4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 10-16-2000, 11:58 AM Thread Starter
Old Hand
Hank's Avatar
Join Date: Sep 1999
Location: Dalton, Georgia
Posts: 667
Thanks: 0
Thanked 0 Times in 0 Posts
4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

I thank everyone for their replys to my original post. Here is the background for those who have not seen that post but care enough to ask: I swapped a 1998 Vortec V6 and a rebuilt TH350 with a new torque convertor into my 88 YJ. The motor was installed using Advance Adaptors motor mounts welded to the frame. It was located to connect the tranny back to the original transfer case (with AA parts)in basically the stock location so as to not necessitate re-doing the driveshafts. The NP231 already had a Rubicon Express SYE kit installed with a Tom Woods rear driveshaft. The Jeep has a Pro Comp 4" lift and the skid plate is in the stock location. The tranny mount is also a AA piece with mounts welded to the skid plate. The Jeep vibrates very bad at idle in gear. It vibrates in Neutral and Park but not near as bad as when it is in gear. I am running a Howell Computer setup. The setup has about 2000 miles on it and no change except that as it gets colder weather, the vibration is not quite as bad in the mornings!?

I have checked the following:
1. PLug wires (and firing order)
2. Motor mounts (I stacked washers, tightened and loosened the mounts. No cracks in the welds - I payed someone to do the work - I can't weld worth a crap)
3. Checked the torque convertor bolts
4. Checked the tranny mounts
5. Checked the motor/tranny alignment - all lined up running and with the motor off. No stress in the mounts to straighten up.
6. New plugs and wires and all filters. Hooked up an OBDII computer to check for codes and sensor voltages - everything operating within normal parameters.
7. Someone suggested unbolting he torque convertor and rotating it 180 degrees - have not done that.
8. Someone suggested swapping in another torque convertor - I have had this one too long to send back - anybody got one I could borrow?
9. I have swapped the computer for another Howell unit and no change in performance or vibration.

Any more suggestions? I have let Foothills 4X4 look at it (of ARCA fame) and Hardcore Offroad Design look at it and no one has any answers. The computer is different from factory and the tranny never was behind this motor in 1998. What gives?

I know two guys who have done this swap - one into a YJ and one into a Toy PU. The only difference was one guy swapped a 97 Vortec V6 and the other guy used a TH400. Neither had any vibration problems. Mine is just like the other guys YJ except for the 97 motor.

Any volunteers!? I would be willing to get my Jeep to you or you to my Jeep if not to $$$$. I live in NW Georgia close to Chattanooga, Atlanta and Birmingham.

88 YJ (sort of)
Hank is offline  
Sponsored Links
post #2 of (permalink) Old 10-16-2000, 12:37 PM
Join Date: Sep 1999
Posts: 5,383
Thanks: 0
Thanked 1 Time in 1 Post
Re: 4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

Now that everybody else has struck out, it's my turn...
And I always bat 1000....

Most V-6 vibration complaints come from guys that played Mix-N-Match with flex plates and/or harmonic dampeners.
The second largest screw up is firing order incorrect. Too many V-6's out there, and too may look alike and people don't have what they thought they had, or have.
Pay particular attention, because we just went through this for another guy, and we fixed his problem in 30 minutes...

FACT. This is a rotating mass imbalance.
FACT. It does it in park, neutral, and in drive before moving.
CONCLUSION. It has to be in the engine, or transmission rotating assemblies.

If not, get one and do it.
I'll post the Vacuum article at the end of this post..... Again....

1. Unless you bought the engine complete, and took it out of a running car yourself, you can not verify the balancer or the flex plate.
2. Unless you took the torque converter out of a known good vehicle, it is suspect.
3. Unless you took the transmission out of a known good vehicle, it is suspect.

If you skip anything, you will have no idea what's going on.

1. Make sure you have the firing order correct, and that all the plug wires are in good shape, and attached properly.
If the plug wires are factory stock, and have more than 50K on them, replace them.
(Spend 8 bucks and get new plugs too.)

2. Verify the distributor position, and make sure your distributor isn't 180 degrees out, and set the timing.
If you aren't sure how to, just ask, I have it written up already.

3. Do the vacuum gauge test.
This will give you more information in one test than any other.
It will help find internal engine problems.

If Everything Checks Out So Far...

4. Unbolt the torque converter from the flex plate, and slide it back so it clears everything.
Start the engine, and see if it vibrates.
If it does, it's almost certainly the flexplate is incorrect, or the harmonic dampener or both.

5. If the engine DOESN'T vibrate with the torque converter disconnected, you probably have a bad torque converter. (More common than you think)
It could also be the transmission it's self. I've seen bad drums and bad gear sets cause the problem you describe, but it shouldn't be happening when the vehicle is in park or not moving.
You may also want to check the front pump. With the wrong torque converter, you can get some pretty wild vibrations.



