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Home Engine Servicing GM’s 3800 V6 Engines

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The Buick 231 cu. in. 3.8L V6 engine has had a production run lasting more than 30 years. Like the small block Chevy V8, this engine has undergone many changes over the years to keep it abreast of changing consumer expectations and emissions regulations.

The first Buick 3.8L was offered in the 1975 model year Skyhawk, Apollo, Century and Regal. The engine was based on an earlier 198 cu. in. V6 that Buick introduced back in 1962. The 3.8L engine shared the same 3.8” bore size as the Buick 350 V8. It also had an “odd-fire” crankshaft, which produced some idle shake and vibration.

Over the years various improvements were made to upgrade engine performance. Here are some of those changes:

1977 — Buick changed to an “even-fire” offset-pin crankshaft to smooth out the V6 engine.

1978 — Turbocharged version of the 3.8L V6 offered in the Buick Regal and LeSabre.

1979 — The engine gained some horsepower with improved cylinder heads (larger valves and ports).

1980 — Larger 4.1L version of 3.8L engine offered with bigger 3.965” pistons.

1981 — Stronger connecting rods and a revised harmonic balancer and flywheel were added.

1982 — 180 hp version of the turbocharged 3.8L V6 offered in Regal T-Types and Grand National. Also, a smaller displacement 3.0L version of the 3.8L V6 with a shorter stroke crankshaft was built for GM FWD cars.

1984 — Direct fire distributorless ignition and electronic multiport fuel injection were added. Also a new camshaft with a larger base circle and 0.015” shorter pushrods were added. This was also the first year for a front-wheel drive (FWD) version of the 3.8L V6.

1985 — The engine was refitted with a single serpentine belt to drive its accessories. The number of bolts on the oil pan was also increased from 14 to 20 to reduce oil leaks. The head bolts also changed to non-reusable torque-to-yield bolts.

1986 — The flat tappet lifters were upgraded to roller lifters to reduce internal engine friction, and sequential fuel injection was also added for improved performance, fuel economy and emissions. The deck height of the block was also reduced 0.035” to accommodate thicker composition-style head gaskets. Some FWD versions of the 3.8L V6 (VIN 3) were offered with roller lifters. FWD versions also got new cylinder heads with pedestal-style rocker arms, and a needle bearing thrust washer for the camshaft.

1988 — Buick now dubbed the engine the 3800. The block casting was revised and a balance shaft added to dampen vibrations. The cast iron camshaft was replaced with a steel camshaft, thinner, low-tension piston rings were added to reduce friction even more, and the mechanical EGR valve was replaced with an electronic digital EGR valve to reduce NOx emissions.

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Larry Carley

Larry Carley

Larry Carley has more than 30 years of experience in the automotive aftermarket, including experience as an ASE-certified technician, and has won numerous awards for his articles. He has written 12 automotive-related books and developed automotive training software, available at
Larry Carley

Latest posts by Larry Carley (see all)

  • Chris

    I have a 2002 Buick Park Avenue that gets warm (doesn’t overheat) and stalls when idling. It won’t start again until it cools down. This started 10 months ago and now occurs after only 15 miles or so of driving. A good dose of water in the area of the coil pack/crankshaft helped and so I replaced the ignition module with no effect (it needed the new grease). Based on other’s experiences, it seems the crank sensor is a likely culprit, so I bought AC Delco part 10456161 and replaced it. The car then would crank but not even start. That part was sent back and the same part was purchased elsewhere, with the same results. Both times, the original part was reinstalled and the car started. I know there’s a system variation learn procedure that you’re supposed to have done (some folks say they skip it), but it has to be done after the car is running and the temperature is up to 158 degrees. Why is the car not starting?

    • Evilcowboy420

      Three things an engine requires to run is spark, fuel and air. But I stand that 4 things are needed as well nowdays it includes the computer. Your crank sensor is bad. You replaced it and the car didn’t start. Thats your computer telling you it needs the relearn procedure done. I would suggest looking that up and doing that but if you don’t want to do that dance then unplug the negative to the battery for 10 minutes after installing your new sensor. This should reset the computer back to defaults then it will have a base line for cranking the engine with the new sensor. You confused it by putting in a working one. The computer accounted all it could for the one failing until the car got worse. So the computer thinks it still has a bad one connected and needs to be accounting for the bad one. By resetting the computer your giving it an opportunity for it to do its thing and relearn it over again.

      The computer makes adjustments slowly over a period of time and values will change until the part that fails craps out and the computer cannot do anything more to help the situation. Hence the no start condition with a new one. When you put the same old one back in it is already calibrated for the crappy one and will start.

      Save yourself a lot of problems and do the relearn after the new one is installed.

