Merc 300 xs optimax 3.2 racing
04-11-2010, 07:01 AM
#11
Registered
Join Date: Oct 2003
Location: sarasota,fl
Posts: 446
Likes: 0
Received 0 Likes
on
0 Posts
Strange
I have 296hrs and 298hrs and love my motors. The air compressors (both) blew at 2350 and change.
I believe the cowling has a design flaw as it sucks in salt water like no tomorow on our cat boats that generate speeds over 100.
Lowers have been great but you need to buy the seal/spacer kit from Mad EFI to keep the water pump seal from pushing out and pushing your oil out. I would avoid welded in hub props, Merc hubs are easier on the gearcases for load and unloading.
My motors are late 06 models.
I have 296hrs and 298hrs and love my motors. The air compressors (both) blew at 2350 and change.
I believe the cowling has a design flaw as it sucks in salt water like no tomorow on our cat boats that generate speeds over 100.
Lowers have been great but you need to buy the seal/spacer kit from Mad EFI to keep the water pump seal from pushing out and pushing your oil out. I would avoid welded in hub props, Merc hubs are easier on the gearcases for load and unloading.
My motors are late 06 models.
04-11-2010, 10:58 PM
#12
Registered
My 2007 30/308 Skater came from the factory with T/300XS. After 3 weeks (30 hours), one motor melted piston 5, and ventilated the block with the connecting rod. The power head was on national backorder so I was down from May 27 to Sep 28.
Since then the only other engine failure was a burned up coil and ignition harness at 97 hours. Presently, I have 120 hours on one and 90 hours on the other, but for some reason the computer shows 120 & 118 hours?
The real problem has been the lower units. I am on replacements 5 and 6. I was cracking them like clockwork, and other owners have reported the same thing.
Since then the only other engine failure was a burned up coil and ignition harness at 97 hours. Presently, I have 120 hours on one and 90 hours on the other, but for some reason the computer shows 120 & 118 hours?
The real problem has been the lower units. I am on replacements 5 and 6. I was cracking them like clockwork, and other owners have reported the same thing.
I've heard of issues with lowers with the 300 XS. You mentioned cracking them. Do you attribute that to water getting into them or that they are taking a beating from being on a cat?
04-12-2010, 07:30 AM
#14
Registered
My 2007 30/308 Skater came from the factory with T/300XS. After 3 weeks (30 hours), one motor melted piston 5, and ventilated the block with the connecting rod. The power head was on national backorder so I was down from May 27 to Sep 28.
Since then the only other engine failure was a burned up coil and ignition harness at 97 hours. Presently, I have 120 hours on one and 90 hours on the other, but for some reason the computer shows 120 & 118 hours?
The real problem has been the lower units. I am on replacements 5 and 6. I was cracking them like clockwork, and other owners have reported the same thing.
Since then the only other engine failure was a burned up coil and ignition harness at 97 hours. Presently, I have 120 hours on one and 90 hours on the other, but for some reason the computer shows 120 & 118 hours?
The real problem has been the lower units. I am on replacements 5 and 6. I was cracking them like clockwork, and other owners have reported the same thing.
Did they do anything different to the sportmaster lower units with the 300XS? Reason I ask is I just ordered two for my Spectre. I have been running 300 Promax's for the last five years and have had zero problems with my sportmaster lowers. I change the lower unit lube in the fall (October) and then once again mid summer (July). No problems. Usually boat from May thru September.
Thanks.
Mike
Mike
04-12-2010, 08:27 AM
#15
Gold Member
Gold Member
Did they do anything different to the sportmaster lower units with the 300XS? Reason I ask is I just ordered two for my Spectre. I have been running 300 Promax's for the last five years and have had zero problems with my sportmaster lowers. I change the lower unit lube in the fall (October) and then once again mid summer (July). No problems. Usually boat from May thru September.
Thanks.
Mike
Mike
Thanks.
Mike
Mike
I change my gear lube every 20 hours, and have not had any water intrusion or internal part failures.
I have been cracking the housing, in the exact spots as others have.
I suspect the older castings were stronger, and probably from a different supplier.
04-12-2010, 08:31 AM
#16
Gold Member
Gold Member
They are mounted high, it is a fast cat, but that is what the lower unit was designed for.
04-12-2010, 11:04 AM
#17
Registered
Mike
04-12-2010, 12:31 PM
#19
Gold Member
Gold Member
04-12-2010, 08:06 PM
#20
Registered
40 hours port lower blew. May or may not have to do with testing props and motor heights. Clutch dog shattered
100 hours starboard power head gone- shot some thing through the side of the block into the side of the computer- think it was #2 but I know very little about motors
117 hours starboard lower blew after about 5 hours on lube, checked port gear lube and looks pretty bad- mechanic says he thinks some thing is going to let loose sooner than later. Snapped the prop shaft- like 1"+ solid metal!
100 hours starboard power head gone- shot some thing through the side of the block into the side of the computer- think it was #2 but I know very little about motors
117 hours starboard lower blew after about 5 hours on lube, checked port gear lube and looks pretty bad- mechanic says he thinks some thing is going to let loose sooner than later. Snapped the prop shaft- like 1"+ solid metal!
