metallic "PING" when truck drops into gear

[willett]

Hey,


sometimes when i drop my truck into gear (often on an incline) there is a loud high-pitch PING noise coming from somewhere in the undercarrige. It almost sounds like someone is hitting a pan with a hammer. NP203, TH 400, 454

anybody else encountered this? Trans was rebuilt not very long ago because the reverse band ripped out of the casting, casting was replaced.

[THE "10" SILVERADO]

Hmm, not sure about a "pang" noise but mine had a rather distinctive "clunk"ish noise because my u-joints were worn and loose. New u-joints fixed that problem.

[INSIDIOUS '86]

Change your octane and see if there is a diffrence
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[willett]

its not a ping from the engine, its somewhere in the driveline

[DesertCat]

Originally Posted by THE "10" SILVERADO

Hmm, not sure about a "pang" noise but mine had a rather distinctive "clunk"ish noise because my u-joints were worn and loose. New u-joints fixed that problem.

Yup, 2nd that...

[INSIDIOUS '86]

It can resonate in the exhaust too. Maybe check your flywheel and see if its cracked were it mounts to the crank. A reverse band ripping out sounds violent.

Check rubber mounts and such as well they rip apart easily
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[Eyegore]

Originally Posted by DesertCat

Yup, 2nd that...

3rd it.

[68Timber]

Originally Posted by Eyegore

3rd it.

Yeah, check the u-joints.

[cory d]

my u-joint that lost some bearins didnt ping, it make a clunk. did it when i put it in got on the gas, let off, shifted and anything that would move the driveshaft. i would look for cracks in the flex plate

[willett]

how big is the view hole going to be on my bell housing?

[INSIDIOUS '86]

Should be an inspection cover that comes off with four screws. Very easy to see in there then
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[willett]

thanks, I'll have a look tomorrow

[Hulk Will Smash]

Mine does it occasionally when the truck goes into reverse. Definitely sounds like its coming from the flex plate or converter area. Like rapping the flex plate with a ball peen hammer.
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[willett]

Sounds like you have the same thing as me Hulk, I'll let you know what i see tomorrow

[83GMCK2500]

When parking on incline, set parking brake while holding foot on brake, THEN shift to P. Next time you go to drive away put it in gear THEN release the parking brake...

I bet the noise you hear is the park pawl in the transmission screaming in protest at the lack of parking brake usage.

[chevybuilder18]

Originally Posted by willett

Hey,


sometimes when i drop my truck into gear (often on an incline) there is a loud high-pitch PING noise coming from somewhere in the undercarrige. It almost sounds like someone is hitting a pan with a hammer. NP203, TH 400, 454

anybody else encountered this? Trans was rebuilt not very long ago because the reverse band ripped out of the casting, casting was replaced.

Sounds like the transmissions rear mounting rubber stud that pokes through the crossmember. Going down the inclines, the tranny might go up a few inchs and drop back down with slamming force. not only that the drive shaft conneted wieght and the transfer case also could make alot of noise along with the tranny. if you are running all time 4 with that gear drive, id also check into a new rubber mount cause both axles could be pushing the tranny up on inclines. the wieght of the vehicle could push on the deacelerating drive shafts and bind the back of the transmission up because engine and tranny are putting the slag back into the trans and engine. could cause some problems in the tranny also

[willett]

thanks chevybuilder, the case has been converted to part time but i'dd definitly take a look

[willett]

okay, after crawling around for a bit it seems like the noise is coming from the front half of my T case.

If i grab the front driveshaft and give it a quick hard spin I hear the 'DONGGGG". This is strange because the front driveshaft has rotational slop and the rear doesn't even flinch. If the T case is in neutral this doesn't happen.

How much slop (if any) as an np203 supposed to have?
The front moves back and forth, the rear does not.

I know this is a chain driven case and I am wondering if maybe the chain has had it?


What kinda T case is in your truck Hulk Will Smash?

[chevybuilder18]

Originally Posted by willett

okay, after crawling around for a bit it seems like the noise is coming from the front half of my T case.

If i grab the front driveshaft and give it a quick hard spin I hear the 'DONGGGG". This is strange because the front driveshaft has rotational slop and the rear doesn't even flinch. If the T case is in neutral this doesn't happen.

How much slop (if any) as an np203 supposed to have?
The front moves back and forth, the rear does not.

I know this is a chain driven case and I am wondering if maybe the chain has had it?


What kinda T case is in your truck Hulk Will Smash?

Chain could be stretched. i also forgot to mention, do you have the bars running from the motor mounts to the tranny and transfer case? looks like you could definately reinforce that. the K10 80s on up had these bars. they were like torsion bars from factory but i bet those bars kept this from happening.

[willett]

there are some funky support bars under there for sure! I'm pretty sure there are 2 that go to the t case, not sure about motor mounts though. I should also have mentioned that this truck is a k20

[motornut]

my 78 was a rear u joint looked fine too the sound seems to carry
has two bars run from the tcase/ fwd
the 88 has a bar from the transfer to the pass side bell housing bolt
and this is it in the 79(78 didn't have it,has the holes )

[chevybuilder18]

Originally Posted by willett

there are some funky support bars under there for sure! I'm pretty sure there are 2 that go to the t case, not sure about motor mounts though. I should also have mentioned that this truck is a k20

Yup... I worked on a K10 80 something but those bars were wierd. i never seen anything like it. 700r4 with the chain driven factory T case. someone blew the 305 in it, and the we put one in it for an old ex friend of mine that i dislike, and he blew the new engine up. but i kept the old 305 bare block and 416 casting heads for payment . Any ways this one had some triangle looking plates in between the block and mounts, we reused them. they went from engine to bottom of the tranny near the dust cover or w.e that thing is

[bmchevy1979]

Originally Posted by 83GMCK2500

When parking on incline, set parking brake while holding foot on brake, THEN shift to P. Next time you go to drive away put it in gear THEN release the parking brake...

I bet the noise you hear is the park pawl in the transmission screaming in protest at the lack of parking brake usage.

x2 the last time park actually worked in my k5 I heard this sound now it just acts like nuetral but the trans still works great and I refuse to but another auto tranny in it maybe a stick

[willett]

It definitely has nothing to do with the parking pawl

[chevybuilder18]

Originally Posted by willett

It definitely has nothing to do with the parking pawl

for a parking pawl, i have slammed my TH350 in park on accident, from 20 mph to a dead stop, it was on rocks but still, should of ripped my park out or atleast made the same metalic ping he is hearing. something wierd is happening. id check the front drive shaft and yokes. if those are fine, dig into the P203. If you have had gears, your probably gonna want them again. make sure if you do a nother chain drive, throw some tacky wheel bearing grease in a cast iron frying pan, throw it on a wood stove or grill and lay the new chain in it. or soak it in motor oil for a week, always does the trick getting the lube in the right spots for break in procedures. Ive done this with timing chains, learned it off my uncle, what a wierd way of doing things