Sudden loud engine noise!!!, Help me diagnose.. but be gentle! Options

[Mueller]

you might be lucky and one of the nuts came off of the rocker arm assembly, BTDT....another time I had one of the rocker arm assembly studs pull out of the head...made a bunch of noise...I didn't listen to the video since I have no sound on my home PC

[Bleyseng]

(IMG:http://www.914world.com/bbs2/html/emoticons/agree.gif)

I think Mueller might have something here. Rockers studs pull out or the nut falls off making a bunch of noise.

[Series9]

I have a new opinion. Let's see if my logic holds up.

At 1400 rpm:

If it were a rod bearing, we should hear the noise every rotation of the crank: 23 events per second.

If it's valve related, we would hear the noise at half crank speed: 11 events per second.

This sounds like 11hz to me. (IMG:http://www.914world.com/bbs2/html/emoticons/unsure.gif)

[Bleyseng]

definately a rocker/valve adjuster noise.....

rod sounds alot different, BTDT


(IMG:http://www.914world.com/bbs2/html/emoticons/popcorn[1].gif)

[bondo]

Sean_V8_914 and hmeeder were just here delivering my new blue flared roller (pics later in a new thread) and listened to the noise. They both think it's a valvetrain noise on number 2. The engine will come out and apart before it's run again, updates then.

Thanks for all the expert ears! (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[qa1142]

my vote....

collapsed Hydrolic lifter - happend to my bus

Have you ever been into this motor?

If is is solids - bent pushrod? How often do you run the beast?

[bondo]

QUOTE (qa1142 @ Dec 4 2005, 05:01 PM)

my vote.... collapsed Hydrolic lifter - happend to my bus Have you ever been into this motor? If is is solids - bent pushrod? How often do you run the beast?

That could totally be it.. I have never been into the motor. I did suspect that it could have hydraulic lifters, because until this point it was always quieter than usual for a 914. (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

I recently bought this car, and it had been sitting for about a year before I bought it. I have since run it evey other week or so, and never had a problem beyond carb troubles.

I had planned to open up the engine anyways just to see what I had, so really this is no problem, as long as the parts don't cost too much.

[bottomend]

The sound appears to be in unison with the exhaust cadence. The frequency also rises with the throttle being opened. It drops as the throtle is closed. The sound does not appears to be eminating from the center of the engine. I can clearly determin the rotational sound of the crank as well as the pulseing of the exhaust.

My only aural experience with T4 engines was with my bus engine that was soon to drop a valve seat. that sounded like there was little pebbles int he cylinder being shaken.

I'm rebuilding a friends engine at the moment and he had a spun bearing. The sound was like a sledge hammer on an anvil. A very strong guy swinging a very big hammer very fast!.

Definatly pop the valve covers and look for weird stuff out of place. If you dont see anything, then you've bassically commited to tearing down the block.

You should post these files over on the Samba baywindow forum. There are a few guys ( "amskeptic" for example) over there who've been diagnosing the T4 engine for a very long time and they could' probably help. Dont worry about it being a 914.. Just tell 'em that bottomend sent cha!

[jhadler]

My first thought was remebering a quote from Star Wars... "Shut them down! Shut them all down!!!"...

Ouch. Painfull to hear. My guess, it's valve related. Could be a valve seat, could be something else. But regardless, please don't run it anymore, and tear it down propper...

Sorry. But hey, it's no where near as bad a noise was when my crank snapped!!! Now -that- was an expensive noise... (IMG:http://www.914world.com/bbs2/html/emoticons/ohmy.gif)

-Josh2

[Katmanken]

How dirty is the oil?

If you have hydraulic lifters AND dirty oil, then yes, your symptoms sound correct. My Vanagon does that sometimes. Start the van, move it to another spot on the driveway and shut it off. Come back a little later and WTF! CLANK! CLANK! CLANK!

It's a characteristic of those darned VW horizontal hydraulic lifters. I look at it as a warning to change the oil with nice fresh synthetic. Clean Synthetic seems to keep the lifters quiet.

