mystery thump
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Topic author - I am smitten with my van
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- Joined: Sat Jul 21, 2007 8:31 am
- Location: West Orange, NJ
mystery thump
Did this ever happen to anyone? This is weird. I have 1988 Astro 4.3 auto. with 115,000 miles on it, all stock all original.I have had it 1 1/2 years. Sometimes when I stop at a light and I am just sitting there in drive at a dead stop I feel a thump. It is about 10 to 15 seconds after I have come to a complete stop. I feel a thump like I was rear ended. The van actually feels like it is trying to move forward. The first time it happened I looked in the mirror to see who rear ended me but no one was there. Anyone ever have this happen or hear of it happening?
Re: mystery thump
My 93 did that for awhile. Then I did some brake work and it stopped. It appeared one of the caliper pistons was sticking and the thump was it popping out and slamming into the rotor.
98 Safari RWD. Stock.
Do you smell what Barack is cookin ?!?!
Do you smell what Barack is cookin ?!?!
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- I get chills without my van.
- Posts: 93
- Joined: Thu Sep 21, 2006 5:01 pm
- Location: Port Moody, BC
Re: mystery thump
I have the exact same issue with my van and I haven't been able to figure it out.
"Damn, youse funny lookin'..."
Todd
Former owner of the Rocket van - v8 powered 1990 Astro
Tall man, no van
Todd
Former owner of the Rocket van - v8 powered 1990 Astro
Tall man, no van
Re: mystery thump
My 89 used to do this until I installed a rebuilt transmission.
I didn't do the transmission swap because of that, though. I replaced the transmission because the original one was slipping when it shifted and was getting hot during normal usage (it would peg the transmission temperature gauge with city driving).
But with the new transmission came an end to the 'bump' at stop lights. I just figured that this was caused by a belated shift back into 1st after the van stopped.
I didn't do the transmission swap because of that, though. I replaced the transmission because the original one was slipping when it shifted and was getting hot during normal usage (it would peg the transmission temperature gauge with city driving).
But with the new transmission came an end to the 'bump' at stop lights. I just figured that this was caused by a belated shift back into 1st after the van stopped.
Rob Shaver
1989 Astro 305 with an MSD 6A ignition and a dash-mounted MSD timing control, a 4160 Holley 465 cfm four barrel carb, and an HEI distributor.
Moog 625 front springs and Energy Suspension poly bushings. Rear OEM sway bar. Edelbrock shocks.
1989 Astro 305 with an MSD 6A ignition and a dash-mounted MSD timing control, a 4160 Holley 465 cfm four barrel carb, and an HEI distributor.
Moog 625 front springs and Energy Suspension poly bushings. Rear OEM sway bar. Edelbrock shocks.
Re: mystery thump
Had the same condition on my 96 2wd as long as I owned it. I also believe it was a downshift. Never bothered me that much guess I got used to it.
Brandon
Bay City, MI
1997 Astro LT 4x4 48,000 Miles,
Custom Lift: 3" body spacers, torsion keys,
4" leaf spring relocation mounts (by ME),
added a leaf spring from a 94 S10 blazer.
All this gives me 5-6 inches of lift.
General Grabber AT2 31X10.50R15
Custom fit Brush guard
Western 7' 6" plow pictures coming soon...
1997 Buick Century 198,000 miles
Bay City, MI
1997 Astro LT 4x4 48,000 Miles,
Custom Lift: 3" body spacers, torsion keys,
4" leaf spring relocation mounts (by ME),
added a leaf spring from a 94 S10 blazer.
All this gives me 5-6 inches of lift.
General Grabber AT2 31X10.50R15
Custom fit Brush guard
Western 7' 6" plow pictures coming soon...
1997 Buick Century 198,000 miles
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Topic author - I am smitten with my van
- Posts: 45
- Joined: Sat Jul 21, 2007 8:31 am
- Location: West Orange, NJ
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- I finally get the smurf thing
- Posts: 161
- Joined: Sat Sep 23, 2006 2:44 pm
- Location: Birmingham, MI
Re: mystery thump
That has happened to me. It is the Transmission, well it was for me at least, I had it rebuilt that problem is fixed just lots more that I have to deal with.
99 sle awd safari
Another addition to cash for clunkers.
Another addition to cash for clunkers.
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- I get chills without my van.
- Posts: 68
- Joined: Mon Mar 19, 2007 6:56 am
- Location: Saginaw, Michigan
Re: mystery thump
My '93 doesn't particularly thump, but it definiitely jumps at stoplights like I have been "nudged" from behind. After careful inspection, I found that it was the air conditioning compressor, releasing its clutch from the engine, causing a surge in the drivetrain. Possibly an after affect from swapping in the V8?
Just what is happening with mine, your dilemma may be different.
Just what is happening with mine, your dilemma may be different.
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- I am smitten with my van
- Posts: 29
- Joined: Sun Feb 25, 2007 6:46 am
- Location: Nevada, TX
Re: mystery thump
A local top-notch tranny guy told me that it's the tail of the tranny.