      Second as for the overheating issue. Who told you water was good to put on a coil pack? Water is an excellent conductor of electricity never a good idea to mix the two. This brings me to you testing out to make sure the coil pack is still good as well as that can cause your no start as well. They run hot and can fail. So check that out. Overheating issues are caused by several things even if it is a slight overheat it is still rising above normal. With these problems use of a digital multimeter can help rule out coolant temp sensor. Usually you want to start small and cheap replacing stuff until you get the right component. Start with a thermostat if that dont help do the CTS then the water pump and then the intake gaskets. More than likely your gaskets have a leak since it is a very common problem. Replace both lower and upper intake gaskets and have the plastic part checked for warpage and replace if necessary.

      Anyways I speak from experience with this engine both the old and new ones. I got a 2004 lesabre and a 89 bonneville. The 04 Lesabre runs like a top with no check engine lights on. The 89 Bonnie is having it’s engine rebuilt by me. So I am pretty knowledgeable when it comes to these engines.

      Anyways good luck

    • weasel

      I know my wife has a 98 oldsmobile eighty eight with the 3800 in it an it did the same thing, Run untill you shut it off then you had to wait till it cooled before it would finally start an run again, After 2 months of pulling my hair out an changing lots of sensors to no avail i took it to the garage, after a couple days he told me the fuel pump needed replaced an gas tank was rusted also needed new plastic lines for it. After he replaced al that it ran perfect again !

  • buickrepairer

    I was trying to remove the supercharger snout without removing the whole supercharger. I think just my outside bearings are bad. I have loosed/removed all bolts that I can see and still can’t get the plate off in front of the snout that holds the tensioner pulley. Any ideas?

  • dkthree

    I have a 98 Pontiac Grand Prix with the 3.8, great engine. It started leaking after warmup lately, but I can tell where the leak is coming from. No white smoke, so I don’t think it’s the manifold gasket. Not the water pump, no leaks all around. Any ideas?

    • James

      When you have no leaks dude it is being dumped into the engine. Sorry to say. You may not see white smoke but that just means coolant is not being burned it don’t mean it isn’t dumping into the crankcase with the oil. Just buy the updated gasket set and plan for the job on a weekend and then enjoy another 5 to 10 years of trouble free 3800 fun. If the gaskets haven’t been changed you should just change them as GM even admitted the OE gaskets weren’t good and recommends you change them.

  • Fred

    Hello. I have a Grand Prix GTP 1999 with 210000 kms. When I accelerate the vehicle starts to shake. I have a feeling it is either the spark plugs or the supercharger. It starts shaking when it just starts to show I have boost. Other than that when I’m just maintaining normal speed without accelerating it drives just fine. Does anyone know anything about this? Thanks

  • John

    I have a 2007 pontiac Grand Prix had a coolent leak so I replaced the two plastic elbows with metal ones problem gone for about 2 weeks then the water pump started leaking so I replaced it worked fine no leaks for about a month then noticed a leak did not no where it was coming from so I replaced the water pump again no leaks for about two weeks now its leaking again not sure from where any ideas

  • Arzola

    I have a 1994 bonneville ssei 3800sc
    First off my car was driving under power :no pickup & you can’t hear the supercharger whine . I was driving home and it sputtered then acted like it was going to die then was fine parked it then it wouldn’t stay started only kept dying no it won’t start.
    I took off the throttle body and cleaned it very well and still at a loss I recently replaced my fuel pressure regulator & fuel filter but that’s all

  • Heith Inghels

    I have the 1989 Oldsmobile delta 88 royale brougham. After market parts are the coil pack, ignition control module, mass air flow sensor. When I did coil pack and ICM, I also replaced spark plugs and wires. As well as put in a new alternator. Engine runs splendidly. I use a full synthetic oil, for the motor and transmission. Engine is passing 226,000 miles.

  • kendall martens

    i have a 2007 grand prix with 3.8 motor…engine light came on and i had it looked at…autozone said it was the #2 cyclinder misfire…put new plug and new wire. also a new ignition coil, also modual…my mechanic said it could be my injector next and that i could probably do that…

    so could it be my injector, and could i do it, and where is it?..
    it runs rough at idle but better at 70 or 80…

    Thank you

  • Sam Summers

    I have a 1994 buick regal GS 3800 and I can not find the ground wire short that keeps the car from getting hot in the summer time

  • Staci Gaddis

    I have a 2001 buick lesabre and I have changed out the ignition control module after she lost power and she has full power, doesn’t misfire but she is difficult to start up in the morning. She doesn’t turn over. There is no engine codes. Any ideas ?

