300xs cold sieze

[mostroker]

please explain what this is and what temp to accquire before throttle up. Have a 2009 300xs with 35 hrs that had to have powerhead replaced , due to what was called cold sieze. I have tried to warm the engine to 133 according to smartcraft and have never started it without warmup of some kind . This all occurred in June with water temps in the 65-75degree range


Modified by mostroker at 10:11 PM 10/11/2011

[Reelsore]

Look at this link: http://www.bbcboards.net/zerothread?id=25496

And also check this one out: http://www.bbcboards.net/zerot...water


Also a ton of other valuable information pinned at the top.

[Stratos Luver]

Is a 300xs typically more delicate than a 250 xs/pro xs as far as running in cold water and chances of cold seizing ?

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Reelsore &raquo;</td></tr><tr><td class="quote">Look at this link: http://www.bbcboards.net/zerothread?id=25496

And also check this one out: http://www.bbcboards.net/zerot...water


Also a ton of other valuable information pinned at the top. </td></tr></table>

+1

Proper engine warmup (to at least 120 degrees) and proper cooldown time (until temps stabilize at or above 120 degrees) are critical to engine longevity.

This applies for EVERY startup, and engine shutdown.

ALL 2-stroke engines (including all Optimax models) will have similar requirements in this area.

COLD SEIZURE (short explanation): This occurs when the cylinder block and cylinder wall have not reached target temperature (and thus have not expanded to their target size). If the engine is accelerated... combustion chamber temps rise rapidly, and since the piston is manufactured from some form of aluminum, it heats and expands at a SUBSTANTIALLY faster rate than the cast-iron sleeve the piston rides in.

Essentially, the piston becomes larger than the hole it's in- forcing rings into the ports, breaking rings, piston material transfers to cylinder wall (or completely hangs, breaking a rod).

Short & sweet: "Engine go BOOM".

[Phoenix Jim]

okay but his happened in June with water in the 60's!

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Puma Jim &raquo;</td></tr><tr><td class="quote">okay but his happened in June with water in the 60's!</td></tr></table>

That doesn't matter. Yes, it's "easier" for the engine to reach proper operating temps in warmer water.... but I've seen cold seizures occur (due to debris in thermostats) with water temps over 80.

[mostroker]

Thanks Don, in this case the motor did not blow it still ran fine just had #5 cylinder drop down 25-30# of compression. When the head was removed the cylinder was scored. That is why Mercury replaced the powerhead , but they said the issue was cold sieze,however the engine never siezed or quit , just lost some power.Thank you again for the explanation.

[herk91]

Don just out of curiosity, how do you know when a carb motor has attained the proper warm up, i.e. the 120 degree mark?

[EuropeanAM]

"Cold Seize" does not necessarily indicate that the engine locked up and wouldn't run... it indicates that the piston "seized" in the cylinder for at least a portion of "one stroke" (resulting in cylinder damage).

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by herk91 &raquo;</td></tr><tr><td class="quote">Don just out of curiosity, how do you know when a carb motor has attained the proper warm up, i.e. the 120 degree mark? </td></tr></table>

That depends on the engine, of course. With 2.5L carb and EFI models, the TELLTALE is a good indicator (since there's little or no telltale until the thermostats open).