opticor

I have the same problem, I have no money right now, but this is what I have done to troubleshoot.

Complete tuneup..quality wires, coil, plugs, air filter, fuel filter, cleaned IACV, cleaned MAF, oil change....needed it anyway.

used a vacuum gauge to test for engine issues...rock solid.

I have an 04 3.9L...internally balanced...so no issue with slipping Damper.

so I have 3 options so far

motor and or trans mounts...will change when I have money.
internal balancing rod is damaged...I have 98k miles...unlikely.
possible bent input shaft on transmission...really hope not.

anyone have any other suggestions, they are welcome.

Andrew

BabyGT

Bent input shaft or balancing problems wouldn't rhythmically pulsate. This is a strange problem indeed.

corker

For anyone that's been inside these engines, can this be a balance shaft issue (does it have a balance shaft)? I haven't had a Ford V6 apart yet to see if something can possibly affect the phasing or operation of the balance shaft to cause this vibration. As I said in my earlier post, I'm grasping for straws here (compression test proved all cylinders fairly even - within a few psi of each other).
Thanks,
Corky

opticor

if your harmonic balancer behind the crank pulley has a counterweight, then it is externally balanced....easiest way to tell, if it looks like a chunk has been machined out of the HB. If the HB is smooth all around...it's internally balanced...after doing some research, i read someone say that it would take tremendous force to damage the balance shaft...grain of salt i suppose. if you have an externally balanced motor, see if the HB slipped on the rubber ring. It does happen.

Js70ne

My car engine shakes when I stop at the light once in a while is this maybe a transmission mount prblem? Coz dealership told me I have broken transmission mount

corker

Opticor, I appreciate the response. The car is back in my garage again with a cracked water pipe (one coming out of water pump) & cracked exhaust right side, again - the engine is shaking itself apart. I included some pics of the HB, from your explanation it appears to be externally balanced. The pics also show the rubber insulator between the HB and pulley - doesn't appear to have moved, but is all dry rotted from age. I think that's the next logical part to change since the engine is mechanically sound. 2000 V6 153,000 miles, 5spd. Vibration same with clutch in or out.
Thanks for your help
Corky

opticor

yeah, if the engine shakes that could be a problem, the trans mount is a fairly cheap replacement to find out....if you replace the trans mount and the engine still shakes, then check the engine mounts next. I need to replce mine as well and i'm hoping it fixes my vibration at around 1800 rpm.

opticor

yep, that's external, good pics too it's hard to tell if the HB has slipped, they are not cheap either. i think someone said rotate the engine to TDC and check the timing marks to determine if the HB has slipped in the rubber ring. I will double check that.

opticor

after doing some research, i hesitate to say it's definately the HB, but a lot of posts point to that being the problem, they say if the rubber is dryrotted and sticking out, it's a much higher chance of it being bad. i would suggest getting an HB from salvage to test with before spending over a 100 dollars for a new one. let me know how it works

opticor

btw what year is your car? so we can determine if it's internally or externally balanced. nevermind i see it's 2000. look at corker's pics and see if your HB matches.