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Mitsubishi Diamante Knock

First time poster from northern Minnesota, I have a 2003 Mitsubishi Diamante that I have owned since 2008 purchased it with 60,000 miles on it. Currently has 131,000 miles. I have always kept my car in good running condition and performed all of the scheduled maintenance per the owners manual. Last month I noticed a slight cold knock on the right side of the engine that would go away when the engine warmed up. I checked the oil and noticed that it was a little bit low (maybe half a cm below the lower threshold on the dip stick). I added oil and continued to drive it, still knocking. Bought some sea foam thinking it was the lifters and sprayed a can in the intake and poured some in the oil. Then changed oil with 5w-30 synthetic, have been driving it for about 500 miles now and the cold knock seems to be getting worse and I can faintly smell burning oil when it is idling as I let it warm up before driving off. By the time I get to work the knock is essentially gone. My oil levels have been fine… My question is, should I be explaining to my wife and fiscally responsible self, that I need to be looking for a new (read used) truck sooner than I had initially planned? haha Or, is this something that can/should be addressed or just drive it until it gives out… The car right now KBB value is $2,300-$2,600.

How is the oil pressure? Comes up quick when on cold start? Oil light doesn’t stay on a bit too long on cold starts? If no oil pressure issues, I’d guess piston knock.

Rod knock is usually a hot oil issue. Oil gets hot and thins out and one rod starts to starve for oil because the clearances are too large from wear. The engine’s life is on short time with that one.

Cold knock is usually a worn piston slapping the bore until the engine warms and expands the aluminum piston to take up the slop. This is annoying but not dangerous. In the old days when cars had forged pistons instead of cast, they all knocked when cold. It will run quite a long while like this. But it is reaching the end, but likely not tomorrow or even next week.

There might be 2 things going on, Seeping oil burning off and something knocking. I had a mysterious one, day after an oil change on startup sounded like a valve knock, It on some days was incredibly bad, but always went away after a bit. Ended up being the bearing in the belt tensioner.

Kelly Blue Book prices are always optimistic. Knock noise from engine reduce value by 75%

@mnhockeydude

Want some fun and a chance to impress the neighbors? Spend $10 to $20 and purchase an automotive stethoscope and carefully probe different engine components. BE CAREFUL with hot or moving parts, belts, etcetera.

I have good luck with mine by applying fairly firm pressure with the probe while listening. I even carefully touch stationary bolts in centers of spinning pulleys, listening for bad bearings.

Be careful of your ears. Those stethoscopes make little sounds into really BIG noises!
Perhaps you can zero in on a noise or if not, you’ve got it for next time, eh?

CSA

is this actually a knock, or a ticking noise.
If it is just a ticking on a cold start, it could be as simple as a cracked exhaust manifold. As the engine gets to operating temp the metal expands and the crack closes up enough that the sound disappears.

The oil burning smell could be a separate issue of a small leak in the valve cover gasket, letting a bit of oil drip onto the exhaust.

Yosemite

Is it possible this is a pre-ignition “ping” rather than an engine knock? If it’s a “ping”, the first thing to do is make sure the spark plug gap hasn’t widened beyond the manufacturer’s spec. The gap gradually widens with miles driven. Other things to try for “pings” is to make sure the octane rating is correct for the engine, and to try other brands of gasoline.

If this is more of a ticking than a knock it’s possible that a lash adjuster can be stuck or is worn. That’s not unheard of on this type of adjuster and is most often caused by infrequent oil changes.
The only way of knowing is by removal of the camshafts and visually checking them.
Infrequent oil changes can cause the hardened steel ball ends on the adjusters to start disentegrating.

Without hearing the noise I cannot say definitively that a lash adjuster is the cause; only a possibility.

@mnhockeydude

Is the noise high pitched or low pitched

high pitched = like clicking a ball point pen, for example

low pitched = like a dull thud

If you have a shop there that does engine rebuilds, you might want to let them look at it and provide an opinion. An experienced engine man might recognize the sound immediately, and with a stethoscope provide an accurate diagnosis. It’s worth the $100 or so.

I learned during my years in North Dakota that the long durations of extremely frigid temperature in that region is extremely hard on bearings. I’d prepare myself for the worst and hope for the best.

Good luck with this.

Yeah I am hoping it is just maybe piston slap and I might be able to get a few more thousand miles out of the engine without too much trouble. The sound is more high pitched. I will try to take a sound byte with my phone after work today and attach it to this thread.

I thought it might be the lash adjuster but since I have owned it I have always had the oil changed between 3,000 and 4,500 miles.

I just had the spark plugs changed at 95,000 miles when they did the timing belt, water pump, distributor cap and spark plug wires.

Car did have an exhaust issue. hole in the flex pipe. Cost $200 to have fixed. Car is still ticking pretty loud oil is fine. mechanic said that it is burning oil in multiple locations and thinks it is likely the valves or the thrasher kocking. The engine is likely not long for this world unfortunately. Time to start working a couple overtime shifts and saving for a new (read used) truck until she fails altogether on me… the research begins…

@mnhockeydude

I would plan on an american truck

If you try to buy a used Toyota truck, for example, you will pay DEARLY for the name and reputation

Really? Problem is I was wavering between an 06-08 f-150 and an 07-08 Tundra. I have found an 08’ Tundra sr5 4x4 with 125,000 miles I like for around $15,000 about an hour from me. The horror stories of the cam phasers and plug blow outs of the 5.4s on the f-150s that I keep hearing about have really steered me toward Toyota… I need a 4x4 that can tow and enough room for my daughter in the back seat. I don’t put a lot of miles on but I tow a trailer a lot.

Weren’t the Tundras the ones with the frame rot and the brake problems, or did they fix that?

Toyota had a campaign to inspect/replace the frames on 2004-2006 Tundras, that campaign expired last month.