I just bought an automatic 1996 4door, 4wd chevy blazer with 203,000 miles. The previous owner parked it and put it up for sale when he was driving home one day and felt and heard a violent shaking/shuddering coming from somewhere underneath the truck. He said the shaking from underneath came at a wide range of speeds as he continued home that day, but not when going very slow like 5-15 mph. When I bought it from him and drove it the 25 miles home, it drove perfectly normal. Even at 70 mph it was fine. You probably cant conclude definitley, but what could the shaking he experienced possibly have been? I checked the truck out best I could and the only thing I found was that the tie rod ends have an awful lot of play in them. Could that possibly cause a scary vibration while driving? Also, there is a fairly strong fuel odor inside and outside the truck when it is running. It gave me a headache driving it home. Where should I start looking to figure that out? And not to get greedy, but would it be advisable to swap to synthetic fluids?

 

You can swap to synthetics at any time. I wouldn't jump to doing any extended drains right away, but synthetics shouldn't harm anything.

As far as the shaking... It's possible that it developed a "death wobble" from the worn front suspension parts... Or the guy just might be over stating the vibration... Who knows. Until you experience it, it is quite difficult to say.

For the fuel smell, you could have a problem with the EVAP system or an actual break in a fuel line. You should inspect all of the lines from the tank up to the engine for wet spots. It doesn't take much of a leak to cause a strong fuel smell, however, something like that shouldn't be getting inside the cab of the vehicle...

 

Thanks swartlkk. I'm actually going to replace as much of the front steering and suspension components as I can afford since the steering is pretty loose in this truck and the front end bounces a lot. Can you recommend a list of steering/suspension parts I should replace based on importance from highest to lowest. As far as the gas smell it was certainly present inside the vehicle. Is there a group of possibilities for that? I did hear a sloshing liquid sound a few times coming from behind the dash at least ten times during the 25 mile drive. Truck has no loss of power. It start right up every time. And even runs pretty smooth. Thanks again.

 

About the only thing that could allow for a fuel smell inside the truck would be a leak under the hood that is being drawn in through the HVAC intake on top of the cowl. I do suppose that if there were a leak somewhere underneath combined with a bad door or rear hatch gasket, it could allow the smell to be pulled inside the truck, but that is kind of remote.

The sloshing in the dash is likely from a restricted heater core. There is also the possibility that the HVAC drain is blocked. The drain is located at the bottom of the HVAC housing where it meets the firewall.

Others have heard such a noise coming from the rear of the vehicle and determined that it was caused by trapped water in some of the body structure. Removing one or more of the plastic caps in the under side of the body allowed water out. Since I have never had the pleasure of having this happen to me or repairing a case were this noise was caused by water trapped in the body, I really can't help you with that scenario.

As far as things to replace in order of importance... That is kind of a loaded question. Unless you have money to burn, I would only replace what is found to be broken or worn out.