what would cause a 1G Eclipse GSX to vibrate before the timing belt goes?

[Crackerjackman]

I have searched the forums and I was wondering what would cause a 1G Eclipse GSX to vibrate before the timing belt goes??? The owner of the car I am thinking about buying said it ran fine and then he noticed that the TB had a slick tear in it so he parked it. He said he fired it up a couple of times after that but didnt drive it and he said that each time he started it it would run rougher. AM I to be concerned and just say ney on the deal or if I replace the TB would that cure the problem. My main concern is getting this car fixing the TB and then getting hosed cause he screwed up something like valves. I also need to know what the compression should be on the car. Would like the info if possible by Noon PST please that is when I am going out to this guys place. Thanks for all your help!!!


Philip

 

[crimsondragon]

If the valves were ####ed up, the car wouldn't start. Simple as that. It does sound like the timing belt is on its way out though. I hope you're not driving the car back. It could also be the balance shaft belts going as well but really, vibrations can mean a lot of things. Bring a compression tester with you and do a compression test.

 

[Crackerjackman]

No I didnt drive it up. I will change the timing belt on saturday at the guys place. She fired up after not being run for almost 2 yrs. Rough idle and around 2500 she stablizes out. The timing is way off so I will do the belt to see if that works. Also would timing cause no boost at 3500 rpms and up??? IT IS NOT A BOOST LEAK!!!!!

Philip

 

[Defiant]

It's jumped timing. Do not start it at all until the belts have been replaced.

 

[Tim Melton]

to me it sounds like the balance shaft belt is probably in the bottom of the timing cover.It probably is what messed up the timing belt by rubbing it.It should be ok though if you dont drive it.

 

[Crackerjackman]

KK I am going down tomorrow to swap belts. Anything else I need to know about or look out for??? I was thinking that the balance shaft belt was broken and thats why it is vibrating. I will find out more tomorrow.

Philip

 

[Colt4G63 also]

Yes!

You should know that you have to take the short bolt out of the back of the block, and make sure that you can insert a 1/4" extension into the block when you have your oil pump pulley arrow lined up. Otherwise you could set your rear balance shaft out of phase.

 

[DSM1G90]

You should know that you have to take the short bolt out of the back of the block, and make sure that you can insert a 1/4" extension into the block when you have your oil pump pulley arrow lined up.

Or, an easier route: "NOTE that there is an easier way to do this. Simply rotate the mark on the oil pump sprocket until it is pointing straight up, and let it go. If the sprocket rotates towards (counterclockwise) the timing mark on the engine, the oil pump sprocket is aligned correctly. If it rotates away (clockwise) from the mark, spin the sprocket a full turn and test again, and it should properly rotate towards the mark now. Now line the mark on the sprocket back up with the mark on the engine. This avoids having to remove the rear access bolt entirely."

When I did my belt, I used this trick above and it saved tonnage of time doing the replacement since that bolt is hell sometimes to find let alone shoving that extension to do the settings.

VFAQ Site - Visual Frequently Answered Questions has all of this info on setting balance/oil sprockets

 

[Crackerjackman]

KK thanks. I have researched a ton on this belt and I have done timing belts on mazda trucks and honda SOHC cars but this is scary cause its an interferance car. Oh well I just have to take my time and check check and check again that thimgs are right. ONce timing is right I should have boost again right??? I repeat I dont have a boost leak.

 

[Colt4G63 also]

I did one yesterday on a 91 GS. The bolt was very easy to remove. I just stood under the car, and it was right there, plain as day. Yes it may be more difficult on a GSX, but worth it in my opinion.

Ps. I make no garantee you'll have boost.

 

[soulweaver]

Your gonna need a special tool for the timing belt tensioner. What I did was take my battery bolt and filed the wings off and used it.

Here is what I followed
Timing Belt VFAQ (Timing Belt TSB - ENHANCED)

 

[DSMcamaro]

this may help you if you do the belt yourself.

YouTube - 6-Bolt Mitsubishi Timing Belt Replacement

YouTube - 6-Bolt Mitsubishi Timing Belt Replacement Part 2

 

[Colt4G63 also]

And when you have the belt on, and have rotated the engine by hand a few revolutions, make sure you have between 3mm and 4.5mm of clearance between the tensioner, and the plunger body.

You can measure that with an allen wrench.

 

[DSM1G90]

I used the drillbit size thing along with making my tensioner tool with a length of 8mm rod and two 13mm nuts jammed together so i could put a socket on it.

 

[Crackerjackman]

OK OK.....Still got the vibration. I made sure that my marks were all lined up and then put the belt on and cranked the cranck 6 times and it all lined up. I fired her up and she idles at a grand....No problem right wrong....Still had a little vibration like a miss or when your car needs a tune up. Killed the car and then fired her up but now she is vibrating really bad like she want to die or like she is camming. I dont know if she jumped a tooth or not. I was really siked cause she was actually idling this time. would bad gas cause the vibration too??? Also on my boost gauge when I rev her up to like 3500 it reads almost at 0 and then when she idles she is reading about 10psi on Vaccum. Do you have to be under a load to get boost??? I am totally new to Turbos and DSMs. Please bear with me on my questions. Thanks.


When I took out the auto tensioner to squeeze it to put the"grenade pin " in there looked like oil coming out from the bottom. Then again when I took off the timing cover it was really grimey. I am stumped. I really want this car and the guy is being nice and letting me work on it so I can trade him my truck for it but it is just looking at more work then it is worth. What is a danger psi for compression on a 91 Turbo GSX???? So when I get the compression done I know. Thanks

Philip

 

[Colt4G63 also]

It's probably got bent valves. Do a cylinder leakdown test, or a compression test. If you have a big leak past some of the valves it should be fairly obvious. If it's grimy in there you probably have a leaky oil seal or a bad water pump which would be the underlying cause of your problem.

 

[DSM1G90]

in there looked like oil coming out from the bottom

You need a new tensioner. When they leak, they're shot and can't do the belt tension right.

Also on my boost gauge when I rev her up to like 3500 it reads almost at 0 and then when she idles she is reading about 10psi on Vaccum. Do you have to be under a load to get boost???

Yep, you need to be under load to have boost - gotta give the motor something to work with. ECU, which controlls the stock boost gauge is getting crazy readings from somewhere in there to send the gauge up that high on idle.

It's probably got bent valves

Thing wouldn't run at 1kRPMS on idle if they were bent...bent valves=zero compression.

Have you checked your base timing instructed by factory specs - being 5*BTDC with the ECU disable plug grounded? Sounds like your timing is way off the marks..even though you got your belt timing right to snuff...

good luck - DSM

 

[Crackerjackman]

Its not a stock boost gauge. it is a aftermarket gauge.

 

[DSM1G90]

where do you have your aftermkt gauge tapped into then? some tap the vacuum line coming from the intake manifold to the FPR...