Author Topic: Got a ticking sound?  (Read 2155 times)

Shovel

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Got a ticking sound?
« on: March 15, 2018, 11:15:45 AM »
I don't..    but I've heard a few other Mitsu V6's ticking and from searching the internet it appears to be a really common result as these engines get a lot of miles and years on them.

Almost 20 years ago I remember somebody from the old forums had found a Mitsubishi-authored procedure for ensuring the hydraulic lash adjusters were bled free of air, and potentially de-gacked of gack accretion..    and I was reminded to go look for it by reading another person remarking on their incessant lifter tick in a laissez-faire "just gonna live with it" sort of way.   

You don't have to live with it! 

For the sake of brevity it can be said that lifter tick on the Mitsu V6 engines (3.0 and 3.5) usually comes down to one (or more) of three things:

  • Mechanical damage
  • Air in the hydraulic lash adjusters
  • Gack buildup causing sticky adjusters or rollers

So the first one sucks, but it's really not common on an engine that hasn't been just absolutely neglected.     I saw one where a head gasket leak had let water into the oil,  then it sat for a long time and the water that gathered in the cam galleys had galled out the cams..   but that's really not a concern in vehicles which haven't had those kind of circumstances. 

The other two you can fix.   

Here is a quote from Doug Miller,  sourced on The Wire forums 18 years ago:

Quote
On the 3.5 and (I believe) the 3.0 V6's as well, there is a device in the valve train called a valve lash adjuster (VLA). This device is like a little piston and cylinder filled with oil. It is different from a hydraulic lifter, and functions to keep the slack in the valve train to a minimum as the engine ages. The VLA has a little ball valve held in place by a spring, and uses oil pressure to take in oil and place constant pressure on its valve. Dirty oil from even several oil changes ago (or a previous owner) can leave particles in the ball valve that hinder its ability to remain pressurized. This leaves slack in the system and you hear it as clicking. It is also caused by getting air bubbles past the check valve that is now stuck at the top of the little cylinder, unable to leave via the ball valve at the bottom.

SYMPTOMS: A valve train clatter on startup that does not go away when the engine is warmed. If it goes away, this is not your problem.

Doug goes on with the likeliest causes:

Quote

    Low oil - now or previously.

    Dirty oil - now or previously.

    High oil - now or previously (con rods slap the too high oil and "foam" it). Note that high oil can be caused by coolant contamination from a blown gasket, not just by overzealous owners. Parking on a steep hill - now or previously. With the engine off, this encourages the VLA to drain its oil (running steep hills are not a problem, unless it's so steep the oil is getting "foamed" by the con rods).

    Parking for long periods - now or previously. Over time they'll drain.

And finally, the fix:

Quote
Now that I've made you all paranoid, here's the laughably simple fix. The VLA's were designed to respond to a pattern of gentle revving to flush the oil out of the little cylinders (those clever Mitsu engineers, eh?)

    Warm up the engine.

    With the engine in neutral, gently rev it from idle to 3000rpm over a period of exactly 15 seconds. Your goal is a constant gradual increase to 3000rpm. At the 15 second mark, drop the throttle (foot off the gas) to idle. Now let it idle for 15 seconds to complete one 30 second cycle

    Repeat the 30 second cycle in #2 from 10 to 30 times. If the problem persists after 30 cycles, this is not your problem. It fixed mine after only 5 cycles - total silence.

So, that process presumably works to "pump" the oil through the adjusters and release trapped air or gack from them.     

I have a vague memory of someone mentioning that the above process is actually one published by Mitsubishi for their service technicians...   does anyone know more about that?    I would love to be able to present the real document (or have a reference number to share if copyright prevents actually publishing a scan of it)   


The following is my opinion and as I am just some guy on the internet,  you should always make your own decisions about your own actions and all that mumbo-jumbo.     

Since we know that another cause of this tick can be from gunk accumulation - either dirt accumulation or the accretion of oil decomposition byproducts (varnishes, waxes, etc) - it might be advisable to look into a high solvency oil cleaning additive and follow the directions on that product to assist in decomposing and eliminating those accumulations of gack.     I personally would use Marvel Mystery Oil for this as it has a long history of safe use in crankcases,  its low viscosity would presumably help with oil velocity and penetration of all the crannies,  it's available everywhere and all that.       I also personally choose to monitor my oil visually and change it at fairly frequent intervals (by today's standards) because oil is cheaper than a new engine..   




Funf

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Re: Got a ticking sound?
« Reply #1 on: March 15, 2018, 01:09:06 PM »
In the 1996 Montero FSM, page 11A-11 (3.0L V6) and 11C-12 (3.5L V6) describes this process under Lash Adjuster Check.

Also, here is a link I saved with further diagnostics regarding to the issue if the revving doesn't cure the issue.
http://www.underhoodservice.com/mitsubishi-tech-tip-curing-valve-noise-at-start-up/

1996 Montero SR

Funf

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Re: Got a ticking sound?
« Reply #2 on: March 15, 2018, 03:09:04 PM »
l also found a TSB on it, saying basically the same thing.

MMSA TSB-95-11-001 - Valve Noise at Start-Up
1996 Montero SR

magoh

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Re: Got a ticking sound?
« Reply #3 on: March 21, 2018, 06:45:22 PM »
Thank you Shovel and Funf. I remember reading this somewhere before but it's good to be reminded and to know it's an official procedure.