Lesabre 2001 knocking

[Gilmour]

Hello,

My 2001 lesabre (~110K miles) developed a knocking sound yesterday, i just noticed when I arrived home back from work that there is this annoying sound that wasn't there before. the knocks increase with the RPM increase, not fully sure if it is a knock or a detonation.

here is what has been done so far:

• with cold start, i almost don'r hear it at idle.
• when the car warms up, it can be heard loud and clear
• I removed the acc. belt, the knocking still there (to eliminate alt/PS/WP)
• no play in the main engine poly
• I noticed (with a scan tool) when the engine warms up, the #1 timing adv. is ~21% and when revving the engine (while parked) it goes up to 26 or 27% - is this normal?
• I tried to use a garden hose, but no help of identifying the source of the noise, w/o the hose it just seem from the engine upper side/block
• the coolant & oil levels are in good condition, no milky oil.

here is what recently was done (few weeks back):

• new fuel filter.
• new strut mounts.
• re-did the LIM with the aluminum framed gasket (due to oil leak under the rubber end of the previously changed one).
• new fuel pressure regulator.

Could it be the knock sensor causing this? , is it a rod ?

Any help/direction is appreciated.

Thanks!

[Tech II]

Ah, and now we know the rest of the story......

"re-did the LIM with the aluminum framed gasket (due to oil leak under the rubber end of the previously changed one). "

Just kidding......there was no knocking prior to this?

Doesn't do it cold, only after it warms up?

[Jrs3800]

A good clean video could help...

Hard to say what you have going on... Could be a collapsed lifter, could be a rod bearing problem..

Could even be the balancer....

[HotZ28]

Originally Posted by Tech II

Doesn't do it cold, only after it warms up?

Originally Posted by Gilmour

when the car warms up, it can be heard loud and clear

It pays to read the whole OP post

[Gilmour]

I will capture a vidoe and post it later on, meanwhile an update:
no codes in the PCM (not even pending).
after driving the car and warming up the engine, it get quite hard to start it, though the battery is new and it doesnt even hesitate when cold and starts with the first cranck at the morning.
another observation, while the car was parked and engine running hot, i revved the engine, the knock is quite loud, however, it goes much lower when i release the throttle and the knocks comes back (louder) when the RPM getting close to the idle.
meanwhile, still couldn't figure if my reading of 21 degree on the timing at idle is normal or a symptom of the issue.

again, thanks all for your help

[Tech II]

HotZ, I just wanted to confirm this to eliminate a cracked flexplate...

Timing data sounds correct....

Is it possible this car was previouisly losing coolant?


we all know about the upper plenum problem.......if you catch it right away, usually there are no problems....

However, ran into a few vehicles where the customer had this problem for awhile, and would just keep adding coolant.....replacing the plenum took care of the leak, but the damage done to the engine by coolant getting into the oil, showed up later(from a couple of weeks, to a couple of months)......

Seen lifter problems, seen knocking problems, and had one vehicle throw a rod, another blew out oil filters because the oil bypass valve in the front cover stuck....

[Jrs3800]

This is sounding more and more like contaminated oil due to either an internal coolant leak or coolant being burned in the combustion process... The oil can only take so much... Problem is that when the oil has had everything it can take the oil can be come acidic of sorts and cause the bearings to pit, its all downhill from there...

But I will await the video to see what we can hear....

Does sound like a bottom end issue tho...

[Gilmour]

finished struggling withe the video upload, here it is:

http://www.youtube.com/watch?v=nSr8CjBghYo

2 more inputs why i thought it's related to timing:

1) when i hear the knocks after the engine warmed up, it gets hard to start the engine, very very similar to wrong timing issue... never happens when the engine cools down
2) today after i finished working, the car sat in the parking for 8 or 9 hours, and got cold, when i started it there were loud knocking (like the ones i hear when hot) maybe for 1 or 2 seconds, right after the RPM stabilized and went down i didn't hear till the engine warmed up. - if it was a bent/broken rod, wouldn't i hear it all the time?

any recommended tests to eliminate the rod option? maybe compression?

by the way,
i did the LIM out of precaution, I didn't want to see coolant in the intake after the engine reached 100k miles, so i replaced the LIM and upper intake (used after market) and just when i re-did the LIM (due to the oil leak) there was not even a single drop of water inside.

