loud noise in 350?

Question

have a 350 with loud noise its a used motor when i put it in it has 40 pound of oil pressure the noise come on untill you put it in drive thats the only time you can hear it. it has to be in drive and pushing the gas alittle to hear it pistons 3,5 have 40 pounds of presure and the rest have 150 it will run fine untill its in drive I am 18 and stumped along with every one else

Answer 1

Cylinder 3 & 5 have the same low compression. Notice they are side by side, could be a cracked head or head gasket. You can bet its above the block so I would suspect the head! Something is allowing the compression to bleed through one cylinder to another. IT IS NOT STUCK RINGS!

musiclick... again you are off track! Why do you run around here advertising that you are some big mechanic and you offer mostly bad advise! you say you have a shop and have for 40 years, you need to be working and stay off Yahoo Answers!

Answer 2

I own a shop, and there is a few things to do. First lets assume the engine had set for a long time. With this is view; the number 3 and 5 cylinders may have stuck rings. Remove the spark plugs on these cylinders, and put about 1/4-1/2 can of WD-40 in each cylinder, and let it sit like over night. Start the engine the next day with these plugs out so it can blow the excess out. Now check the compression on them. It should now be up to the 120-130 area, if it is stuck rings. One with stuck rings will sound like it is blown up. If the compression is back up, then reinstall the plugs and run it for a while, then change the oil & filter. This should fix it. If it does not have compression on them any better than 40 lbs each, then you may have to do this again. If it does not straighten out, then you may have a blown head gasket between the two cylinders. Bad valves would make it pop out of the carb or the exhaust like pretty loud. I have seen this before on engines that have not been ran in a year or two. The WD-40 works real well, but you got to get plenty in there, and give it time to work. A stuck ring will do this, but the compression being down on two cylinders beside each other also screams blown head gasket between the two cylinders. You have to rule out it being the rings though, and besides a can of WD-40 doesn't cost that much. Get a big can though.
Glad to help out, Good Luck!!!

Answer 3

You have major motor damage!! You have already diagnosed it yourself. The thing with compression tests is all of the holes need to have similar compression, within about 10 psi of each other, to be assured the motor is sound. You do not as stated you have 40 psi is cylinders 3 & 5. I suspect from the sounds of it that you have a piston problem. With a piston problem you will most likely have further damage to the walls and most likely the crankshaft rod journals. My advice is to get another rebuilt 350 or rebuild this one. These can be readily repaired, but it will be expensive. My question is it worth it? Good luck.

Answer 4

must be your rods and/or crank are failing ... that should make the rods rattle (does it sound like that) and you does no longer get finished compression on those cylinders. could be a valve difficulty too yet that's often a exceedingly different noise the two way it seems such as you're looking a a teardown. Drain the oil and look for signs and indications of metallic first a stable indicator. one million) in case you think of its the bearings, pull the pan off the backside and look at the crankshaft for signs and indications of harm (if the rods are beating up on the crank which would be ordinary to % out.) 2) for the valves initiate with pulling the pinnacle and notice whats there. IF the valves have not punched into the pistons you're able to wreck out with basically new or resurfaced heads and new valves. the two way, seems such as you're in for some paintings. you desire to to head with a rebuilt motor and sidestep the difficulty fullyyt... stable luck... .

Answer 5

your symptoms almost sound like a cracked piston,
you say loud noise so I'm going to say It's probably not a wrist pin.
Chevrolet engines are good for spinning a rod bearing and still holding some oil pressure, either way if it is indeed (loud) the engine will have to come out and be looked at

Answer 6

Pull the valve covers to inspect rocker arm action while its running.Loud clacking along with severe oil squirting leads me to think that stuck valves and overpumping of the lifters is creating this hell.Check the pcv valve to make sure it is working. this second avenue of intake mixture is important. First run the carb dry of gas then carefully fill with 2-stroke mixture.Secondly add Berryman's chem to the crankcase(1 pint). Run engine for 2 minutes then pull pcv loose to allow engine to stop gaging on fumes and return to idle. Idle for 30 minutes.Repace oil with 15-40W And run til hot then change again with 15-40W.

Answer 7

rebuild it... bad valves and rings....im not stumped. low cylinder pressure..ask anyone who knows anything....i an 55 and have a compression gauge.... working on cars 40 years. and oil pressure only means the oil pump is pushing oil. It doesn't mean you have good rings and valves.

Answer 8

sounds like trans or eng or trans mount problem if it only does it in gear. check your eng mounts and trans mount. also make surethe torque convertor bolts are tight and the flexplate is tight and not cracked

Answer 9

it may not be an engine problem at all check to see if your torque converter and flywheel are tight since it only does it in gear

Answer 10

from what i get out of what you said it is rebuild it time