Also, let's say the cam timing was set appropriately from the start, but I had a lean mix and there was unnoticeable detonation, causing metal though. I wonder if the cam can get worn sufficiently to change the timing dynamics over time. Maybe a lean mix could change the shape of the cam over time just enough to necessitate resetting the cam timing. Just a thought. The lifters looked great; I haven't lost any power (that I'm aware of), seems like a strong motor. If the cam were worn in any significant way there would be a loss of power, poor idle, etc. I would think.

b

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I'm scratching my head. Remember when I wrote that it sometimes would shudder on a long drive and then clear up again? That was a couple of head gaskets ago. I pondered if it might be the tranny, but the head gasket damage leads me toward engine internals. Keep reading....

Last three test drives went like this: 1) after I had tightened the lash, the shuddering started as soon as I got on the highway, just warmed up and it continued until I got her home; 2) as soon as I got home, I pulled the valve cover, hot, and I loosened the lash quite a bit, then I drove her for 20 miles and it had only a very slight vibration, hardly noticeable, hmm...feedback from the system, maybe, maybe not.... 3) did the same drive the next day, hadn't changed anything, but the shuddering and vibration was more pronounced, but still driveable, not anywhere near the worst I'd seen. I didn't drive it for a week.

Yesterday, I took her for a 45 minute drive into the desert. I haven't changed anything since last time, the lash is really loose, timing at TDC, cold plugs. I got on the highway, it was just warmed up, I live about a mile from the highway. I got her up to 60 mph and the shuddering started heavily this time, the steering wheel was shaking. No changes had been made since last two drives. I was determined to drive it a bit more to see if I could record more symptoms. After 10 minutes or so the shuddering diminished quite a bit. I kept driving, if I kept it under 60 mph, the vibration was minimal, but very little power up hills (or maybe I was afraid to push it due to vibration). I kept going. After 20 minutes the vibration was almost undetectable, I got her up to 70 mph, no vibration in the wheel! I drove another 25 miles, smooth as silk, up some inclines, etc. no problem. Pulled off the highway after a total of about 50 minutes of highway driving, idle was steady, perhaps a slight misfire, but nearly undetectable. Power seemed down though, sluggish in traffic (but recall I retarded the timing 10 degrees). Pulled over, let her cool down for about 45 minutes, filled her with gas. Took her back on the highway to go home. On the way back the pattern was exactly the same as on the way out, first ten minutes bad vibration, then, after 20 minutes or so, pretty smooth the rest of the way home.

As I was driving, during the worst shuddering/shaking in the steering wheel, I put her in neutral and revved her up, seemed fine, no misfires or falling on its face, smooth revving. Strange thing is...the shuddering/vibration seemed to continue, even in neutral coasting down the highway. This makes me think it's the tranny or drive line. Boy, this is confusing me, really.

The tranny was rebuilt a year ago; I don't think it's the tranny, but why would I still have a vibration going down the highway at 60 mph in neutral while I'm revving the engine and the engine sounds fine/smooth? I suppose it could be the engine and I just think it sounded smooth as I rev it; it sure sounds like its revving smoothly at that time, but I suppose it could still be shaking. Could be it revs fine in neutral but any load on it and it shakes...but the car was still shaking while I was in neutral and revving it...hmmm.

I'll warm her up and check the tranny fluid, but I know it's full, I have no tranny leak to speak of, just a drop or two every so often from where the cable mounts.

Could this be a torque converter issue? If so, why am I burning through head gaskets? If it were the tranny, wouldn't it be a constant thing, or can fluid pressures be "off" and then correct themselves over time? I'm totally confused. Drive shaft? Could I have done damage to the drive line driving it home with the blown head gasket, where I was essentially running on 4 cylinders for 50 miles? If it were the drive line, why would it shake at 10 minutes of driving, and, like clockwork, smooth out after 20 minutes of highway driving? Coincidence? I'm telling you, I timed this with my watch...

BTW, my slip yoke shaft is about 2.5 inches out of the tranny tail (to the universal joint). It was like this from the time I installed it, I was unaware that this was a bad thing. The U joints were new and the driveshaft was balanced by a shop. I can get a longer drive shaft, make sure the yoke shaft shows less than 1". Maybe the yoke shaft not being fully in was fine while the engine was running smoothly, but when I blew the head gasket, the rough running did some damage to the drive line in this area? I can pull the driveshaft and see if there's damage to the yoke or splines. I crawled under there and pulled/pushed on the shaft, there was about 1/8" of lateral play. I never tried that before this all started, so I don't know if this is a new thing, but before this head gasket/detonation issue, the drive line was as smooth as silk.

