Engine buzz/vibration over 4.5k rpms- balance shaft?

[tbnsw]

Hi everyone

I just bought my 3rd DSM, a clean 90 Laser Turbo with 56k miles. It had a new timing belt, balance belt and tensioner 5k miles ago. My problem is that when the engine hits around 4500 rpms, the engine sounds really buzzy and there is a vibration. It runs fine, boosts good, doesn't miss or anything. I'm wondering if whoever did the balance belt didn't line up the shafts correctly? If this is the case, would I harm anything by leaving it the way it is? Could it be a harmonic balancer? Any other ideas or things to check?

Thanks for the help
Shawn

 

[BUCK]

Either one of those is a good guess - although if Shafts were out of time you'd typically see Vibes at idle. All the original Harmonic Balancers seem to be bad on these things.

 

[tbnsw]

Thanks for the reply, Buck. I will look for a vibration at idle, though I didn't notice one before. I guess I will also try replacing the harmonic balancer. If that doesn't clear it up, can I just leave it, or will I damage something?

 

[BUCK]

Man that thing is like a VIRGIN DSM with only 56K miles! - All this buzzin' might just mean that sumbitch is HAPPY!

 

[Talon007]

Almost 100% sure its the B shaft, you dont always get a vibration at idle.

 

[tbnsw]

Yeah it sure is! It's near mint. I'm still amazed I found it! I'll attach a pic to my sig when I get a chance.

So how would I go about re-tuning the balance shafts- is it involved enough where I should take it in? I've replaced a 14b turbo before but never done anything timing belt related so I'm a little unsure of myself.

Thanks again for the replys everyone.
Shawn

 

[Talon007]

VFAQ explanis it step by step and with pictures.

 

[realitytb]

that is a very good fine for you your lucky if you find one under 100,000 miles anymore

 

[tbnsw]

I found the VFAQ walkthrough after I posterd- sorry. But I'm wondering, is it possible to remove the balance shafts without removing the timing belt? In the VFAQ thhey only talk about doing it with the t-belt off. Since the belt is new, I would prefer not to touch it.

Thanks

 

[BUCK]

I found the VFAQ walkthrough after I posterd- sorry. But I'm wondering, is it possible to remove the balance shafts without removing the timing belt? In the VFAQ thhey only talk about doing it with the t-belt off. Since the belt is new, I would prefer not to touch it. Thanks

No.