Hope that's it. It'sa cheep fix.

Oh yeah, a FRAM oil filter can makeit happen too!

Ken

[bondo]

Ok, I pulled a valve cover, and here is what I found...

The number 2 exhaust rocker has about 5 mm of clearance. Considering the circumstances, it seems unlikely that this is a dropped seat (happened with engine pretty cold). The tip of the valve also seems to be sitting at about the same height as the others, not lower.. so it looks like the pushrod side of the rocker isn't coming out far enough, not the valve side being stuck in. So now my thoughts are collapsed hydraulic lifter, or bent pushrod. Could anything else cause this? The rocker shaft is in place and tight, and the valve adjustment locknuts are tight. Keep in mind it happened suddenly.

It looks like my next course of action is to pull the rocker shaft, pushrod tube, pushrod, and lifter.. does this sound right?

[bondo]

I just had an epiphany that basically slapped me in the face and said "It's a collapsed lifter, duh!"

It has about 5mm clearance, AND it's spring loaded towards the valve! So there is not any actual clearance, but it can be wiggled about 5 mm, and if you let go, it springs back against the valve.

So now the question is: Do I pull and clean out the lifter, or just fill it with fresh oil and some CD2 and run it until the noise goes away? (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[Joe Ricard]

Lifters are easy to pull. I would pull the suspect and soak the lifter in PB blaster then exercise the lifter to make sure what ever was sticking it is gone. then put lifter in cup of motor oil and exercise it again till it pumps up with oil. should come back. If not then pull all that hydraulic lifter crap out and go solid.

[bondo]

Success! I filled it with synthetic, and let it run for 15 minutes.. the clicking gradually faded, and now it's nice and quiet!

Unfortunately the tank was near empty and it almost immediately ran out of gas. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[Katmanken]

Getting the pushrods correctly seated into the hydraulic lifters can be a trick sometimes and can account for noise and misadjustment. Change the oil with synthetic, make sure the pushrod is in the appropriate place in the center of the lifter, not to one side. If it is to one side, you can damage the lifter. Recheck the valve adjustment. If you adjusted to a gap of .006 and ran it ,the pushrods are slopping around (NOT GOOD)and you need to readjust ALL valve gaps.

Hydraulics have no gap and some preload. Correct adjustment is 2 half turns of the adjuster screw (in tighter) past valve contact. Some adjust it in to just touching the valve, run it for a while and then turn it in 2 half turns tighter. That allows collapsed lifters to fill and then you adjust the valves correctly once they are fully pumped up.

See Boston Bob's website for a full how to....

By the way, the manual is WRONG at 2 FULL turns past contact. Been discussed mightily on Vanagon forums.

That should do it. Mine rarely clank after a synthetic change (20w50), a new good filter and an adjust. Fram filters kill hydraulic lifters too.

Good luck!

[bondo]

I never took it apart or messed with any adjustments, so it should be OK.

[Katmanken]

Check the valve gaps. Do you know who adjusted them last? Hydraulics have no gaps. Hydraulics can be finicky to adjust if you don't know the tricks.

[bondo]

QUOTE (kwales @ Jan 7 2006, 06:14 PM)

Check the valve gaps. Do you know who adjusted them last? Hydraulics have no gaps. Hydraulics can be finicky to adjust if you don't know the tricks.

No idea who adjusted them last, but I did notice a little bit of clearance on the others. The engine hadn't been run in a month though, so they may have leaked down. One of these days I'll get around to trying to adjust them, but for now it runs fine and is quiet.

Hydros require a hydro cam, right? So I at least know I have a non-stock cam and can't go back to d-jet?

[bd1308]

well...the late vanagons had L-jet on them and were hydro.....

so i think it might be okay ???

b

[bondo]

QUOTE (bd1308 @ Jan 7 2006, 06:51 PM)

well...the late vanagons had L-jet on them and were hydro..... so i think it might be okay ??? b

That's good to know. It's got dual weber 40s on it now. Seems to go well enough, but it has a flat spot which I suspect is advance related (non-stock dizzy).