Stuck lifter?

[xtremerevolution]

I'll see how things go on Saturday when I replace the pushrods and clean out all the lifters. If I'm still getting false knock, I'll do what Alec recommended.

 

Very good information man.

[xtremerevolution]

The Regal is parked until Saturday.

 

The ticking noise got louder on my way home. Very, very little power. I tried to accelerate past half throttle once, and heard two exhaust popping noises. I drove 60 mph the whole way, and the engine felt like it was about to die. Just ran really rough, and had very little power, and sounded really groany, if that makes any sense. Accelerating up a hill was a nightmare. I can only guess the car was retarding timing a LOT because I could barely go up a hill at 2/3 throttle without downshifting, which I didn't feel like doing given the car's condition.

 

When I parked it, it sounded like a misfire in the exhaust. Definitely wasn't even.

[RobertISaar]

that popping was likely a VERY retarded amount of spark advance... cars going into DFCO do that as well when they drop down to like 9* of advance to help with compression braking.

 

i imagine the cat was NICE and glowing...

 

and your fuel economy has probably went to hell with it.

[xtremerevolution]

that popping was likely a VERY retarded amount of spark advance... cars going into DFCO do that as well when they drop down to like 9* of advance to help with compression braking.

 

i imagine the cat was NICE and glowing...

 

and your fuel economy has probably went to hell with it.

 

Didn't bother to look at the cat. Probably was running rich as hell. Either way, whatever was making that valvetrain noise just got fed up and failed completely.

 

This better not be a valve. I really don't feel like pulling off the head again. I'm realistically thinking pushrod or lifter.

[Night Fury]

Two things:

 

1. Andrei maybe the knock sensor is actually registering valve train noise?

 

2. Thanks Robert for that information! My brother drives a Nissan 250SX(think that's what its called) Anyways, he's constantly complaining about a bit of a rough spot in the engine running, I rode with him once and I literally told him it felt like something was pulling timing but I had no idea what....

[xtremerevolution]

Two things:

 

1. Andrei maybe the knock sensor is actually registering valve train noise?

 

2. Thanks Robert for that information! My brother drives a Nissan 250SX(think that's what its called) Anyways, he's constantly complaining about a bit of a rough spot in the engine running, I rode with him once and I literally told him it felt like something was pulling timing but I had no idea what....

 

I'm 100% sure the knock sensor is registering valve train noise. Why else would the car run extremely well right up until the temp needle hits the first hash, then start running like complete crap. The only explanation is that the ECM ignores the knock sensor up until it hits that temperature threshold.

[Night Fury]

Oh, I thought we were trying to determine the cause here my bad lol

[xtremerevolution]

Oh, I thought we were trying to determine the cause here my bad lol

 

Its ok Buck, we still love you.

[Galaxie500XL]

I had a Pontiac V-8 years ago that did something similar...I know we're talking a totally different engine, one that had no computer controls..

 

Anyhow, the problem turned out to be a bad timing chain. As the motor warmed, the chain would stretch and do all sorts of bad things to the cam timing. Ran like crap, and actually sounded as if it had a rod knock.

 

Anyhow, on our cars, the knock sensor is going to hear that noise, and immediately begin backing down the timing to save the engine, somthing my poor old Pontiac coudn't do. That's why it seems sort of OK when it's cool, and gets progressively worse as it heats up.

 

I may be totally out in left field here, but after following this thread for awhile, I'm beginning to think this may be where the trouble lies.

 

What do you all think?

[Night Fury]

Its ok Buck, we still love you.

 

yay!

[Addicted to eaton]

I had a Pontiac V-8 years ago that did something similar...I know we're talking a totally different engine, one that had no computer controls..

 

Anyhow, the problem turned out to be a bad timing chain. As the motor warmed, the chain would stretch and do all sorts of bad things to the cam timing. Ran like crap, and actually sounded as if it had a rod knock.

