HT4100 4.1, 4.5, 4.9 Discussion, 84 Eldorado 4.1 V8 (HT4100) "E" engine, M57 tranny, Noise from lower end in Cadillac Engine Technical Discussion; Hello everyone. I am a new poster to the forum. I have spent countless hours browsing through almost every archive ...
84 Eldorado 4.1 V8 (HT4100) "E" engine, M57 tranny, Noise from lower end
Hello everyone. I am a new poster to the forum. I have spent countless hours browsing through almost every archive here. I must say there are some very knowledgable folks out there and I thank you for your input.
Here is my scenario. I recently purchased an Eldorado with 76,000 miles. When the engine begins to warm up I hear what I believe to be a slight knocking or thumping coming from the lower end of the motor. I must admit I would like some definition of "thump" and "knock" because the sound I hear is very close to what I perceive to be a "thunk." I have researched any information I could find on the "main bearing thump" issue and I am wondering if this applies to my specific cadillac (4.1 engine).
The engine appears to be mounted in a standard type fashion although I am uncertain if it is a transverse type or not. The engine doesn't have a serpentine belt so I am also unsure of which belt to remove (accessory belt?) so I can verify if the problem is actually the main bearing thump.
On the recommendation of bbob and others I have used the "golden seal" in my coolantand have changed to a 15W-40 Rotella oil with an added bottle of GM EoS. I cannot speak for the quality of oil or coolant used by the 1 owner before but the records indicate that the vehicle received regular GM/Cadillac maintenance.
A few more points I should include; The car does not have any loss of power or feel sluggish in any way (no more then a 4.1 in a heavy car should) and the computer diagnostics come up clean. I did use a stethiscope to try and locate the sound and my best guess is somewhere from under the crank.
I suspect a rod bearing or main bearing but I would like some input before going further. Besides the noise, the car shifts, runs, and rides like a dream :P
My questions are these:
1) Is this model engine (4.1 "E" Engine, vin code 8) in this car prone to the Main Bearing Thump.
2) Where should I begin in diagnosing this problem. I can recreate the sound if I place the vehicle in drive, hold the brake, and lightly accelerate (place a slight load on the engine) after the car has been driven for a little while.
I thank you in advance for any information you folks can give.