Mercury Racing blue motors: 500EFI, 525 EFI, 575 SCI. Pros/cons/maintenance/etc.
11-08-2010, 02:22 AM
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Mercury Racing blue motors: 500EFI, 525 EFI, 575 SCI. Pros/cons/maintenance/etc.
Hey guys.. wondering if some of you with lots of merc racing engine experience can help me out, and others too.. didnt find a thread like this when I was searching. Basically if you could list
1. Pros/cons/inherent flaws/ weak points
2. Merc recommended service interval + actual real world failure points/service needed (in hours) for major work like heads, valves, springs, etc.
3. Fuel octane requirements.
(Obviously some of these issues will be vastly different depending on how the engines are run+maintained, but just general ideas and tips would be great!)
for the 500EFI, 525 EFI and 575 SCI.
Trying to judge what would be the best engine package to look for a recreational / occasional fun-run use. Thanks in advance for sharing your expertise
1. Pros/cons/inherent flaws/ weak points
2. Merc recommended service interval + actual real world failure points/service needed (in hours) for major work like heads, valves, springs, etc.
3. Fuel octane requirements.
(Obviously some of these issues will be vastly different depending on how the engines are run+maintained, but just general ideas and tips would be great!)
for the 500EFI, 525 EFI and 575 SCI.
Trying to judge what would be the best engine package to look for a recreational / occasional fun-run use. Thanks in advance for sharing your expertise
11-08-2010, 07:36 AM
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They are all good engines. I think the 575 has the easiest/cheapest foundation to add power to. Its easy to bolt on a intercooler and smaller supercharger pulley and get around 700HP out of it.
Well maintained and not beat, i would guesstimate 250-300 hours before freshening the top ends, and then full rebuilds around 500-600 hours?
Well maintained and not beat, i would guesstimate 250-300 hours before freshening the top ends, and then full rebuilds around 500-600 hours?
11-08-2010, 07:36 AM
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I recently posted a question on stainless marine or headers. Then I asked about CMI. At that point the threat went nuts. Everyone hated CMI headers. I was very confused on this as so many people use CMI and love them... I dug deeper into it and found that Merc Racing used CMI Headers after having a ton of engines go south using Gils (reversion problems). Problem is that Merc told CMI what grade stainless to use (lower) and to bypass the heat treating of the finished tubes. So what happened, the headers crack leak water in the engine and if not caught will quickly destroy it in short order. It seems standard CMI's are fine but the Merc/CMI headers really gave CMI a bad rap. Now you can buy the CMI header for around $4000, I believe the inferiour Merc version is $8000. Another example on merc's outragious mark-up. The rockers used in the new blue engines are Scorpion Endurance Marine Rockers, they list for around $400.00 merc price around $800.00. Anyway I'd personally skip the blue motor. Go to Young Performance, Wesco Racing, ect and have a great builder build your engine. It will cost you less and be a MUCH better engine. Do some digging on here about blue motors, you'll be shocked at what you'll read and how Merc didn't stand behind their product.
On another note about Mercury quality. A buddy of mine somehow got water in his oil reseviour in his new 40 hp Merc outboard. It took out the crank, we tore it down to rebuild it and its not possible. Its a throw away engine. The block and the head are welded together? IMO Merc needs to stop letting the bean counters run the show and start letting the engineers focus on long lasting, repairable products.
On another note about Mercury quality. A buddy of mine somehow got water in his oil reseviour in his new 40 hp Merc outboard. It took out the crank, we tore it down to rebuild it and its not possible. Its a throw away engine. The block and the head are welded together? IMO Merc needs to stop letting the bean counters run the show and start letting the engineers focus on long lasting, repairable products.
Last edited by endeavour32; 11-08-2010 at 07:40 AM.
11-08-2010, 07:44 AM
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I recently posted a question on stainless marine or headers. Then I asked about CMI. At that point the threat went nuts. Everyone hated CMI headers. I was very confused on this as so many people use CMI and love them... I dug deeper into it and found that Merc Racing used CMI Headers after having a ton of engines go south using Gils (reversion problems). Problem is that Merc told CMI what grade stainless to use (lower) and to bypass the heat treating of the finished tubes. So what happened, the headers crack leak water in the engine and if not caught will quickly destroy it in short order. It seems standard CMI's are fine but the Merc/CMI headers really gave CMI a bad rap. Now you can buy the CMI header for around $4000, I believe the inferiour Merc version is $8000. Another example on merc's outragious mark-up. The rockers used in the new blue engines are Scorpion Endurance Marine Rockers, they list for around $400.00 merc price around $800.00. Anyway I'd personally skip the blue motor. Go to Young Performance, Wesco Racing, ect and have a great builder build your engine. It will cost you less and be a MUCH better engine. Do some digging on here about blue motors, you'll be shocked at what you'll read and how Merc didn't stand behind their product.
On another note about Mercury quality. A buddy of mine somehow got water in his oil reseviour in his new 40 hp Merc outboard. It took out the crank, we tore it down to rebuild it and its not possible. Its a throw away engine. The block and the head are welded together? IMO Merc needs to stop letting the bean counters run the show and start letting the engineers focus on long lasting, repairable products.
