1999 GMC Safari Knocking!

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Old 08-06-09, 11:18 PM
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1999 GMC Safari Knocking!

Ok guys... Bought 1999 GMC Safari ALL Options/Loaded for 400.00 200k

we will be using it for like 1 or 2 trips per summer - nothing else the issues is

there is a Knocking in the engine

Knock happens on cold or hot doesnt matter

Start Engine - idle - it has a knock
Rev up - knock goes faster but pretty much stay same pitch/tone

let off the gas knock slows down

so the knock is changing speed depending on acceleration

doesnt seem to loose any power at all. no stalling, stuttering, etc..

The only lights that come on in the dash happens at idle the check guage light and Service engine light come on at idle & the oil pressure guage fluxes at idle..

rev the motor and all goes back to normal

Code reader states BANK 1 Running Rich .. BANK 2 Running Rich

The guy I bought it from kept claiming a Mechanic replaced the Valve cover gasket & checked the lifters and such --

he claims its a lifter ticking

We are going to change to 10-40 since the vehicle will only be run during summer, use better filter, & run some good cleaner through the engine to help remove some carbon


from the description ive given.. any ideas?

is this a 400.00 Rod knock ready to Die or is it a lifter tapping

we plan on taking a trip on sept 4th
I had planned on replacing the oil & filter, changing air filter, & running some good cleaner through it

Someone recommended I cut open the oil filter and see if there is metal shavings in it. this would indicate rod knock

I appreciate any help and advice
Thanks
 
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Old 08-07-09, 05:29 AM
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With 200k miles, and oil pressure fluctuating at idle, I would guess that it is a rod knocking. You can change the oil and run the cleaner, but I doubt it will help. A rod knock will get quiet when/if the cylinder is killed while the engine is running, and sometimes will get quiter on deceleration. Either way I would not take it on a trip until the noise was positively identified and fixed.
 
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Old 08-07-09, 03:08 PM
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any other ideas and suggestions?

i mean ive heard exhaust leak can sound like this
a power steering pump going out can sound like this
and misc other things.

I am hoping this guy wasnt being a ******* and lying about the work. I should have asked for paper work showing where he had it in a shop.

everything else on this van is in excellent shape. body, interior, exterior all perfect

starts right away, runs strong, transmission shifts without any notice at all

its just this friggin Knocking noise thats driving me mad with worry

if need be ill pack my CRX up and use it for the trip But lol I dont like packing a CRX full of camping gear
 
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Old 08-07-09, 03:16 PM
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Normally you can find a rod knock by disconnecting 1 spark plug at a time. Lifters have always been more of a tap or click/clatter in my mind. P/S pump? Never heard that. Exhaust leaks are more of a "chuff" sound at idle in my experience, depending on where it is.

Lifters, bad pulleys, alternator, P/S pump can normally be isolated with a mech's stethescope. Other noises with a length of hose held to your ear and moved around the engine bay and along accessories.
 
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Old 08-07-09, 05:11 PM
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Is there ANY change form Neutral to Drive.....??????

Ive seen quite a few broken flywheels that make a rod knock noise......

I agree with twister......I wouldnt go anywhere past walking distance from home until the noise is Identified and fixed....It will only get worse , not better....And when he has had enough, he will blow apart in spectacular fashion, and leave you standing on the side of the road with your thumb sticking out.....
 
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Old 08-07-09, 08:36 PM
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i have never noticed any change from neutral to drive

it just seems to be a single tapping noise. no double tapping, or any variance

just a slow steady knock in perfect rythm - you give it any gas in in neutral, park, or otherwise and the knocking speeds up with it again in perfect rythm

I work in a Basic Shop. Oil, Tires, Batteries, misc work - no deep engine work

this guy came into the shop and wanted to take the 4 Brand new tires from this VAN and put them on his other van

well they are different Size Rims, & Different Lug Patterns, so we could not change em out.

