Maybe drop the car off at the "Doctors" and let him drive it for a while?

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12.70 @ 104.6

He's in my speed dial...

This one has me scratching my head. Seems like all the peripherals are working, evidence pointing to innards. Electrical is the one I'm most uncertain about, but I have checked the usual suspects (at least with crude swap and try methods, ECU (checked ground), engine ground, coil, dizzy, cap, rotor, plugs, system is charging, no spikes that I've observed during the episodes, played with timing, no difference).

I can check the drive line again, but I think it's the motor. The power is way down, it didn't climb my hill to my house as easily as before, not a crawl but not the peppy SL6 it was. Also the temp gauge dropped down when it was running rough, seems like a misfire, dead cylinder. I'm not sure if you could see that video (it was 34 Mb) and I may have been mistaken, but although the engine was revving up and down smoothly (quick throttle response too) in the garage when I got it home, it sounded awful and different, almost like the whine of a turbo inside, but I don't have a turbo and it's never made that sound before. Also the tappets are way louder than they were in the morning when I left for work. Somethings amiss inside I think. I'll fire it up again tonight, see if it stills sounds as bad as I thought it did yesterday.

Maybe when I blew the head gasket, I stretched the timing chain or something. The detonation issue definitely was causing metal, who knows what I did to the cam and bearings (lifters look good but maybe they pounded the cam lobes into submission). It's just weird how after I changed the head gasket it ran fine (I say fine, but not as strong as when first broke in) for a few hundred miles then started this issue, but it's gotten worse and more frequent, I think I've just been band aiding it along, skirting the real issue.

Sounds extreme, but I'm thinking of pulling the engine and checking out the innards. The worst that can do is tell me I'm wrong so I can check off another box. Besides, my rear seal is leaking and I want another crack at that...

B

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Started it up this morning, just to see what it sounded like (I was tired and irritable when I got it home on Monday). Damn thing sounds great (why am I complaining, I know, I know...). I'll look more closely at the drive line - I hadn't checked the wheel bearings yet as suggested by someone. Question: if there was a drive line component putting a drag or vibration on the engine, would that account for the fresh oil burping through the breather? I've been seeing that ever since the head gasket blew, even after changing it.

brian

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Sounds like compression pressure is getting into the crankcase? Or maybe the oil level is over-filled?

Something about the ring lands getting hammered, at the same time as the head gasket..

No idea how to test such a theory in the car, although there must be a way...or through the process of eliminating everything else.

I am gonna guess that the vibration is engine related, considering all the issues you have been working through. It may be driveline related, but why would that show up all of a sudden?

If it were my time and $$ invested, I would take it to a shop and have a second pair of eyes and ears confirm or eliminate what you are experiencing, then you can fix the problem, in stead of chasing symptoms..

My brain is pretty much where you are, could be suspension, but it seems like there's something else going on. And, yes, an independent look may be the best thing; at the very least because I've been round and round with this and a fresh perspective is always a good idea.

I changed the oil after the head gasket and had replaced the dizzy with a freshly rebuilt unit (same specs as old one, new plastic gear (correctly installed)). I should check the new dizzy gear for wear (would indicate internal mechanical turmoil) and my oil plug for any new fuzz (same indication) and also check for timing chain slack (forgot to do that when I was in there last time). If I don't see any wear on the gear or fuzz, then that was likely the detonation causing that (which I believe is solved) but if I do then it points to something internal still going on.

It would be great to have cameras mounted in the engine bay and underneath pointed at the drive line and suspension to see what is vibrating and what isn't during the shaking. I'll also check the wheel bearings this weekend to see if that is the issue (doesn't seem that would shake oil out through the breather, you'd need internal pressure to burp it out, I didn't have any issues with oil coming out of my breather before this started).

Brian

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I had a drive line guy check it out. He believes the drive line is fine, it is the engine. He said the engine had a vibration that starts noticeably around 1500 rpm, no matter if in gear or not. As a demonstration he had me sit in the car, with it in neutral or park and rev then engine to 1500 rpms and hold it there steady, you can feel the vibration through the steering wheel. So, it seems there is something about the engine doing this. I can check for slippage of the harmonic balancer, use my piston stop tool and check the timing mark, and check for chain slop, I'll do that this weekend. Maybe the valve timing theory is still solid, off time event causing vibration?

b

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I guess I should also remove the inspection plate and see if the torque converter shows any obvious signs of rotational imbalance while the engine is running, if not, then that result might also point to engine (don't know if drive line guy did that, probably not).

b

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I started it up with the inspection cover off, the torque converter seemed to be rotating smoothly, I didn't notice any rotational misalignment, looked good. But at 1500 rpm I did get a noticeable vibration in the steering wheel, in park or neutral.

I hooked up the timing light, the timing mark was pretty jumpy, wouldn't hold still at idle or revving engine.

