Questions and Answers If you have general RC questions or answers discuss it here.

Fixing Broken Engine Mounts

Reply

Old 10-02-2006, 11:40 AM
  #1  
plasticizer
Junior Member
Thread Starter
 
Join Date: Sep 2006
Location: Winfield, IL
Posts: 11
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Fixing Broken Engine Mounts

I managed to find an engine at a flea market and got it for next to nothing. It runs fine, but the engine mounts on both sides are broken off on the front portion. Only the two rear mount holes are still intact. Is there a way to rebuild that broken off section so that it will hold? The only thing I can think of is building up layers of JB weld in there. Has anyone done that successfully with JB weld?

plasticizer is offline  
Reply With Quote
Old 10-02-2006, 12:02 PM
  #2  
JPMacG
My Feedback: (2)
 
Join Date: Jan 2002
Location: Ivyland, PA
Posts: 2,277
Default RE: Fixing Broken Engine Mounts

You may be able to find a spare engine case from someone. Typically when an engine wears out or is crash damaged the case survives. What engine is it?
JPMacG is offline  
Reply With Quote
Old 10-02-2006, 12:30 PM
  #3  
Gremlin Castle
My Feedback: (14)
 
Join Date: Feb 2004
Location: Arlington, TX
Posts: 1,467
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Fixing Broken Engine Mounts

I repaired a Saito case last month for a fellow club member. It had both front holes broken off also. I took a piece of .062 aluminum sheet and cut out two blanks the size of the original mount. I then drilled two holes to match the original bolt pattern of the mount and clamped installed one on top of the remaining mount on each side. Then I layerd the JB weld in place to fill in the broken area and filed the area smooth to match the bottom of the mount and redrilled the front holes. If you do the work neatly it takes a second glance to tell that the mounts have been repaired.

Good luck with your repair.
Gremlin Castle is offline  
Reply With Quote
Old 10-02-2006, 01:23 PM
  #4  
aerowoof
 
Join Date: Jun 2006
Location: pembroke, NH
Posts: 2,953
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Fixing Broken Engine Mounts

there are aluminum solder rods available that you have to dissasemble the engine to use the propane torch that can build up the ears and then re drill the mounting hole.
aerowoof is offline  
Reply With Quote
Old 10-02-2006, 01:46 PM
  #5  
MinnFlyer
Senior Member
My Feedback: (4)
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Fixing Broken Engine Mounts

You could also buy one of those "Clamp" type engine mounts
MinnFlyer is offline  
Reply With Quote
Old 10-02-2006, 10:44 PM
  #6  
plasticizer
Junior Member
Thread Starter
 
Join Date: Sep 2006
Location: Winfield, IL
Posts: 11
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Fixing Broken Engine Mounts

Gremlin: Has the one you fixed with JB weld had any run time on it since? I would be curious how well that would hold given the nature of the location...vibration, heat cycling, oil, etc.

I think I will have a go with some aluminum welding rod and see. If that fails, then it will be new case time or maybe just use it for parts.
plasticizer is offline  
Reply With Quote
Old 10-03-2006, 07:01 AM
  #7  
flianbrian
Senior Member
 
flianbrian's Avatar
 
Join Date: Mar 2002
Location: Suthrun, IL
Posts: 329
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Fixing Broken Engine Mounts

I've done similar to Gremlin for one broken through a front mounting hole. In use, though, I had an aluminum bar with two mounting holes as a clamp over the flange, not trusting the JB Weld....
flianbrian is offline  
Reply With Quote
Old 10-03-2006, 08:04 AM
  #8  
Dsegal
Senior Member
 
Join Date: Oct 2002
Location: Philadelphia, PA
Posts: 2,065
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Fixing Broken Engine Mounts

See Joe Wagner's column in the August, 2006 issue of Model Aviation.
Dsegal is offline  
Reply With Quote
Old 10-03-2006, 09:44 AM
  #9  
Gremlin Castle
My Feedback: (14)
 
Join Date: Feb 2004
Location: Arlington, TX
Posts: 1,467
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Fixing Broken Engine Mounts

I have not followed up on the repair. The JB weld functions mostly as a spacer for the aluminum strip that overlays the mount. I would not put much faith in the ability of the JB to bond to the old case and be the sole structural material around the bolt hole.
The aluminum brazing rod may not do much better as the cases usually have a high silicon content to improve the flow of the molten metal during the casting process.
ORIGINAL: plasticizer

Gremlin: Has the one you fixed with JB weld had any run time on it since? I would be curious how well that would hold given the nature of the location...vibration, heat cycling, oil, etc.

I think I will have a go with some aluminum welding rod and see. If that fails, then it will be new case time or maybe just use it for parts.
Gremlin Castle is offline  
Reply With Quote
Old 10-16-2006, 07:43 PM
  #10  
plasticizer
Junior Member
Thread Starter
 
Join Date: Sep 2006
Location: Winfield, IL
Posts: 11
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: Fixing Broken Engine Mounts

Well I took the OS FS 40 four stroke apart and attempted a "weld" on the mount with Dura-Fix aluminum rods. After cleaning the area good and wire brushing it with a stainless brush, the mount area was heated with a small butane handheld torch. It should have been plenty hot after 1 minute to melt the rod, but nothing.....2 minutes...nothing....3 minutes...5 minutes...nothing. I kept the flame on the case away from the mount when I tried the rod each time. It did not even attempt to melt any of the rod. According to what information I have from the Dura Fix distributor, it seems that the OS engine cases are made out of some series 2000 alloy, which is the only alloy series the rods don't work with. I found this bit of info online as well. http://www.alcotec.com/qanda6.htm

So it looks like I will either just rig up a JB weld base with something else on the top and bottom, or just replace the case. I think they cost about $40 from Tower. Though I am not sure how to get that camshaft bearing out of there.

Also, how does one go about getting the proper positioning on the camshaft upon reinstallation? I am assuming 1 tooth off either way will not be a good thing.
plasticizer is offline  
Reply With Quote

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service