Wondering if maybe I've solved the detonation issue and I have a completely different issue with the vibration/shuddering. Perhaps the feedback on the lash adjustment was random chance and not feedback at all...

Brian

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You caught my eye mentioning steering...........


I had a sticky caliper on my truck and it did this.

In fact, I got a lot of similar symptoms that you have with that sticky caliper.......

And it didn't do it all the time......


If you don't have disks up front, I supposed a drum could do the same thing with glazed shoes, drum, and bad wheel cylinder....

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

...I'll check the calipers (and the drive shaft yoke). I do have disk brakes up front.

b

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In my experience shuddering in the steering wheel comes from the area of the car attached to the front suspension.

Driveline vibrations come through the seat, or make the rear view mirrors shake. Also they are consistent, that is at 45 MPH under load or what ever speed.. but much less under coasting.. so if it is driveline you should be able to reproduce it anytime you want. Never heard of a transmission causing a shudder. Although I have blamed a transmission myself, until I woke up realized it was a U joint.

Try to keep the K.I.S.S. principle in mind. (easy to say, not easy to do when faced with a challenging and seeming complex symptom) I've been chasing a vacuum leak for 2 months now, and have yet to actually find the problem, I've made gains, as the car runs better, but I am still somehow overlooking the main cause, which is right in front of me.

Ed,

If it were a sticky caliper, what signs am I looking for when I pull the unit, will there be signs of misalignment or wear on the unit? What did you see when you fixed your issue?

Brian

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You really don't see anything (unless the pads are worn lots more on one side)

It's feel. wheel hard to turn and/or hot.

Compare how easy it is to turn the wheel with the front of the car jacked up.

When it's exhibiting the symptoms, pull over and compare the temp of wheel hubs with your hands (take off any hubcaps beforehand, and it maybe really hot)

Sometimes the drag on the wheel isn't there when cold or all the time. So you may need to jack it up just after driving.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

i'm not noticing any hard steering, but that said, I never tried to hit the brakes during the shuddering either, seems like that would help identify if its a brake caliper. Also, I have an IR thermometer, so I could zap each side, see if there's a noticeable difference. i'm going to jack it up anyhow to pull the drive shaft, so I can pull the wheels and check the brakes at the same time.
B

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If I find it is some suspension/driveline issue, I'll move this post over to the correct topic bin...
b

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It sounds like you have multiple issues. If the occasional shuddering at speed is not related to the engine running rough and misfiring, then I'd put those observations in a different box for now.

Burning head gaskets between cylinders is exactly what my engine was doing after I shaved the head. My DCR is lower than yours, calculated around 7.6, but we were running on 87 octane. After we stopped chasing our tails about torque sequence and deck flatness, I finally got around to checking the total advance and found we were maxing out at >40 degrees at high RPM. We would blow a head gasket in less than an hour when road racing at sea level. I ended up recurving the distributor to limit max total advance to 28-30 degrees. (We don't run vacuum advance on this engine.)

A curious thing I noticed when disassembling my dizzy is that the slot length on the mechanical advance governor was not long enough to account for the mechanical advance I was seeing; however, I only measured the timing curve once before taking it apart. After I welded up the slots to reduce the mechanical advance, I checked the total timing multiple times and found the results to be shaky and not very repeatable. The distributor was good and tight, without appreciable slop. After I swapped to a Pertronix ignition I had hanging around, the timing curve got much smoother and more repeatable.

What I'm suggesting is your ECU may warrant further attention. I know you tried two different ones, but they could both be acting funny when they get hot. You could occasionally be seeing more ignition advance when running hot than you see in your garage. (Coils also have a tendency to act up when hot even when running fine cold, but I'm not aware of any way an ignition coil could change your spark advance.)

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Thanks, I think that maybe my detonation issue was causing the metal; I may have fixed that by dialing back the timing, enriching the fuel mix, etc. My total mechanical advance was less than 30 before I retarded the timing by 10 degrees..

Anywho, I figure maybe I fixed that issue, but hurt something else in the drive line when I drove it 50 miles with a blown head gasket, running on 4 cylinders, shaking, shuddering the whole way. I'll check my motor mounts, driveshaft, etc. Current thought is drive shaft, yoke into the tail shaft isn't far enough in and it has some lateral play. I'll pull that and check for damage to splines and/or yoke (hopefully not deeper in the tranny).

