dingster Posted September 22, 2004 Share Posted September 22, 2004 I just bought a 90 LS400 with 140k. I have no idea when the Tbelt and water pump was replaced or if they where ever replaced. I have an engine vibration. Upon cold start or around 1500rpm the engine vibrates quickly a few times for a split second and this repeats maybe every second or two. It is not that bad, I guess kinda like how a diesel engine would vibrate but not as noticable. When rpm builds the vibration also speeds up. This happens when the car is stopped or moving so I doubt it has anything to do with the tranny or the rest of the drivetrain. Is this an indication of the water pump about to go south or could this be something worse? Could it be misfire? Since this is a ODBI car I assume it doesn't log any DTCs for misfire? Any help would be appreciated. TIA. Quote Link to comment Share on other sites More sharing options...
gdaelemans Posted September 22, 2004 Share Posted September 22, 2004 Usually water pumps start leaking when they are about to give up the ghost. I've had a slow leak for a few months now, suspected the water pump, and I finally got around to replacing the water pump - the technicians confirmed that was the source of my leak (I've got 180K on a '91). As for the vibration, could it be something else on the accessory chain, such as the A/C compressor? That has much more "inertia" than the water pump... just a thought. Quote Link to comment Share on other sites More sharing options...
VMF Posted September 22, 2004 Share Posted September 22, 2004 your engine might also start to overheat a little bit. if the water pump will seize it will fry your t belt and you will have to pay for towing, os it is better to change it asap Quote Link to comment Share on other sites More sharing options...
dingster Posted September 22, 2004 Author Share Posted September 22, 2004 Thanks for the reply guys. Is my motor interference or non-interference? Quote Link to comment Share on other sites More sharing options...
92Lex Posted September 22, 2004 Share Posted September 22, 2004 non-interference. Quote Link to comment Share on other sites More sharing options...
Em91 Posted September 22, 2004 Share Posted September 22, 2004 Sounds like you may need a tune up. I would change the spark plugs and the wires. Also, while you are at it check your motor mounts if they are broken you can have a vibration there. Quote Link to comment Share on other sites More sharing options...
iamfiredup Posted September 27, 2004 Share Posted September 27, 2004 I actually have this issue of vibration right now. When I purchased my LS 1 month ago, the engine was smooth as silk. I since have had the fan bearing mount (don't know the actual part name) replaced and it has had a lot of vibration ever since. Could it be caused from the belts being too tight? Quote Link to comment Share on other sites More sharing options...
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