 

Anyhow, on our cars, the knock sensor is going to hear that noise, and immediately begin backing down the timing to save the engine, somthing my poor old Pontiac coudn't do. That's why it seems sort of OK when it's cool, and gets progressively worse as it heats up.

 

I may be totally out in left field here, but after following this thread for awhile, I'm beginning to think this may be where the trouble lies.

 

What do you all think?

 

you know, He has a Very Very good point. i Didn't think about that. Its gettin up there in miles..

[xtremerevolution]

I had a Pontiac V-8 years ago that did something similar...I know we're talking a totally different engine, one that had no computer controls..

 

Anyhow, the problem turned out to be a bad timing chain. As the motor warmed, the chain would stretch and do all sorts of bad things to the cam timing. Ran like crap, and actually sounded as if it had a rod knock.

 

Anyhow, on our cars, the knock sensor is going to hear that noise, and immediately begin backing down the timing to save the engine, somthing my poor old Pontiac coudn't do. That's why it seems sort of OK when it's cool, and gets progressively worse as it heats up.

 

I may be totally out in left field here, but after following this thread for awhile, I'm beginning to think this may be where the trouble lies.

 

What do you all think?

 

I put my head as close as possible to the timing cover and that is certainly not where the problem is coming from. In addition, the repetition of the noise wouldn't be precisely matched to one valve's movement and increase in repetition with each increase in RPMs. Its very, very consistent, predictable, and repetitive. A worn or stretched timing chain wouldn't be that repetitive. Plus, the noise happens the moment you turn the car on when cold.

 

Also, it doesn't gradually get worse. Its absolutely wonderful until it reaches the first temperature hash mark, and at that point the ECM flips the switch to start reading the knock sensor inputs and the car instantly starts running like shit. Its without a doubt false knock coming from the valvetrain.

[Galaxie500XL]

You're probably right...but I did come up with an idea that could eliminate the possibility...take the front valve cover off, and turn the engine forward and back by hand, watching the movement of the rocker arms. If you can turn the engine several degrees before affecting the movement of the valvetrain, immediately after reversing rotation of the crank, there's a lot of slop in the chain.

 

Otherwise, I'm barking up the wrong tree.

[xtremerevolution]

You're probably right...but I did come up with an idea that could eliminate the possibility...take the front valve cover off, and turn the engine forward and back by hand, watching the movement of the rocker arms. If you can turn the engine several degrees before affecting the movement of the valvetrain, immediately after reversing rotation of the crank, there's a lot of slop in the chain.

 

Otherwise, I'm barking up the wrong tree.

 

I like you, so don't take this the wrong way. I'm not trying to shoot down every idea you have, but here's why what you mentioned wouldn't work.

 

The timing chain on a 3800 isn't like that of a small block chevy. These have a timing chain tensioner with a hefty spring. What happens if you turn it in the normal direction is that the tight end will receive the force, as it normally should. If you reverse the engine, you'll be putting force on the end that's held down by the dampener, and you'll have a brief rotation during which the cam won't move because you're putting force on the slack that the tensioner was picking up.

 

Here's what I'm talking about:

 

 

So if you put tension on the end that the dampener is pushing down on, your valves won't move, even on a brand new crate engine.

 

This is contrary to a small block chevy engine, which won't have a tensioner to pick up the slack from a chaing that could gradually stretch.

 

 

This is why 3800 chains are labeled as lifetime chains, because even if it does stretch a bit, the tensioner will pick up the slack.

[Galaxie500XL]

Xtreme;

 

Absolutely not a problem. I had totally forgotten about the tensioner on the Buick V-6....

 

I would assume if the tensioner failed, there would be all sorts of ugly noises...

 

 

It's an odd problem, hope it gets sorted out soon!

[xtremerevolution]

Xtreme;

 

Absolutely not a problem. I had totally forgotten about the tensioner on the Buick V-6....

 

I would assume if the tensioner failed, there would be all sorts of ugly noises...