The reason I'm thinking this, is when on my last highway test, when it was shuddering, I put her in neutral and revved the engine. It sounded smooth, but the steering wheel was still shuddering...seems like a drive line issue.

Yes, depending upon what I find, I'll move this over to the appropriate place in the forum.

brian

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I've continued this thread over in "transmission" section, as I'm investigating my drive shaft and tranny now...will continue here if engine is the issue, otherwise looking at other sources of vibration currently.

brian

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OK, just got back from Europe, it was good to get away from things and drive on the left side of the road (those roads in Ireland are really narrow!). Important note, Irish butter is sooooo good.

Recall, where I left off, I had done a long test drive and the shaking seemed to smooth out after 20 minutes of driving. OK, so I had investigated the drive line, there was an issue with the motor mount and tranny mount rubber being torn up from the blown head gasket, driving it home on 4 cylinders. I hadn't noticed these damaged items previously. I replaced the motor and tranny mounts, the tail shaft seal and bushing (it had signs of wear) and I still had some vibration, but it was running OK (seemingly). The slip yoke appeared to be out too far, so i replaced the driveshaft while i was at it....the thought was that I had indeed fixed the engine issue and had only these residual drive line issues to take care of. The new drive shaft was balanced at a shop, new U joints and slip yoke.

Well, I took it for a test drive on the weekend, it seemed OK, I didn't feel hardly any, if any, vibration but I had a whine I hadn't heard previously. After about 15 miles or so of test drives the whine disappeared (u joint?), but I did notice a slight vibration in the wheel at about 60 mph. Hmmm, perhaps if that's all there was, I could manage this way (I had measured the drive line angles, all good there.)

I drove it to work today, after about 40 miles she started running rough, and I got the vibration back in the wheel big time. By the time I got her home tonight, it was running pretty badly, lots of vibration. The thing is, it doesn't run that rough idling, only under load. But, the mechanical noise is a lot louder, way more ticking than I had this morning when I left for work (recall, I was getting metal) and there is a noticeable loss in power (I also noticed that my temp gauge dropped a decent amount, maybe I'm running on less cylinders under load, less combustion, less heat).

So, whatever the underlying problem, I haven't solved it. I had checked for compression, spark, back pressure, timing, etc. the only issue that I could find was a lean condition on acceleration, and I fixed that. There is no more detonation sound that I can hear, that seems to be gone. That said, clearly something is wrong. Same symptoms as before, it is running rough, fresh oil burped out of the valve cover breather, and I can tell my intake vacuum is affected because my power brakes' pedal firmness changes abruptly during the shaking episodes (seems like I gain vacuum, pedal gets easier, go figure). There is definitely a misfire of some sort under load, rough running. At idle or not under load it is barely discernible.

What I can't figure out is why I was still getting some vibration when I put it in neutral while coasting on the highway. I suppose the engine could have still been shaking but sound smooth when I revved it, I'm at a loss there.

Anyway, it's running super crappy while driving, but idles relatively smoothly. Here is a video from when I got home today: http://tinyurl.com/gvbbok2

Sounds pretty good, right? Runs like crap when driving it. I've never seen an engine idle and rev so nicely and drive like a sick puppy. Spark suppression under load? Weak under load due to excessive cam wear (from the detonation issue)? I am way outta my league on this one...

brian

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If engine idles smoothly, vibration must be coming from drive train. Where you replaced U joints and most of the problem went away, than squeaking came on, and now vibration is back, one of the U joints has most likely failed.

Probably a needle baring got loose during installation and it took that one leg of the joint a few miles to self destruct, or the prelubed baring had some defect out of the box.

Pull the drive shaft and feel how each cap responds to full motion, or has any play.

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82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

I'm not sure how to diagnose this issue, would a dyno test help root out the issue? I'd hate the pull the engine only to find it's something non-mechanical.

Could I have excessive cam wear and it still have great compression? I keep thinking this is a valve timing issue, the cam is worn down or something. The lifters looked great, but I didn't get a good look at the cam lobes and it was making metal....

On the electrical side, I swapped out distributor, ECU, coil, cap/rotor, no change. Starts immediately, quick throttle response, timing at TDC, total mechanical well below 30 (20 range). I checked exhaust back pressure, intake leaks, AFR is good (now), cold crank compression shows 180 psi in each cylinder.

It started with a detonation issue under load, that was real, but was running fine otherwise, I can't help but think the cam has worn excessively and is causing weird misfire/timing issues. I suppose it's time to pull the engine and do some internal diagnostics, see what the cam/chain/gears look like, if they're worn or not and still in sync.

brian

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