1990 LeSabre LM3 Vibrating Crankshaft - Thoughts on my plan?
 

I've got what I think is an interesting problem...well, actually 2 problems, but I believe them to be directly related. I have a 1990 LeSabre that has an intermittent knock at idle and during initial acceleration, as well as an oil leak from the front crank seal. The car has 107,000 miles, and has been well maintained--never driven hard.

First the noise: The knocking noise is most prevalent at idle, and right at initial throttle acceleration. Once the rpm's raise, the noise settles waaaaay down. It will not knock 100% of the time, but it's frequent. In trying to identify the source, I removed the serpentine belt and started the engine. The knock became louder. This eliminated the harmonic balancer as the culprit, but would seem to indicate the noise coming from the crankcase. While running the car and looking closely at the harmonic balancer, I can see the slightest of side to side movement---which for lack of a better description would appear to look like it is vibrating slightly. The same is true for the harmonic balancer center bolt as well. The movement isn't much, but you can definitely see it. I also took a prybar and pried gently on the balancer to see if I could get any side to side movement out of the crank manually, and I could not.

Secondly, the oil leak: I have an oil leak that is getting onto the balancer and slinging oil all over the front of the engine, leaving me with a nice mess. The area directly inside the back of and under the balancer seemed to be wettest, and I could see a track of oil coming from the face of the timing chain cover. Believing it was the seal, I replaced the old one with a new GM seal. The job was easy, the cleanup was not.

Now, after taking the car out last night, I came out later to find my leak was still with me, and I had a new stain in the driveway. Hooray. So this morning, determined to find the source of the leak, I brought the car into the garage, re-cleaned the engine, top and bottom, put the car on stands, started the car and got underneath to watch---Lo and behold, I found the oil seeping from the bottom of the front seal again. I watched it appear from the direction of the block and head out towards the balancer.

I believe the movement of the crank and the leak at the front seal are directly related. I would be hard to seal a crank that shimmys or vibrates side to side. So at this point, my plan is to pull the engine and install a new crank kit and new connecting rod bearings.

Having said all of this, does anyone have any advice or insider information they could give that would help this job go as smoothly as possible. It appears pretty straightforward to me. Oh yeah, and being a 1990, I will need to identify the crank casting on mine before ordering the kit---apparently, GM used 2 different cranks in 1990.

Thanks for reading!

Dave

I have noticed a similar movement in my harmonic balancer and bolt in my Park Avenue and my dad's former Bonneville (1990 SSE). Both ran (or are running) fine without issue.

Are you sure there is not separation from the harmonic balancer?

Absolutely. I had it removed to replace the front seal and inspected it on the bench. The balancer looks like new, and is bonded tightly on both sides. I also performed the balancer "run" test to be 100% sure. When I removed the serpentine belt and ran the engine, the knocking noise actually got louder not quieter.

I forgot to mention, when I inspected the balancer I noticed it has a 2013 date code on it, which would explain why it looks new.

Did you notice a groove in the shaft of the balancer, where it mates with the seal?

You do realize all the work involved in replacing a crankshaft on this?

No groove, That was one of the first things I looked for when I popped it off. I would have sleeved it if it did.

As for the work? Sure, it's pretty easy once you get the engine on the stand and roll it belly side up. I won't consider ordering any parts until I know exactly what the source of the noise is, and what needs replacing. I'd like to believe it's a main bearing since the noise gets louder with the belt and all tension on the crank removed...but I won't know for sure until I get inside to see what's what.

It's on the agenda for this week. :thumbup2

Well, then, good luck....

Thanks.

Oh, I also forgot to mention another important piece of the puzzle...the engine is quiet and knock free when stone cold. There is a slight knock on startup that immediately goes away as soon as oil is moving through the system, then the engine quiets right down. The detectable knocking (as described in my first post) begins once the engine has warmed. Again, leading me to believe I have the early stages of a bearing issue. Mains or rods? Both?? I'll soon find out.

If there's any interest, I'll keep this thread updated with findings, pics, etc...

Sure, some pics would be great....

