PontiacBonnevilleClub.com

it was fine a few days ago. went to get a pizza and now it does this. runs fine otherwise, no laboring or trouble turning over, idles fine, can't use overdrive though...it has oil and oil pressure, no metal filings in the oil that is on the dipstick, actually looks pretty clean. it is also squeaking! What gets me is it was perfectly fine and silent before. it only sat a few days. how does this problem just *happen?* I had been running SAE 30 oil since i got the car, only recently switching to 10w30 after the LIM repair. please tell me the oil i am using now didn't cause this...i knew i should have stuck with SAE 30. it never failed me on my other vehicles.

https://www.youtube.com/watch?v=99hESuh ... e=youtu.be

That could be the harmonic balancer.

i have had a Buick in the past with a harmonic balancer knock (the LN3 was notorious for it) but doesn't that go away with revving the engine up? isn't there free play where you can rotate the accessory belt to notice? this one seems to get worse (you can hear it when revving it in the end of the video) with RPMs. during driving it is horrid on takeoff from a stop, but sorta quietens after 30MPH.

Unless harmonic balancers fail differently on the L27s (i really hope it's the balancer) it sounds like rod knock. but i would expect the engine to have self-destructed by now since i've driven it ten miles. can an engine suddenly develop rod knock like this? it ran fine four days ago (well, five now) and it started this all of a sudden last night. i've been babying it seriously because i need the car still, although i am buying a truck later this July, for work/bad weather mainly. it might be a daily driver until i narrow down what exactly happened to my bonneville.

Any metal/sparkles showing up in the oil? I haven't ever heard a failed balancer in person, but the slight squeaking it's making when you rev it kind of sounds more like a bearing to me.

Also, (can't remember if it was you or not) but didn't you have your intake gaskets fail and hydrolock the motor a while back? If so that definitely could be the cause.

What was the oil pressure on cold start with the sae30 oil?

If you pull the drivebelt and the issue remains, it is in the motor. Also, the sound does sound like a bearing. I wonder what the chances are of it being a balance shaft bearing.

I don't see how running the right oil would cause a spun bearing. Being able to get proper oiling when cold will help it circulate better. One of two things caused the issue, most likely.

1) Water got in the oil and did damage before you did the lim fix. It's pretty common to happen to L36s..

2) Years of running oil that was too thick when cold did damage.

See if there's any belt play, and if the sound changes when you take it off. If that's not it, drain the oil and look for the shiny stuff.

It sounds too tinny to be rod knock to me.

well whatever is it sounds horrible it only got worse today when I went to the park. no belt Play I checked it twice. I Will try to Get a recording while driving if it helps.

The hydrolock was the first sign i had of the LIM problem. that was a long time ago. it was fixed a month or so later, and has been great since. until this started. i am not kidding, i drove a long distance a few days ago, then on my way back (as i was getting home) the heater core started to spray coolant out the floor vents so i parked it until i could make a bypass hose to bypass it until later. it seems the instant i started the engine up after i bypassed it this started. i am not sure how bypassing the heater core would cause this, or how a heater core blowing up could cause anything to mix with the oil. when i had done the LIMs, i got the oil changed to 10w30 and so on from there. i am not sure however if the change of oil caused this. it seems too sudden for it to be, i have seen what happens to engines without oil or with insufficient oil pressure and they don't go from running fine to instantly knocking themselves to pieces. they gradually get worse, louder and louder and BLAM! this problem is just inconsistent. one time it is quiet, the next thrashing to pieces sounding, the next knocking but no squeak, and so on. i have not yet tried removing the belt but i doubt that it's outside the engine. the sound seems to be internal but not exactly sure where. i do know that i cannot remove the engine or do any heavy work at home as they do not allow mechanic work (i had to take extra care to not make a mess doing the LIM) and i lack the proper tools for an engine rebuild. if this is an imminent engine failure i am afraid i'll have to junk the car. i have neither the time nor the skill, nor the tools, nor a proper garage to do a rebuild.

Here's another video, with my driving it. i'm afraid to go past 35 or accelerate too fast as it really gets horrible sounding if i do.
https://www.youtube.com/watch?v=V835If- ... e=youtu.be


to answer other questions posted, i have been running SAE 30 in every car i owned. it has never failed me before. often i buy used cars and they have noisy engines and that oil helps. pressure with SAE 30 on a cold winter start is about as normal as any other oil goes to probably 70 psi or more. usually holds around 40 when warmed up.

Same for the 10w30 i'm using now. other than the change of oil, and the bypass hose i have no idea what caused this. it was fine, parked, started the next time doing this instantly. no warning. went from normal, parked, then this. if the oil indeed caused this my next vehicle will only get SAE 30. as i stated that oil has served me well for years.

Video was taken on the drive back from the park. some 10 or so miles. it seemed better but as i said this sound gets loud, then quiet, then loud. it varies. if it were rod knock wouldn't it just make loud knocking and self-destruct by now? for kicks i did put it in neutral and check the trans fluid, it was fine, no burnt smell or odd color. i'm at a loss.