Is A Vacuum Gauge A Mandatory Tool??.... You Bet Your Life It IS!!

The entire combustion process demands continuous high and low pressure cells to operate.
A vacuum gauge lets us 'see' the invisible low pressure cells inside the engine, and with a good working knowledge of a few basic principals of nature, we can figure out what is wrong with an engine.

This is mostly for those of you with stock engines, or engines that have been slightly modified, which is most of you...

1. Vacuum readings are mandatory to tune ANY carburetor. The most tuneable carburetor on the market is a Holley, and you will learn to live and die by the vacuum gauge tuning one of them.

2. Nearly every fuel injection system has a manifold pressure sensor. That Manifold Absolute Pressure (MAP) sensor, combined with input from other sensors, determines fuel delivery volume and ignition advance in modern vehicles.
It's the fuel injection computer's vacuum gauge. Fuel injection wouldn't work without it.

3. Many millions of transmissions have vacuum inputs. Those inputs can be tuned by knowing what the vacuum is doing when the transmission is supposed to be shifting, and how to change the input of the vacuum information into the transmission.

4. Nearly every single older ignition system has a vacuum advance canister. It is impartial to know what the vacuum in your engine is doing when the distributor advance curve is programmed into the distributor.

5. Knowing what your 'Normal' engine vacuum is supposed to be is really the key in finding problems easily with a vacuum gauge. Taking vacuum readings, especially idle vacuum, is real easy, takes virtually no time, and will be a life saver when something goes wrong.
Taking regular vacuum reading at idle and through the RPM range up to about 2,500 RPM is the ONLY way to know exactly what is 'Normal' for your vehicle, especially if you have modified the engine in ANY way...

Use an UNDAMPENED or UNDAMPED vacuum gauge. None of the fancy and expensive 'buffered' or oil filled gauges, they are worthless for our purposes.
Most of the better vacuum gauges intended for automotive service are satisfactory.
Try to get a quality gauge, Sears or better. A cheap gauge can not only miss a lot of things, but can give false readings.

(paraphrased from a rebuild manual)
1. A steady reading between 16 and 22 in.Hg. at idle...
This is normal for most vehicles.
Radically cammed engines have lower, less steady readings.

2. Normal range at idle, with sporadic drops below normal,
This could indicate a sticking valve.

3. Normal range at idle with needle vibration of about 2 in.Hg.,
This could indicate an ignition problem. Check plug gap, dwell (yes, electronic ignitions have dwell too), cap, rotor, and plug wires.

4. A steady reading slightly higher than normal.
This can be caused by a dirty air filter, or overly advanced ignition timing.

5. A steady reading 3 to 12 in.Hg. lower than normal.
This could indicate one or more of the following conditions,
Intake or carburetor vacuum leak, Late ignition or cam timing, Worn piston rings.

6. Gauge needle drifts slowly over a range of 4 to 5 in.Hg. at idle,
This could indicate an idle mixture that is too rich or too lean.

7. Gauge needle fluctuates rapidly between 10 and 21 in.Hg. at idle,
This could occur when one or more valve springs are weak or broken.

8. Gauge reads normal at idle, but drops slowly as engine speed is increased to 2,500 RPM,
This could indicate a restricted exhaust system.

9. Gauge reads below normal and fluctuates rapidly over a range of about 3 in.Hg. at idle, then the needle becomes steady as engine speed is increased,
Worn intake guides usually cause this reading.

"I Have The Body Of A God... Buddha"
Junk Yard Genius is offline  
post #3 of (permalink) Old 10-16-2000, 07:38 PM
Join Date: Sep 1999
Posts: 1,491
Thanks: 0
Thanked 0 Times in 0 Posts
Re: 4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

i think TR is right,
i've seen folks miss match small block chevy and V-6 "Harmonic balancers and Flexpates"
GM makes 2 standard Harmonic balancers (8" & @6 1/2" O.D. i think) and to 2 standard Flex plate (12 3/4" & 14" O.D.) combinations
i think your V-6 uses a smaller harmonic balancer which means you need the large diameter flexplate.
if you do have the 12 3/4 inch flexplate you will also need to run a different starter for the 14"er.
i'm pretty sure about my numbers, but check this out with a good small block Chevy knowlegable guy before yanking everything out[img]/wwwthreads_images/icons/smile.gif[/img]

<font color=red>3/4tonYJ</font color=red>

3/4tonYJ is offline  
Sponsored Links
post #4 of (permalink) Old 10-16-2000, 11:17 PM Thread Starter
Old Hand
Hank's Avatar
Join Date: Sep 1999
Location: Dalton, Georgia
Posts: 667
Thanks: 0
Thanked 0 Times in 0 Posts
Re: 4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

Thanks for the input (I think) TR. If you did not read all of my original post - I pulled the engine myself from a 1998 S10 PU with 1400 miles on the odometer. I know the guy that owned the truck and saw it after the wreck and the motor still ran great. I have changed the plugs and wires...twice.... gapping the plugs and verifying each time the firing order using a service manual. The tranny was fine but I had it rebuilt anyway since it had some miles on it. The converter came from Summit Racing so they are suspect.

