OEM vs. rebuild....why the lifespan difference?
11-10-05, 02:36 PM
#1
Constant threat
Thread Starter
OEM vs. rebuild....why the lifespan difference?
It seems that by and large (with obvious exceptions of course) that rebuilds are typically lasting only about 30K to 50K miles, based on most posts about the subject. Why is this?
Most of our original engines lasted somewhere around 75K to 130K miles! Is it because the rebuilds are maybe looser toleranced? Is it because a lot of rebuilds are actually seeing increased duty from mods (different ICs, injectors, ECUs, turbos, exhausts, etc) that might have been the cause of the OEM engine failing? Is it even fair then to compare or expect a rebuild to have the same ~100K life?
Most of our original engines lasted somewhere around 75K to 130K miles! Is it because the rebuilds are maybe looser toleranced? Is it because a lot of rebuilds are actually seeing increased duty from mods (different ICs, injectors, ECUs, turbos, exhausts, etc) that might have been the cause of the OEM engine failing? Is it even fair then to compare or expect a rebuild to have the same ~100K life?
11-10-05, 02:47 PM
#2
1) Most rebuilds involve some/all used components. So the surface finish, flatness, etc are just not as perfect. Mazda's new parts I believe exceed the requirements for re-use, which is a common standard used in making rebuilds. This includes Mazda remans, which are arguably not as good as original.
2) Most rebuilds that see the end of their life were run harder and higher hp than stock. This is a totally subjective assessment on my part.
3) The shops doing rebuilds, while many excel in craftsmanship, _sometimes_ are not close to the factory for cleanliness, quality of tools and measuring devices, etc. I think this mostly applies to DIY rebuild jobs, but sadly many professional shops could be better.
If you compare a rebuild using all new housings, with stock porting and turbos and boost, to a new OEM motor, the lifespan should be very similar. Unfortunately many/most rebuilds are not comparable to the stock motor, and most customers won't pay for all new hard parts. So a good comparison is hard to make indeed.
Dave
2) Most rebuilds that see the end of their life were run harder and higher hp than stock. This is a totally subjective assessment on my part.
3) The shops doing rebuilds, while many excel in craftsmanship, _sometimes_ are not close to the factory for cleanliness, quality of tools and measuring devices, etc. I think this mostly applies to DIY rebuild jobs, but sadly many professional shops could be better.
If you compare a rebuild using all new housings, with stock porting and turbos and boost, to a new OEM motor, the lifespan should be very similar. Unfortunately many/most rebuilds are not comparable to the stock motor, and most customers won't pay for all new hard parts. So a good comparison is hard to make indeed.
Dave
11-10-05, 02:50 PM
#3
IMO, it's because most people don't do a stock rebuilds. Typically, if someone is going to do a rebuild, they want porting and other things done to beat the crap out of it. 
A reman is a rebuild, just a stock rebuild. There should be no reason a stock rebuild from other than Mazda is any less reliable *if* they follow/use Mazda's requirements.
A reman is a rebuild, just a stock rebuild. There should be no reason a stock rebuild from other than Mazda is any less reliable *if* they follow/use Mazda's requirements.
11-10-05, 02:51 PM
#4
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Exactly.
Rebuilds tend to be asked to produce more power.
Furthermore, most rebuilds are not done with new rotor housings.....but I guess I'm in the minority side of that argument...
Rebuilds tend to be asked to produce more power.
Furthermore, most rebuilds are not done with new rotor housings.....but I guess I'm in the minority side of that argument...
11-10-05, 03:15 PM
#6
Originally Posted by adam c
Used part don't last as long, and the quality of the build is not as good as from Mazda.
Keep in mind that at least here in the US, Mazda does not rebuild the motors. That is contracted out to a 3rd party something like every 2-3 years.
If whoever is building a Mazda reman and another shop both use the EXACT same requirements for the motor, they should last exactly the same amount of mileage (i.e. they both replace parts when they should, use the same tolerances, etc).
11-10-05, 03:20 PM
#7
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Originally Posted by bajaman
Most of our original engines lasted somewhere around 75K to 130K miles!
Is this an opinion or do you have some stats on this?
The original engine on my first FD died at 35k miles. A lot of other original owners also had their engines replaced at the 30-50k mile mark. I vaguely remember reading about this back in the mid to late 90s. Iirc, that was why Mazda started offering remans at such a nice price point and also replacing engines slightly outside their warranty periods.
I agree with what the others said regarding why some remans don't last long - pushing the power envelope, re-used parts and poor build/tuning/mods.
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11-10-05, 03:27 PM
#8
development
reman's have been pulled apart with blank front counter weights...ie. no balancing done to the rotating assembly.