 

 

It's an odd problem, hope it gets sorted out soon!

 

Yeah, there would be a lot of ugly noises, and even more ugly noises coming from me because I'd have to pull a ton off the engine to get the timing cover off.

 

Taking it apart on Saturday, so I'll take pictures and let everyone know when that's all done.

[RobertISaar]

fun facts for future reference:

 

GM OBD1 uses wideband knock sensors... so more or less, 1 sensor could be used in any engine reliably. the knock filter(in the MEMCAL on OBD1) filters out MOST, if not all noise that does not occur at the natural knock frequency of the enigne(which is determined by bore). a 3.8" bore(all buick 3.8 and 3800s ever IIRC, chevrolet 3.8 was a different bore/stroke combo) correlates to 5939Hz. if you can generate that tone(i like using audacity), you'll notice it's an annoying noise...

 

i've heard of some dyno operators having someone tap into the knock sensor and listening to the engine as it was being tuned. if they heard the tone, they let the operator/tuner know that knock was happening.

 

now AFAIK, GM only made 3 knock sensors for OBD1 engines... i believe they MIGHT be tuned to different sensitvites... a good example is a thirdgen camaro with a TPI 305 swapping in the hotter TPI350 cam... a lot of people who did this picked up MASSIVE amounts of knock according to the ECM, but could find no trace of it at all on the plugs or pistons. then they swapped in a TPI350 knock sensor, and all of a sudden, false knock was gone and they made more power due to the ECM not pulling timing. i believe that the 350 sensor was less sensitive to noises other than real knock.

 

now, what does this have to do with a L27? well, if you are STILL picking up what you determine to be false knock, you should look into getting ahold of a less sensitive knock sensor. i BELIEVE the 3800s would have the most sensitive knock sensor available for a few reasons:

 

roller cam

roller rockers(?)

balance shaft

a timing chain with tensioner

the massive amount of timing that is run to get best power/emissions out of the motor

 

now, determining what would have a less sensitive sensor MAY be able to be done with looking up some cross-references as to what used what sensor and some reasonable assumptions.

[xtremerevolution]

Couldn't I just relocate it and wrap it in something and call it a day?

 

I'm hoping that fixing this valvetrain noise will solve my problems.

[RobertISaar]

Couldn't I just relocate it and wrap it in something and call it a day?

 

that's like making sure you drop a steak in the dirt multiple times before cooking... why? GM gave us some incredibly cutting-edge stuff back in the day, it would be a shame not to use it to it's fullest potential.

[xtremerevolution]

that's like making sure you drop a steak in the dirt multiple times before cooking... why? GM gave us some incredibly cutting-edge stuff back in the day, it would be a shame not to use it to it's fullest potential.

 

Because its making my car a miserable wreck, lol. I'm, sure it would be great for a stock car.

 

I'll see how things go on Monday. I went to the yard today and got lids for the fuse boxes under the hood (since I lost mine), an upper intake insert, 4 lifters, all 3 coils in great condition, and a spark plug wire guide for the front bank for $30. Woot!

[alec_b]

Why only 4 lifters?

[xtremerevolution]

Why only 4 lifters?

 

Because I only wanted to get them in case a few of mine were bad. I'll be taking mine apart and cleaning them thoroughly, so I figured it would be good to have some spares just in case. That, and I didn't feel like paying for all 12.

[jtwmechanic]

is it possible that it could be piston slap?

[xtremerevolution]

is it possible that it could be piston slap?

 

Didn't have piston slap before, so I can't imagine why it would start now and be that severe. I have a very strong feeling its not piston slap. It sounds exactly like a valvetrain noise.

[jtwmechanic]

havn't heard piston slap in your particular engine but in toyota and honda piston slap sounds just like a loose rocker or stuck lifter and isn't usually audible at idle until it gets a lot of play and gets increasingly louder with rpm to a point. this symptom is a very constant. usually will not be noticable until engine starts to warm. but i'm probally wrong, just a thought.