Bart Chilcott Posted June 24, 2020 Report Share Posted June 24, 2020 I’m trying to resolve some vibration issues at 2500 rpm and above on my IO-360. It’s enough that it’s destroyed two landing lights and cracked the cowling above the spinner. I’ve had my propped dynamically balanced and insured that the cowling isn’t touching anywhere. Next on my list are my Lord Engine Isolators. They were last replaced in the year 2000. So they are 20 years old and have just over 1000 hours of service. They show no detectable engine sag and have no visible cracks. Do they have a useful life? Has anyone had experience with replacing them based on age as opposed to clear signs they need replacing? Thank you in advance for your help. Quote Link to comment Share on other sites More sharing options...
carusoam Posted June 24, 2020 Report Share Posted June 24, 2020 They often get tossed at engine OH... or failure... or sag... Other things that cause vibration... broken engine mount welds... When seriously concerned... change them out and inspect the engine mount closely... Rubber parts can be tested for their qualities... But, the act of testing them requires removing them from the mount... You May find an engine donut has split... PP thoughts only, not a mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Bart Chilcott Posted June 24, 2020 Author Report Share Posted June 24, 2020 32 minutes ago, carusoam said: They often get tossed at engine OH... or failure... or sag... Other things that cause vibration... broken engine mount welds... When seriously concerned... change them out and inspect the engine mount closely... Rubber parts can be tested for their qualities... But, the act of testing them requires removing them from the mount... You May find an engine donut has split... PP thoughts only, not a mechanic... Best regards, -a- Much appreciated Carusoam! We’ve looked closely at the steel engine mount but haven’t found an issue. I do believe I will go forward with installing the new isolators and look close at the actual mount. Quote Link to comment Share on other sites More sharing options...
bradp Posted June 24, 2020 Report Share Posted June 24, 2020 Non AP opinion only. Pay close attention to the engine mount for occult cracks. Have a three blade prop? Are the engine mounts functional but need a shim as they’ve sagged over the years? Quote Link to comment Share on other sites More sharing options...
Bart Chilcott Posted June 24, 2020 Author Report Share Posted June 24, 2020 (edited) 16 minutes ago, bradp said: Non AP opinion only. Pay close attention to the engine mount for occult cracks. Have a three blade prop? Are the engine mounts functional but need a shim as they’ve sagged over the years? No sag on the engine at all. AI has inspected for cracks several times, non visible. Running a two bladed prop that I just recently had dynamically balanced and the balance cane out perfect. That’s why we are zeroing in on the isolators. Given their age, it seems the next logical path. Edited June 24, 2020 by Whiskey Charlie 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted June 24, 2020 Report Share Posted June 24, 2020 There is a method of swapping them out... support the Engine in place... Some metal shims end up with slots for some reason to add them while the bolts are in place... PP thoughts only, a bunch of questions for your mechanic... Best regards, -a- 1 Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted June 24, 2020 Report Share Posted June 24, 2020 A couple of mine (1996) were busted, the gel inserts that you can’t inspect. 1 Quote Link to comment Share on other sites More sharing options...
Bart Chilcott Posted June 24, 2020 Author Report Share Posted June 24, 2020 10 hours ago, ArtVandelay said: A couple of mine (1996) were busted, the gel inserts that you can’t inspect. Good to know Art. We’re you experiencing any unusual vibration? Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted June 24, 2020 Report Share Posted June 24, 2020 Good to know Art. We’re you experiencing any unusual vibration? Not really, of course it was much better after new mounts. I only discover it because I pulled the engine to overhaul it. Quote Link to comment Share on other sites More sharing options...