Originally Posted by rynberg
Furthermore, most rebuilds are not done with new rotor housings.....but I guess I'm in the minority side of that argument...
11-10-05, 04:07 PM
#9
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My buddies rebuilt street ported motor lasted just over 60000miles. All it did after all of this time was lose a little vacuum at idle (went from 12in to 10in). Those miles were very hard miles at no less than 12psi of boost on the factory turbos so I guess it depends on your luck and tuning. BTW the parts that were used for the rebuild were all used except the gaskets.
R.K.
R.K.
11-10-05, 10:33 PM
#11
Originally Posted by Mahjik
If whoever is building a Mazda reman and another shop both use the EXACT same requirements for the motor, they should last exactly the same amount of mileage (i.e. they both replace parts when they should, use the same tolerances, etc).
11-11-05, 12:06 AM
#12
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From what I hear the factory remans are either a hit or miss. Some last a long time and some are defective from the beginning. I hear that Mazda now has a new contractor doing the remans who is SUPPOSED to be better than the previous one. However the price has already gone up mostly due to a lack of cores.
My first engine went 95K in totally stock form with only street driving. A factory reman was put in under warranty at that point. The car how has 60K miles on the reman with mild bolt on mods and about 100 hours of track time. I never exceed 10 psi. Its seen over 240F many a time and boiled over once. Still runs ok. We'll see for how much longer...
My first engine went 95K in totally stock form with only street driving. A factory reman was put in under warranty at that point. The car how has 60K miles on the reman with mild bolt on mods and about 100 hours of track time. I never exceed 10 psi. Its seen over 240F many a time and boiled over once. Still runs ok. We'll see for how much longer...
11-11-05, 02:09 AM
#14
I think you guys are overlooking something.
WHen you bought this car new (or whoever did) it was quite expensive. For those who are/were not rich, you had a big car payment on top of maintenance costs and insurance. When these cars were new, they were priced not too far under that of a 'vette.
For those of you who have ever had/have a new car and know the costs that come with it, you know that you usually don't beat the **** out of it for the first few years. Also, when a car is new, it gets more normal, daily driving, and even more road trips. As such, the car had more miles put on it when it was newer, and those miles were generally easier.
As time went on, people traded the cars around, values fell considerably, younger people were able to get the cars, and in general their maintenance fell off and their treatment probably worsened. This is much the case today. Even many who pay for rebuilds do so fully intending to modify or drive the car hard consistently. THese cars are no longer anyone's daily driver or commuter...we all have a new(er) car, or a beater of some sort, to fill that duty. SO most of the miles that these cars see are hard ones. And they dont get driven many miles per year. So if the average stock original motor lasted 6 years and 75k miles, it's easy to see that replacements might only last 3 years or 30k miles. Because most of the miles these days are city/hard miles.
Also keep in mind that regardless of how well (or not) the block is rebuilt, many (or most) times the external accessories are not replaced or checked, or even installed properly. Things like fuel injectors, pressure regulator, wiring, sensors, thermostats, etc. Many of these parts do not look bad to the eye, and when installed they will appear to function acceptably. But if you think about it, if an injector is delivering 5-10% less fuel than stock, you are that much closer to tearing the engine up. IF an alternator is only charging 90% as well as it should be, or a ground or power connection is a bit dirty then you can cause electrical and control system issues which can contribute to failure. Think about all the parts outside the engine that are old, and all of the ways these parts may not perform 100% like they did when new.
I will agree that many rebuilds have used part content and some may not even be clearanced or assembled as well as they could be.
Due to all these factors you'll never see rebuilds last as long or longer than original engines did, with a few exceptions of those who a) beat the original engine to an early death or b) baby the replacement to last longer.
WHen you bought this car new (or whoever did) it was quite expensive. For those who are/were not rich, you had a big car payment on top of maintenance costs and insurance. When these cars were new, they were priced not too far under that of a 'vette.
For those of you who have ever had/have a new car and know the costs that come with it, you know that you usually don't beat the **** out of it for the first few years. Also, when a car is new, it gets more normal, daily driving, and even more road trips. As such, the car had more miles put on it when it was newer, and those miles were generally easier.
As time went on, people traded the cars around, values fell considerably, younger people were able to get the cars, and in general their maintenance fell off and their treatment probably worsened. This is much the case today. Even many who pay for rebuilds do so fully intending to modify or drive the car hard consistently. THese cars are no longer anyone's daily driver or commuter...we all have a new(er) car, or a beater of some sort, to fill that duty. SO most of the miles that these cars see are hard ones. And they dont get driven many miles per year. So if the average stock original motor lasted 6 years and 75k miles, it's easy to see that replacements might only last 3 years or 30k miles. Because most of the miles these days are city/hard miles.
