How long are motor mounts good for?

rvator51 · #1 03-27-2008, 09:56 AM

Our RV4 was built in 1989 and the rubber motor isolation mounts are now 18 years old. Does anyone know how long the motor isolation mounts are normally good for and whether we should replace ours or not?

az_gila · #2 03-27-2008, 10:53 AM

Quote:

Originally Posted by rvator51

Our RV4 was built in 1989 and the motor mounts are now 18 years old. Does anyone know how long motor mounts are normally good for and whether we should replace ours or not?

Tom... Lord has their inspection criteria here.

http://www.lord.com/Home/ProductsSer...0/Default.aspx

If they look good (i.e., not damaged) then deformation (aka sagging) would be the problem.

The Lord deformation measurements could probably be used as a guideline for other makers mounts...

gil A

WilburD2 · #3 03-27-2008, 11:18 AM

Those are some old mounts! I don't know of any age or hour limits on mounts for GA aircraft but there are simple things to check.

Are they hard? Can you press them with your hand or fingertip and still make a dent? With them out of the aircraft, have they taken a permanent set from the washers and/or mount itself? Any splitting? Splitting on the outside or the inside? Missing any chunks? Oil/fuel soaked?

Your mounts may be prefectly fine, but after 18 yrs and in Arizona? I'd be willing to bet if you changed them you would have a noticeable drop in airframe noises and vibrations.

Good luck!

pierre smith · #4 03-27-2008, 01:42 PM

Hi Tom,
As cheap as they are, I'd have to agree with the others that new ones will only improve the airplane and remove the normal "sag" that lowers the prop/spinner in the first couple of years.

If they've been oiled down, the rubber may even be separating from the steel back plates.

Regards,

gmcjetpilot · #5 03-27-2008, 05:15 PM

I deleted this and re posted as a new thread "Engine Mount Inspections". I miss read Engine Mount for the metal weldment not the rubber isomer Vibration Dampers. New Thread

rvator51 · #6 03-28-2008, 03:27 AM

Quote:

Originally Posted by az_gila

Tom... Lord has their inspection criteria here.

http://www.lord.com/Home/ProductsSer...0/Default.aspx

If they look good (i.e., not damaged) then deformation (aka sagging) would be the problem.

The Lord deformation measurements could probably be used as a guideline for other makers mounts...

gil A

Thanks Gil.
I guess we have to take them out to do the deformation check. We have an annual coming up in a couple of weeks, so I will add that to the list. Thinking about just buying a set of 4 pair from Vans for $240 and replacing the old ones anyway.

rvator51 · #7 03-28-2008, 03:39 AM

Quote:

Originally Posted by gmcjetpilot

Look metal fatigue and hidden weld defects are always a cause for cracks in steel. Do RV's have a particular problem with engine mounts? No. (with a RV-4 caveat, below)

Hi George,
I wasnt very clear with my original message. I was referring to the rubber isolation mounts that go between the engine and the engine mount. You make some good points about the engine mount.

gmcjetpilot · #8 03-28-2008, 03:20 PM

Quote:

Originally Posted by rvator51

Hi George,
I wasn't very clear with my original message. I was referring to the rubber isolation mounts that go between the engine and the engine mount. You make some good points about the engine mount.

Doha! ha ha OK no problem, just replace them with some LORD Corp Mounts, don't buy cheaper vibration engine mount isolators Van sells in my opinion. I beleive van sells "VIP", Vibration Isolation Products, Inc. d.b.a. Pacific Molded Technologies.

Don't BUY the $60 mounts (vibration elastomeric mounts) from Van. Yes they work, are safe, but the LORD product is far superior even at 60% more the cost. Van always goes for the cheaper discounted stuff. The engine Vib Isolator is a place I don't scrimp on. I think Van should also cary the better LORD mounts. The ones he sells are a third tier brand. Here is a thread on LORD mounts with a post of difference. POST

DO you have conical? If you do Van DOES sell the LORD conical mounts for $99 each.

Dynafocal? Get the LORD mounts from somewhere else. They cost a little over $100 each. If your vib isolators are 18 years old, replace them, regardless of oil, cracks or sag!

If they are not LORD mounts and you upgrade to NEW LORD mounts you will feel a difference I guarantee it.

The part numbers are:
Dynafocal> J-9613-40 x (4)
[same as the Mooney M20J (1976-up) Lyc. IO-360-A3B6D]

Conical> J-1552 x (8)
[alternative part # J-6230-1 x (4) ? double check call LORD's 877 number)

Any Vib Isolator over say 2000-2500 hrs and/or 12 years, should be replace out right as preventative maintence. They may still hold the engine on the plane but they lose some quality. LORD mounts will last longer. Yea cracks are death, replace for sure.

There's a visual inspection you can do, a certain sag and compression from new that is allowed. If you go to Lord Vibration aviation web page you will find their specs. If in doubt just replace them, it may cost a few hundred but well worth it in lower vibration. (But yours are shot by age and condition)

http://www.lord.com/Home/ProductsSer...0/Default.aspx

http://www.lord.com/Home/ProductsSer...7/Default.aspx

KatieB · #9 02-21-2016, 08:38 AM

Does anyone have a good link to Lord's inspection criteria?

Mine are fairly hard, no visible damage, but 9 years old. I should probably buy new ones, but they are just so expensive.

az_gila · #10 02-21-2016, 09:37 AM

Quote:

Originally Posted by KatieB

Does anyone have a good link to Lord's inspection criteria?

Mine are fairly hard, no visible damage, but 9 years old. I should probably buy new ones, but they are just so expensive.

Last page of this Lord document seems to be the replacement link for the old one above...

http://ww2.lord.com/emea/Documents/P...alAviation.pdf