No one willing to try to list off other things that could cause this? Or is that the only two anyone else can think of as well?

 

K this is going to sound stupid because i know nothing about cars... but loose engine mounts?

 

Wouldn't that be at all rpm though and not a specific range? Another thing I was thinking is possibly broken flywheel bolts causing an imbalance?




BTW, another thing I was thinking. Isn't the 2-3k range where the 4G63 has the most vibrations that the balance shafts are supposed to cancel out? Also I am not exaggerating the vibration. I have been in DSM's with no balance shafts this is many many MANY times worse. Also like I said outside of that rev range everything is smooth.

 

hey ripper....did u find the problem...im having the same issuse.

 

um, no my father has not yet found the problem. The car is back in Georgia, i'm stationed in Germany for the next few years. So I can't directly look at anything on the car for a while.

He did tell me he's going to look at the clutch assembly first though.

 

I would concentrate on the balance shaft belt first and if the vibration is that severe then I would not run the engine again without looking under the timing cover.

 

I am not sure all of your mods, but the Shep Trans have some crazy vibration in them sometimes, which leads me to think it could be the gearing in the transmission. Is it specific to a gear, or just the RPM range in general?

 

It does not have to be in gear to cause the vibration. So I don't think it has anything to do with the rest of the drivetrain. I think it is with some part of the engines rotating mass. (Balance shafts, flywheel, etc. etc.)

Crazy vibration...my thoughts:

1. Loose mounts I'll have him check before he pulls the trans.
2. Something wrong with the clutch assembly (TOB took a shit, broken clutch fork..maybe only on one side)
3. Do a compression test
4. Any CELs?
5. How much knock (if you know or have a way to know) do you have?
6. Is the tranny/flywheel/clutch/pressure plate all bolted tightly? If one of these comes loose you could experience the problem you're having now.

1. I'll have him check before he pulls the trans.

2. Very possible

3. How would compression fall into this? Though I know I do have a bad cyl #2 It's like 124psi where as the highest is 142psi and the others in the middle Last time I checked. Thats more than the 15psi limit the book says to service the engine at. But I have seen/read of others with this issue and they didn't have this problem. Your suggesting a MASSIVE difference in cyl pressure I assume?

4. No CEL's

5. Little knock, I wasn't finished tuning it so I never got the fuel and airflow maps dialed. Soon as I realized the issue wasn't just the exhaust touching the rear diff I stopped driving it. Also it does it anytime it's in that 2-3k rev range, throttle position has no effect.

6. Also very likely, my old man put the clutch assembly in the car while I was in Iraq the first time and did not use locktite. Also I'm not sure if I knew at the time or gave him the correct torque spec for the flywheel bolts.

I guess I will just let him look at the clutch assembly & flywheel and see if he finds anything. Maybe send him some new bolts and locktite this time around too. (hope it's something simple like that or the TOB) Don't see how TOB could cause this either though...but i'll buy it for now. (Could you explain to me how it could?)

 

Crazy vibration...my thoughts:

1. Loose mounts
2. Something wrong with the clutch assembly (TOB took a shit, broken clutch fork..maybe only on one side)
3. Do a compression test
4. Any CELs?
5. How much knock (if you know or have a way to know) do you have?
6. Is the tranny/flywheel/clutch/pressure plate all bolted tightly? If one of these comes loose you could experience the problem you're having now.

 

I had a massive vibration that I could not find for a while, thought it was clutch imbalance or balance shaft problem. I replaced the clutch and flywheel with not fix and even cut the belt to the balance shafts with no noticeable change in vibration. Ended up being that the wrist pins to piston had excessive play, replaced the pistons and all was good.

 

I forgot all about balance shafts. They could be the issue...if you have them.

 

Front and rear balance shafts out of time maybe?

I've read in the past that the vibration from them being timed wrong is worse than when they're removed.

 

Your balance shaft belt may have jumped a few teeth throwing a shaft out of time.