On another note about Mercury quality. A buddy of mine somehow got water in his oil reseviour in his new 40 hp Merc outboard. It took out the crank, we tore it down to rebuild it and its not possible. Its a throw away engine. The block and the head are welded together? IMO Merc needs to stop letting the bean counters run the show and start letting the engineers focus on long lasting, repairable products.
11-08-2010, 07:47 AM
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I recently posted a question on stainless marine or headers. Then I asked about CMI. At that point the threat went nuts. Everyone hated CMI headers. I was very confused on this as so many people use CMI and love them... I dug deeper into it and found that Merc Racing used CMI Headers after having a ton of engines went south using Gils (reversion problems). Problem is that Merc told CMI what grade stainless to use (lower) and to bypass the heat treating of the finished tubes. So what happened, the headers crack leak water in the engine and will quickly destroy it in short order. It seems standard CMI's are fine but the Merc/CMI headers really gave CMI a bad wrap. Now you can buy the CMI header for around $4000, I believe the inferiour Merc version is $8000. Another example on merc's outragious mark-up. The rockers used in the new blue engines are Scorpion Endurance Marine Rockers, they list for around $400.00 merc price around $800.00. Anyway I'd personally skip the blue motor. Go to Young Performance, Wesco Racing, ect and have a great builder build your engine. It will cost you less and be a MUCH better engine. Do some digging on here about blue motors, you'll be shocked at what you'll read and how Merc didn't stand behind their product.
On another note about Mercury quality. A buddy of mine somehow got water in his oil resiviour in his new 40 hp outboard. It took out the crank, we tore it down to rebuild it and its not possible. Its a throw away engine. The block and the head are welded together? IMO Merc needs to stop letting the bean counters run the show and start letting the engineers focus on long lasting, repairable products.
On another note about Mercury quality. A buddy of mine somehow got water in his oil resiviour in his new 40 hp outboard. It took out the crank, we tore it down to rebuild it and its not possible. Its a throw away engine. The block and the head are welded together? IMO Merc needs to stop letting the bean counters run the show and start letting the engineers focus on long lasting, repairable products.
I remember talking to a local boater that i know a couple years ago. His boat had twin HP500 mercs. They were tired. Rather than pull them, have a shop rebuild them, he decided to just order up two complete hp500's from merc. It was nearly 40k for two of them from merc. 20k for a 502 chevy that has a holley carb, dart intake, crane valvetrain, and all other gm parts, heads, crank, etc. For what he spent, he could have built 800hp engines out of his old motors, or spend 1/4 of that and had them freshened up and kept them stock. There are some guys out there that think certain merc engines had magical parts inside them, thats why they were so expensive. I havent seen anything inside a blue motor blow my mind yet!
The markup on merc's stuff is ridiculous, especially engine components. Buying a holley carb from merc will run you 2-3 times as much as summit or jegs, for the same carb.
11-08-2010, 08:02 AM
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Thanks for the input. I have heard many stories of blue motor problems.. and the infamous 525 CMI header problems too. I am 100% staying away from custom built motors becuase I want a newer model (2002+) boat that is EFI and fairly turn-key. I like the fact that EFI era blue motors seem to have a solid block and heads for the most part, (better then the 496's) i.e. if I maintain it will and dont run it too hard it should get me many hours of reasonably troublefree use.
However, there is absolutly nothing wrong with a carbureted engine. 90% of the guys out there you see with motors loading up, stalling, etc, is a matter of wrong carb tuning. I have supercharged engines, with a much more agressive cams than pretty much any blue motor out there, and never have i had the engines load up from idling too long, etc. I blip the key and they fire instantly. Sure on a cold morning, i may have to idle them up for 20 seconds or so because i dont have chokes, but reallly not a big deal.
Once a carb is setup properly, they can give many seasons of turn key performance. And, easier to modify to accept engine upgrades.
I also know of several people i boat with with merc blue engines that have had more issues sending their ecu's back in, and trying to get programming right, etc etc. I cant tune a ecu at the dock, but i sure can tune a carb at the dock.
So being a do-it-yourselfer, i prefer carbs. Especially on a non-stock engine. Problem is these days, not many mechanics/marinas have anyone knowledgable with carbs.
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11-08-2010, 08:33 AM
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I appreciate the relative simplicity of carbed system, thats what I currently have and i never have starting or idling problems on SBC's. I just think EFI is better for how I will use it, and hopefully less tinkering. I will be keeping the motors 100% stock most likely so no worrying about tuning/ECU. Its usually more cost effective to just trade up boats if you get the 5mph itis.
11-08-2010, 05:55 PM
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Mild Thunder; well said synopsis on engine basics. Just my .02 cents, but I've run a number of stock mercury products and recently upgraded to a new boat with a blower motor - nearly 800 hp, carbed and custom built (not merc). She starts, runs and shifts flawlessly, my engine will shift around the dock at nearly 500 rpms and never stalls; it lumps along with the cam profile beautifully. Its all about setup and preventative maintenance. Save some coin, go with a custom builder; spend the extra money on an imco drive and fuel!
