Buick 3800 Engine Problems and Diagnostics

The Buick-3800 Engine is truly a reliable engine. However, some problems do appear and Shop Carmel can help you out in this regard. We have come up with some of the major problems commonly found with this particular Buick engine. Thereby, the diagnostics for each problem will also be discussed below. 

Some Common Problems in Buick-3800 Engine

  • The leak of intake manifold coolant 
  • An intermittent hesitation or chuggle
  • During driving intermittent misfire 
  • Cracking of engine without start

The leak of Intake Manifold Coolant 

Buick-3800 engine’s coolant leaks particularly in engines of Series II 3800. Similarly, its manifold plastic intake has been a trouble for people. 


The gasket manifold intake by OEM tends to weaken after covering 60,000-above miles if it runs in an area where the cylinder head gets seal coolant passage due to the manifold. 

An Intermittent Hesitation or Chuggle

You may feel an intermittent hesitation or chuggle during cruising at the speeds of the highway or while light acceleration. It happens when the automatic TCC’s (transmission torque converter) intermittent operations do not set fault codes or there is no check engine light.


This problem is not because there is any issue in the clutch solenoid or the clutch for the torque converter. However, the sole reason for this problem in engine-3800 is the faulty input. The TPS (throttle position sensor) of the engine makes wrong input to the PCM computer (powertrain control module computer).

However, this problem in engine-3800 can be fixed by changing the throttle position sensor (TPS). 

During Driving Intermittent Misfire 

It happens during driving either by a worn spark plug or by a feeble coil. 


Whenever, the intermittent misfire occurs when you are driving first, inspect your spark plugs after removing them. There must be a gap between these spark plugs of 0.60 inches. However, if you found your spark plug fine, leave it, and go for examining the ignition wires. 

High resistance can be produced by wires with 100,000-above miles’ mileage. Moreover, this resistance may result in a misfire in your engine. If you find such wires, damaged wires, loosely fitted wires, or cracked wires in your engine replace them all. Though, if you find your wires and plugs in good condition then do not replace them. 

However, even after replacing the damaged wires and plugs or replacing them your engine behaves in the same manner check codes of a misfire by utilizing a scanning tool. Moreover, Keep the light of the check engine on and make sure that you get 1-2 codes of a misfire for the cylinders creating misfires.

Furthermore, the number of the cylinder is indicated by the last digit of any misfire code. Let’s take an example of a cylinder with code P0302, the 2 in this code shows that the number cylinder is the one that is misfiring. 

The strength of the ignition coil also matters a lot in misfiring problems. If the ignition coil is weak it may lead to misfiring incidences. The fire cylinders of the 3800 engine have 3 ignition coils such as 1 and 4, 6 and 3, and 2 and 5. 

However, if you get misfire codes from any of those paired cylinders it proves that the root of this issue is the bad condition of the ignition coil. Thereby, it proves that there is no other reason behind misfiring. Some misfiring like a lean misfire is caused by reasons like vacuum leak, EGR leak, or bad fuel injector. Similarly, compression misfire occurs because of sticky or leaky valves. 

You can easily replace the weak coil in the ignition module. However, if any of the bad coils remained unattained the problem will not resolve. Shop Carmel would suggest you replace all of the coils if your engine is high mileage or weak, to avoid such problems on road. 

Cracking of Engine without Start

There can be many reasons that leads to no start, however; in the Buick-3800 engine, the most generalized reason is the bad CKP sensors and ICM. Where CKP means crankshaft position and ICM means ignition control module. 


Firstly, the CK or crank sensor can be diagnosed by evaluating the diagram of your vehicle’s engine wiring. Secondly, you need to test voltages of circuits for the ignition module and many crank sensors to search the fault. Moreover, 4-8 volts must find when you turn the key on between every crank sensor. If it tests bad replace these crank sensors. 

Final Thoughts

Practicing the above mentioned diagnostics will definitely help you out in resolving the problems of Buick 3800 engine. Share your suggestions in the comments section.