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kl2657
11-03-2011, 01:58 PM
Has anyone out there replaced the rubber engine mounts on their 912ul installation? I'm in the process and was looking for guidance on how remove/replace the bottom two mounts. Can this be done without removing the engine?

Also, does anyone have any advice on separating the exhaust manifolds from the muffler? Mine is pretty well seized together...

Thanks!

jrevens
11-04-2011, 08:46 PM
Mouse Oil is good at freeing seized exhaust pipes. I think it may be available from Aircraft Spruce.

foxkit3
01-08-2012, 03:36 PM
Hello. Would like to replace the rubber engine mounts on my 3 with a 912 set up. Were is the best place to but them??

kl2657
01-08-2012, 08:11 PM
I purchased mine from Kitfox. I will tell you that it was not a fun job replacing them. I was able to do it without removing the engine. It took removing the rails mounted to the engine one at a time to get enough clearance to slide in the new rubber. Be very careful and patient trying to get the engine mount bolts aligned as you reinstall the mount rails as it is easy to cross thread them.

airdawg
01-30-2012, 11:17 AM
Just replaced the isolators in a Speedster with a 912UL. You do not need to remove the engine but it is a painful process. The key is to support the engine and completely remove the engine mount brackets that connect the motor to truss. Work from the isolators towards the front of the motor. Get the isolators in by tipping the brackets up at a 45 degree angle. Then get your bolts in. Then get your next bolt in(this one sucks)and don't forget the washer that goes between the engine block and the bracket. You will definitely need a engine hoist and a second person. Good luck! I would also check the dimension of your spacers to make sure they comply with the Kitfox service bulletin.

Jesse
05-31-2015, 10:34 AM
I just resurrected my grandfathers model 5 kitfox as it has sat in his hangar unused for 15 years and have been doing a lot of little work as i keep noticing new items that are needing to be fix/replaced. The most recent being the rubber engine mounts. The 2 upper mounts look fine to me and don't feel hard or appear cracked but he 2 lower ones look to be sagging. This is a picture of one of them. Engine runs normal idols fine at 1800 rpm but wondering if this is cause for replacement. Seams like i fly for an hr then spend a 2 weeks fixing little things and then repeat the process. Anxious to hear what people have to say on this topic. Thanks all!!

Jesse
05-31-2015, 10:41 AM
The other lower mount.

Dave S
05-31-2015, 07:34 PM
Jesse,

Haven't seen any responses.....don't know that I can answer your question with certainty; but, two things that can be considered are the age and sagging.

If you have the installation manual; take a look at the Vibration Isolator detail which shows a cross section of the engine mount socket and the parts that make up the assembly. A point to keep in mind is the engine mount socket has a smaller diameter in the center of the mount than what you see on the outside.....if there is enough sag/wear....it isn't beyond possibilities that metal to metal contact could occur between the minor diameter of the engine mount socket and the metal bushing that the bolt goes through.

I remember it being a bit of a challenge to get enough compression on the rubber mounts to get the nut started on the bolt on my build when everything was new - probaby due to compressing the rubber hose bushing that goes between the front and back Lord rubber bushing.

Keep your spirits up on the maintenance stuff you are finding.....:)

Sincerely,

Dave S
KF 7 Trigear
912ULS Warp drive

St Paul, MN

Paul Z
05-31-2015, 07:39 PM
I'll be at the Airport to morrow to work on my plane it is a SLSA, I get a comparison picture of my bushings. Mine are 5 years old.

happiestflying
06-28-2015, 10:14 PM
Just purchased a Kitfox IV Speedster with the 912 ULS, and the first thing I noticed during the pre-buy inspection was these mounts. Mine are much more worn than the photos here, yet there doesn't seem to be any sag. It was a judgement call on the purchase, but I had read this thread by a complete fluke a few days before I bought the plane.

I guess this is going to be the first major repair that I'll be taking on, other than that we rebuilt both carburetors before I flew it home 1100 NM from Canon City Colorado to the Seattle area. That solved some major discrepancies in EGT's and lack of full power and rough running.

Ran like a champion all the way home. Thanks to Cory Thompson at Fremont County Airport (1V6) for taking on the carburetor task.

Paul Z
06-29-2015, 08:48 AM
I'll be at the Airport to morrow to work on my plane it is a SLSA, I get a comparison picture of my bushings. Mine are 5 years old.

Here is a photo of my plane only 5 years old. I'll post another in a second post.

Paul Z
06-29-2015, 08:49 AM
I'll be at the Airport to morrow to work on my plane it is a SLSA, I get a comparison picture of my bushings. Mine are 5 years old.

Second photo

Spook712
12-30-2018, 01:11 PM
Hi Jesse,


I bought a 20year old Sries 5 and have the same situation(if not more pronounced sagging wise).


Could you post what you did to fix it if it had to be fixed.


Pauls Engine Mounts look a lot mor "in line".


Thanks,
TUNA

DesertFox4
12-30-2018, 02:21 PM
Jessie hasn’t logged into this site since May 2016.

Spook712
12-30-2018, 02:37 PM
😔 too bad

So what does the forum say to the condition of the engine mount?

Spook712
12-31-2018, 10:35 AM
I got a reply from him via E-Mail :-)

Wheels
01-02-2019, 11:12 AM
I bought a 912UL powered IV that had 58 hours on it. It sat in a garage for about 10 years and then I bought it and started upgrading the necessary components.
The Rubber mounts were shot.
I wish I had known then what I know now, but the bottom line is ... replace them if they are old.
It's not worth the excess wear from vibration on that motor or associated airframe components.
Paul Leadebrand once told me that idling during taxi at 2200 plus was just fine because brakes were cheaper than gearboxes. His point is, if there is a sacrifice to be made, do the cheap one. Rubber in the mount system is cheap by comparison to just about everything else on the motor.
Blue skies

Spook712
02-05-2020, 09:18 AM
Just changed the engine mounts (Series 5 912ULS).

Not a joyful task but anyhow.
I put the engine on a hoist and lifted it up just enough to free the mounts ( they were sagging a lot ) and changed one at a time.

The mount I got here in Europe (Ulm Technology Silent Block) have a shorter bushing than the ones from 1994 Kitfox. I think I read something about shortening the original ones, but can't find it anymore.

The engine sits now nice and firmly in the mounts, no sagging.

Greets from Germany,
Tuna
240312403224033

4Hummer
02-05-2020, 06:20 PM
I put some pics in this thread: post #37 This is for a model 4
https://teamkitfox.com/Forums/threads/10277-Mike-s-Kitfox-IV-rebuild

Pretty easy if you go about it the right way. Bottom bolts, Remove the 2 bolts (17mm) that connect the engine cradle to the bottom of the engine block, and you can easily slide the bottom bolt right out still in the cradle


Cant seem to be able to cross post images.