2002 Pontiac Gran Prix 3.1 Valvetrain Clatter

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#1
Make
pontiac
Model
gran prix
Year
2002
Miles
80000
Engine
3.1 V6
Hi Batauto,
The vehicle is a recently purchased 2002 Gran Prix that had a lifter tick and typical leaky lower intake manifold corners. I changed out the intake manifold gaskets which took care of the antifreeze leak to the outside of the engine. While it was apart, I inspected the lifters and cam and found no reason for the lifter tick. It's got another 5000 miles on it since and the lifter ticking noise is still there and even a bit louder. I'm planning on pulling it apart again. Does this GM V6 have an issue with the lifters that I can pinpoint and replace?
The engine has about 80,000 miles. It was real clean inside.
Thanks in advance for any help,
Nick in WI
 

nickb2

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#2
Hi, sorry for late response, but this is a classic on pretty much any gm v6 of that era.

Collapsed lifter are very common, most don't worry about it. The engine will run fine. But for those that it annoys, a new lifter set can be had for cheap. Usually, when I do an upper job on these older pushrod engines, I always suggest a new lifter set. when you do the upper and lower intake, you have them straight in your face.

E-bay is full of cheap sets to get the last few miles out of this pushrod thing. I liked them, they came out of factory knocking on crank with low oil pressure. My paychecks back then were guaranteed. ;)

Something like this should do.

see link here. https://www.ebay.com/itm/12V-Lifter....1L+189Cu.+In.+V6+GAS+OHV+Naturally+Aspirated
 
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#3
My 1998 Chevy Malibu 3.1 had a minor lifter or crank knock brand new when started for less than a minute . Being an ex factory rep I insisted on it being corrected. After much discusion, etc. they tore it down and had to replace the crankshaft and a rod. Of course, knowing dealers as I do they may have said that just to get reinbursed from the factory??? I never saw the crank or rod. But at least the knock was gone and still is.
 
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#4
JACK My 2¢ - A dealer's mindset, likely they had a crank and rod from a CPL and your model matched - sound likely to you?
 
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#5
kev2-- could be. I do know they tore it down because I found a nice pro 10 mm socket still stuck on a bolt under the engine years later. It was not mine and the car has never been in any other shop since the repair. My guess is it really was a crank. Doesn't matter, it's history now.
 

nickb2

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#6
Why is it that it always the 10mm socket that gets lost. All my pro sets no longer include a 10mm socket. I dropped most of them in an engine bay of some sorts and just don't care anymore. If is a hassle to get it, just give, give keys to client, let some guy like jackc find decades later.

When I go to canadian tire for tools, I buy 4 10mm sockets just to do a month of work. Then when that backfires, I go steal my co workers 10mm sockets, and that is just to funny when I drop that all to familiar sound. My buddies at work hear me say "shyyte" then they laugh at my arse and ask, (did you just drop another snap on 10mm?) Yup, thats why I buy ten or 16 of these a year.

I found a nice pro 10 mm socket still stuck on a bolt under the engine years later.
 
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#7
Thanks nickb2! I really appreciate the response.
I pulled the engine apart yesterday. Everything looks clean just like what it did 5000 miles ago.
The lifter making all the noise did not come apart easily. the inner piston was stuck in the bore. With a little prodding it came out. There was a little bit of crud stuck inside. I hosed it down with brake cleaner and reassembled it. It functions like a new lifter should.
I'm still replacing the whole set today though.
I'll report back when it is running!
Later,
Nick in WI
 
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Hi nickb2,
Got it all assembled and running last night. The valve clatter is exactly the same as what it was with the original parts.
All the camshaft lobes looked like new as do the valve stem tips, rocker tips, and pushrods.
The engine looks great inside. It uses about a quart of Mobil 1 in 6000 miles. It runs great; just sounds terrible. And I don't mean the "normal" tappet clatter these engines make. It sounds like a collapsed lifter(s.)
There's no dash light on for low oil pressure. I may look for a port to check it though anyway with a mechanical gauge.
It's my 17 year old daughter's regular (cheap) driver. She's embarrassed by it due to all of her friends diagnosing it as a bad engine (in their 17 year old perceived experience of the world.)
Not sure what direction to go in from here. What do you think? Attached is a movie I took prior to taking it apart. Like I said above, it sounds the same now with the new lifters.
Thanks in advance,
Nick in WI
 

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#9
I would disable one cylinder a a time to see how the noise was affected. Due to the "waste spark" design, simply removing a spark plug wire will essentially kill two cylinders, so the best way is to remove all wires (one at a time) from the coils and put a paper clip up into the plug wire end, and then reinstall the plug wire onto the coil. Now you will have a engine that will idle, and you can easily "kill a cylinder" by touching a grounded wire to each paper clip (carefully).
Wild card would be cracked flexplate.