I checked for vacuum leaks using a stethescope - not a gage I realize but I will pick up one tomorrow from the shop at work (I run a vehicle fleet and even though I do not work on the trucks I can borrow the tools - sometimes). You suggest a brand if I can't get one from work that is like you describe?

The "distributor" does not have a cap or rotor in the conventioanl sense and I do not know what I am looking at. It is very similar to an '86 Buick Grand National's coil pack if that makes sense to you.

One more thing...the motor did not have a fan or clutch on it. I ordered one from GM performance parts that bolted to the water pump pulley for this particular motor.

Thanks TR for the pointers - it may be a day or so before I can check all that you descibe. I don't know if I appreciate the attitude - I guess it goes with the experience of problem solving and finally being right.

I do understand why things vibrate - just like people getting sick, it's just that I cannot fix them either.

88 YJ (sort of)
Hank is offline  
post #5 of (permalink) Old 10-16-2000, 11:42 PM
Join Date: Sep 1999
Posts: 5,383
Thanks: 0
Thanked 1 Time in 1 Post
Re: 4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

If he actually does the tests, instead of ignoring the procedures and saying he already checked everything, he will probably find the problem.
If he ignores the test proceeders, and does hit and miss work, he may, or more likely, may not find the problem...

He's already gone one round with no progress, and just frustration...
I've seen supposed 'experts' that screwed around with things so long....

Like the guy that was supposed to be the be all and end all of engine building in the area.
He screwed with an '81 Z-28 for two months and couldn't get the engine to run correctly.
Said he had $2,500 in machine work alone in the engine, and just couldn't understand why it wouldn't run right.
I bought the car for $400, took it home, Verified the timing, the outside ring on the harmonic damper was loose and slipped around the hub, so the timing was WAY off....

I did have to pull the heads and put in new head gaskets because the detonation had hammered his economy gaskets out between cylinders, and I wanted to have a look at the heads and cylinders anyway...
A head set, new timing cover and harmonic damper, and the car ran like a scalded dog!
Sold it a week later for $6,500.
It's still running around the neighborhood here somewhere, I just saw it the other day....

It's almost always basics...
A supposed 'mechanic' down the street had a problem with a small block chevy he just installed...
Said it was a mystery problem, that he had been working on it for three days, and it couldn't be fixed.
His best guess was a broken cam shaft...

He fed me free Sunday beer, so I took 20 minutes to look at it...
The distributor was two teeth off, nearly firing the wrong cylinder when the vacuum advance was hooked up, that is, if the vacuum advance worked at all...
#6 Plug wire wasn't connected to the cap, connector was pulled down in the boot...
#2 & #4 plug wires were switched at the plugs,
#7 plug wire wasn't connected at the plug, pulled up in the boot,
Didn't matter anyway, #7 plug wire was burned through where it had been laying on the exhaust manifold,
#1 plug was broken,
The HEI was so full if red dust and carbon I don't know how it was firing,
The cap and rotor had seen more birthdays than my dog, and he's 75 in dog years....
Choke was wired shut,
Fuel line was all but twisted shut just before the pump...
No inline fuel filter I could find at all, just the rock filter in the float bowl inlet, with enough crap in it that I couldn't get it clean enough to blow air through, even after soaking it in carb cleaner....

And that's just what I found in about 20 minutes.
After a parts store run, We had it running in about an hour...
Cost them about $120, and after the aggravation, and being sure the new engine was shot, it was a small price to pay...

It's not just 2 and 2 with the V-6 engine...
You have odd fire, even fire, buick, chevy, and a host of other potential problems.

If he does the list by the numbers instead of just telling us he did it 'right' and it doesn't need to be checked again, we will find the problem.
I've fixed this same complaint probably 100 times before, and all but about 9 or 10 of those times, it was harmonic damper, plexplate/ flywheel, or torque converter.

We'll get this one whooped too!!

"I Have The Body Of A God... Buddha"
Junk Yard Genius is offline  
post #6 of (permalink) Old 10-17-2000, 07:35 AM Thread Starter
Old Hand
Hank's Avatar
Join Date: Sep 1999
Location: Dalton, Georgia
Posts: 667
Thanks: 0
Thanked 0 Times in 0 Posts
Re: 4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

Hey TR...sent you a private message.

Man have I got some work to do!!!

More questions later!!

