Syclone#892
Member
Hi all figured I would let you all know something I found interesting. I will give a little background info first.
Cliff notes at bottom
So I bought my sogt not running but with a used 60k sogt short block in it(hotrod v6 old engine) so after getting it to my shop I check fuel pressure which was at 20. Old owner put in a brand new tbi fuel pump not a cpi. I put in a new pump and it tries to start so I start playing with the dist and it was only off by about 60-70 degrees. Truck runs and doesnt sound to bad. I started to drive it and was noticing a rattling noise. Had a good mechanic friend take it for a spin and his guess was exhaust leak or bracket bouncing around somewhere. Well the exhaust was junk, replaced entire thing from manifolds back, new y-pipe, new magna flow converter, new gibson stainless exhaust. Noise is still there. So I find the fuel lines with no brackets to hold them in place so I get those tied down so they won't be moving and the noise is still there. My thought now was either engine or trans maybe converter?
Well I did some checking on tsb's for this truck and it seems gm had a problem with the first run of balance shaft engines. They used a needle bearing for the rear of the balance shaft and this bearing would cause a rattle type of noise. So I think I figured out the problem. Well gm's fix for this was to remake this whole setup and use a bushing similar to a cam bushing on the rear. While doing this they also decided to change the oiling passage for this bushing. So basically back in 92-93 gm was putting goodwrench engines in these to get rid of these needle bearing engines which means I have to either rebuild the old stock engine or find a way to remove balance shaft. You can't just take it out because you will have a major internal oil leak. Someone on the board mentioned to just replace the cam and timing chain with a nonbalance shaft engine. I looked at the old engine and thats not possible because there is a gear behind the timing chain gear that runs the balance shaft so if you used the nonbalance cam the gear would be in to far and you wouldnt be able to put the chain on.
Well after thinking this over for a while I thought why can't I just remove the gear off the balance shaft, its an inverted torx bolt and the gear comes right off.
Well I finally got around to doing that this weekend and my noise is gone and this thing runs great now night and day difference. I think this loud rattle was making the knock sensor go crazy but I forgot to check that before doing this.
I am writing this since this is not something most people have ever heard of so I know its not common at all anymore and hopefully this will help some people out.
I can not guarantee this will not screw up the engine in anyway but I do not see how it could plus I have over 200 miles on it so far.
Do see which engine you have look at the pass front of the block by the ac compressor and right in front of the head, there is a flat spot with stamped numbers and letters. The needle bearing engine has XFK in it the bushing engine has XJF in it.
I hope this helps out some fellow So gt owners and if anyone would like I should be able to email that tsb if you would like to take a look at it.
Oh also forgot what sucks is the engine the previous owner of my truck took out has the bushing there was probably nothing wrong with the old engine
Cliff Notes
Balance shaft engines may make a rattle noise caused by a defective bearing for the balance shaft. Only way to truly fix is replaced engine with different style or take gear off balance shaft, thus eliminating balance shaft. There is a tsb for this I should be able to email if anyone is interested. Block code(pass front of block) for bearing block has XFK in it and bushing engine block code has XJF in it.
Anyone with questions or what not please ask away and I shall answer to the best of my ability
Cliff notes at bottom
So I bought my sogt not running but with a used 60k sogt short block in it(hotrod v6 old engine) so after getting it to my shop I check fuel pressure which was at 20. Old owner put in a brand new tbi fuel pump not a cpi. I put in a new pump and it tries to start so I start playing with the dist and it was only off by about 60-70 degrees. Truck runs and doesnt sound to bad. I started to drive it and was noticing a rattling noise. Had a good mechanic friend take it for a spin and his guess was exhaust leak or bracket bouncing around somewhere. Well the exhaust was junk, replaced entire thing from manifolds back, new y-pipe, new magna flow converter, new gibson stainless exhaust. Noise is still there. So I find the fuel lines with no brackets to hold them in place so I get those tied down so they won't be moving and the noise is still there. My thought now was either engine or trans maybe converter?
Well I did some checking on tsb's for this truck and it seems gm had a problem with the first run of balance shaft engines. They used a needle bearing for the rear of the balance shaft and this bearing would cause a rattle type of noise. So I think I figured out the problem. Well gm's fix for this was to remake this whole setup and use a bushing similar to a cam bushing on the rear. While doing this they also decided to change the oiling passage for this bushing. So basically back in 92-93 gm was putting goodwrench engines in these to get rid of these needle bearing engines which means I have to either rebuild the old stock engine or find a way to remove balance shaft. You can't just take it out because you will have a major internal oil leak. Someone on the board mentioned to just replace the cam and timing chain with a nonbalance shaft engine. I looked at the old engine and thats not possible because there is a gear behind the timing chain gear that runs the balance shaft so if you used the nonbalance cam the gear would be in to far and you wouldnt be able to put the chain on.
Well after thinking this over for a while I thought why can't I just remove the gear off the balance shaft, its an inverted torx bolt and the gear comes right off.
Well I finally got around to doing that this weekend and my noise is gone and this thing runs great now night and day difference. I think this loud rattle was making the knock sensor go crazy but I forgot to check that before doing this.
I am writing this since this is not something most people have ever heard of so I know its not common at all anymore and hopefully this will help some people out.
I can not guarantee this will not screw up the engine in anyway but I do not see how it could plus I have over 200 miles on it so far.
Do see which engine you have look at the pass front of the block by the ac compressor and right in front of the head, there is a flat spot with stamped numbers and letters. The needle bearing engine has XFK in it the bushing engine has XJF in it.
I hope this helps out some fellow So gt owners and if anyone would like I should be able to email that tsb if you would like to take a look at it.
Oh also forgot what sucks is the engine the previous owner of my truck took out has the bushing there was probably nothing wrong with the old engine
Cliff Notes
Balance shaft engines may make a rattle noise caused by a defective bearing for the balance shaft. Only way to truly fix is replaced engine with different style or take gear off balance shaft, thus eliminating balance shaft. There is a tsb for this I should be able to email if anyone is interested. Block code(pass front of block) for bearing block has XFK in it and bushing engine block code has XJF in it.
Anyone with questions or what not please ask away and I shall answer to the best of my ability
