!?$!?$?! Vibration!

[Kaegi]

sounds like a good plan. if you look on ebay and around the dodge truck parts suppliers you will find 230 engine parts dirt cheap. sometimes 5 bucks a piston for over size NOS! the 251s and other 25 inch engines parts are more but the 218,230 and other 23 inch engines were made as late as the 80s and used all over the world. still being used in lots of places on the planet in forklifts, generators, pumps, farm equipment, and some militaries are problaby still using some M37s. ;/) .so parts are plentiful. A good machine shop shouldn't even blink about working on one. its just a straight 6 with a forged crank. no different than something newer.

[ashyers]

Kaegi,
The good machine shop nearby is often up to their eyeballs is sprint car and drag racing motors. They do excellent work, but have been known to turn away oddball stuff. I need to find some time to go over and discuss things with them. I know the spare motor has a std. bore and the crank is .010/.010 so I have something to work with. I thought I'd found a torque plate locally, but it seems to have been lost in a move . Do you have any thoughts on piston quality?

Andy

[Kaegi]

I have used new and NOS and never had any that were poor fit. If you go new I think you will only find good quality American made. the NOS are really well packaged because they were made for the military. you can find NOS wrist pin bushings and rods and mains as well. I have found ebay the best place to round up parts especially if I ma not in a hurry.

here is one good deal but can be found for less sometimes. http://www.ebay.com/itm/1942-60-Plymout ... 2068361261

always by the gaskets new. any parts store has or can get those same day. I like to run a copper head gasket so that takes some searching sometimes.

[ashyers]

We finished up rolling in the bearings on Friday and found some interesting things along the way. The spare motor I have has larger (5/16") holes drilled in the crankshaft than the motor in the truck (~1/4"). I believe the motor/crank in the truck is older, but who knows! The oil passage in the upper 1/2 of the thrust bearing is also somewhat smaller in the new bearings. We also found that the motor in the truck has a much thicker flywheel than the spare motor.

Swapping the bearings brought the endplay back to spec and the oil pressure is greater, but there was no appreciable change in the vibration that's been bugging me. At this point I'm reasonably sure it's just poor internal balance. It has the vibe with the fan belt removed and the clutch/pressure plate removed. It's not likely to get sorted out until the motor is rebuilt.

Maybe it's time to get working on the spare?!

[Elwood]

We finished up rolling in the bearings on Friday and found some interesting things along the way. The spare motor I have has larger (5/16") holes drilled in the crankshaft than the motor in the truck (~1/4"). I believe the motor/crank in the truck is older, but who knows! The oil passage in the upper 1/2 of the thrust bearing is also somewhat smaller in the new bearings. We also found that the motor in the truck has a much thicker flywheel than the spare motor.

Swapping the bearings brought the endplay back to spec and the oil pressure is greater, but there was no appreciable change in the vibration that's been bugging me. At this point I'm reasonably sure it's just poor internal balance. It has the vibe with the fan belt removed and the clutch/pressure plate removed. It's not likely to get sorted out until the motor is rebuilt.

Maybe it's time to get working on the spare?!

The thicker flywheel sounds like the military flywheel (which should be eight bolts to the crank flange). The civilian flywheels were thinner, at least the ones that I've seen, and some (all?) of the civilian ones had only six bolts between the flywheel and the crank flange. The bolt spacing is the same, just two opposite holes aren't drilled.

This topic might be of interest: http://www.g741.org/PHPBB/viewtopic.php ... eel#p50535

Sorry to hear that the vibration problem wasn't solved. Something is out of balance, but since the vibration is a relatively new thing, I'd be hesitant to blame it on an original imbalance of the crank/rods/pistons assembly. Something else has changed recently.

[ashyers]

Elwood,

"Something is out of balance, but since the vibration is a relatively new thing, I'd be hesitant to blame it on an original imbalance of the crank/rods/pistons assembly. Something else has changed recently."

This has been bugging me too and here's what I'm thinking. With our constant tinkering we've fixed a TON of issues with the truck and I think what we may have done is fixed our way into a new issue. It's possible the vibe has been present, but was masked by other issues.

