Rumble/Hum at Idle

[abuck99]

Julian,

Did loosen or disconnect the TC mount when you did the engine mounts?

I found the condition of my 12yr old TC mount visually in fair shape when I installed the Slee belly skid, but later found after mounting that the TC mount had swollen with age and cause some minor contact issues between the top of the TC and the floor pan at the hi-lo shifter. The new mount solved it.

 

[2001LC]

It may be like the front differential bushing in that movement there is not a very good indicator, it takes looking at the rubber.

I'll be pulling some 10 year old mounts, when I pull an engine. I'll post up some pictures if I see any torn rubber. For now I'll put in list as possible needed part.

I found the minor tune-up yearly in the fall, as temp and winter gasoline blend changed, work well for me. But this only became issues "as vehicle aged". Could be, new mounts would have made vibration less noticeable each year.

I had a low hum at idle when the AC was off. The LX470 had 202k on the odometer. After changing the spark plugs it was gone.

I'd be interested if you found any plugs tight or loose, checked gap of old plugs and what you found, also if you had history of when last changes?

 

[Julian Stead]

As I remember there was long studs on the TC mount, I am sure I unwound these all the way to the last couple of threads after I didn’t get enough height lifting the engine. Not really sure you have to do this as It ended up being my jack just didn’t have the height but it was done. So yes I did loosen it.

 

[LXG8R]

Dropbox - Photo Nov 18, 6 59 46 PM.jpg

I'd be interested if you found any plugs tight or loose, checked gap of old plugs and what you found, also if you had history of when last changes?

@2001LC one of the plugs was loose.

 

[2001LC]

Thanks. I've been noticing inner plugs (#3, 5 & #4, 6) loose all to often. For this reason I'm on the lookout for a pattern.

I'm guessing those are not factory installed plugs, but the second set. Looks like #2 had a bit of oil, possible tube seal minor leak. #4 looks like it was loosest. #6 has a bit of blacking (escaping gases) above washer contact seal point same as #2, as if a bit loose also. I'm assuming laid out in order: left top to bottom #1, 3, 5, 7 and right #2, 4, 6, 8. Your burn looks good and even.

Gap is important test, 1.3mm (FSM) or over need replacing. If 1.1mm they're good, if 1.2mm I replace. Resistance is also test, but they rarely fail that test.