 

We will see, it's not a high priority for him at the time since it's another 2yr's before I will be getting close to going back to the states. Although he did say it sounds/feels like something heavy thats out of balance. Which goes back to the flywheel/clutch.

 

Since you still have your bs in and a new belt on them could it maybe have skipped a tooth on the front bs? Just throwing an idea out there.

 

Yea it's possible and I mentioned it to him, he didn't seem to think thats what it was though. When he gets around to tearing into and we find out more, i'll update the thread.

 

Well, it's been a while. Since I will soon be heading back to the good old United States of America, my old man decided it was time to tear into the Talon to see if he could figure out what the massive rpm based vibration was and possibly repair it before I get home.

So far he did check the motor mounts and the balance shaft, he said the belt looked fine on the BS and the timing marks all lined up, so assuming everything was done in accordance with the proper procedure then that's not it. So he has started removing everything in the way of dropping the trans to inspect the clutch assembly/flywheel. I really have my fingers crossed on this one that it's something not serious.

 

Well, it's been a while. Since I will soon be heading back to the good old United States of America, my old man decided it was time to tear into the Talon to see if he could figure out what the massive rpm based vibration was and possibly repair it before I get home.

So far he did check the motor mounts and the balance shaft, he said the belt looked fine on the BS and the timing marks all lined up, so assuming everything was done in accordance with the proper procedure then that's not it. So he has started removing everything in the way of dropping the trans to inspect the clutch assembly/flywheel. I really have my fingers crossed on this one that it's something not serious.

The timing marks can line up and the rear balance shaft can still be off by 180*. Ask him if he moved the oil pump sprocket, and if he did, which way it wanted to move when "settling". This happened to me when I did my first timing belt. I couldn't feel any vibration (stock tired motor mounts), but I could hear it as the RPM's started to rise.

Edit-The timing mark on the oil pump sprocket should want to rotate back towards the timing mark IIRC. Check the VFAQ on it and double check.

 

Had a very similar experience to this with my '90 TSI. It turned out that the Fidanza flywheel had a crack in it. It literally made me feel like the car was just going to fall apart due to the vibration. Hope it's something like that for you and not a rotating assembly issue. BTW the crack that was in my flywheel was between two of the bolt holes which then allowed the flywheel to literally bounce around an 1/8 inch.

 

I'll mention this to him since he's currently in the process of pulling the trans to inspect the clutch assembly.




P.S. thanks for the original idea, at this point it seems several people are just saying the same thing. That said i'll mention to him the thing about the marks lining up but the BS being 180* out as well. But I don't see how thats realistically possible since it was fine, I don't see how it could keep jumping teeth to that point and the belt not be destroyed / seriously messed up.

 

Well, he pulled the trans the other day and says that the clutch and flywheel look fine. *sigh* I was really hoping it would be something related to the clutch/flywheel or balance shaft.

So I guess the next step is to pull the engine and start inspecting it. :wall:

 

Dude the Rear Balance shaft/Oil pump sprocket is out of phase, Stop munking around with the car and taking parts off that do not need to come off. Pull The T belt, Grab the oil pump sprocket and line it up according to the mark.

Turn it to the left some and see what happens. If it falls towards the mark its right if it falls away from the mark its out 180*


I hate to say this but it sounds as if neither of you know what you are doing, The car was never timed correctly from the get go.

Take it to someone that knows what they are doing and pay to have it fixed.

 

This isn't me doing the work, it's my 65yr old GM tech father back in Georgia. I'm still in Germany. And it WAS timed correctly, I drove it without issue for several thousand miles once I replaced the timing belts, pulley's and tentioner. It was only shortly after I got it to Oklahoma where I WAS stationed at the time that the issue popped up. I had to trailer it back to Georgia before I left to Germany.

I don't really see how it's possible that the balance shaft got from where it's supposed to be to 180* out, but i'll advise him to check it again and send him some stuff I found on VFAQ to help him understand what he's looking for. Because I honestly don't see how it could be anything internal other than the BS either.