I asked him why he is changing em over he said. "I am going to scrap this van and use the other" I asked him why and his answer was one of the lifters keep collapsing in this one
and its causing it to knock

he swore a mechanic pulled top end off and found the collapsed lifter and thats what it was. but it fell again

-- sooo after listening to it, and looking over the underside and seeing its in excellent shape just that knocking

we concluded ok its a carbonized valve not closing all the way thats tapping or a collapsing lifter due to carbon

we had no thought of Rod knocking

I asked they guy how much he would sell it for and he said "since I cant really swap the new tires out ill sell it for the price I paid for the new tires" he settled on 400.00 and the tires in total which were actually Bought from us were about 400.00 total

so it made sense to me and I thought it was a honest and good deal

if this turns out to be a rod knock im basically out 400.00 and whatever the cost to fix it.

now my next situation is

I have a Grandfather who operates a shop and small private dealership

however he is like 30 miles away

should I risk driving to his shop and letting em tear this thing apart? or what?
 
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Old 08-07-09, 09:56 PM
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You have two options...

1) risk driving it , since it will be torn down anyway, once it reaches its destination, or
2) Tow it in, and minimize the damage in the hopes that it can be repaired.

Something to think about....."Does it misfire??"... Usually a collapsed lifter will KILL a cylinder, and cause a misfire......A ROD-KNOCK typically will not cause a misfire, but will shake a bit from an out of balance condition..
 
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Old 08-07-09, 10:22 PM
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"Something to think about....."Does it misfire??"... Usually a collapsed lifter will KILL a cylinder, and cause a misfire......A ROD-KNOCK typically will not cause a misfire, but will shake a bit from an out of balance condition.. "

hrm.

I have had no misfires. none on code reader and none noticed

and have not felt any unusual shaking or vibrations either

its got a really smooth ride just the knocking that scares me

I may have confused a collapsed lifter that was FIXED with a Pushrod issue

it seems possible to me that a bent pushrod would indeed cause a knocking noise and would cause valves to not properly close and open. which in turn could cause spark knock

-- carbon build up could have caused the bent pushrod as well.

whats the take from you guys on this?
 
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Old 08-08-09, 10:13 PM
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Updated

UPDATE ... UPDATE


Ok guys taking all the advice from here and other forums and my boss who is a veteran mechanic.

I tore out the center console. and popped the hatch off the engine (I call it a dog house) lol

Vortec V6 4.3 I believe

on the left hand side (Passenger side) I hear it plain as day a tapping / knocking - more like a tap. tap. tap. tap. that is in rythm with the speed of the engine

accel it taps faster
decel it taps slower

---------------------
sounds like something is tapping right beneath the valve cover -- I stuck a Long thin funnel end to the valve cover and cupped my whole ear into the top end of the funnel

and you can hear it load and clear

so something on the top end valve train is causing a knock/tap on the valve covers its gotta be top end

whats my next step aside from popping the cover off the engine because LMAO there is NO room to work in this thing. you should see the rig I had to make to just get the hatch bolts undone for access

im am wondering if I shouldnt do what I listed previously

Brand new oil, good filter, change air filter, and decarbonize this thing as much as possible

whats your take on it guys?

I hear that running a quart of Tranny fluid through the oil will also help clean carbon out? wouldnt this foul the plugs to hell?

thanks guys
 
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Old 08-09-09, 06:49 PM
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Fixed it / solved

OK Guys Awesome news


Fixed it..

it must have been a collapsed lifter & all I did was I flushed the oil out, put in brand new 5-30, used a High Mileage oil filter, replaced air filter,

and added 1 pint not even a Quart of Marvel Mystery Oil to the crankcase

...let it run idle for 15 minutes, then I kept it revved for about 5 mins or so, then drove around the block a bit and what do ya know the lifter is clearing up and starting to function again

the tick is low and intermittent which signals to me that there is gunk and sludge built up against the lifters and causing them to not pump up properly

imma run this a bit .. add some fuel treatment in a few days, & see where she goes

it looks like I will be taking this van on our vacation after all
 
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