Bad vibration, rattling, around 4,000 rpm

[DIRQUIN]

I have just purchaced a 1990 awd eclipse. I have done a few maintenance items and just getting ready to get it road worthy. It has sat for 2 years. I have replaced all the timing components. It had a frozen slave cylinder, and a twisted pedal assy. I have fixed these, and have gotten it running. When I rev the engine above 3,500 to 4,000 rpm I get a realy bad vibration, and a knocking noise. I have narrowed it down to the rear of the engine. It is stronger just below the bell housing bolts, then just above the bolts on the block. I was told it has a 2,600 act clutch in it. I cant verify that just yet. I have installed the new slave cly. and it doesnt feel like it is any stronger then a stock clutch. It also doesnt disengage all the way. It drags in all gears, and wont let me put it in gear while the engine is running. Im going to try and bleed the slave again and see if that helps with that issue, but I still have the vibration. Has any one ever had this issue before, or herd of it. Also, just to add to the vibration help, when I rev it from the throttle body, it is so bad I cant hold on to the cable rocker. If that helps. Thanks in advance, Dave.

 

[DIRQUIN]

I pulled my trans today. I have found some disturbing things, and some ok things. I do have an ACT clutch. This is good. I have found that the person that put it in didnt know what they where doing. The top two bellhousing bolts where loose, and the bottom front and rear tabs on the engine block where broken. This alowed the engine and trans to seperate at the lower half, causing the flywheel to rub and cut in to the transfercase. I dont know yet if the flywheel is bent, but from just a quick glance it should be fine. Now to the hard part. How to fix the engine block. I have the tab off the front part but not the rear. It was missing alltogether. So, Now I must find a way to weld the front tab back in place, and find a way to make a rear one. Any suggestions? I have some 1/4 inch thick plate steel and many other steel pieces that I can use. Has any one run in to this problem, and how did you fix it? Thanks.

 

[4pistons]

Unfortunalely the only way to fix it is to have it welded by a competent welder who can do cast iron. You'll have to pull the engine and the area must be thoroughly scrubbed clean of oil and grease and wire brushed. Even then it might not be a good repair. Your welder will be able to tell you when he sees it.

Plan B would a different block.

Rick - '91 GSX

 

[Drifte]

Your vibration sounds like you got the balance shaft 180degrees out of time. Very common. If it comse back to it we can tell you how to render that issue. As for needing the lower 2 tabs welded; its possible to do it in the car. You will need to take the car to someone, or have those guys with a truck and a welder in the back come out and look at it.

...And I thought I had a rough time getting a few of my dsms going. good luck.

 

[DIRQUIN]

Im a prety good welder. But all i have is a mig welder. I know I can clean it off good enough. I'll cook all the oil out with a torch. I have done some cast iron welding before. I also have some steel plates that I was thinking about wraping around the outside of the tab just to give it a little more strength. Now the fun part is I'm going to have to make a rear tab myself since the originale one is missing. What I cant deside on is to make it so I put a bolt all the way through and have a nut on the other side, or try and thread the steel, like it was. I havent desided weather to pull the motor to have a better shot at all the angles, or leave it in. I would like to have it out so I can just scoot the trans over and line everything up so I know it will work right and not droop down again. If the balance shaft is 180 out does it only vibrate at certain rpm's, or would it be all the time? Thanks.

 

[Drifte]

balance shaft out of time tends to vibrate above 3/4krpm. Whenever I have delt with this and it does vibrate I dont rev much higher so I dont know.

If your a decent mechanic pulling the motor wont be a big deal. Get a guy to stick weld/braze whatever it needs. Be sure its kept nice and square, no warping. I think you know what needs done at this point so best of luck.

With the balance shaft out of time: go to vfaq.com and read up on the timing belt job. I believe they list how to time the balance shaft, which includes (and I assume you forgot) to take a long screw driver and put it in the back of the block (once you remove the bolt blocking it). Its hard to describe but I believe vfaq explained it best...I dont have BS's anymore or most of the time, so I cant recall the exact process.