88 YJ (sort of)
Hank is offline  
post #7 of (permalink) Old 10-17-2000, 08:35 AM
Way Outta Control
Join Date: Sep 1999
Location: The Palouse
Posts: 13,432
Thanks: 1
Thanked 3 Times in 3 Posts
Re: 4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

Just one though on everything that's gone on before...

1. Remvoe all the plugs.
2. Put the transmission in neutral.
3. Put a socket and ratchet on the cranshaft pulley bolt.
4. Put a little oil in the cylinders.
5. Rotate the engine by hand clockwise "feeling" for any bind.
6. Rotate the engine by hand counter clockwise "feeling" for any bind.

If the drive train is misallinged internally, crank, bearings, rods, cam, etc., when the missalingments point of highest interference is reached, the problem will show up as a bind similar to a U-joint bind showing up as a vibration.

The engine should turn fairly freely by hand... and if there are not binds found then I'd start with TR's list one by one.

By followind TR's list, in step, in order, you can do some mighty fine troubleshooting... Remember, that right now you don't know what the problem is... and by eliminating the biggest causes of failure, you eliminate reasons for the failure that exist in volume or parts of the drive train selected.

Sometimes it's just as valuable to know "What's not wrong." Remember Occam's Razor Theory... The principle reasons one should not make more assumptions than the minimum needed.

By eliminating that which it is not.. you eventually find out that which it is. Another rule in troubleshooting most problems... if you haven't made progress in findig the problem in 15 minutes... you're on the wrong track.

Change your prospective, you've been too close to the problem for too long.

Good Jeepin'


Wnat to see my ride? It ain't pretty but it's paid for! Go to: http://vanevery.homestead.com
LEVE is offline  
post #8 of (permalink) Old 10-17-2000, 09:06 AM
Posts: n/a
Re: 4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

I have just one piece of advice to add, I would put the jeep up on four really good jackstands (wheels off the ground) and then test drive the jeep through all parameters.
This may give you some added insight into what conditions the vibrations are most noticable under.

good luck, jjc

post #9 of (permalink) Old 10-17-2000, 09:23 AM
I Might Just Know What I'm Talking About
Pete88YJ's Avatar
Join Date: Sep 1999
Location: BOSTON
Posts: 1,748
Thanks: 0
Thanked 0 Times in 0 Posts
Re: 4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

The only thing I will add is the only part I didn't understand - why does it have a Howell computer on it? Why isn't it the stock GM one? Was that computer on it when you saw the motor run really well in the S10?

Just because someone sells something and it's supposed to fit your application, don't mean it's gonna work. [img]/wwwthreads_images/icons/crazy.gif[/img]

Howell's been suspect with their 258 kit by more than a few people [img]/wwwthreads_images/icons/tongue.gif[/img] and a few people have had trouble getting it to run well.

Good luck

88YJ, 4"susp, JKS 1.25" body lift, 33"BFGMT, 9000# winch, homemade rear tire carrier, reb. 258, 999 auto, 4.10 axles, weber 32/36 carb w/adj. reg., GMHEI, CJ dash, ...and one moonguy[img]/wwwthreads_images/icons/cool.gif[/img]
Pete88YJ is offline  
post #10 of (permalink) Old 10-17-2000, 11:59 AM
Join Date: Sep 1999
Posts: 5,383
Thanks: 0
Thanked 1 Time in 1 Post
Re: 4.3 swap-Stumped - Was Vibbbbbrrrrraaationnnn

Now we have more information, so I can give more attitude...

The engine came from a wreck.
This means maybe a bent crankshaft.
Do as LEVE suggested, and try to find a 'Bind' in the rotation.
This will show a bent, and/or broken crankshaft pretty quickly.

You can usually watch the front harmonic damper when the engine is running, and if it 'bounces' you have a bent or severely out of balance rotating mass.

As for my attitude,
I don't write this stuff to be ignored.
I have one clown that took a write up I did, ignored the directions, stuck a screw driver in cylinder, and cranked the engine over by hand.
Ruined the piston, cylinder wall, the head, and the screw driver....
Now want's me to pay for a new engine because he couldn't follow directions.

I get 40 to 50 e-mails a day from people asking questions about stuff that was covered in the write up they are quoting...
They say the printed it out, but don't read it....
So instead I have to answer the same questions that have already been gone over time and time again...

Please, just follow directions. LEVE and I have the answer for you, if you follow directions.....

As to your crank trigger, coil pack ignition....
Use a vacuum gauge to find ignition problems on that vehicle.
Read the vacuum article, you can find bad plugs, wires, coils instead of distributor cap....
The vacuum gauge will locate it.
It's not unusual to have bad coils on the coil pack ignitions either.... Something else to consider....

"I Have The Body Of A God... Buddha"
Junk Yard Genius is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome