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Discussion Starter · #1 ·
Folks-

Got an '85 P type that I just had a new timing belt and water pump installed in (while I was waiting on another shop to rebuild transmission after 353K miles on the old transmission).

Anyway, transmission and new clutch seem fine, but I have a bad engine vibration starting pretty distinctly at 1250-1300rpm (while sitting idle with clutch peddle depressed). Vibration seems to stay there while rev'ing higher, but not *quite* as noticeable since the frequency is faster. Engine seems to run smooth at idle speed.

*However*, upon looking over the engine while trying to find the cause of the vibration (loose plug wire, vacuum hose, etc.) while the engine was stopped, I happen to notice a 'chunk' was missing out of the crankshaft pulley. This chunk was gone from the back side of the pulley on the part of the 'flange' where the timing mark 'nick' is at (but not the nick itself; that is still there). If you measured the arc of the missing section, it would probably measure about two inches long and comes 'in' from the outside edge of the flange probably about 1/3 of an inch or so (just an eyeball guess; kinda like a cresent moon shape that is missing). The missing section is quite obvious. No compromise to the proper seating and running of the belts.

Ok, so finally here's my question: Could a section missing out of the crankshaft pulley like this cause an engine vibration that would be this noticeable? I can see where it could, but then again, it does not seem that it would be *that* much missing mass to set up this much vibration, so I don't really know.

Any body had this happen before? I don't know if this piece was broken off before (I don't think that it was) and seeing as it was removed to also replace the front oil seal when the timing belt was replaced, I'm betting it was boken at the dealer and they just aren't fessing up to it. I thought the vibration could be because the timing was not properly re-set after the new belt was installed, but the dealer that performed the work says the timing tests good. Dealer has verified that the new clutch and pressure plate are ok. Flywheel ok as well (the car is back at the dealer and we are all scratching our heads as to the cause of this problem). Jeff Watson in Texas says one of his mechanics commented that it may be the timing (the new belt off the mark by maybe one cam 'tooth'), but that it also could *possibly* be the broken crankshaft pulley. Not real keen on getting a new crankshaft pulley if it's not gonna fix the problem.

Any comments/suggestions/feeback would be GREATLY appreciated!
 

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I'd say that if the dealer broke the pulley, they should fix it. Period.

While reading your post, I was thinking exactly what Jeff Watson said. The timing could be off by one tooth on either the intake or exhaust cam. I helped a friend put his 5M-GE back together and we thought we had the timing set right. We saw similar symptoms to what you describe, slight engine vibration just above idle, car felt like it was just a bit low on power. A few days later we re-checked the timing and sure enough it was off by one tooth on one cam when the other one was lined up.
Simple to fix. Just get the motor to TDC, line up the marks as close as you can. Loosen the tensioner bolt, have an assistant pry the tensioner back to get some slack on the timing belt and you can slide the belt off one of the cam gears. Then turn the cams slightly to get them lined up perfectly and slide it back on. It will be a bit tight, but it can be done. It would help to have a couple of people to assist you. One to pry the tensioner back and another person to help you slide the belt off/on because it is a real tight fit.

Hope that helps.
 

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Earl & Dean,

Am wondering if the missing chunk on the crank pulley throwing off the "balance" of the pulley???? Remember, the crank pulley also has the harmonic balancer attached to it, so because a chunk is missing, that is what might be askew???

And yes, if you can prove that the repair shop broke this, then yes, they should replace it.
 

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If it wasn't shaking BEFORE you took it in then THEY have caused the problem and THEY should pay to fix it.

If they don't ... :nutkick:

My older brother works at a GM dealership and $hit like this happens all the time. I don't mind paying a premium price for premium service but most of the dealers want you to drive your car untill the first oilchange and then start giving you reasons to buy another new one.

I hate 'em... :mad:
 

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A small broken piece of pulley shouldn't cause that vibration as I've read about that before on the supras message board. However, if the shop broke that pulley then they should replace it!
 

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Discussion Starter · #6 ·
CJSREDPRA said:
Earl & Dean,

Am wondering if the missing chunk on the crank pulley throwing off the "balance" of the pulley???? Remember, the crank pulley also has the harmonic balancer attached to it, so because a chunk is missing, that is what might be askew???

And yes, if you can prove that the repair shop broke this, then yes, they should replace it.
Well, that' really my question: can a piece like this being gone throw the balance off enough to cause this vibration? As I said, I could see that if *enough* mass was missing, it certainly could cause it to be off balance (and this is not necessarily a small, little piece missing). On the other hand, I would think (gut feeling) that it *shouldn't* be THAT sensitive to a piece missing from it. So, that's why I was asking if others had had to replace their broken pulleys because it was causing this kind of vibration.
 

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you have to remember that the camshaft spins at half the speed of the crankshaft. if the engine is at 3k the cams are spinning at 1500. that's 25 times a second. not exactly enough to make a 750 pound engine vibrate alot. it can be rough if the cam timing is off. on one cam anyways and can feel like you have a performance cam without the performance.
 

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The chunk out of the pully shouldnt be a problem.....my pully on the 5m is like that and i dont get a vibration.

a friend of mine has the same sort of vibration in his mk3, this has only been there since he done his trans, they suspect its the touque converter or something around there..

hope this helps.
 

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I've got an '83 with the same vibration. It appears @ 1300 rpm where it is most noticeable when the car is sitting still. But when under load it is only noticeable when driving in 5th gear @60 mph and up or accelerating in 5th. It can also be felt in the shifter when decelerating, most noticeably in 2nd. I've been chasing it now for almost a year and a half. A buddy of mine (master mechanic) recently diagnosed it as a valve problem ( one intake and one exhaust) and will necesitate refurbing the head. I feel it has to be this as I have changed all rotating/moving parts on this beast. Best of luck as this adventure was expensive. But on the bright side, the car handles better than my original '83.

Best Regards,

Robert B. Sawvel

PS You might try removing the injectors and having them cleaned and calibrated first.
 

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ah crap. i thought you said camshaft pully. the crankshaft pully can cause that vibration. it's the harmonic balancer remember. a peice out of it can throw stuff off alot and you need to take it in to get fixed before they have to install a new mainbearing in the front of the engine too.
 

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Make sure to replace that crank pulley bolt anytime the crank pully is removed. My first 5M-GE swap was due to a loose crank pulley, the bolt will stretch when torqued and reused.
 
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