    • Anon

      Two suggestions: 1- Replace the coils. (one can often get away with replacing coils and not the ICM but changing the ICM almost always require new coils)
      2- Replace plug wires and inspect plugs

  • Mike

    Im changing the starter on a 96 buick lesabre with the 3.1l engine, any tips suggestions

  • Constance

    I have 2002lesaber 3.8motor I’m not sure what is wrong with it I’m not sure if my transmission needs flushed or if its something else but the motor or the RPMs read really high and it felt like it jerked and it died it’ll start I haven’t tried to drive it

  • torrance moses

    how do you replace the voltage regulator? i have a 2001 pontiac bonneville.

  • Tim Turner

    2005 Bonneville, have replaced intake gasket and all the sensor gaskets. Engine runs great. It skips when in overdrive when slightly accelerating. no water in oil are oil in the radiator. Any suggestions?

  • daniel swagg

    My 96 regal cranks but won’tstart i changed the plugs wires crank sensor n starter.almost wants to start but I don’tthink spark is getting through. What can be the problem here

  • JZ

    1991 Olds 98. Wonderful car. Constant SERVICE ENGINE SOON light. Runs great. I wouldn’t care except I’m in CA and need smog certification. OBD says 41 camshaft sensor. Anyone have shortcuts or look fors on diagnosing and/or replacing? Thanks.

  • Bakari Hernandez

    I have a 97 Buick Rivera super charged the engine replaced at 74000 miles but the replacement engine has a miss fire code on 1 and 4.. ignition codes. Shop say it’s old stored codes I replaced everything plugs, coils , wires and injectors engine runs smooth. .when i replace the coil 1 and 4 it drive good but after a while the problem persist. Coil module I replaced with 3 different used ones but the same code (1&4) appears after reset. But before it come back on it drives normal . Also the 3rd solenoid will not open. The check engine light flashes after its it warm up on the road.

  • Nile Kerr

    Parked my 87 buick lasabre after work, ran fine. Would not start next day. Replaced starter and battery and no change. Checked spark and determined it was weak. Replaced all coil packs, plug wires and plugs.Check camshaft sensor and it was damaged so it to was replaced. Still no start. checked fuel pressure and was ok. Pulled spark plugs and found they were wet. Proceeded with changing the crankshaft sensor.While cranking the engine after installing the crankshaft sensor,white smoke began pumping out of the throttle body along with an oil mist. Hmmm..never seen that before..thus led to a compression test of all cylinders(3.8 6cyl 231cu). No compression at any of the cylinders. Compression test was done dry, and wet. No change..Place thumb over no.1 cylinder hole and felt vacuum, but no compression. Coolant seems to be full. No visible coolant in oil. Blown head gasket? Broken timing chain? Plugged converter? Turns over as if the timing chain is broke, but spark is present. Back- pressure instead of air intake through the throttle body has me stumped. Even looked up the tail pipe for obstruction thinking eddie murphy paid me a visit. Could use a few professional opinions or suggestions,for i am not a professional auto mechanic.

    • amarkel


  • Ethan

    I have a 99 Pontiac firebird with a 3.8, and I’m wondering if the 1.6 rocker arms from a small block chevy will work on it

  • Eddie

    Curious how long the stock coils will run for? Thanks

  • Joe

    You state “The coil pack on these engines runs hot, so it’s important to make sure there is heat sink grease under the coil to transfer heat. If the coil module gets too hot, it will fail.” What is this heat sink grease that you speak of and where exactly would it be placed?

    • Crankshaft

      The heat sink grease is lightly and evenly spread between the metal mounting base for the coil pack and the bottom of the coil packs. It transfers the heat better between the two surfaces. Unless you removed them, the factory applied compound should be present. If you do remove the coils, you should remove the old compound and apply new. Remember too thick of an application is not good either. You can get this at any electronics parts or auto parts store.

  • Crankshaft

    My 97 Buick Lesabre (3.8) with 45k miles has started what appears to be a shaking
    similiar to a misfire at around 30 mph and under moderate accelleration. I do not feel it in the steering wheel and I get no check engine light. The shaking goes away if I ease up on the gas.I get very smooth accelleration if I do not work the enginge hard. Today, I even heard a low pop noise like a backfire under the hood when I pushed it a little harder on accellerating. It idles very smooth and accellerates very smoothly till I get over 30-35 mph. I would appreciate any suggestions.

  • radbrad1502

    I have a 98 regal gs supercharged it’s been modeling at around 600 or 700 rooms and it will also act like it will die when stopping a stop light .and also when I’m driving I punch it and it lags a bit then goes out out will sputter a little bit b we for Driving sometimes not often the idle and stop sign dying is often.almost 90 to, 95% of the time I till of maf sensor sounded like there’s a vacuum leak I cleaned it there wasn’t a gasket any ideas if this doesn’t work?

    • Rusty Middleton

      try the intake manifold

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