One or more tappets started making the noise they do about 500 miles ago and have worsened but seem to reached their loudest. I can do the adjustment procedures (15 seconds at 3,000 RPM/repeat) and the noise goes away for up to 48 hours and then returns quickly.

I recently had the intake and all that off while removing the butterflies for air trim and really don't have time to dig back into it now.

Can I drive it as is without causing more damage? It's just the tapping from the hydraulic slack trim right? No harm to drive on it for a few thousand miles?

No harm usually in driving as-is for 3-4,000 miles?

Thanks!

 

You are correct - what you describe is the hydraulic valve lash adjuster noise. It does sound like at one of them does not want to hold pressure even after you run through the re-bleed procedure. How many times you repeat the process? You need to repeat the 15 second revs/15 second idle cycle 10-30 times to get full effect of removing any trapped air. If no change occurs after 30 times - replace lash adjusters. If you can get even 48 hours out of it, at least do the bleed procedure every other day until you have a chance to replace them. But first try to bleed them with more then few cycles.

 

The VLA noise stops after 8 to 11 times of doing the rev cycles but returns after 2 days of city speed driving. Are you saying to do the rev procedure 30 times to complete the air ejection, and then it may not return? I'll try that once or twice if so. Can't do that every other day...wastes a bunch of gas...probably an entire gallon.

Could it be the type of oil I used on my last oil change? It started a couple hundred miles after my last oil change, I noticed. I rarely use the same brand of oil for changes.

Lastly, does it harm any other components to leave it noisy for a while? If not, I'll leave her be (noisy) until something else requires pulling valve covers off...and all that other crap on top. Thanks!

 

You can try once to run the procedure 20 or 30 times. As far as oil - what grade oil are you using? I stick with what is recommended - 5x30 grade. Some people use heavier grade. Not sure if that will help. Make sure your oil level is good. #1 thing that starts VLA noise is low oil level and sucking air into the pump.

 

I use 5w-30 also. This time I added Slick 50 last oil change, I'd gotten for free. Lol...did that mess with the motor? I don't know...

So now when I run the bleed procedure the tapping does not stop. I did it 50 times yesterday and still no success. It was clearing it up by try 12 just last week. It would get quiet and return a day or two later. The noise has gotten louder and seems to have reached peak. Sounds like a Yugo-diesel now, lol.

It still ceases the tapping at 2,900 RPM or above though. It gets entirely quiet at 2,900-3,000 rpm. And returns after it drops below 2,900.

Is it worth changing only one VLA, if only one is bad? Or maybe just that sides 3?

Is this harmful to the motor, or just noisy and annoying? I'm in no rush to repair it now but would like to drive it.

 

Since the noise does not go away after so many re-bleeds, you can conclude that the lash adjuster had failed. As far as how many to change - it is entirely up to you. On one hand, replacing the busted one is the least expensive (but you have to test every one of them in order to find the bad one). Option #2 - one head at a time - more money but you get all of them taken care on that side. Going for gold - getting all of them replaced is of course the most expensive, but you know that you are done with them all for long time.
The problem is that replacing even a single tapped involved tearing into the top of the head. You will likely need new valve cover gaskets and possibly cam seals, so having to repeat this in a few month would really suck. That is a decision you have to make.
I can't tell you if it is harmful for the motor to have a failed VLA. I do not have any experience with this myself. Personally, having the engine sound like diesel is annoying enough that I'd be looking for parts at the earliest opportunity

 

Timely response.

I'm rebuilding my 3.5L engine and have debated VLA cleaning vs replacement. Current plan was to clean which was this weekend's plan. My engine had a slight VLA tick for 120k miles and I was unaware of the bleed procedure prior to the engine spinning two rod bearings. Rock Auto sells new VLA's but they are $4.16-$5.42 each, so around $120 for a complete set plus shipping.

Given the effort I've been thru and the costs for same, I'm kind of thinking about replace all, but i don't know about the quality of the replacements nor how to do a detailed inspection of existing. Rock Auto has Enginetech, ITM, and DNJ brands of VLA's.

 

So there's 24 of these VLAs? One for each valve?

It's accessed through the valve covers right? As in taking the covers off and bang they are up high? Or down below other parts closer to heads?

I'm looking for something that shows pictures and explanation of process so I can do this at home one weekend.

Thanks..

 

Yes one for each valve. After valve covers are removed then you need to unbolt and remove the rocker shafts. Lot's involved, trust me.

https://mitsubishiforum.com/forum/mi...removal-48920/

 

There is an improved upon set of VLAs that have a 3mm oil hole rather than 1mm. The company says it reduced clogging from motor wear debris and improves lubrication.

The set is about $240. The company sells your set 3G74 on eBay but I've had to email and ask about if it has a set for my 3G75 3.8L motor.

Here's the link to company:
http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=290588332336&cat egory=9886&pm=1&ds=0&t=1460240013331

sales@spring-loaded.co.uk