I've had my wheels/tires balanced and rotated, and also had the transmission shop check the flexplate/TC connection and transmission mounts. The differential place was clear: differentials don't cause vibration. (but they will make NOISE, which is just a higher-frequency kind of vibration ... wasn't worth questioning....) They suggested my U-joints, or take her to the only driveshaft guy left, up in Valencia.
I think it's my engine. I definitely have a vibration at idle. Here's what it fels like;
-- on a cold start, the engine chugs in 4/4 or even double-time: BOOM-buh-buh-buh HOOM-buh-buh-buh. Cold/damp morning I can see steam out the exhaust pipes pulsing. Oddly, though this might be subjective, I feel like right after starting, the exhaust out the driver's side is warm/hot, while the pass. side exhaust is distinctly cooler.
-- Was at mechanic's a couple weeks ago, he said the idle sounded good but smelled rich. (It was not chugging so much that time.)
-- WHen I start it at idle, there's definite vibration from the engine I can feel in the steering wheel. The vibration is a constant frequency, but pulses and ebbs in amplitude, with a period of about 5 seconds. Clerely two different periodic vibrations making harmonics. Maybe one is related to ignition and the other is the mass of the block moving/shaking w/r/t frame?
(My steering column is loose -- something I'm going to fix and Loctite today -- so it's very obvious when the wheel visibly shakes then calms down, about 5 seconds between peaks. I cannot get video of this, I realized because ******* Apple iPhone image stabilization is probably working hard to cancel out what I want to see. Maybe if I stand outside the truck or use a tripod I could capture it.)
So, today/tomorrow I' going to
-- Replace motor mounts if I can by myself
-- put her up on stands and run the drivetrain, try to rev it up and maybe get video of it.
-- take the stethescope to all the front accessories to see if any are screaming
-- check harmonic balancer for play or wobble
-- remove fan and fan clutch then run engine to see if vibration changes
-- Hopefully replace my water pump (currently orig with '73 engiine, I think a short) with a year-old AC Delco long pump from my old engine.
Gotta get up, get out, get there, get under, get busy.
BRetty
Edited - i have a spare LONG water pump, not a LUNG pump.