11-08-2010, 06:43 PM
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Here's a shot at answering your questions:
1)
HP500 (carb) had valve springs that broke and sometimes reversion problems. Other than that, pretty much bulletproof and reliable.
500 EFI - basically no problems except some (rare) had head gasket leaks -that may have been from too high water pressure due to LWP B1 drives that debuted about the same time. On a Fountain with a pair of 500 EFI's and LWP B1's it was easy to develop 35+ psi water pressure ... merc made a blowoff valve kit that could be installed to limit pressure. Early 500 EFI's didn't have the low pressure mechanical fuel pump and were susceptible to vapor lock. Not very many electronic sensors to go bad, either. For a bone stock engine, it is my favorite of the one's you listed. Didn't have the valve spring issues of the HP500.
525 EFI ... headers... headers .... headers.... occasional sticking valve issues .... and mucho electronics ... when they run, there is nothing like them and when they won't run .... there's nothing like them - plan on $$$ diagnostics fees and parts costs when they don't run. For the most part, you can't diagnose them yourself without diacom software or something similar, and just trying to replace parts, hoping you choose the right one gets expensive, quick. Otherwise, nice engines. Did I mention header issues? I currently have a Fountain with the 525 EFI. One day in late June, it started throwing a 3 beep code and running real rough at idle/midrange. Couldn't find a shop to hook up the diacom software for 3 weeks (they were all booked up, middle of summer surge). Was going to miss 4th of July weekend, so we took a stab at it and changed out the IAC, based on the way it was acting. Well, $200+ spent on the IAC plus overnight shipping and it still wouldn't run worth crap. Turned out to be the MAP sensor for ~$300 more for diagnostics, sensor and shipping ... and still missed 4th of July weekend.
575SCi ... early one's had Weiand blowers (good) and weaker head gaskets, later ones had B&M blowers that gernaded, but better head gaskets. All of them didn't like humidity and would sometimes foul out the sparkplugs due to gas flooding on hot humid days. Otherwise ok. Required premium fuel. My wife and kids didn't like the whine (howl) of the blower when sitting in the back seat. I didn't mind it, sitting in the front seat
2.
most went 200+ hrs with routine maintenance, except the 575's with the B&M blowers ... some didn't make it 100 hrs.
3.
all recommend 87 octane except 575 which requires premium.
Many parts are now "obsolete" and no longer stocked by Merc for the 500 EFI and 575s. They are now "non current" engines.
You didn't ask about the HP500 but I added it anyways. Other than valve springs, it is a simple, reliable engine and easy to diagnose / work on (for most items).
1)
HP500 (carb) had valve springs that broke and sometimes reversion problems. Other than that, pretty much bulletproof and reliable.
500 EFI - basically no problems except some (rare) had head gasket leaks -that may have been from too high water pressure due to LWP B1 drives that debuted about the same time. On a Fountain with a pair of 500 EFI's and LWP B1's it was easy to develop 35+ psi water pressure ... merc made a blowoff valve kit that could be installed to limit pressure. Early 500 EFI's didn't have the low pressure mechanical fuel pump and were susceptible to vapor lock. Not very many electronic sensors to go bad, either. For a bone stock engine, it is my favorite of the one's you listed. Didn't have the valve spring issues of the HP500.
525 EFI ... headers... headers .... headers.... occasional sticking valve issues .... and mucho electronics ... when they run, there is nothing like them and when they won't run .... there's nothing like them - plan on $$$ diagnostics fees and parts costs when they don't run. For the most part, you can't diagnose them yourself without diacom software or something similar, and just trying to replace parts, hoping you choose the right one gets expensive, quick. Otherwise, nice engines. Did I mention header issues? I currently have a Fountain with the 525 EFI. One day in late June, it started throwing a 3 beep code and running real rough at idle/midrange. Couldn't find a shop to hook up the diacom software for 3 weeks (they were all booked up, middle of summer surge). Was going to miss 4th of July weekend, so we took a stab at it and changed out the IAC, based on the way it was acting. Well, $200+ spent on the IAC plus overnight shipping and it still wouldn't run worth crap. Turned out to be the MAP sensor for ~$300 more for diagnostics, sensor and shipping ... and still missed 4th of July weekend.
575SCi ... early one's had Weiand blowers (good) and weaker head gaskets, later ones had B&M blowers that gernaded, but better head gaskets. All of them didn't like humidity and would sometimes foul out the sparkplugs due to gas flooding on hot humid days. Otherwise ok. Required premium fuel. My wife and kids didn't like the whine (howl) of the blower when sitting in the back seat. I didn't mind it, sitting in the front seat
2.
most went 200+ hrs with routine maintenance, except the 575's with the B&M blowers ... some didn't make it 100 hrs.
3.
all recommend 87 octane except 575 which requires premium.
Many parts are now "obsolete" and no longer stocked by Merc for the 500 EFI and 575s. They are now "non current" engines.
You didn't ask about the HP500 but I added it anyways. Other than valve springs, it is a simple, reliable engine and easy to diagnose / work on (for most items).
Last edited by bob_t; 11-08-2010 at 07:47 PM.
