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Author Topic: merco 61 front bearing seal leaks fuel  (Read 1214 times)

Offline George Waters

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merco 61 front bearing seal leaks fuel
« on: July 03, 2012, 07:49:58 PM »
Does anyone work on these engines or know where to get a front seal for one? I have one that runs very well except it pushes  about one half oz. of fuel out the front bearing per flight. It is a new motor with little time on it , I believe. I have 3 of these and may need to have one re ringed, does anyone do this? Thanks in advance, George
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Offline Bill Little

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Re: merco 61 front bearing seal leaks fuel
« Reply #1 on: July 03, 2012, 08:07:43 PM »
Hi George,

You can get really great rings from Frank Bowman.  Boca Bearings carry bearings for our model engines, and they have sealed front bearings.  Tom Dixon used to do a lot with the Merco .61, so he would be another to check with.  Not sure if Randy Smith has any Merco parts. ??

Bill
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Offline Bill Hummel

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Re: merco 61 front bearing seal leaks fuel
« Reply #2 on: July 03, 2012, 08:32:33 PM »
Scott Riese in the northwest worked on Mercos a few years ago, did an excellent job! I believe he is listed here on Stunthanger.
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Offline Chris Wilson

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Re: merco 61 front bearing seal leaks fuel
« Reply #3 on: July 04, 2012, 09:09:12 PM »
Are we talking about a 'shield' or 'seal' here?

A seal will attract friction (that is the price of sealing) whereas a shield will not and personally (despite what Boca Bearings sell) I would not want a bearing seal anywhere near the front end of my engines.

You want some oil blow by as evidence that lubrication is actually being present and a 'shield' will give you this whereas an oil tight 'seal' will stop flow dead in its tracks.

Perhaps a draw back groove or tube would be a better option if a shield doesn't fix the issue?

« Last Edit: July 04, 2012, 10:01:31 PM by Chris Wilson »
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Offline Balsa Butcher

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Re: merco 61 front bearing seal leaks fuel
« Reply #4 on: July 04, 2012, 09:41:51 PM »
Not an engine expert here but I have run Merco 61s. Some of their machining left a bit to be desired. The front of the case where the bearing sits may be out of round causing leakage around the bearing. Or the back of the race may be machined at an angle so that the bearing is not seating properly. It does not take much. If only one out of your three are like this, you are lucky. I'd park this one and run the other two.  8)
« Last Edit: July 04, 2012, 11:22:33 PM by Pete Cunha »
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Offline Andrew Tinsley

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Re: merco 61 front bearing seal leaks fuel
« Reply #5 on: July 05, 2012, 01:47:36 PM »
Hello Pete,
I am surprised that you have had trouble with the Merco 61s in this area. I have run them for many years and still have about a dozen (did I say I like the Merco61?). I have never had a problem with leaking at the front end, except when a front bearing is shot. I am very surprised that you have a bearing housing out of round. It must be quite a challenge to machine it without getting it round! Maybe someone tried to force in a bearing out of square and did the damage that way?

Regards,

Andrew.

P.S. I have used sealed bearings and shielded bearings and couldn't tell any difference in performance.
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Offline Balsa Butcher

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Re: merco 61 front bearing seal leaks fuel
« Reply #6 on: July 05, 2012, 02:05:43 PM »
Yes, after thinking about it-out of round probably not. At any rate, the engine runs great although it is not mounted on a plane at this time. Some creative machining by a friend cured whatever ailed mine and caused a similar issue. Still, if I had three and one was giving me problems I'd be tempted just to move on to the good ones. But that's just me. For the record, it is the single plug version w/ Frank Bowman ring. Highly recommended. 8)
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Offline Chris Wilson

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Re: merco 61 front bearing seal leaks fuel
« Reply #7 on: July 05, 2012, 04:58:34 PM »
Quote from: Andrew Tinsley on July 05, 2012, 01:47:36 PM


P.S. I have used sealed bearings and shielded bearings and couldn't tell any difference in performance.

Hey Andrew,
                   if you couldn't tell the difference in performance then it couldn't be much of a seal against oil.

But I suspect that most 'seals' are proof against grease not high temperature pressurized oily environments.
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Offline Brian Hampton

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Re: merco 61 front bearing seal leaks fuel
« Reply #8 on: July 05, 2012, 08:46:28 PM »
I have a Moki M5 (very similar to an Enya 60-IIIB) which absolutely poured fuel/oil past the front bearing. I fitted a sealed bearing but only after removing the rear seal and washing out all the grease. I considered making a tiny hole through the front seal to allow a small amount of fuel/oil through it but after considering just how much was flooding along the crankshaft I figured it'd still get more than enough lubrication.
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Offline Andrew Tinsley

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Re: merco 61 front bearing seal leaks fuel
« Reply #9 on: July 06, 2012, 02:23:05 AM »
Hello Chris,
Just stating what I oberved, I simply fitted what my supplier termed a sealed bearing, because he didn't have my normal shielded bearing in stock. Using the props that we normally do in stunt, I doubt if there would be much of a difference in observable rpm. I would agree with you if we were talking high rpm engines, but a big prop in the 8000rpm region, well I doubt it and I certainly didn't see much variation, maybe if I had used a tacho?

Regards,

Andrew.
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