I checked the timing chain for slack...turned the crank so the dampener mark was at TDC, zero on the timing tab, the distributor rotor was pointing directly at tower #1. OK, that's good, then I slowly turned the crank in the other direction until I saw movement in the rotor...the rotor didn't start to move until I was well past 10 degrees retarded on the timing tab, it went past the 10 degree mark, I'm estimating to about 15 degrees before the rotor button started to move - I measured somewhere between 3/4" and 7/8" of chain stretch (FSM says if more than 3/16" replace chain). So, it looks like I have stretched my rollmaster double roller chain quite a bit.

I also put my snail gauge on my breather pipe, at idle it reads 3 kg/h of vacuum, the vacuum to the pvc hose was reading 6 kg/h sucking from the intake. When I revved the engine to a few thousand rpms, I read a net positive pressure (blowby) at the breather, even though the intake is still reading 6 kg/h vacuum at the pvc hose. Also, oil was spraying out of the breather stack (I don't have a baffle, but before this all started, I had no issues with oil coming out of the stack through the breather). This would also explain why my rear seal is spewing oil as well, I have positive crankcase pressure, even with the intake pulling vacuum at the pvc.

I think I found my Gremlin, my timing chain is badly stretched. I believe this would cause a bad vibration if it's changing the valve timing, and that would produce crankcase pressure, does that seem reasonable?

Brian

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Bad rings allow blow-by which pressurizes crank case. Yes, that positive pressure will cause oil to blow by seals and gaskets.

Time for a leak-down test, and compression test.

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It's time to pull her out and check the internals. The peripherals have been stable, and I've checked them all at least in some fashion - there is chance it's a peripheral but I think it's internal. No doubt I stretched the heck out of that timing chain. I want to see what the internals look like, particularly the cam lobes and the bearing surfaces - I was seeing metal, both magnetic and non-magnetic...

I'll run a final compression test before I pull the engine, just so I can see if the numbers changed from when I changed the head, but I don't have a leak down tester (on my Christmas list though). It's academic at this point, it's gonna get a hone and new rings anyhow while it's out.

brian

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A couple questions?

What would stretch a super premium timing chain that bad in so few miles?

Why would your problem come and go if it is the timing chain? Seems like it is stretched all the time it should be acting funny all the time.

Glad you have some ideas, and I really hope that fixes it.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Hi Rick,

I suppose it was when #3 and #4 were communicating with each other, it was jerking pretty badly. I agree, I didn't imagine it was stretched so badly, that's why I didn't think to check it early on. By the way, you can pick up that Rollmaster set at buydart.com for $99, see: http://www.buydart.com/romacrollmaster- ... 16349.html

As for the coming and going, it seems that with all my work around the head gasket, retuning the carbs, drive line tinkering, I've got it down to a steady vibration at 1500 rpms, appears to consistent now. Recall some of those earlier tests were when the tranny was cockeyed and the motor mounts were torn up still. It runs pretty good, I just can't drive it this way, something's amiss, the crankcase pressure is spewing oil through my breather and on my valve cover and my rear seal is leaking like a sieve. The vibration is making my tail shaft seal and my pinion seal leak, it's going all the way through the drive line.

I believe I'm dealing with some second order thing here, I think it's prudent to pull the engine, do some internal forensics. I don't think the crank would be out of balance suddenly or anything and the push rods were straight as an arrow. I think it's valve timing related. Maybe I'll see abnormal wear patterns in the bearing surfaces, I can check the connecting rods and look at the cam profile. I played with the valve lash so many times, there's no telling if I was losing lash or not (but the lifter surfaces looked great). I'm thinking that pulling the engine is the natural next step. There is a chance I pull the engine, redo the internals and still have this issue, but I'm betting against that...even if that does happen at least I have more data.

Brian

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In retrospect, I think what happened was, that I had a lean issue which was causing a detonation, that is for sure. It was obviously detonating unnoticeably for a time, it was slowly eroding the head gasket. I only noticed it going up steep hills under load, where I thought it was an exhaust manifold leak/ticking. I was getting small amounts of metal in the oil, but I wasn't sure if that was residual from breakin period. The turning point was when the head gasket failed. I fixed the lean issue, redid the head gasket. But apparently, there was some secondary damage, certainly the tranny and motor mounts were torn up, I fixed those. Recall, early on, I was speculating that the weird vibration, odd running was due to a sticky valve or valve timing event. I retarded the timing, made valve lash adjustments etc. which appeared to improve the situation, but not fix it. I think I'm dealing with something internal. I'll report back on any findings in that regard. I'll pull it out this weekend and start to break it down.

brian

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Has this engine got Cast Aluminum Pistons?

Is it possible that the mild detonation over time has damaged the ring groove in the pistons, giving a poor seal at speed.. ?

These are stock pistons I believe. Anyway, we'll see what condition the innards are in shortly.

b

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