I had taken a 96 Astro tranny in for a bench rebuild. When I went to pick it up, I noticed that the tail was packed with grease. I asked why. He asked me if I'd ever stopped and a few seconds later it felt like someone bumped into me. He said it was the driveshaft popping back and forth. Packing the tail with grease, will avoid the problem.
I had taken a 96 Astro tranny in for a bench rebuild. When I went to pick it up, I noticed that the tail was packed with grease. I asked why. He asked me if I'd ever stopped and a few seconds later it felt like someone bumped into me. He said it was the driveshaft popping back and forth. Packing the tail with grease, will avoid the problem.
Re: mystery thump
Be careful that the grease that you use in compatable with the trans fluid. I don't know much about it, but I'll bet you could mess something up if you use the wrong thing.97TurboAstro wrote:A local top-notch tranny guy told me that it's the tail of the tranny.
I had taken a 96 Astro tranny in for a bench rebuild. When I went to pick it up, I noticed that the tail was packed with grease. I asked why. He asked me if I'd ever stopped and a few seconds later it felt like someone bumped into me. He said it was the driveshaft popping back and forth. Packing the tail with grease, will avoid the problem.
You can replace the cylinder like bushing that the yoke rides in in the tail shaft, it can cause this when worn. So can a groove in the yoke.
I've heard that out of adjustment rear brakes and/or bad shocks can aggravate this condition because of the nose-dive thing.
Most of my rides bump, shake, and lurch from old age or high miles. I don't mind.
Re: mystery thump
Right On!rlsllc wrote:Most of my rides bump, shake, and lurch from old age or high miles. I don't mind.
As long as its not from doing this... http://youtube.com/watch?v=Xuow49t-Bjw
Brandon
Bay City, MI
1997 Astro LT 4x4 48,000 Miles,
Custom Lift: 3" body spacers, torsion keys,
4" leaf spring relocation mounts (by ME),
added a leaf spring from a 94 S10 blazer.
All this gives me 5-6 inches of lift.
General Grabber AT2 31X10.50R15
Custom fit Brush guard
Western 7' 6" plow pictures coming soon...
1997 Buick Century 198,000 miles
Bay City, MI
1997 Astro LT 4x4 48,000 Miles,
Custom Lift: 3" body spacers, torsion keys,
4" leaf spring relocation mounts (by ME),
added a leaf spring from a 94 S10 blazer.
All this gives me 5-6 inches of lift.
General Grabber AT2 31X10.50R15
Custom fit Brush guard
Western 7' 6" plow pictures coming soon...
1997 Buick Century 198,000 miles
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- I sleep in my van
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- Joined: Sat Sep 09, 2006 8:28 pm
- Location: Canton/Holly Springs GA (Atlanta)
Re: mystery thump
Yea, the splines get dry and the yoke will bind on the splines when the angles and torque and the moon and the stars all line up just right.97TurboAstro wrote:A local top-notch tranny guy told me that it's the tail of the tranny.
I had taken a 96 Astro tranny in for a bench rebuild. When I went to pick it up, I noticed that the tail was packed with grease. I asked why. He asked me if I'd ever stopped and a few seconds later it felt like someone bumped into me. He said it was the driveshaft popping back and forth. Packing the tail with grease, will avoid the problem.
There have been various fixes for it.
Some times the yokes have a small hole for a tidbit a trans fluid to lube the splines.
I thought there was a special "grease" for that application.
I would guess that any non-dino oil that was "wetted" onto the splines would last awhile.
My 90 Astro never did it but my 99 dually did it all the time.
I was told getting my beauty sleep was a waste of time.
1990 Astro (Z motor) mostly original @ 343,584 miles (552,944.8488960001 Canadian) (03/2008). Bad startup puff. Starting to spray for skeeters. Gone 06/07/08.
1993 Astro with a bad W motor. Parked next to a chicken coop in Talking Rock GA
I'm 'tween Canton and Holly Springs (North NorthWest of Atlanta GA)
I haul bottled water everyday- between 500 and 2500 pounds (226.796185 and 1,133.980925 Canadian) INSIDE the van.
1990 Astro (Z motor) mostly original @ 343,584 miles (552,944.8488960001 Canadian) (03/2008). Bad startup puff. Starting to spray for skeeters. Gone 06/07/08.
1993 Astro with a bad W motor. Parked next to a chicken coop in Talking Rock GA
I'm 'tween Canton and Holly Springs (North NorthWest of Atlanta GA)
I haul bottled water everyday- between 500 and 2500 pounds (226.796185 and 1,133.980925 Canadian) INSIDE the van.
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- I get chills without my van.
- Posts: 93
- Joined: Thu Sep 21, 2006 5:01 pm
- Location: Port Moody, BC
Re: mystery thump
This is interesting.
http://answers.yahoo.com/question/index ... 123AA8D2jv
http://answers.yahoo.com/question/index ... 123AA8D2jv
"Damn, youse funny lookin'..."
Todd
Former owner of the Rocket van - v8 powered 1990 Astro
Tall man, no van
Todd
Former owner of the Rocket van - v8 powered 1990 Astro
Tall man, no van