Hi everyone,

I did a search for my problem and read previous posts, but I did not find anything that fit completely with what I am experiencing.

I have a 02 Montero Limited with 55K miles on it. A few months back it started to make a Loud Knocking noise on cold starts that would go away within 5 minutes of driving or so. It was not there all the time either, it would be there for a few days in a row, and then go sometimes up to 3 weeks without a sound. It seemed the warmer it was outside, the less it did it. I tried taking it to the dealer a couple of times, but they always said they could not replicate the noise. Which is believeable since it was not always there.

Here is where the story turns, I just got the fluids changed in the car at a reputable place in my area. Oil, Transmission Fluid, Radiator Fluid were all changed, ever since then the noise has been much louder. The noise takes longer to go away too, 10-15 minutes of driving. The noise also goes away is when I am accelerating and the engine is at higher RPM's of about 2500+, but when the engine shifts into a higher gear and the RPM's drop again, the noise comes back.

Here is a video link, this is pretty close to what my engine sounds like now:

http://www.youtube.com/watch?v=_0CBQcccLDM

I know it can be a bearing, but with a bearing would the noise go away at higher RPM's? And why since the fluids were changed did the noise get worse?

A little background, I bougt the vehicle with 35K miles on it, I have given regular oil changes with synthetic oil since I got it. I can't say how well the car was maintained before I purchased it, but physically the car was in great condition, so if that speaks to how they may have maintained the engine, then they may have done their part. But maybe they didn't.

Any opinions would be great.

It is going back to the dealer tomorrow morning, I am just looking for some opinions on what I may be getting into.

Another note, I bought the car as a Certified Used Mitsubishi with the 10 year / 100K mile drivetrain warranty from the original in service date, so it is still under warranty. Has anyone ever had any work done under a Certified Used Car warranty? Is Mitsubishi pretty easy when it comes to their warranty's? Or am I going to be in for a long road to get them to cover something?

Thanks in advance for any opinions.

 

It's likely to be valve lash adjuster noise. It happened to me after I let the oil get too low. It sounds like a loud knock - I too thought it was a bearing problem.

But I found this link and the procedure worked wonders. The noise stopped and has never come back.

http://www.4x4wire.com/mitsubishi/te.../lifter_noise/

(This procedure is also written up in the factory manual so it's not junk science)

Good luck.

Ron

 

Thanks for the reply, but after looking at the link you provided, I don't think this is my problem. Here is a quote from the link that makes me think this:

"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."

The loud clanking/knocking that I have does go away after 10 minutes or so of driving and the engine is warmed. And sometimes it may even go a week or two without making the noise.

Thanks though for the help.

 

From digging around a bit, I think I have the probable cause of the noise. It meets all the symptoms of being a Piston Slap. It's only there when the engine is cold, goes away as it warms up.

Does anyone think this is the case? Or has anyone else had Piston Slap in their vehicle?

The car is at the dealer as of today, hopefully they find it. And hopefully it is under warranty!

 

I have the same problem in one of my 3.5L Montero Sports but it has over 210,000 miles on it. I find it hard to believe that any 6G72 or 6G74 that has low miles and has been well maintained has piston slap. Since the severity of the problem changed with a fluid change, two things to check. Does it have a FACTORY oil filter? Was the correct weight oil used? I use 5W-30 and it makes a huge improvement in reducing the severity and frequency of this issue. Cheap filters also are problematic on these engines (and most Japanese engines). Spend an extra buck or two and use a factory filter. They make a difference.

 

Since I bought the car, I have gotten regular oil changes at the dealer I bought the vehicle at, so I would assume they were using factory oil filters and the correct grade oil.

This past time I did not go to the dealer only because I moved and the dealer is now about a half hour drive. So I went to a shop right down the street. I can't say what filter or oil they used, but the problem was there well before I took it to them.

But yeah, my car having only 55K on it should not have piston slap, unless there is a manufacturer defect, or maybe that the first owner didn't maintain it the first 35K miles. All I can say is that the symptoms seem to fit.

In any case, I should hopefully know what the problem is in the next couple of days.

 

its a failing timing belt hydraulic tensioner.

 

Thanks, I did some research on that, and it could definitely be the problem. I am at 55K miles, not had a timing belt replacement yet, so that sounds like it could be it.

I am calling the dealer tomorrow if I don't hear from them, I will post what they say the problem is.

 

if its only there cold, and its not always there, thats what it probably is.
the tensioner is hydraulically charged and sealed, to allow for constant pressure on the belt over its lifespan (during expansion and contraction, etc).

it leaks, and allows the belt and pulley to bang around. As it warms, the remaining fluid in the tensioner expands, allowing it to stop the belt and pulley from whipping around.

If it is leaking and failing, it will eventually make the noise ALL the time, and could result in the timing belt jumping off one or more sprockets, damaging the engine.

 

Well, just got off the phone with the dealer, they say that it appears to be an internal engine problem. He said that the master technician is in there looking for the cause.

Looks like I will be without my car for a while.

Good news is, they say it looks like it will be covered under the drivetrain warranty.

I should know more tomorrow hopefully and get a definite cause of the problem.