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Username Post: Engine rattle        (Topic#333742)
4dr 57 
Valued Contributor
Posts: 4668

Loc: Texas Hill Country
Reg: 11-10-04
03-08-16 04:27 AM - Post#2613872    


Unless I pull the fuel pump fuse before starting this 97 LT1 engine and spin it for 3-5 seconds, it will rattle/knock on a cold start.

Some other odd info-#2&4 cylinders have a higher (180 psi) compression while all the other cylinders are around 170.
It seems I hear a dull knock even after it's warmed up. It does Not use any oil or water.

Can I infer it may be the rods? Would a cracked piston act the same way? Thanks



It's all good. mostly




 
Shepherd 
Frequent Contributor
Posts: 2080

Loc: Lake George, NY
Reg: 11-11-15
03-08-16 12:46 PM - Post#2613995    
    In response to 4dr 57

Good oil pressure, using the recommended oil? Is it louder warmed up? The compression variation is not an issue.



 
4dr 57 
Valued Contributor
Posts: 4668

Loc: Texas Hill Country
Reg: 11-10-04
03-08-16 04:17 PM - Post#2614041    
    In response to Shepherd


Yes, good oil pressure (recently added a 1/16" washer behind the spring for a tad more at idle.)
Yes, using the recommended 10w30 oil. No, it's very much quieter when running, muted even.
I've run the valves and they are set at 1 turn down.Made no difference.

I recently read about air being trapped at the front of sbc engines but that GM had started drilling a small hole in the plug at the end of the engine oil galley, but I don't know if that would even pertain to these engines.
The lifters may have a built in design to prevent it by 97. Thanks.

It's all good. mostly




 
Shepherd 
Frequent Contributor
Posts: 2080

Loc: Lake George, NY
Reg: 11-11-15
03-08-16 05:39 PM - Post#2614063    
    In response to 4dr 57

Based on your info, strong chance this could be "piston slap". Very tough too confirm without a tear down.



 
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