 

Well the balance shaft's have been checked, and rechecked. My father found nothing so he pulled the engine, it's currently on a stand and re-checked it again before he started tearing it down. He found nothing wrong so now he's going to start tearing it down until he finds something wrong!

At this point me and him both are wondering just what the heck. Honestly I am very hesitant to bring this up but it has been in the back of my head but makes no sense to me. I have only ridden in two other peoples DSM's and owned two, this being my 2nd. The other two I road in both had poly mounts, but one had the balance shafts removed and the other did not. Here's the weird part, the first one was a 2g GS-T, oly mounts and still had it's balance shafts, it also shook horribly. The other a 1g like mine, AWD TSi, had them removed and had poly mounts and the vibrations from it were what I would have expected, a little vibration at idle and low rpm and that was honestly about it, nothing that bad at all. But isn't that backwards of what you should expect!?!?

I'm tempted to just order the B/S removal parts have him remove them, throw it back in and see how it is then.

 

Ok, so my father basically confirmed today that it is not the balance shafts. Or at least it's not a result of them being out of phase. He left the spark plug in cyl 1, to make sure he was on the compression stroke, and at TDC all marks lined up perfect.

What he is thinking about doing is removing the belt off the front shaft, and then pulling the rear balance shaft, and since our next door neighbor has his own machine shop, turning down the weights on the rear lower shaft, then re-installing it. And seeing what happens. The idea behind doing this vs a normal removal is to avoid having to mess with high oil pressure issue and porting the oil filter housing relief port.

My question is, should the oil pressure be effected if the shafts are installed but not turning?


Also as a recap, he checked and re-checked the flywheel, clutch disk, pressure plate, harmonic dampener and now confirmed the shafts are in sync. So before we try the above he's going to pull the oil pan just to make sure there isn't something funny going on with one of the shafts like the weight on one somehow damaged, or broken shaft etc.

 

Did you have him pull the bolt in the back of the block to see if he can put a screwdriver through when all the timing marks are lined up? If the screwdriver can't go through, the oil pump shaft is out of phase. Not sure if you said he did that?

 

I did not, I have been sending PM's with a few questions to Loki, he brought that up as well. Which was the first time I had heard about that bolt. I e-mailed the information Loki PM'ed me to my old man. I'll call him tonight and make sure he got the e-mail. Since the engine is out on a stand it shouldn't take but a min to pull the bolt and check.


P.S.
I would like to thank Loki, Rook, Hot97 and anyone else I might be skipping over that has actually contributed to this thread.

 

http://vfaq.com/mods/timingbelt-1G.html

There's a picture of the bolt about 3/4 down. Since you have both shafts, you might as well check both going off of this.

Its common for guys to turn down the rear shaft and eliminate the front shaft all together. When doing that, you'll need to remove the front bearing and replace it with another, but put it in 180* off to block the oil passage. You will have some more oil pressure, but with still having the rear shaft working, won't be as much.

 

Well, it would appear that for YEARS the rear lower balance shaft has been out of phase. I suppose that the installation of the polyurethane motor mounts just made it noticeable. I had the engine's timing set at a shop in Duluth Georgia, it was a DSM specific shop. I can't recall the name now, but anyway I guess the rubber worn out engine mounts just kept me from really noticing the vibration.

The reason I say this, is that my father just checked the inspection port for the rear lower shaft and it WAS 180* out. So he rotated it 180*, and tried sticking the screw driver in it again, and then it went in deeply without hitting anything like it should.

I suppose the thing that threw me, and him was just that I did not notice it YEARS ago. So I assumed that it was fine. So now he's going to address one or two other small things that are just a pita to do with the engine installed. And then put it back in and fire it up. I fully expect the problem to be gone now.

Thank you again Loki, Rook and any others that contributed. I will note if it in fact is resolved or not once the engine is back in and fired up.