What is this "thud" after starting

Virtually every time I start my `04 Ranger (4.0 Auto) I hear, and feel a thud coming from the engine\transmission area, as best I can tell from sitting in the drivers seat. Sounds like a stuck brake caliper when it releases. I am sure it is not the A\C clutch, the sound is too loud for that. Can happen on completely level ground with no contact with the break pedal, no application or release of the parking brake. So am sure it is not in the wheel assembly\suspension. Just in here reading post and came up with this puzzle, will pay more attention to it in the coming days and post anything I find. Any clues?

Reply to
Jesse
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Broken motor mount, maybe? Just a guess on my part. SC Tom

P.S. Wish my desk was smart enough to post. LOL.

Reply to
SC Tom

I would almost bet it is the blend door for the AC/heat. Just about every truck I have owned will make this noise. When shutdown, it seems the door opens and when started and the vacuum builds, the door slams shut. Making the thump you hear.

Reply to
Marlin Singer

That sounds like something to check into. It is always just a couple of seconds after starting. Do you think it would do that in any position on the heater control, or would there be a position that would cancel it out?

Reply to
Jesse

My '99 F350 does it too, it is the blend door making the noise in mine. Just a "character flaw".

Spdloader

Reply to
Spdloader

Not sure, you might try making sure everything is off before you shut down, and if you park on a slope where you are nose up, you might try nose down. I have found it to be no big deal, just quirk.

Reply to
Marlin Singer

I think you may have the same "problem" a lot of folks complain about. It's possible it's a vacuum controlled door in the ventilation plenum cloing (or opening, I can't remember which way it goes)

Can you feel it in the floorboard when it happens? If so, that'd be my guess. Nothing to worry about.

Reply to
invalid unparseable

I think it probably is.

is the A/C OFF, Fan OFF Temp @ cold ?

I had the same thing on starting but after turning all the dials to 'off', it stopped.

After that, I once inadvertently left the dials on A\C what I got home, and when I started up next AM,, it was back..THUD!

Reply to
Rudy

I had a concern that is was the transfer case kicking the 4X4 in and out. But I think and can safely agree it is nothing to worry about anymore. Thanks for the info all.

Reply to
msyjsy

I have a similar thump when I start up my F-550 PSD, usually about 2-3 seconds after ignition. The truck tech says it has to do with some sort of damper thingie in the heating system, and is completely normal. I've been hearing it now for 2 years and 30,000 miles without any problem developing.

Regards, John Kinney

Reply to
John Kinney

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