Vibro-matic dashboard

[veeman]

Whenever I drive my 81 caddy TD, I notice there's quite a bit of vibration coming from the dash area... seemingly in the areas right in front of the driver's seat.

Now, since it is an old diesel, I do expect some vibration, but this seems to be a bit much.  I notice it most at idle (obviously) and it seems to diminish / stop when I press on certain parts of the dash.   Doesn't seem to be the glovebox either... I've emptied it and it still happens.

The vibration / noise seems to vary, so it's worse sometimes than others.  It only marginally bugs me, but others riding in the truck remark about it a lot.

Before I go tearing into the dash and pulling things out, has anyone ever had any success in pinpointing specific rattles or putting insulation in certain places?  Any ideas

I'm thinking maybe there's some bracing / ducting or something in there that's causing the racket...

[BlackTieTD]

hi veeman...my advice is take the dash out. obviously that's extreme but it works! i've tried a few different dashes since the US one like you have, including a couple of old cracked german rabbit ones from the 70s, and a few from cabbies. i am using one from an 81 cabby right now and it seems to rattle the least of them all. probably just coincidence.

there are 4 (IIRC) tabs in the back that the dash mounts slide onto. they are covered in felt which breaks down over time. i would pull the dash and see if the felt is still ok... maybe replace it with rubber or change the dash to a bolt-thru style like mkII and use some rubber pads on any contact points.

or just leave it out.  

[zyewdall]

Try a little dab of silicon glue on all of the contact points.    It's not really strong enough for holding stuff, but works great for preventing parts from vibrating against each other.

[mortskeg]

Hey, veeman
I don't know how relevant this is to your situation but it seems like I've fixed a bunch of rattles just through fuel timing/ idle adjustments and of course the passenger side engine mount replacement if it's bad.  Unfortunately, I guess the true diesel engine mount has been out of production for a while, and that gas one is not quite as nice about dampening the vibes.

Where on the dash can you press to stop the rattles?

Hope this helps.

[Master ACiD]

make sure you have good injectors and a proiperly adjusted pump. check the motor mounts as previously said and finally bump up the idle speed a bit to get rid of the shakes. seems like i see alot of diesels that are set to idle at too low of an rpm.

[veeman]

Thanks for all the replies.  That gives me more to go on...

>>Where on the dash can you press to stop the rattles?

Seems like it's right on top of the instrument cluster and radio.  Sometimes I can push down on the dash to make it stop, other times, I can push the dash towards the windshield and make it stop.   I guess that'd indicate that I need to take a look at the metal mounting tabs.

Might not be a bad idea to take the dash off anyhow... there was a mouse living in the caddy for a while when the PO hadn't driven it.    I have that critter (the mouse, not the PO)  to blame for making me think my heater blower box was on fire.  He left some leaves / wood material around the ballast resistor coils in there...  Who knows what else he did under there...

[BlackTieTD]

I guess that'd indicate that I need to take a look at the metal mounting tabs.

i agree. i don't have mine bolted in so sometimes it works itself loose from the dash tabs and i have to push it back on to stop the rattling. you could try to get the dash to bolt in slightly tighter to the windshield and see if that stops it from happening. my bet is the felt under there is junk by now though.

[mortskeg]

Might not be a bad idea to take the dash off anyhow... there was a mouse living in the caddy for a while when the PO hadn't driven it.  

Fun fun.  Yeah if you do that you might want to take a dilute bleach-water solution in there with ya too since that dried mouse pee can be nasty stuff (haunta virus).  Good luck chasing those rattles.

[wyldman]

Felt,foam tape,and rubber washers.

You can remove the dash,and put the above products everywhere things touch to help eliminate the vibration.

Make sure all the screws are good and snug,and not stripped.You can also add screws to help secure panels and components better too.

Don't just pay attention to the dash,but everything underneath it too.

[zyewdall]

make sure you have good injectors and a properly adjusted pump. check the motor mounts as previously said and finally bump up the idle speed a bit to get rid of the shakes. seems like i see alot of diesels that are set to idle at too low of an rpm.

Good point, if the vibration is at idle.  What is a good idle speed?  For some reason my truck will idle fine at about 700rpm, but the VW doesn't sound like it's happy idling till about 1k - 1,200rpm.  It seems like it should idle at 800rpm though. Maybe need to adjust the pump timing?  Or just keep the idle set at 1k.  If it drops to a few hundred rpm (when I was diagnosing fuel problems it would run at really low rpm for a few seconds before stalling if I wasn't quick enough to get to the key to shut it off) the whole engine bounces up and down violently.  I thought it was going to come out of the engine compartment once.  Glad I got that problem fixed.

[bhtooefr]

Idle on the ME and MF engine codes is 880 RPMs, according to the sticker under the hood, or 950, according to the 1985 edition of the Bentley for the Golf/GTI/Jetta.

I'll believe the 880 RPMs, though.

[Master ACiD]

i would shoot for around 900 rpm's idle.  dont think you really need to go over 1000 to get a smooth idle.
then again, most people dont have a tach so you kind of have to just guess at what the idle speed is.


to give a point of reference when the engine is set up properly and everything is in good working order a 1.6 diesel shouldnt idle much worse than a 1.7 gas engine thats slightly out of tune.

on the other hand, a nicely tuned diesel with a 500 rpm idle will shake the dash like a mad man.

[mortskeg]

Just thought I'd throw this in for reference-
As near as I can tell with my w-term tach (not perfectly accurate) my 1.6 idles pretty good at about 850-900 rpm.  However my 1.5 needed closer to 1100 rpm to run smooth.  Go figure.

[fspGTD]

Download the .pdf manual from this link:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=321

(consider printing the thing out by the way... it's got some great info in it! but over 100 pages)  I have the actual original hardcopy version though, and it's great.

... then for vibration problems, seek to page 124 of the manual (120th scanned page of the .pdf) and just go through the steps.

Pay very close attention inspecting your passenger side motor mount for tearing/separation near the top where the rubber is place in tension by the weight of the motor.

If you've tried all that, the situation should be about as good as the A1 diesel can get.  Unfortunately a totally silky smooth diesel by modern standards in an A1 platform is just not going to happen due to the "shaky" nature of the engine from it's high pressure and high-pressure injection pump, couples with a primative motor mount design of the A1 platform.  The problem unfortunately gets worse if you have a diesel motor in an A1 that puts out a lot of torque necessitating firmer motor mounts.  

Other threads related to A1 motor mounts:
http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=4037&t=566
http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=4037&t=704
http://www.vwdiesel.net/phpBB/viewtopic.php?t=20
http://www.vwdiesel.net/phpBB/viewtopic.php?t=654
http://www.vwdiesel.net/phpBB/viewtopic.php?t=1541