My truck is a 1965 Dodge A100 with a 225 slant super 6 package. The engine in these vehicles is between the driver and passenger seats in the cab. The truck has been experiencing a rhythmic vibration at freeway speeds for the past couple of weeks. No idea what it is. On Monday night, while driving on the freeway, there was a serious bang around the front of the doghouse. Truck is still running and I scan the gauges for signs of trouble. Voltmeter is at 12, I may have lost a fan belt. AAA tows me home. Next day, fan belt is off and so is the outer ring of the Vibration damper which was still present having been caught by some suspension pieces. The rest of the damper is still attached to the front of the crankshaft.
I drove the truck about a mile before I was able to get off the freeway and safely off the road.
Could this be the reason for the vibration?
Could the engine be damaged by one mile without the damper?
What are your thoughts?

Top suspects are wheel balance, the universal joints, and the engine and transmission mounts.



Ugh, no fun. But it's a separate failure, not related to the freeway-speed vibes. The vibration damper damps harmonic vibrations in the crankshaft so it won't crack. Those vibes are not the kind you can hear/feel from the driver's seat.

No, you're probably fine. The crankshaft in that engine is a seriously rugged chunk of forged steel.



You need a new vibration damper, and you'll need to carefully find the № 1/frontmost cylinder's TDC (the one between compression and power strokes, with both valves closed) and make a new timing mark across both rims of the new damper, because all the replacement dampers come with the mark positioned for the later distributor-side timing indicator tab, not the earlier manifold-side tab. This is an excellent opportunity to pull the timing cover, install a new seal in it, check the timing chain for slop (likely, with high enough miles to lunch the damper) and install a new one.

And then check all four wheels for proper balance, the universal joints and engine/trans mounts for wear, and the driveshaft angularity to nuke the highway vibes.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan, thanks for the reply. A new vibration damper is already on its way with the timing mark on the drivers side. I will verify the timing mark for TDC with fingers crossed. Will probably have to pull the rad to get some room to work. An A100 pickup is same as the more popular van in this area. I think I have a puller that can take off the rest of the VD and help on install. Have you heard of a vibration damper coming apart like this before? Thanks again!

Gary

I had it happen on my race car while breaking in the cam. Outer ring came off and ran across my toes while heading across the shop floor.
I'm surprised more don't do it, being as the elastomer (rubber) goes bad with age.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 225 nitrous
64 Valiant Signet
64 Valiant 4dr 170

Do you have the outer ring
Check out north damper doctor and damper dudes. Both in California, both rebuild dampers with new rubber between the 2 cast iron halves. Last time I used damper dudes, turnaround time was quick.

Sorry about your issue, new damper should fix the engine.
You might have a, a couple of U-joints going bad as well.
You should check them while you are down.

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Hyper_pak

Wish I had a 65 A100 pickup. Any chance we could see some pictures?

Fellow in my area has a Mopar A-100 PU, a Ford Econoline PU, and a Chevy Greenbrier PU. Not sure what years they are, but nice looking, and drivers.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 225 nitrous
64 Valiant Signet
64 Valiant 4dr 170