04 explorer, pulsing when you let off the gas

[fadeds]

3 days ago I bought an 04 explorer with 87k miles. The truck is extremely clean. I test drove it and everything seemed fine. I got a deal on it because my brother is an employee there. So when I talked to the manager he tells me everything the truck needed for inspection and everything that there service department found wrong. Everything was minor, or so I thought. They told me that above 40mph there was a pulsing, which I didnt feel in the test drive. He tells me the mechanic says its gonna need tires and thats whats making the pulsing, ok I'll get some tires. Well when Im driving home about ten minutes into my ride everytime I get above 45mph and let of the gas I feel this vibration. The only way I could explain it is it felt like a bent drive shaft or something of that sort. It only does on deacceleration. My problem is that with the deal I got I bought the truck as is, so there probably not gonna fix it. I took it to a friend who's a mechanic and he said he's never felt anything like it in 35 years. He's gonna look at it next week. Does anyone have a clue on what it could be? I'm really praying its not the tranny! Any info would be most appreciated. Thank you.

 

[BrooklynBay]

Welcome to this forum! Check the driveshaft, U joints, bearings, and balance the wheels.

 

[88racing]

Welcome

 

[fadeds]

That's what my wife's grandfather said also. Thanks for the reply. I'm glad to be a member here. These kind of forums are awesome, having people to help you out like this makes the blood pressure stay at the recommended levels. Thanks Again.

 

[grof]

my 2004 explorer had similar problem, it turned out to be rear axle nut wasn't tight.

 

[fadeds]

Well I have an update to my issue. The other day I turned into a parking lot with a 20 degree or so slope and the tranny slipped a bit. Also before I bought the truck I had no idea that the tranny was a closed system. Why would they design it like that? You cant even check your fluid levels, or can you? Hopefully tomorrow when I bring it in to the shop they have more of an idea of what the hell is going on.

 

[BrooklynBay]

Check the sticky thread called the 5R55W fluid fill for information on how to check the fluid level, and add fluid if necessary.

 

[fadeds]

So I took my truck to a tranny shop yesterday. There theory is that the last person to service the tranny used the wrong fluid and it isn't downshifting properly. Has anyone heard of this before? This is all new to me. I've had Chevy's for the last 15 years and never had a tranny problem. I have to say that the explorer is alot smoother ride than my blazers were.

 

[markfothebeast]

Some transmissions are very particular with the fluids that you use. My old 5-speed Mustang with manual trans used auto trans fluid. But if you think about it transmission fluid serves 3 purposes. Cooling, lubrication, and hydraulic pressure.

 

[fadeds]

well i got new tires this afternoon and the vibration went away. I still feel a slip sometimes when going from park to drive or reverse. Also when it gets up to 3rd gear if i back off on the gas then tap on the gas you can hear a thud. like something isn't catching. the u-joints have been checked, i wonder if its something in the rear diff.

 

[waskly]

Well I have an update to my issue. The other day I turned into a parking lot with a 20 degree or so slope and the tranny slipped a bit. Also before I bought the truck I had no idea that the tranny was a closed system. Why would they design it like that? You cant even check your fluid levels, or can you? Hopefully tomorrow when I bring it in to the shop they have more of an idea of what the hell is going on.

trans is low on fluid if it slips in these conditions.