At this point what I know is the vibe is engine generated. Something hits a harmonic at 2500 RPM. As I see it this could be ignition related or an internal issue, I'm not sure what's left! Since the truck is currently out of action due to transmission snap ring issues I may swap some parts and use the old shotgun approach on the ignition. I hate doing things that way, but... I'd like to test my spare dizzy anyway.

Andy

[Elwood]

That approach seems reasonable.

Barring some failure such as a nut falling off a connecting rod bolt, or a broken piston skirt, I can't see how an engine vibration could suddenly start emanating from the bottom end. And any of those things would have shown up when you dropped the pan (if not sooner!). Maybe some sort of serious piston wear, combined with a pre-existing imbalance, could be enough to tip the engine into a vibration, but that seems like a very low probability, and I'd think you'd hear that as well as feel it.

Which brings up the question: have you gone around the engine with a mechanic's stethoscope when it's in the vibration RPM range?

Have you had the distributor apart since the vibration started? Replace the cap and rotor first and see what happens? Then the spark plug wires?

If you're going to pull the distributor, might want to drop the oil pump at the same time and look inside, and check the shaft and body for wear.

If you still can't find it, un-fix all of those other repairs, and at least you won't notice the vibration anymore.

[ashyers]

Elwood,

"If you still can't find it, un-fix all of those other repairs, and at least you won't notice the vibration anymore. "

That's humor only w30bob could understand!!!!!!!!!!!!

Just spoke with the local engine shop. They heard flathead and said "NO". They did supply the name of someone down in San Jose who does like the old motors and spoke to him for about an hour. He's very straight forward and enthusiastic. My sense is he'd be excellent to work with. He's also very busy! He said to call in about 2 months...

As far as the current oil pump/dizzy combo, they are both mechanically in good shape. I'm thinking if there's an ign. issue it's secondary wiring, that's been a PITA since we started working on this truck! I'll swap the dizzy and wires since it's quick. We have not played with a stethoscope yet. I will say there's nothing to hear from the motor, just a vibe. Dave of dcturckparts suggested a "mechanics ear" setup, I need to find one cheap online.

Andy

[ashyers]

Since I mentioned Bob I didn't want him to feel left out. Bob here's some photos .

Mains from front to rear, upper is 1st of pair

Mains Upper 1st 1-4.JPG (103.02 KiB) Viewed 2470 times

Here's 1 and 2 up close

Mains Upper 1st 1-2.JPG (109.92 KiB) Viewed 2470 times

Here's 3 and 4 up close

Mains Upper 1st 3-4.JPG (104.4 KiB) Viewed 2470 times

[just me]

Just to add confusion. I spent the day searching a new crank for my truck. The T245 I got the crank out of had a thin 6 bolt flywheel on it. The crank has 8 holes. It was in a B1 truck with an NP420.

[w30bob]

Hi Andy,

Wow...........I was just sitting there, watching O'Reilly, and my ears started burning! I wasn't sure who........but someone was talking about me. So I grabbed my tablet, and since this forum is my home page, I popped over into Technical.......and read your post! Nice bearings! Sorry to hear that vibration hasn't gone away.

Just to refresh my memory........did you pull plug wires to confirm the vibe isn't related to combustion? The other things to consider, and I don't know how far you want to tear into your engine, would be the after effects of the excessive crank end play. Those would manifest as wristpin bearings getting ready to say goodbye or timing chain/gear wear. I assume you dropped the crank to change the bearings.....did you happen to grab the rods and see if they had any excessive side to side movement? Thanks again for the pics.....great stuff!

regards,
bob

[Elwood]

Andy, if you haven't already found the flathead Mopar truck forum over on P15-D24.com, you might be interested to read this: http://p15-d24.com/topic/41945-high-fre ... vibration/

[ashyers]

Elwood,
Thanks! I actually read that a few weeks ago .

Andy

[52PLOWERWAGON]

I think its just an old truck thing that they all do

especially army trucks they ride like lumber wagons

[Elwood]

I think its just an old truck thing that they all do

especially army trucks they ride like lumber wagons

True, these are not the most sophisticated machines ever assembled, and the precision of a small block Dodge/Plymouth flathead six is not comparable to a Rolls-Royce Merlin, for example, but it shouldn't be buzzing as Andy described. There's something out of tolerance going on. Small problems unattended develop into bigger problems over time, and other than a '58 Plymouth Fury named Christine, I've never seen a car with a defect that could fix itself.