hey guys thanks in advance for any suggestions. i have an 87 camaro with 305 4bbl. i had a leaking intake gasket and when accelerating and when it shifts to bottom end of gears it sounded like a diesel engine. would go away at higher rpms. i thought that the vacum loss from the intake leak was causing it to either not let the vacum advance and all work properly(early dtonation) or deposit build up causing the same thing. doesnt do it till it is warmed up a little. sooo got the intake fixed at the shop and when i picked it up it still made the same "diesel" sound. went back to the shop made him ride with me and he said he didnt really hear it but may be the harmonic balancer. does that sound logical? also he said water pump is starting to weep. could that make a bad rattling that sound like its a diesel engine? again thnx for any suggestions.

 

the water pump can cause a noise like that. if its starting to weep, i would say replace it and see if the noise goes away. if not, were here to help. it isnt hard to replace either, nor is it expensive.

 

im tryin to figure out how a balancer could make that noise. lol. doesnt make much sense to me either. if not the pump like the kid is sayin it could be a shield. like exhaust manifold shield or catalytic converter shield.

 

doesnt sound like a sheild it truely sounds like a diesel. i think im gonna do the water pump begging of the week

 

Your mechanic must not have an old school ear. I wouldn't be surprised if what you are hearing is octane knock (sounds like marbles in the cylinders). It can happen when the engine is under a load if the timing is too far advanced, or if the pistons and heads have a lot of carbon buildup, or if you're using cheap gas. However, your engine has/had a knock sensor which would tell the computer to retard the timing till knock goes away....before your ears can pick up the sound. A few things come to mind: knock sensor or related circuit's not working, your computer controlled distributor has been replaced with a stand-alone type, you still have the computer distributor but the harness from the computer isn't plugged in.

 

what is the easiest way to try and clean the carbon off? cause the intake was leaking and making it run real lean and there was oil leaking in. so it might very well have carbon build up.

 

Seafoam the engine. Doing this can only help if your engine has any deposits. But like I said earlier, if you are hearing octane knock, check your other things first. If your engine's knock sensor/distributor is still hooked up like factory, you should not be hearing a knock/pinging.
http://www.youtube.com/watch?v=4b6kI1RCOtE

 

i completely agree with 69, as it could be spart knock. but if the mechanic said the water pump was seeping, it needs replaced. when i bought my car, the water pump was shot. the bearings in it were roaring. i also work at a toyota dealership right now, which are plauged with faulty waterpumps. some of the 4 cylinder cars that come in, when the pump starts wobbling and the pulley and impellar start hitting stuff, its sounds really bad. i have also seen and heard failed balancers, and they did not make a dieseling noise. just very bad vibrations. here is a video of my car, you can easily here the water pump
http://www.myspace.com/video/casey42...art-up/2957699

 

little update. had the water pump changed.... also found and replaced a broken transmission mount. sound is alot quieter but i still hear it. gonna try cleaning for deposits tommorow morning.

 

ok sry its been so long. but the car has been in and out of the garage. the water pump that was changed went out and had to be redone. while standing there with the mechanic i notice the recently changed intake gasket leaking. so he had to redo both of those. in the process he cracked the intake so had to he replaced intake with eldelbrock intake. picked it up yesterday and the idle was a little high about 1500. so now my issue is that the idle is so high. and it wants to stutter or loose power while driving. more so when you try to get into it a little. when i went to get smokes this morning i was able to get it to choke right and idle down but by the time i got to the station it was idling at 1500 again and dieseled on me. its a qjet carb. is there anything he should have changed or adjusted after switching to the new intake? but the rattle sound is gone lol. any ideas?