Also keep in mind that regardless of how well (or not) the block is rebuilt, many (or most) times the external accessories are not replaced or checked, or even installed properly. Things like fuel injectors, pressure regulator, wiring, sensors, thermostats, etc. Many of these parts do not look bad to the eye, and when installed they will appear to function acceptably. But if you think about it, if an injector is delivering 5-10% less fuel than stock, you are that much closer to tearing the engine up. IF an alternator is only charging 90% as well as it should be, or a ground or power connection is a bit dirty then you can cause electrical and control system issues which can contribute to failure. Think about all the parts outside the engine that are old, and all of the ways these parts may not perform 100% like they did when new.
I will agree that many rebuilds have used part content and some may not even be clearanced or assembled as well as they could be.
Due to all these factors you'll never see rebuilds last as long or longer than original engines did, with a few exceptions of those who a) beat the original engine to an early death or b) baby the replacement to last longer.
11-11-05, 04:29 AM
#15
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Originally Posted by John Magnuson
My first engine went 95K in totally stock form with only street driving. A factory reman was put in under warranty at that point.
Am I reading this wrong? Are you saying your car had 95,000 miles on it and Mazda gave you a replacement engine under the terms of the warranty? If that is true, please tell us your story because you got one hell of a deal.
11-11-05, 07:53 AM
#17
Rotary Enthusiast
I recently pulled apart a reman from Mazda. It had new rotor housings, new rotors and most other pieces were new.
However, the side housings they used were crap. They had grooves out of tolerance with bits missing that probably was created by a broken seal. The coolant passages already had a little gunk buildup. They did not pay attention to where sealing material ended up, the oil pickup tube had a bunch of gunk over the screen (probably sealer), and the overall build quality was poor.
With the way the engine was put together, it's highly unlikely that it would have lasted 110K like my original engine did. When they build these new, they used 'all' new parts.
RotaryResurection is dead on as well. Most people use the old 100K wiring and accessories for a rebuild, so reusing your injectors without getting them cleaned and checked is probably a sure way of guaranteeing a shorter engine life.
However, the side housings they used were crap. They had grooves out of tolerance with bits missing that probably was created by a broken seal. The coolant passages already had a little gunk buildup. They did not pay attention to where sealing material ended up, the oil pickup tube had a bunch of gunk over the screen (probably sealer), and the overall build quality was poor.
With the way the engine was put together, it's highly unlikely that it would have lasted 110K like my original engine did. When they build these new, they used 'all' new parts.
RotaryResurection is dead on as well. Most people use the old 100K wiring and accessories for a rebuild, so reusing your injectors without getting them cleaned and checked is probably a sure way of guaranteeing a shorter engine life.
11-11-05, 08:28 AM
#18
Originally Posted by adam c
I meant that the quality of build is not as good as an original engine (which was the original question BTW). Of course, you already knew what I meant
11-11-05, 08:39 AM
#19
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the owner before me blew the stock motor at 91K and put in a reman since the car was sold to me at 97K and its my daily driver. since june i've put it to just a little under 105,000 and just when a 2,000 round trip to Tx and back to Fl. my only power mods are dp, cb, and intake but it sees WOT maybe once every other day. not a long run but maybe threw a gear or passing someone on the highway. it hasn't skiped a beat yet. also i do take care of all the maintance which is the main reason i think its done so well even if it only has 14,000 on the new motor.
also i do take care of all the maintance which is the main reason i think its done so well even if it only has 14,000 on the new motor.
11-11-05, 09:55 PM
#20
Senior Member
I was able to purchase a brand new motor from Malloy this past Spring. Ray had a few available. I paid $4k minus $600 he gave me for my core, so net was $3,400. His remans at the time were $2,400 w/ core, so for $1K additional I was able to get an all-new motor from Mazda. I got 96K on my original motor (I'm the 1st and only owner) and it was still running well when removed in August. I debated about the reman for a short time, but for $1K I'm feeling pretty good about my decision to go new. Hope to get another 100K out of this one. Light mods are the key!
11-12-05, 11:31 AM
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3400 is a great price for an all new motor....I thought they were more like $5k
after talking with several people, I wanted to go with the 3mm seals, though (I'm running 15 psi)
after talking with several people, I wanted to go with the 3mm seals, though (I'm running 15 psi)
11-12-05, 11:40 AM
#22
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Originally Posted by RotaryResurrection
I think you guys are overlooking something.
WHen you bought this car new (or whoever did) it was quite expensive. For those who are/were not rich, you had a big car payment on top of maintenance costs and insurance. When these cars were new, they were priced not too far under that of a 'vette.