Sound seems to come from the passenger side of the engine too. right around where the transmission connects. on takeoff the sound is horrific, and quietens after the 2-3 shift. it will get very very loud after you get to 40-45mph. you cannot use overdrive as it will lose power and make a very loud SQUEEEEEEAAL! until you shift to D3. but even in D3 it pulses and seems to have trouble running around 45-50. until i know what the cause is i have been driving it very short distances and not exceeding 35mph.

i want to believe it's in the transmission somewhere or in the torque converter but when i accelerate in park or in gear it sounds like it's coming from inside the engine. can a dropped rocker cause this?

Unless a blockage or some other smoking gun is found, there will be no way to actually know what happened. Sometimes a bearing just won't hold out forever. Unfortunately, all anyone can do is speculate really.

As far as oil grade, you really really really should run the called for oil, unless you find it actually needing it on a case by case basis. That's what Dad has always taught us, and he's never had a spun bearing in anything but an old tractor. Hundreds of thousands of miles in series one 3800s on proper grade engine oil.

I really wish I could figure out what this is. is it a spun bearing? what I don't understand is the sudden nature of it. how does a known reliable engine go from running Great to this in an instant without warning ?

seems to me that running the 'called for oil' ended up destroying this engine. with such high miles i knew i should have stuck with 30 weight.

Like I said, we can only speculate, especially over the internet.

well my next car will only get SAE 30 since it has never let me down, plus I stick with what has worked. I will never use 10w30 ever again. i really liked this car and that was all that changed. and now it is dying. too many miles it really needed 30W.

now all i can hope for is it actually making it the 30 miles to the junkyard on its own power. i cannot afford the towing rates. should have stuck with the oil i had been using. learned my lesson.

about all i can do is drop the pan and shake each rod until i find which one's loose. the fact it still starts, runs, idles within spec and has oil pressure tells me i might get by with a new bearing. would not surprise me if it were the same cylinder that hydrolocked.

At least diagnose it first.

And run the right oil in any engine until there is a need for something else. Do yourself a favor.

nickdalzell1 wrote:well my next car will only get SAE 30 since it has never let me down, plus I stick with what has worked. I will never use 10w30 ever again. i really liked this car and that was all that changed. and now it is dying. too many miles it really needed 30W.

now all i can hope for is it actually making it the 30 miles to the junkyard on its own power. i cannot afford the towing rates. should have stuck with the oil i had been using. learned my lesson.

about all i can do is drop the pan and shake each rod until i find which one's loose. the fact it still starts, runs, idles within spec and has oil pressure tells me i might get by with a new bearing. would not surprise me if it were the same cylinder that hydrolocked.

You will get a few weeks on a new bearing at most if you don't machine the crank. Journals have to be flat to maintain an oil film. A spun bearing grooves the surface, which allows all the oil to escape to the grooves, and the high spots will impact the bearing. The squeal is most likely a main bearing and the knock is the adjacent rod bearings.

Look at the oil close, you aren't looking for shavings, you are looking for a shimmering under a bright light at just the right angle. Use a magnifying glass, it's like a super fine powder that glitters.

Bearing failure is always 'sudden' with no warning on the crank. 10w30 did not kill your engine. If journal bearings were that sensitive to oil composition engines would rarely last past an oil change..

It could have just been it's time too. Not all 3800's last forever. Even yours putting in 20+ years and 275k+ miles before cutting loose (assuming it is terminal) has put up a very good fight.

Really hard to tell from the sound heard in the videos. I agree that it sounds way to "ding ding" metallic to be a rod bearing alone. I had one go on a BBC decades ago, and still remember just why it is called a "rod *knock*" And, it does not sound harsh enough for the piston to be hitting the cylinder head due to a bottom rod bearing or wrist pin end failure.
Of course, the bearing may have been damaged due to the hydro-lock, so failure there is definitely a possibility.

Please.... try what has been suggested here first: Pop off the belt. It is easy, just put a wrench or socket/ratchet on the tensioner and rotate it until there is enough slack to slip the belt off.

Things which could also be the source of such a noise: Partial failure of a timing chain. Fracture in the flywheel/flex plate, or a loose/sheared torque converter bolt.

What part of the country do you live in? I just bought a '93 SSE with a rotted subframe. 125K miles. Engine ran great when I first looked at it early in the year, have not started it since, as it has a broken trans line due to the drive-train falling out. I will be listing the car for parts in a month or two, many projects come first. Having some problems with my motor too, but is not mechanical....

i live in Kentucky. (owensboro)

going by videos of 3800s online with failed or spun bearings they sound exactly like mine. the squeaky squeak and horrid thrashing on higher rpm and all.

when i mentioned swapping the bearings i was intending to make it the 30 miles to the junkyard and drop it off, sell it and get another car. i cannot drive it that far as is. i do not have the time, money, knowhow or the proper tools to swap engines much less rebuild this one. sadly the car is toast.

ok, an update.

i tried changing the oil (again) and filter. no dice. removed the belt. the squeak is gone but it is still thrashing. tried removing the valve covers hoping to find a dropped lifter, stuck valve, or bent/broken pushrod. nope. definitely bottom end.

i have a dilemma. i do not think i can save this engine. i need to somehow get the car 30 miles at highway speeds, to the car lot so i can replace it. sadly it is so bad i am afraid to go beyond 35. and even then it sounds like it could throw a rod any second. runs fine though!

i am hoping a set of bearings buys me enough give to get it over the bridge to trade.