PT20J Posted June 25, 2020 Report Share Posted June 25, 2020 21 hours ago, Whiskey Charlie said: No sag on the engine at all. AI has inspected for cracks several times, non visible. Running a two bladed prop that I just recently had dynamically balanced and the balance cane out perfect. That’s why we are zeroing in on the isolators. Given their age, it seems the next logical path. Something doesn’t make sense here. I’m not sure what you mean that the dynamic prop balance came out “perfect.” Are you saying that it was 0.0 ips? That would be hard to believe. The balance test uses an accelerometer bolted (temporarily) to the engine to measure vibration. If the prop balance showed low vibration, then how can you be getting the vibration you describe? What rpm did you optimize during the prop balance? Quote Link to comment Share on other sites More sharing options...
Bart Chilcott Posted June 25, 2020 Author Report Share Posted June 25, 2020 14 hours ago, PT20J said: Something doesn’t make sense here. I’m not sure what you mean that the dynamic prop balance came out “perfect.” Are you saying that it was 0.0 ips? That would be hard to believe. The balance test uses an accelerometer bolted (temporarily) to the engine to measure vibration. If the prop balance showed low vibration, then how can you be getting the vibration you describe? What rpm did you optimize during the prop balance? By perfect, I mean very very good. No it wasn’t 0.0. I can remember the exact number off the top of my head. The technician who performed the dynamic balance told me the figure and stated it was as good as it gets. He also told me that while the prop was in balance, the aft portion of the test was off. As I understand it, the dynamic balance is on two planes. He felt that his balance test showed either something internally with the engine, an issue with the engine mount it’s self or the lord isolators were allowing vibration. So yes, you can have a prop that is spot on and still have vibration. 1 Quote Link to comment Share on other sites More sharing options...
RobertGary1 Posted June 25, 2020 Report Share Posted June 25, 2020 I replaced my 20 year old ones when I changed the engine. Couldn’t tell the new ones from the old ones. -Robert Quote Link to comment Share on other sites More sharing options...
PT20J Posted June 26, 2020 Report Share Posted June 26, 2020 9 hours ago, RobertGary1 said: I replaced my 20 year old ones when I changed the engine. Couldn’t tell the new ones from the old ones. -Robert Same for me. The E uses an IO-360-A1A so dynamic counterweights can’t be an issue. Skip 1 Quote Link to comment Share on other sites More sharing options...
flyingchump Posted March 20, 2021 Report Share Posted March 20, 2021 On 6/25/2020 at 9:28 PM, PT20J said: Same for me. The E uses an IO-360-A1A so dynamic counterweights can’t be an issue. Skip This peaks my curiosity.. I have a 66E with the IO-360-A1A and I have some vibration that I'm chasing down. Are you saying that replacement of the rubber engine isolators wont do anything to improve vibration because the engine is counterbalanced? Quote Link to comment Share on other sites More sharing options...
PT20J Posted March 20, 2021 Report Share Posted March 20, 2021 44 minutes ago, flyingchump said: This peaks my curiosity.. I have a 66E with the IO-360-A1A and I have some vibration that I'm chasing down. Are you saying that replacement of the rubber engine isolators wont do anything to improve vibration because the engine is counterbalanced? No, i meant that dynamic counterweights can’t be a source of the problem because that engine does not have them. Skip Quote Link to comment Share on other sites More sharing options...
A64Pilot Posted March 20, 2021 Report Share Posted March 20, 2021 Elastomers can harden when they get old, often getting hard is why they eventually split. Of corse when they harden they don’t absorb vibrations very well. Sometimes a vibration can come from a weak cylinder, it could even be as simple as a plug. ‘I’ve never seen a prop balancer use anything but a single accelerometer and of course it measures only one plane. However you can do a “strobe” run on many balancers, what that does is map the vibe level on a whole range of frequencies, then look for a peak at a frequency, if there is one look to see if an accessory spins at that RPM. I concur with you changing the isolators though, even if they were perfect at 20 years they owe you nothing. Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted March 20, 2021 Report Share Posted March 20, 2021 I was having a similar problem, my baffling was cracking, I had new mounts, but when they checked my prop balance it was .7+ , after rebalancing it’s 0.01. You need to do both. Quote Link to comment Share on other sites More sharing options...
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