For those of you who have ever had/have a new car and know the costs that come with it, you know that you usually don't beat the **** out of it for the first few years. Also, when a car is new, it gets more normal, daily driving, and even more road trips. As such, the car had more miles put on it when it was newer, and those miles were generally easier.
As time went on, people traded the cars around, values fell considerably, younger people were able to get the cars, and in general their maintenance fell off and their treatment probably worsened. This is much the case today. Even many who pay for rebuilds do so fully intending to modify or drive the car hard consistently. THese cars are no longer anyone's daily driver or commuter...we all have a new(er) car, or a beater of some sort, to fill that duty. SO most of the miles that these cars see are hard ones. And they dont get driven many miles per year. So if the average stock original motor lasted 6 years and 75k miles, it's easy to see that replacements might only last 3 years or 30k miles. Because most of the miles these days are city/hard miles.
Also keep in mind that regardless of how well (or not) the block is rebuilt, many (or most) times the external accessories are not replaced or checked, or even installed properly. Things like fuel injectors, pressure regulator, wiring, sensors, thermostats, etc. Many of these parts do not look bad to the eye, and when installed they will appear to function acceptably. But if you think about it, if an injector is delivering 5-10% less fuel than stock, you are that much closer to tearing the engine up. IF an alternator is only charging 90% as well as it should be, or a ground or power connection is a bit dirty then you can cause electrical and control system issues which can contribute to failure. Think about all the parts outside the engine that are old, and all of the ways these parts may not perform 100% like they did when new.
I will agree that many rebuilds have used part content and some may not even be clearanced or assembled as well as they could be.
Due to all these factors you'll never see rebuilds last as long or longer than original engines did, with a few exceptions of those who a) beat the original engine to an early death or b) baby the replacement to last longer.
WHen you bought this car new (or whoever did) it was quite expensive. For those who are/were not rich, you had a big car payment on top of maintenance costs and insurance. When these cars were new, they were priced not too far under that of a 'vette.
For those of you who have ever had/have a new car and know the costs that come with it, you know that you usually don't beat the **** out of it for the first few years. Also, when a car is new, it gets more normal, daily driving, and even more road trips. As such, the car had more miles put on it when it was newer, and those miles were generally easier.
As time went on, people traded the cars around, values fell considerably, younger people were able to get the cars, and in general their maintenance fell off and their treatment probably worsened. This is much the case today. Even many who pay for rebuilds do so fully intending to modify or drive the car hard consistently. THese cars are no longer anyone's daily driver or commuter...we all have a new(er) car, or a beater of some sort, to fill that duty. SO most of the miles that these cars see are hard ones. And they dont get driven many miles per year. So if the average stock original motor lasted 6 years and 75k miles, it's easy to see that replacements might only last 3 years or 30k miles. Because most of the miles these days are city/hard miles.
Also keep in mind that regardless of how well (or not) the block is rebuilt, many (or most) times the external accessories are not replaced or checked, or even installed properly. Things like fuel injectors, pressure regulator, wiring, sensors, thermostats, etc. Many of these parts do not look bad to the eye, and when installed they will appear to function acceptably. But if you think about it, if an injector is delivering 5-10% less fuel than stock, you are that much closer to tearing the engine up. IF an alternator is only charging 90% as well as it should be, or a ground or power connection is a bit dirty then you can cause electrical and control system issues which can contribute to failure. Think about all the parts outside the engine that are old, and all of the ways these parts may not perform 100% like they did when new.
I will agree that many rebuilds have used part content and some may not even be clearanced or assembled as well as they could be.
Due to all these factors you'll never see rebuilds last as long or longer than original engines did, with a few exceptions of those who a) beat the original engine to an early death or b) baby the replacement to last longer.
11-12-05, 10:19 PM
#23
Senior Member
Originally Posted by Improved FD
3400 is a great price for an all new motor....I thought they were more like $5k
after talking with several people, I wanted to go with the 3mm seals, though (I'm running 15 psi)
after talking with several people, I wanted to go with the 3mm seals, though (I'm running 15 psi)
11-13-05, 01:56 AM
#24
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+1 to what Kevin said. Although there hasn't been a definitive poll on this, there is no doubt in my mind the average original motor lasts much longer than the average rebuild.
11-13-05, 02:32 AM
#25
As nice as that "brand new" engine block is, if there were a way to monitor usage and results, I would put good money on it not lasting as long as the first one, due to the factors I listed above. Even though you have a 0 mile 0 year block, you have 96k 10 year electronics, fuel, cooling, etc. systems going back onto it. It will never be like it was when it was new off the showroom floor.