UPDATE
 

UPDATE:

I pulled the engine over the weekend and found the cause of all of my problems. The oil pickup was plugged solidly, causing the engine to suck oil from the bypass. Apparently an earlier failure of the cam timing chain gear resulted in nylon debris entering the oil pan and thus plugging the pickup causing oil delivery issues to the crank bearings. The front main really took a beating, which absolutely accounted for my knocking on startup, when warm (at idle), balancer "shimmy", and oil slinging from the front crank seal.

The rear main showed some pretty good wear, but not as much as the front. The #2 and #3 mains looked fine, as do all of the rod bearings.

The crank is in the shop now, and it looks like it will take a cutting of .020 to bring it back. I should have the crank and new bearings (crank and rod) back by the end of the week...then the fun of reassembly and re-installation begins! :thumbup2

Glad you found the issue, let us know how it runs once you get the crank back, and get it all installed.

Are we talking about the LN3?

If so, they did not use a nylon timing set. That went the way of the old LG3, or the 3800 predecessor.

I am glad that you found a pretty substantial issue however.

Thank you, will do!


I did not know that. The muck clogging the pickup screen was tough stuff...even lacquer thinner didn't touch it. Since the LN3 didn't use nylon, I have no idea what could have gotten in there and did that. I'm not taking any chances trying to clean the old pickup, I am also replacing it with a new unit.

Thanks for the info. I'm glad I found this issue when I did...we'd have hated to lose a car this nice over something this easily fixed!

FINAL UPDATE:

I got the crank back last Thursday. Mains turned .020 and rods .010 under....I reassembled the engine on Friday and installed in the car Saturday, and I am happy to report SUCCESS!! The engine is quiet, the balancer runs true and the oil slinging is now a thing of the past, and it runs like it did when it was new. Total cost to fix: $175.00 :thumbup2

Here are a few pics of the car I took last evening. These pictures show the reason I was so determined in fixing this problem.

https://www.gmforum.com/attachment.p...ine=1464006582

https://www.gmforum.com/attachment.p...ine=1464006582

https://www.gmforum.com/attachment.p...ine=1464006582

Glad it runs good now, and yeah I can see why you were determined, that car looks extremely well taken care of, thanks for sharing those pics!

As a rookie, one of my first oil changes was on a LeSabre.....I released the hood latch, and I am trying to lift that hood from the front to no avail.....finally a tech came over laughing and lifted it from the rear....

This is what an older car can look like when an owner cares about their ride!
Dave I got to say great job on assembly & getting the engine re-installed! :thumbup2
You will be again enjoying your Olds for many years ahead now!:D
Finally I got some competition for under the hood detailing! ;)

Thanks guys, it feels great to have it back. I take a lot of pride in caring for my vehicles. This job (as all I undertake) was done completely by the book...all of the retainers, clips, loom retainers etc are all in their respective places, just as they were installed at the factory, and all of the fasteners removed were torqued to factory specs on install.

Life is good!! :2thumbup:

Looks like a freakin' Buick to me, Soft Ride!:cool:

I think he had a little of that Hard Cider or Labatt's before he posted, he he :D

Awesome looking car! Is it missing a cooling fan on the passenger side? Our Bonneville had one, but I don't know if it's missing in your case, or if Buicks skipped them.

YA it even has the badges in the photos! ;)
I had two other Olds tabs open, so I guess I had Olds on my brain.
I did realize my mistake shortly after the post, but decided not to edit, to see if anyone would correct me, and how long it may take...:cool:
Ya not long LOL.. :thumbup2 Nice Buick LeSabre. :)

Lol...I caught Soft Ride's little faux pas but let it slide on by...I'm easy that way :D

rjolly87---thanks for the compliment! This car only came with one fan. It kicks on at both 195º engine temp and when the A/C is turned on. GM set thier cars up both ways....as a "for example; I had a 1987 Corvette with only 1 fan, and a 1989 IRCOZ with 2 fans. Why? Who knows...but as long as it keeps the engine cool and moves enough air past the condenser to keep that interior air cool (meaning my wife doesn't overheat) then I'm a happy camper!

Thanks Soft Ride for the compliment. We really enjoy this ol' girl! :thumbup2:

I hope this thread may help someone else down the road that may encounter this issue. Acted on early enough, it's inexpensive to fix if you can do the work yourself.