Engine Knocking... Video added

[tfitz2001]

Guys:

The 1990 Q, 207,000 miles, is having some real issues. View the video to get an idea of the sound that I am hearing:

[youtube]http://www.youtube.com/watch?v=L9cIC-SE ... e=youtu.be[/youtube]

I have changed ALOT on the car over the years... in no particular order and some of which I may have been overlooked:

Injectors, spark plugs (NGK), belts, knock sensors and harness, hoses galore, ABS, IAC, MAF, A/C compressor, alternator, fan clutch, plenum gaskets, radiator, and others... Worst part is that I have struts, engine mounts, and some O2 sensors that I was planning to install over the next few weeks. Bummer.

Have NOT changed the plastic chain guides. Never had a good weekend to do the job, and cash has been tight with Family issues and such.

So I am looking for possiblities here, valves sticking? Solenoid failure? Rod bearing failure?

[OwnerCS]

Can you determine if the tapping noise is coming from around the front of either valve cover?

There are timing chain guides that sit on top of the heads. When a chain develops slack from a failing or clogged chain tensioner, the extra slack in the chain will slap against the head mounted guides and make a tapping noise. If chain slack is the issue, the noise from the chain slapping the head guides is a warning to get the issue corrected ASAP before the chain jumps and you lose the engine.

A picture of the cylinder head chain guide is on the left side of the following picture just above the chain.

You can see the chain should not touch the guide unless an excessive amount of slack develops.

[tfitz2001]

It is definitely from the Passenger Front of the engine. Since the beast is not moving for awhile, I guess I have no excuse but to open her up tomorrow and take a peek. Hopefully no major damage has occurred at this point.

[elwesso]

Normally the chains won't slap, and that's definitely not a chain slapping issue anyway. When the chains slap it sounds kind of like getting a spoon stuck in the garbage disposal.. I've seen engines that had guides totally broken apart and they were still quiet and smooth as always! At 200k+ with the guides not being changed, my guess is they're all broken off and down in the oil pan. What can happen though is that the little pieces get stuck in the oil pickup causing oil starvation, which could be why you're seeing this.

It's interesting that it kind of "skips" a beat every so often. It almost sounds more valve train related, but it's hard to say. What I would do is check the oil pressure, that will be a good way to tell what's going on. If you have little to no oil pressure, you're probably looking at a bad rod or main bearing and that means you'll be looking at an engine swap, most likely.

[tfitz2001]

Well this is a bummer...

I don't have a lift and tried to drive the car onto a couple of ramps to gain access to the oil pressure switch. The car couldn't even make it up the ramps under full throttle. I hooked my ECUtalk to it and found only a knock sensor fault. The complete loss of power and the knocking does suggest a catastrophic failure of the engine.

Sadly this car is starting to become a time and money trap. I think that I am going to have to part with her. Been a hell of a ride.

[elwesso]

Definitely understand that. Unless the car is mint, it's hard to spend $1000 on a car that would barely get $800 if it was running.

[OwnerCS]

Are you in Fayetteville?

[tfitz2001]

Right next door in Farmington. Sent you a PM...

[Q451990]

Hard to say from the video, but I'm going to guess that's HLA (Lifter) noise. Unless you have some really long or short ramps, I'm guessing the bumper was hitting them?

Heath

[tfitz2001]

Heath:

These were ramps that I have used several times before. They are a bit longer, about 4 feet long and only rise about 10 inches. Just enough to make oil changes and transmission changes a bit easier. The car would not even accelerate up onto the ramps even at full throttle, I even gave it a two feet running start! Just a complete loss of power and such, but the knocking does get worse periodically, sometimes skipping (like lifter noise) but there is something really clunky about the noise that I don't like at all.

[OwnerCS]

The noise from mine sounded like the VH45DE in this video. I was convinced it was HLAs. I tried several types of HLA cleaner and other snake oil remedies without success. It turned out to be caused by a non-functional tensioner allowing chain slap against the driver side head mounted guide. The same noise appeared on one of my VQ30DE vehicles after it would sit all night until it reached normal operating temperature. It also turned out to be chain slap caused by a failed tensioner. The VQ30DE has a known tensioner issue.

This is all I have to compare in the video. Notice how rusted the front tensioner cap appears in the video picture as compared to the rest of the engine..

[youtube]http://www.youtube.com/watch?v=ripuVvmsA7M[/youtube]