miles, condition, engine type, original components and intended use. A 400K ’69 911T is very different from a 70K ’83 911SC with Mahle Nikasil. An original 2.0 901 is very different from a MFI 3.5.

I think a “proper” rebuild is, As Steve says on his site; “For a street engine, we feel that a proper rebuild should last as long or even longer than the original OEM powerplant.” The advantage we have over the original Porsche engineering is many years of hindsight. The discussion is how to achieve that in every situation.

There is also the appropriate consideration of the cost of a proper (read expensive) rebuild compared to installing another engine.



That said this is the fun of Porsche engine building “art.” I know the fun that guys like Steve Weiner, Jerry Woods, Dieter Inzenhoffer, Chuck Stoddard and I have had over the 30+ years. John Cramer is doing that in the DIY arena, as many others have.

The great feature that Wayne provides us is easily sharing this collective knowledge and archiving it for future generations.

Best,
Grady

[Grady Clay]

It looks like we had simultaneous posts.

Originally posted by Henry Schmidt
You have hit the nail on the head with price. MM quotes $3800 or so for a rebuild and BA's quote has $7800 labor. Both extremes are ludicrous, although I must say if you know the real cost going in a shop should be able to charge what they want. Around the high performance world there seems to be a "perception of excellence " attached to a high price.
There are way to reduce the cost of a 911 engine rebuild (low overhead, in house machine work, reduce build time do to experience and the most important & least appreciated, knowing what parts need to be replaced and what parts don't). The last item can only be learned through experience. Either yours or some that is borrowed. That is where this forum works it's best. The freely shared experience of experts willing to help.

The definition of rebuild varies from builder to builder.
As I see it you have many layers of repair.
Reseal = disassemble and reassemble to repair leaks (mainly gaskets, seals and gluing technique)
freshen up = add bearing, rings, rod bolts, valve inspection to an engine of know quantity. IE: 10hrs on a race engine
rebuild = return engine to factory specs. Valve job, new pistons as needed (at this point up grades make sense)
remanufactured = restore engine to as new condition (within reason, reusing main components)

Henry, well said.

We should not get too detailed as to specifics as every engine and situation is different. The most difficult part is no one knows what is necessary until you get into the project. However this is very useful to define the processes levels and to realize what (unexpected?) issues arise.

I wouldn’t call “Both extremes are ludicrous.” Both are possible but simply extremes. MM chooses a “bait and switch” business model. Bruce and I are both retired 20+ years from doing this honestly.



I agree with Henry’s presentation: Reseal, Freshen, Rebuild, Remanufacture. I would add Top-end and Build to the list. There is also a lot of overlap, particularly if some problem is discovered.

I would define the list as:
Reseal = Disassemble and reassemble covers and components to repair leaks (mainly gaskets, seals and gluing technique). This might include valve covers, chain covers, oil return tubes, thermostat O-ring, cam oil lines, sump gasket, breather gasket, crankshaft seal, flywheel seal, oil cooler O-rings and others. It wouldn’t include leaks at the cylinder base gaskets, chain housing-to-case and similar that require disassembly of the basic engine.

Top-end = Add reconditioning of the heads and cam drive area (tensioners, ramps, etc.) This would include Resealing. This would not include (normally) removing the cylinders.

Freshen = Add bearing, rings, rod bolts, valve inspection to an engine of know quantity. IE: 10hrs on a race engine. In my posts I usually refer to this as a “Maintenance rebuild.” This is for keeping a good engine in top form and preventing any problem from getting out of hand. I do this on my race engines at 25 hours. There is benefit on a street engine at 75K miles, hotrods less.

Rebuild = Return engine to factory specs. Valve job, new pistons as needed (at this point up grades make sense).

Remanufacture = Restore engine to as new condition (within reason, reusing main components). This is the extreme rebuild where the case is rebuilt and all new wear parts.

Build = This is where you build a “new” engine. Occasionally this is truly new with all new parts but usually is a combination of spare parts (both new and used) to create something that Porsche never sold. This is the ultimate fun “art” of Porsche engine building.


When considering a 911 engine repair, a critical issue in the decision making process is the uncertainty in the condition and what is necessary. If someone came to me today with a running but otherwise unknown engine, the first words out of my mouth would be “This can be VERY expensive, $24K and more.” A DIY and a honest shop customer should hear that number up front.

The next decision is to do inexpensive and non-intrusive investigation. That could include measuring the cranking compression, cylinder leakage, inspecting the sump & oil filter, removing covers for inspection, bore scope the combustion chambers, etc. Here you get to find oil leaks, broken cylinder studs, cam drive condition and more. These are all things that can be done without removing the engine from the car and, with a few gaskets and some oil, the 911 is still drivable. You guys can offer estimates of cost of this. It is labor intensive so DIY is cheep.

The advantage the pros have is how clear their crystal ball is (and it is always fuzzy). I think the proper approach is to look at all the common issues and consider the worst case (say 95% level). I think it unreasonable to consider the “norm” (average) because you are wrong 50% of the time. It is absolutely wrong to “hope for the best.”

Once an engine is disassembled it cannot be restored to its former running condition – you are committed to some level of repair. Some of the junk we see probably is from someone “just put it back together” where RTV is less expensive than a new valve cover gasket. Here we are talking about proper repair as a minimum and “best in the world” as the goal.

The lists in Wayne’s and Bruce’s books are great. We used to have a 6-page legal size list. Everyone should do their own engine-specific list. There is an advantage to making multiple lists for various levels of repair, updates and improvements. This is what a good shop does to generate an estimate. No matter how careful and detailed you are, there will be unforeseen issues. Remember, Murphy is in charge.

The list above is fraught with potential problems. I’ll pick an example.
You start a Reseal and you find broken head studs. You get into this repair and while you have the chain housings off you discover a bad jackshaft sprocket. The only correct repair is a Rebuild. Big difference. It doesn’t matter that this is a shop setting or DIY, the repair needs to be done properly.

When I discuss my 25-hour race engine number, I am regularly asked if this is necessary. My answer is “What is the alternative cost if there is a failure?” The same is true with any repair. Cheep-shot and shoddy work comes back to haunt. Real pros won’t do this. Quality DIY shouldn’t either.

Best,
Grady

[svandamme]

Grady , you really should write a book some day
you can obviously write , and get good information in readable sentences... and you OBVIOUSLY have plenty of experience for us to learn from...

for real, write the book allready.. and tell me where i can pre-order the thing!