So this may raise a couple of eyebrows to the purists but for me, its no big deal.
Since day one with my car, the top end chatters when I first start the car - and no it is not and I repeat not a cam chain problem.
What it is, is the VVT system losing oil pressure after the car sits. My assumption is an oil check valve has stuck or failed altogether.
The sound of the chatter is completely dependent on the ambient temperature and the engine temp as well.
Hot days result in a louder chatter while cold days result in a more muted chatter. Probably oil viscosity related
If I leave the car for 10 minutes and restart - no chatter
After 30 minutes or so, it will chatter again on startup.

So I stumbled onto these Sea Foam videos on YouTube - lots of them - and based on every test they have done against other products, the Sea Foam comes out on top.
I am confident that it does what it says it does - if it can do it. Meaning that the parts are not actually broken or so dirty that nothing could ever help.
My attempt here is in the hopes that the oil check valve(s) are merely contaminated to the point of not doing the oil-checking anymore so I have tossed 8 ounces of sea foam into the oil to start to see if it can possibly clean up the issue.
It certainly beats the alternative of tearing down the VVT to replace the part that causes the problem.
Have already put 300 miles on the engine running the sea foam in the oil and will be changing the oil now. I will put in a additive that claims to clean throughout the oil life like Marvel Mystery Oil and then throw the sea foam in there again 300 miles before the next oil change.
I am not delusional in thinking this is a one time treatment thing but it may have an effect over a longer period as more fresh oil and sea foam pours through the clogged parts.
We shall see -

And while I am at it, I am also going to unload a can of spray sea foam into my throttle body to see what changes happen because of it.
The tests I have witnessed show all kinds of quieting and performance improvements after a single treatment.
Thought I would do some compression tests before and after just to see what happens. Might be that nothing happens but hey - its all experimental at this juncture.
I will post any and all updates here as I go through the process.
Fingers crossed

 

Hi Bernie,

I live 70 feet from the Pacific Ocean, so Sea Foam is something I try to keep out of my engine !

Be that as it may, you have found a likely solution, similar to what I used in older engines with sticking hydraulic valve lifters. There's nothing like the scientific method, attempt, observe, and report, to demonstrate what works for you. The precautions you are taking with oil changes seem prudent, and your engine will like you for it.

All the best,

Jerry Lippmann
1999 XK8 Conv 146K mi

 

I too read many testimonials online about how remarkable Sea Foam works. I put it in my 1100 ACE motorcycle to fix a tappet sound, in my Briggs and Stratton 20hp lawn tractor to fix an oil consumption issue, and in my Mercedes 560SL to make the timing chain sound happy. I can definitely report it made me feel better, but it had no detectable effect on these engines.

 

My XKR doesn't do that but my Ford Expedition did until I gave it a quart of TX7 from PolyDyn. The effect was truly amazing and I heartily recommend the product.

 

Greetings,
Have had the same problem.
Used premium gas and added 3oz of mineral oil (approximately $2 at Walmart) to the oil every other fill up.
In addition added 3oz to fuel every fill up.
For what it's worth was told by smog technician that O2 sensors were very "clean". Don't know what correlation there is though.
Valve noise reduced over time.
Again, for what it's worth.

 

Hey All,

Thanks for following the post.
Car is now 300 miles in to the sea foam treatment and I am ready for an oil change.
Understanding the placebo effect, I can say that just in the last few cold starts of the car, the chatter sounds a little lighter than before. I may be totally imaging this but I have lived with the sound from day 1 and feel I have a good memory on this.
Who knows but since the cost of admission is so cheap here, I will keep going.
Next step is to do the oil change with my chosen oil - Royal Purple 5W-30 XPR full synthetic (no oil threads please), and I am going to add a quart of Marvel Mystery OIl to the oil as well since it can live in the oil for the duration. The Sea Foam treatment says to only add the product 300 or so miles before the oil change.
I will do this procedure through several oil changes before coming to a conclusion whether or not it did anything. I figure it has probably taken many thousands of miles to get to the state it is in, so I shouldn't expect an overnight result.

As always, I will circle back and update with anything I learn along the way.
I have the spray can treatment sitting here too but I haven't gotten around to doing that just yet. Will update after I do.
Go to YouTube and search "Project Farm". This guy does some amazing tests on products and really puts the Sea Foam claims to the test.

 

Bernie, Through ownership of other high tech vehicles, I've found that a good 0W-30 full synthetic oil makes my cars start up easier and quieter. My barn-find 2005 XK8 with 83,000 miles on it suffered from noisy startup and sluggish engine operation when I first got it so I added half a quart of Marvel Mystery Oil to my oil a few hundred miles before each of the first three (5,000 mile) oil changes. The first time DID remove noticeable gunky residue when I drained it, so I would advocate adding the MMO before an oil change, rather than keeping that gunk in suspension until you change it again. If your oil level is currently low enough, there's no reason not to add a full quart of MMO 300-500 miles before changing it...

Also, after considerable research, I've recently tried adding 1 oz of (Walmart Supertech) TC-W3 ashless 2-stroke oil per 5 gallons of premium gas after every other fill up, and am noticing even quieter start ups, smoother running, and a surprising increase of 1 - 2 mpg on trips. It burns clean, doesn't clog the catalytic convertor, and seems to act like a top end lube; the engine is much more responsive than it was when I bought the car. Lots of interesting discussion posted online over the past 10 years on different forums; no one has reported any damage to any 4 stroke engines that I can find, only improvement. To each their own, but I'm convinced that MMO and TC-W3 2-stroke oil are worth the cost and effort. (I've put over 22,000 miles on the car while restoring it over the past 3 years; planning another 4,000 mile touring trip this summer...)

Keep us advised on your progress!