Thanks for all your help and inputs.

[Jrs3800]

Sorry to say that is a rod knock... The engine is done...

I have been there and done that as well....

If you decide to replace the engine don't go for another series II...

Get the series III L26... Most W bodies like the Grand prixs had these from 05-09...

Look for the 06-09 GP 3800 Vin 2( Vin 2 is the L26 )... Its a drive by wire set up but you will simply ditch that and install your upper parts as well as the Misc items required for your car...


You hear that brief knock on start up as the oil has not been circulated yet, but it quiets down as the cool oil is thicker and can lubricate the bearing... Once it warms up the oil thins out some, parts expand... Your bearing is in a word of sorts rolling and at times the two halves are are creating a wedge, this is whats happening when the knock suddenly goes away taking up for the gap between the rod and the journal... This will only get worse and either lock up or spit the bearing out... One way or another your looking for a rebuild or a replacement engine.. Sad to say...

[Gilmour]

that is bad news, can it be confirmed by compression test? does it sound like piston or a valve rod?
Puting in adifferent engine is not an option in my country, so i have ekther to fix it or get the kind of engine
Thanks.

[Jrs3800]

Its the connecting rod bearing thats bad... But this is not a 0 deck motor, meaning the crown of the piston come slightly above the deck of the block... Part of what you are hearing is the piston slamming the head...

[Gilmour]

appreciate your help, does it still makes sense that i don't hear it when the engine is cold?
Thanks

[Jrs3800]

Yes it makes perfect sense...

My vid isn't that good but listen close... Mine had already gotten tight... Listen to it start and pay close attention... It was tight on the start, but made no noise till it ran a brief time and I reved it up a little... All said and done the # rod bearing, rod and crank were destroyed... also at the time my car had a 1000 amp 115 reserve battery turning it over... It never failed to start the first time every time till that day...lol

[Gilmour]

hmmmm, ok , i am getting used (slowly though) to the fact that the rod bearings are actualy the issue...

assuming i want to fix this engine, can i just replace the bearings? (after dropping the oil pan)? i know it may it is not the perferct solution...

the second question which bothers me, what may have caused this? the i didn't get coolant in the oil, if I fix it without finding out what caused it, i may end up with the same issue...

Thanks!

[Jrs3800]

Originally Posted by Gilmour

hmmmm, ok , i am getting used (slowly though) to the fact that the rod bearings are actualy the issue...

assuming i want to fix this engine, can i just replace the bearings? (after dropping the oil pan)? i know it may it is not the perferct solution...

the second question which bothers me, what may have caused this? the i didn't get coolant in the oil, if I fix it without finding out what caused it, i may end up with the same issue...

Thanks!

At this point I don't think you can get away with simply replacing the bearing... From the sounds of it you may have already suffered damage to the crank... If thats the case you can't put a new bearing on a rough surface, it will lock up or fail in short order...

Something happened with this car, it may have ingested coolant slowly over time somewhere along the line.. There are other possibilities.. I have seen some engines die and early death for no reason and others that run 300,000 miles like there is nothing to it...

I beat the original Series II in my 95 Bonneville like I stole the car... When I took that motor apart all of the bearings in the bottom end were in great shape... Never had a rod knock or oil pressure issues... The replacement for this is in the vid that you saw... 3800 #3 is in the car currently and has done 30,000 miles with no issues, so its at a total of 90,000ish now...

Its hard to say what causes failures... Some make 100,000 miles some go much much farther....