Olds 307 Knock

[YaoGuaiCutlass]

Hey all, I have a 307 Oldsmobile engine in my '86 Cutlass Supreme. Today I went and started it up and it ran fine up until I put gas in it. It started to run sluggish about 1 or 2 miles away from the gas station. It sounded different too. I stopped at my buddy's house and let it cool down so I could put oil in it (thinking it may be low on oil). I put a quart in and drove maybe 3 or 4 blocks away to the next gas station and put 2 more quarts in. I drove it home very careful thinking it may break down and leave me without a vehicle. When I got home I popped the hood (while it was running) and heard a tapping/knocking from under the drivers side valve cover. I pulled the valve cover and started it up and thought I noticed a rocker going faster than the others. It was also spitting out more oil than I believe it should. Needless to say I put the valve cover back on and started it back up and heard the knock again. I revved the motor and the knock subsided for awhile and started back up when I revved it again. I know the 307 isn't the best motor but for right now I need this motor to run so I can get to school and work with no problems. From what others have said and other forums I have read or said it sounds like it can be anything. Bad gas, carbon, loose rocker, lifter, timing gear plastic, piston ring and other stuff. It hasn't really been running to hot but it's been hot here soon maybe that's a factor?

Please let me know what you all think of this. I really need this car to stay running for a few more months before I transplant a new motor in it.

By the Way....I can provide video if needed....

Thanks!

 

[techg8]

pull a plug wire on the cylinders near the knock, one at a time and see if it kills the knock. That would point to rod knocks, bearings and or wrist pin type problems as the cause. If pulling a plug wire doesnt change anyting then it might be valvetrain related.

 

[YaoGuaiCutlass]

pull a plug wire on the cylinders near the knock, one at a time and see if it kills the knock. That would point to rod knocks, bearings and or wrist pin type problems as the cause. If pulling a plug wire doesnt change anyting then it might be valvetrain related.

When I started it up this morning there was no knock, but when I revved up there is a very slight knock. Sounds like tapping on the Valve cover but I don't feel it when I place my hand on it (both covers). Last night and this morning when I started it up there was a lot of gray smoke coming out the exhaust and it smelled real bad. Also, I have never had smoke like this come out the exhaust. I did put gas from a different gas station in and it wasn't running sluggish anymore. Any thoughts on this?

By the way...I pulled the plugs 1 at a time there was no change in the knock.

 

[seawolf18]

If the knock doesn't go away then you may have a broken rocker arm, or you broke a valve spring and the valve fell into the cylinder. IF you dropped a valve, the engine would be done, and most likely unrebuildable. White or grayish smoke could also be coolant being burned. Burning oil is usually a blue color out the back, and raw fuel is black. If your exhaust has a maple syrup smell, your burning coolant. Pull the valve covers, and see if there is anything that is broken. You may also want to do a compression test on the engine. IF you have two adjacent cylinders with low compression, its an indication of a head gasket problem.

 

[YaoGuaiCutlass]

Okay guys, I found out what the knock is....It's my torque converter....It's all bolted in to the flywheel but I believe I left it in 1st gear too long.... Can I change a torque converter while the trans is in the car? Is it easy?

 

[67rstbkt]

Okay guys, I found out what the knock is....It's my torque converter....It's all bolted in to the flywheel but I believe I left it in 1st gear too long.... Can I change a torque converter while the trans is in the car? Is it easy?

IF it is your torque converter, then the transmission must be removed to get it out - or at least moved out of the way enough to provide the required space, but that would be far enough that it would basically be out anyways.

 

[jae]

May I ask how did you determine it was the torque converter? Also, with the oil you've added how many quarts of oil do you have in the engine now? Was the engine low on oil?

Changing the converter is no bad but the trans has to come out. Be prepared for fluid to leak once you remove the driveshaft so drain the fluid first but you still will have some fluid leakage. Also this gives you a chance to inspect the fluid for shavings, debris.

Basically once out, the converter is removed from the input shaft and the new one is put on. Before putting the new one on, put about a quart of trans fluid in it, put a new seal onto the input shaft, coat the input shaft and the mounting surfaces of the converter. Next install the converter, and during install rotate the converter while pushing it on to seat it. You will kind of hear / feel it click move towards the trans as it seats. Once fully installed the outer surface of the converter will be inside of the trans bellhousing mounting surface somewhat (depends on where you measure) but it must be fully seated or you can ruin the front pump during reinstall to the car. Replace the rear seal of the trans before reinstalling it in the car.

I know these are really basic instructions but gives you the jist of it. This can also give you a chance to check the flexplate for cracks or if the bolt holes elongated.

 

[YaoGuaiCutlass]

May I ask how did you determine it was the torque converter? Also, with the oil you've added how many quarts of oil do you have in the engine now? Was the engine low on oil?

Right now I have no clue. It sounds like the torque converter, then it sounds like the rockers or lifters. I am at my wits end and nerves are shot. Last I remember was the night I got pulled over for "Drag Racing" another Cutlass (which was proven false) I left it in 1st a little longer than usual. When I was pulled over the car ran decent, once I left it ran decent, next morning it ran okay until I got to the gas station a few blocks away. I put gas in and drove about a mile and it started running sluggish and started chugging along. It sound like it needed oil so I put a quart in and went to another gas station and bought 2 more quarts and got home and let the car sit. I checked the oil and it was normal, transmission fluid was normal. It sounded like a lifter but when I pulled the valve covers everything was normal. I pulled all the plugs one by one and nothing out of the ordinary. When i get on the ground and listen to the torque converter it sounds like it's moving around too much. Something odd I noticed is I can move my crankshaft around pretty easy which is not good I am guessing....

 

[Fox80]

The fact that you can turn the crank easy is not a bad thing, a worn motor will spin free. If you have the inspection cover off the transmission are any of the converter bolts loose on the ring gear? That is the only thing I have seen make noise with a converter, I suppose a rotor vein could have broke free but I've never seen that happen, more than likely when you "left it in first gear to long" you probably hurt something in the valve train. Like the above posts said by pulling the plug wires you kind of eliminated a bottom end problem (kind of) so I would still give the valve train a very good look over, do a compression check because my guess is you bent a valve by over reving it, this will show by near zero compression in one cylinder. Olds motors have very low spring pressure as the whole motor in general can't survive high rpms so they " valve float " very easily

 

[jetsetw31]

All these suggestions are solid. But here goes a simple trick to determine WHERE your trouble is. Your gonna try the poor mans Stethoscope. Find a long screwdriver, or you can use the tire iron. (lug nut tool in the trunk.)
Put the handle lightly to your ear while the engine is running and place the end on the top of each valve cover, over the 8 cylinders positions. You will hear ticking on all the spots, the loudest ticking or tap, will be your problem cylinder. That will be where you start from.
My two cents:
1. Since the engine is running and you say when you cold start it, you don't hear the noise that much til it warms up. I'm guessing valve train trouble also.
2. From your description, I also think you may have put too much oil in the engine. So check your oil level.
3. About the smoke out the tail pipe. Is your Radiator low or empty? Then that might mean you blew a head gasket.
The good news is that It is running. Seemingly meaning no major damage, depending on what your investigation uncovers.
Good luck. I hope it's a small issue.