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another one for you engine guy's

Old 01-10-2013, 01:27 AM
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jvdd
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Default another one for you engine guy's

Hi

One of the guy's who comes playing with us was running his boat which has a K30 in it.
The first run went very well and ran out the tank, we refueled it and when it was his turn it wouldn't start.
I noticed that the barrell was lose on the crank case moving a few mm each pull.
He tightened the bolts and the motor started and ran but will only turn in one direction with out stalling and is hard to start now.

What I would like to know it what issues could have been created by the barrell being loose
and If we do a strip down what should I be looking for, I think the base gasket is one thing that may be damaged.

thanks
jim
Old 01-10-2013, 01:59 AM
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Default RE: another one for you engine guy's

Jim,
May have damaged the piston and ring if it allowed the cyl to lift enough. First question is why the cyl bolts came loose in the first place? I would also invest in a 5mm Recoil kit as I have had to redo several threads in the RCMK cases, looks as if the alloy cases are a tad too hard(brittle)
Cheers
Old 01-10-2013, 07:28 AM
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Slow Motion
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Default RE: another one for you engine guy's

I only build RCMKs and I have them apart many times in a season. If the case threads are being pulled or broken it is from way too much tightening. The RCMK castings and billet parts are a very high quality and I have never damaged any threads. The cylinder bolts need to have a split lock washer under each bolt and if the cylinders are not going to be taken off regularly the bolts should have a light touch of antisieze grease on them. Snug the bolts hand tight but don't reef them down. Reuseable copper gaskets are much better at holding a uniform torque as they don't squish down releasing some of the installed torque.
Old 01-10-2013, 09:12 AM
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t-max97
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Default RE: another one for you engine guy's


ORIGINAL: Slow Motion

I only build RCMKs and I have them apart many times in a season. If the case threads are being pulled or broken it is from way too much tightening. The RCMK castings and billet parts are a very high quality and I have never damaged any threads. The cylinder bolts need to have a split lock washer under each bolt and if the cylinders are not going to be taken off regularly the bolts should have a light touch of antisieze grease on them. Snug the bolts hand tight but don't reef them down. Reuseable copper gaskets are much better at holding a uniform torque as they don't squish down releasing some of the installed torque.

If your NOT going to be removing them often why would you put antisieze on them?
Old 01-10-2013, 10:18 AM
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Slow Motion
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Default RE: another one for you engine guy's

Anytime dis-similar metals are assembled together like steel bolts into aluminum, over time oxidation sets in and the bolts will become welded to the aluminum. Then when you try to remove them, damage can be done to the bolts and/or the case threads. How are you going to do routine engine maintenence if you can't get the bolts out easily? IE; replace ring, pin bearing, crank bearings and seals, gaskets, ect.
Old 01-10-2013, 05:30 PM
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t-max97
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Default RE: another one for you engine guy's

Oh ok makes since. lol
Old 01-10-2013, 10:29 PM
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Default RE: another one for you engine guy's

ORIGINAL: Slow Motion

I only build RCMKs and I have them apart many times in a season. If the case threads are being pulled or broken it is from way too much tightening. The RCMK castings and billet parts are a very high quality and I have never damaged any threads. The cylinder bolts need to have a split lock washer under each bolt and if the cylinders are not going to be taken off regularly the bolts should have a light touch of antisieze grease on them. Snug the bolts hand tight but don't reef them down. Reuseable copper gaskets are much better at holding a uniform torque as they don't squish down releasing some of the installed torque.
Happened with 3 engines that I bought whilest swapping the steel bolts over with SS bolts and lock washers, the threads came out with the orignal bolts. The engines were new just out of the box. I do this with all my engines as I run on salt water. You don't need antiseize on the bolts just oil the threads in the cases and bolts.
Still comes back to the question is why did they come loose in the first place?, were they not done up tight enough or is there a bad vibration that caused them to come undone.
Cheers

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