94 cutlass supreme 3.4 with engine knock

[94cutty3400]

got a cutty super cheap. 3.4 "X" motor. no knock at idle. knocks like crazy when revved up, parked or driving. anyone have any ideas as to what this is before i get upset and sell it off. i am capable or repairing but not wanting to nickel and dime it till the problem is solved. thanks.

[3100 MPFI]

My 1995 Cutlass Supreme did the same thing.

It was the engine itself. and needs to be replaced.

Try to find out if it is an engine KNOCK, or a TICK. If it is a tick, you can fix it, but if it is a KNOCK, then it needs to be rebuilt.

Here is a vid of the twin cam knocking in my 1995. If yours sounds similar to this, you need a new engine, or your engine needs to be rebuilt.

Mine originally did not knock at idle, but I had to drive the car 10 miles to get it home, and they wanted $200 to tow it. Since I knew the engine was bad anyways, I went ahead and drove it.

http://s174.photobucket.com/albums/w86/riven2129/?action=view&current=tdcknockin.flv

[phantomgreen]

That sounds real sexy

[94cutty3400]

mine does not sound like that. we tore into it this weekend and replaced rod bearings. found some were wore and some were not. replaced them with standard size and oversize bearings. did not help.

i hate to break the news to everyone who reads this, but me and 99% of my buddies are FORD men. i am just saying this because we are usually v8, rear wheel drive guys. we can turn a wrench with the best of them...but this sideways mounted, front wheel drive stuff is not coming too easy.

i do not have very much in this car at all and it is well worth fixing. it is for my 16 year old daughter. i have to fix this car to get her out of my truck.

oil pressure is fine. slight "lifter knock" at idle ( i know this car does not have what i call conventional lifters). really bad knock when revved even the slightest bit.

come on guys, i know you guys have to have some input on this. please help.

[3100 MPFI]

collapsed lifter? I am more of a pushrod guy myself.

If it is something with the lifters, it is not too hard to change them out. Just have to pull the cam carrier, and then retime the engine when you put it all back together. Maybe a couple of hours to do.

[93Oldsdroptop]

You said that you replaced the rod bearings, did you notice if any of the rods were bent?

[grandprixgtp_91]

Could you get a sound clip? my one gtp had a bad knocking noise that turned out to be the timing chain tensioner, the tensioner broke, the car still ran fine but knocked really bad. if you can get a nice clear sound clip it would really help us help you. also one more test you can do is unbolt the torque converter and push it back ,then fire it up and rev it to see if it goes away, this will eliminate the tranny , also same goes for the acessories, take off the serpentine belt and start it, this will rule out power steering pump or water pump or ac compressor or alternator.

Jake

[94cutty3400]

the guy i got the car from said he heard the knock and immediately parked it. it has been driving about 2 miles since then at 20mph max and no gunning the engine. we figured the rods would be fine since it was found and hardly ran after that...

yeah, i can get a sound clip. i will get it tonight (the car is in a buddy's garage).

it also has an oil leak on top of the engine. something about an o-ring that costs $1.50, located under the intake. someone said you had to pull the head off to get to it cause this thing has a shaft on it. it would be item no.6 on this diagram... http://60degreev6.com/gallery/showimage.php?i=428&c=10

[grandprixgtp_91]

well no.6 is the drive gear that the o-ring goes on, and yes to do the repair properly you have to pull the head. now that is alot of labour and money, so you can either lift it up until it hits the head, spray some good brake cleaner in there to get rid of the oil residue. load it up with rtv silicone ,spin it around and move it up and down to make sure it gets everywhere, push it down and dont tighten the bolt, leave it overnight , then in the morning tighten the bolt and that will take care of it, or you can slip an oring over the top and use rtv, or you can use jb weld, theres a few different ways that all work, but if you do it the right way and pull the head then go to the dealer and spend the $5 on the oring there, its a special brown oring, that is updated to last in there . most dealers stock that part. but if you pull the head then u have to retime the engine, and that can be tricky if you have never done it, and you should replace the belt and pulley while its off.

Jake

[94cutty3400]

sorry guys, sound clip will not come tonight. we are letting the oil drain to tear back into it again.

i will get it asap because i think it will really help someone who has heard it before diagnose what is wrong with this motor.

[grandprixgtp_91]

yeah, sorry to be picky, but please try to keep it away from regular , engine noise, because if you record it next to the engine running,it might be overpowered by the accessorys, and then its really hard to tell what the noise is.

Jake

[94cutty3400]

no problem. i am open to suggestions.

would a collapsed lifter cause motor to backfire?

are you not supposed to use different sized rod bearings?

[grandprixgtp_91]

well a collapsed lifter would definalty make the motor run like crap ,
and unless you have machined the crank you sould not use different size rod bearings. you actually shouldnt have changed them unless you had zero oil pressure or really low. if you put in different size rod bearings you will probably sieze the rods to the crank, and if you did spin a bearing, just replacing them will not fix the problem, you must have the crank machined, or you will spin the new set in less that 30 seconds.

Jake

[94cutty3400]

ok, another question. what if i find a 3.1? will it bolt right up? will it be a 3.4 motor pull and a 3.1 motor install? computer work with 3.1? motor mounts?

ok, maybe that was more than "another question"?...

[grandprixgtp_91]

well in theory everything will bolt up , but electrically everything is different, it will still be less work to just fix your 3.4 DOHC.

Jake