Engine sounds like a diesel, knocking & tapping very loud *video*

[Ski Bum]

What would cause my engine (91 GSX) to sound like a diesel engine? When i start it it taps and knocks as if there was no oil anywhere in the engine when the oil is fine. This happened all of a sudden without any major modifications.

Symptoms: Engine starts normally and horrible sounds begin. Idle rises just as it would during cold start. All gauges and functions appear normal. After 15 seconds or so the engine begins to loose RPM's and threatens to die. Throughout all of this the horrible knocking and tapping occurs.

This all began after shoving the wiring harness and ECU back into place behind the HVAC yesturday. I think I may have unplugged the ECU while the battery terminals were still connected.

Also I installed a turbo xs MBC the day before (14-15psi) but that did not cause any problems then.

What sort of tests could I run to diagnose this and eliminate possible culprits?

I added this video that will hopefully give you a better idea of what I'm describing.

right click and save as:
http://www.onestopautodetail.com/images/Jason's%20Page/Tapping%20GSX.wmv

 

[1gnasty]

sound like a rod knock to me

 

[wolf20043]

sound like a rod knock to me

Julias sounded just like that when we bought it, it turned out to be the balance shaft bearings. I would start by drainging the oil and see if You have metal shavings in it. If so You found Your culprit.
Mike
It would also idle fine with the noise until it warmed up and would start dying and running like crap.

 

[Ski Bum]

Ok, so I noticed that the timing belt felt awfully loose so I pulled all the drive belts, pulleys and timing belt cover to get a better look. The balance shaft belt and timing belt are both very loose. I can move them over an inch very easily. I'm thinking that during my timing belt change I probably didnt get the tension adjusted right?

I did post a thread earlier about a squeeling/humming coming from the belts, probably related.

In the mean time I'm going to get the mitsu timing belt tools and make sure the adjustments are right.

 

[1gnasty]

Julias sounded just like that when we bought it, it turned out to be the balance shaft bearings. I would start by drainging the oil and see if You have metal shavings in it. If so You found Your culprit.
Mike
It would also idle fine with the noise until it warmed up and would start dying and running like crap.

it could be jost to be shure drain the oil and check for
metal shaving on it
by the way a loose belt wont make the car idle like that
or die out after a while

 

[Precision]

Sounds alot like a colaped lifter, that would explain the noise and the idle.

 

[Ski Bum]

Ok, so today I finished reinstalling the timing belt and balnce belt. They were both so loose, I'm surprised they didnt fall off.

Today I went through the whole painstaking process to attain the proper tension. Finally I got everything where it should be. The car started rught up and the gruesome sound from before was gone. I hooked up a timing gun and the timing was so far off the mark on the pulley couldnt even be seen. The adjustment I made on the cam angle sensor was probably close to 10-15 degrees (on a circle), as far as the distance I had to turn the CAS to reach 5 degrees advance. I had to turn the CAS left which I think is advancing the timing?

While the belts were off I noticed coolant on the side of the block. I wiped it away and found it was seeping from one of the bolts holding on the water pump, which I had replaced. I checked the bolt and it was barely hand tight So I retorqued the rest of the bolts which too were not tight. The leak went away.

After that the idle stabilized for a while and the engine ran smoother than ever. The car actually feels like it has ALOT more power than it did after the first time I attempted to replace the timing belt. The idle still is a little sporadic which is another story.

So today was good in the sense that I got my car running and seemingly better than ever. However there are a few concerns I have. while leaning over the engine during idle and blipping the throttle I can hear an almost electircal short-type sound coming from either the #4 injector or the TPS. It only occurs initially when the rpms are raised from idle.

The second is a wah wah wah humming sound coming from one of the pulleys (not the pwer steering or a/c pulleys, I disconnected those to investigate). I havbe heard that is a sign of a bad water pump however I just replaced mine?

The last and of most concern is a strange metal on metal grinding coming from somewhere in the engine. That never sounds promising. It was more apparent when I first started up the engine after piecing it back together. I thought it may have been oil starvation for a few RPMS because it apparently went away after a while. I can hear it, again while leaning over the engine and hitting the throttle, only up to about 2k rpms then releasing the throttle, letting it return to idle and just before the rpms reach idle speed I can hear the sound. It sounds to me like ball bearings rotating without any grease. -What could have happened originally that caused the timing and balance belt to become so loose. It seems like it is related to the se new problems, specifically the greasless bearing sound.

Lastly I wanted to add that I am very thankful for all of the help i recieved from you DSM guys and girls. I am new to the DSM world coming from 4 subarus and a regular NASIOC fixture. I can honestly say that there is ALOT more information compiled about the DSM's than any subaru forum. I would not have been able to do half the things I have done to my GSX wothout this site and other contributing site. i.e VFAQ. Thanks for everything!

 

[1gnasty]

happy help a other dsm owner
like i said before look at the oil and check
for metal in jost to be shure

 

[girlieracr4g63]

Jeez where in the world is it idleing? Try turning it down ,and see if you can get a more clear sound of where the knocking is coming from.


Wendy

 

[Ski Bum]

happy help a other dsm owner
like i said before look at the oil and check
for metal in jost to be shure

I just changed the oil a week ago with mobil one, arrgh, that stuff is not cheap!

I guess though that $30 is worth some protection against something alot worse.

Jeez where in the world is it idleing? Try turning it down ,and see if you can get a more clear sound of where the knocking is coming from.


Wendy

The idle, when stabilized and not doing the surge thing sits at 750-800 rpms. The original knocking I had is gone now there are just the 3 new issues. The greasless bearing sound also resembles something rattling like a heatshield or loose nut but I cant seem to find it.

 

[girlieracr4g63]

I just changed the oil a week ago with mobil one, arrgh, that stuff is not cheap!

I guess though that $30 is worth some protection against something alot worse.




The idle, when stabilized and not doing the surge thing sits at 750-800 rpms. The original knocking I had is gone now there are just the 3 new issues. The greasless bearing sound also resembles something rattling like a heatshield or loose nut but I cant seem to find it.

Does it make that sound all the time? Does it make a difference when you press in the clutch? Could be the release bearing (throw out bearing). Some make a terrible chatter.


Wendy

 

[1gnasty]

I just changed the oil a week ago with mobil one, arrgh, that stuff is not cheap!

I guess though that $30 is worth some protection against something alot worse.

that is not bad at all i use amsoil and i change my oil every 1500 miles or so
i know it sound crazy

 

[PSI NRG]

Ive had this same kind of knocking problem before... i thought it either had to be timing or a rod bearing... checked timing it was ok but when i checked the oil i saw little flakes so i figured it was the bearings, when we pulled the motor out we pulled the pan off and inspected and of course #3 cyclinder the bearing was worn to nothing. Good luck!