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11-07-2010, 05:32 PM
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#1
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Registered User
Country: Spain
Location: Mallorca
Occupation: Marine Service Manager
Interests: Boats,bikes and rally cars
Boat make: Phantom 21
Engines: Merc 135hp/merc XR2
Cruising area: Balearics
Join Date: Jun 2009
Location: Mallorca
Posts: 56
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Blown motor........!
hrew the boat in the water today and had great fun untill the motor went on sick leave.
I have just rebuilt the motor ( 2l 135hp Mercury 2000) after buying it with a fault, when running flat out it slowed down ........let it cool down and it would be fine again.........? this was only happening at flat out (WOT).
So stripped it threw in 2 new top pistons (which were scored ) did away with the oil system and running it on premix.
first time out today ran it around for a few hours and was fine, was running it about 3k rpms and every 10mins ran it upto 4/5k and seemed to be OK. then on the way back ran it flat out 6kish and it started to slow on the pistons backed off a little and went a bit longer then floored it again and it siezed and stopped!!!!!!!!!!!!
So before i start ripping it apart again whats the likely cause??? i wanna say lack of oil but was running it on 25:1??????.
I have had an XR2 do a similar thing due to a blocked carb, but my carbs were cleaned and rebuilt last week??? just before i ran it??
Any ideas chaps would be greatly recieved...
thanks
Matt
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11-07-2010, 05:54 PM
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#2
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Registered User
Country: Spain
Location: Mallorca
Occupation: Retired
Interests: Boats, boats and boats
Boat name: Patriot and Forca
Boat make: Phantom 21. Falcon Bonito 36
Engines: 200hp Mariner. 2 x GM 6.5 Twin Turbo Diesels
Cruising area: The Med
Join Date: Nov 2006
Location: Mallorca
Posts: 716
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Hi Matt, I'm running 50:1. I thought this was the norm. Pete
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11-07-2010, 06:03 PM
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#3
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Registered User
Country: UK
Location: Guernsey
Occupation: Network Engineer
Boat make: Argo 21
Engines: 2.5 EFI
Cruising area: Channel Islands
Join Date: May 2009
Location: Guernsey
Posts: 426
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25:1 is wayy to much oil, more oil thickens the mix and the fuel travels slower through the jets actually making it run lean
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11-07-2010, 06:14 PM
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#4
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Registered User
Country: Spain
Location: Mallorca
Occupation: Marine Service Manager
Interests: Boats,bikes and rally cars
Boat make: Phantom 21
Engines: Merc 135hp/merc XR2
Cruising area: Balearics
Join Date: Jun 2009
Location: Mallorca
Posts: 56
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i was running 25:1 for the first tank as it had new 2 new pistons and all new rings???? thought i would run it with a bit much oil to help, then the plan was 50:1 in the next tank???
makes sense what you are saying Scooby Hugh,
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11-07-2010, 07:04 PM
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#5
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Martyn W
Country: uk
Location: Guernsey Channel island
Occupation: wholesale food sales
Interests: Burning fuel!!!
Boat name: The Magician, A Fine Pair
Boat make: ring20b, chriscraft stinger 26
Engines: merc XR2, 2X AQ311B 5.7's
Cruising area: channel islands
Join Date: Jul 2009
Location: Guernsey Channel island
Posts: 284
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25/1 is fine for a run in period,
after that i run my XR2 33/1, yeah it smokes a lot but keeps the motor sweet.
what kind of fuel pump does your motor run? is it a diaphram vacume type pump or en elec extermal pump?
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12-07-2010, 09:39 AM
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#6
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Registered User
Country: Spain
Location: Mallorca
Occupation: Marine Service Manager
Interests: Boats,bikes and rally cars
Boat make: Phantom 21
Engines: Merc 135hp/merc XR2
Cruising area: Balearics
Join Date: Jun 2009
Location: Mallorca
Posts: 56
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Running just the stnd engine/block fuel pump.
Which i put new gaskets and diaphrams in only a few weeks ago. I have always found those stnd merc pumps pretty good???
Going off to take the heads off in a bit to see the damage???
Just thinking back it did get a little noisey just before it stopped so would that spell out lack of oil???
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12-07-2010, 09:52 AM
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#7
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Registered User
Location: hayling island
Boat name: snow monkey
Boat make: extreme 24
Engines: mercruiser 6.2
Join Date: May 2004
Location: hayling island
Posts: 2,082
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raced mine for 3 yrs on 30/1 and never missed a beat,including pleasure use
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12-07-2010, 12:44 PM
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#8
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Le Cat
Country: France
Location: Paris
Occupation: Computer Sales
Boat name: Le Cat
Boat make: Argo Cat 18
Engines: Mercury 2.4EFI
Cruising area: Paris
Join Date: Mar 2004
Location: Paris
Posts: 753
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Your piston break in time seems short, how many hours before you went to 6k rpm ?
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12-07-2010, 01:30 PM
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#9
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Registered User
Country: Spain
Location: Mallorca
Occupation: Marine Service Manager
Interests: Boats,bikes and rally cars
Boat make: Phantom 21
Engines: Merc 135hp/merc XR2
Cruising area: Balearics
Join Date: Jun 2009
Location: Mallorca
Posts: 56
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probally 3 .5 hours total??? i replaced the 2 top pistons and all the rings????
your probally right , i did get a bit over excited. i did think short burst would be OK????
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