Fixing Tappet Noise on a Buick LeSabre with a GM 3.8 (3800) Engine

This has been a heck of a couple of months in terms of the Severance family cars. Brent’s Sunfire died with a rod knock at 140K mies and I bought him a little Subaru Forester. Mandy’s Pontiac Grand Am blew a head gasket at 140K and had coolant coming out the tail pipe (still being repaired). Teresa’s Subaru Tribeca, had it’s 110K checkup that cost $835.

As if all that were not enough, the venerable Dr. Chuck-mobile, my ultra-reliable 2001 Buick LeSabre with 210K miles had a few issues as well but ended up with a happy ending. But let me start at the beginning.

I have had three Dr. Chuck-mobiles since 1998. They all have the GM 3.8 (3800) V6 engines. I would buy them at about 105K miles for around $4500 and then drive them for 100K miles and the sell them to someone else in my family and for $2000 and then buy another “new” one with 100K miles. My family loves GM 3.8 liter engines. Across my parents, brothers and sisters, we have probably had 20 GM cars with 3.8 liter engines. My parent’s garage looks like a auto repair shop in rural Mexico. We literally have in stock nearly every part that goes wrong with the GM 3.8 liter engine. My brothers Scott and Christopher can disassemble and reassemble everything from the engine to the running gear with their eyes closed. We leave transmission work to the pros at Lansing Transmission – they have never steered us wrong.

In 1999, I had a green Pontiac Bonneville. In 2004 I switched to a while Oldsmobile 88, and in 2008 I purchased my current Buick LeSabre. I really wanted a LeSabre because it was quiet and smooth and had a neat display that gave you an instantaneous gas mileage readout during my 120 mile round trip daily commute between Ann Arbor and Holt Michigan.

I really liked the LeSabre and my goal is to not stop at 200K miles but for once in my life get a car to 300K miles. So when it turned 200K back in December, I decided that it was time to do a complete maintenance job to celebrate the milestone and prepare for the next 100K miles. I was going to change bearings, shocks, struts, brakes, calipers, rotors, and do a transmission service. So we bought all the parts and my brother Scott did all the replacements and gave me the car back.

About 1000 miles after I got the car back, it started to develop the loudest tappet noise I had ever heard. In the morning after the car sat all night, it would start and for about five minutes make a tappet noise so loud that it sounded like a midget was under my intake manifold with a sledge hammer. It was so bad that the car ran as if it were missing one one cylinder. I think that the exhaust valve was not opening. It was hard to keep the car running because it was so bad. It even threw a check engine light sometimes after it chugged so badly.

But after about 5 minutes the noise would go away and everything would be perfect for the rest of the day. Even starts after it sat a few hours were noise free. It only made the horrible tappet noise for five minutes in the morning after it sat all night.

I felt a little sheepish because to save money a few months earlier I had let one oil change go over 10K miles. When I finally got it changed the oil was pretty bad. I figured the tappet noise was because it got too dirty and gummed things up.

So I went into the oil change place and asked them to do their $79 engine cleaner treatment and then put whatever magic goo they had to quiet tappet noise. They charged me $22 extra for Lucas Heavy Duty Oil Stabilizer. It looked the consistency of honey as they poured it in. They swore that it was the “best stuff ever”.

The tappet noise was gone for about 1500 miles and I was feeling pretty good. And then mysteriously it came back even louder then before. I had just put over $1000 of repairs in this car and I was not about to spend the next 100K miles with that noise on every morning start.

So I asked my brother Chris what he would do in the situation and he gave me some advice that was the same as what I have seen all over the Internet. I was to remove a quart of the oil and put in a quart of Marvel Mystery Oil (a.k.a MMO). MMO was less than $5 at my AutoZone. I still had less than 2000 miles on my oil change so I went back and asked them to drain a quart and put in the MMO. The kind of scoffed at me and told me that the Lucas was the best stuff ever. I told them I just wanted the MMO put in and did not want a lecture. I had tried it their >$100 way and it failed after 1500 miles.

So I drove out from the oil change and immediately drove 120 miles that day to and from Ann Arbor. The next morning, the tappet noise was reduced by 1/3 and it went away a little more quickly. For the next 500 miles it got slowly better. After about 750 miles it was quite tolerable where you actually had to turn the radio down to hear it and it went away in a minute. After 1500 miles, even after sitting a whole night, the engine starts flawlessly with no sound at all.

This is an amazing development given how loud and how bad the tappet noise had become. I am feeling much better now.

My next oil change is in about 750 more miles and I will put Marvel Mystery Oil as one of the quarts and likely do that for the rest of the life of the car to keep it nice and clean internally.

Of course you may find your results differ. I am sure there are lots of reasons for tappet noise. And maybe whatever gunk or varnish that needed dissolving was near a lot of oil flow and was easily cleaned up. Another advantage I have is that my driving is not stop and go. I get in the car and drive 60 miles at highway speeds until I arrive at work and then turn around and do the same at night. So there was plenty of oil flowing and the engine was fully warmed up pretty much every time I drive.

I will see how it goes. But for now I feel good about the quest for 300K miles with all new parts, a fresh transmission service, and now no tappet noise.

6 thoughts on “Fixing Tappet Noise on a Buick LeSabre with a GM 3.8 (3800) Engine

  1. Lars


    I do not know your name but I am glad that I found this article. I just own a 3.8 Pontiac Firebird V6 and have some problems with it. I just so much hope you get in contact with me, I work with a friend on my car but we have some problem we do not understand and since you may can give help here I would be happy to hear from you. Write me a mail and I send you the contacts

    This is no spam, I am also in the Firebird Nation Forum but people can not help me, they all been like “What the heck you are talking about man”

    Would be nice to hear from you


  2. Ray

    I have a 2004 Buick Lesabre. It now has 262,000 miles on it. The tappet noise you are talking about, mine started last week. Glad I found this article and plan to try the marvels as you suggested. Lucas has not fixed the problem and the noise is somewhat random as well. Varies along with engine speed. Thanks again for your article it was a relief to know its not just another $1000 repair job.

  3. Michael

    All you had to do was get a bottle of seafoam motor treatment add it to your oil, the whole bottle and the noise wI’ll be gone completely completely by 20 miles. And it’s called a collapsed lifter, fixes it every time seafoam!!

  4. ed shelton

    had several 3.8 engines and the tapping and usually a stuck or collasped lifter ,but mmo will un stick and free it up every time for five to ten bucks. better than 100.00 or more to tell you need lifters.wrong;;;;.ask me and i tell no lies .im a good machanic.lucaqs will dom more harm getting trapped in oil filter.people dont think additives stick to oil filters like slime and poor oil flow mmo is moe natural oil.

  5. Mikel

    I have a 04 Grand Prix GT. Had a bad knocking sound and I didn’t know where it was coming from, so I did the screw driver test, found out I had a upper knock instead of the ferocious rod knock…I tore the entire engine apart, got out my lifters, all were fine, no collapses, except cylinder #6 Lifter, it was fine but it was stuck with gooy buildup. Oh, this was after Castro GTX and Lucus was in the engine. So, I drained all the old oil out, will run transmission oil in it, drain that, then replace it new Castro GTX 75,000 High Mileage and Lucus. Rebuild the engine and see how it goes…at 232k miles, it runs extremely strong.

  6. Billard 8 ball pool

    You’re so cool! I don’t suppose I’ve truly read through a single thing like that before.
    So nice to find another person with a few genuine thoughts on this issue.
    Seriously.. thanks for starting this up. This website is something that’s
    needed on the web, someone with a little originality!

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