UPDATE: Sludged Cobalt

[jk_636]

So as promised, here is an update of the sludged cobalt.

Yesterday the engine got its monthly 5 minute motor flush and oil change. New fill was 4 Qts ST conventional 5w30 +1 Qt MMO

First, the oil filter (Fram CH9018)

This was the oil out (5 minute motor flush + 3 Qts ST 5w30, 1 Qt ST 5w40 + 1 MMO)

He also changed the Engine air filter. I am assuming this one was probably still the factory filter installed in 2010 (Replaced with Wix 49117)

He then went out and took it for a spin and posted the following updated video:

https://youtu.be/UBHInvTIR00


Thoughts?

 

[mx5miata]

valvetrain noise - "tappat"

does the sound go away at higher engine speed?

 

[jk_636]

I am not sure. I will ask when I speak with him later. We have been operating under the assumption it is the result of sludgd motor and timing chain tensioner/guide.

 

[AZjeff]

You're doing your part to de-sludge the engine, good work. No help on IDing the sound but you likely aren't going to fix it. The owner has 2 choices, run it til it breaks or have it fixed now. The cost of negligence is going to be high either way.

 

[jk_636]

At first I was hopeful that maybe the amount of sludge buildup was keeping oil from effectively lubing the top of the chain but at this point I almost feel certain (taking into consideration the susceptibility the EcoTec engine has for failed timing components, coupled with the amount of sludge inside the engine) that it is a broken timing component, and not a lack of lubrication.

Good news is, between the chunks and speckles of sludge found all over the media, the desludging process is working!

 

[andyd]

Any chunks in the drain pan? Judging by the filter, the process is working. Apparently the pickup screen is clear enough so it hasn't starved. I would rinse and repeat. Please post next filter pics.

 

[Snagglefoot]

A few years back I helped a guy rebuild a 350 Chevy. The dried out sludge in the engine looked like black popcorn.

 

[slacktide_bitog]

That oil filter looks good! I know the Ecotec filters have a bad reputation for buckling, so that one did great! When is the next oil change going to be?

Will you pull the valve cover again soon?

 

[JLTD]

Chunks. I see chunks....good they're coming out but bad if they lodge in the wrong place.

 

[UncleDave]

Sounds like timing chain guide and tensioner rattle the slipper and guides are most likely wasted. Id also guess the cam faces are galled and opening up clearances.

You've already recovered some "lease on life" but the damage the owner did through neglect was permanent and all you can do now is drive it till it dies and or open it up and fix it all. Given the abuse It suffered when it dies It isn't worth the surgery -when it finally kicks the bucket I would pick either a reman engine or a wreck that shows no sign of abuse.

XW-40 something may quiet it down a bit.

Great C&Ps thank you.

UD

 

[bullwinkle]

Still sounds like timing chain slapping-but, at this point, not a lot of sense tearing into it without a complete rebuild. Any signs of metal chunks in the filter at all?

 

[Oldtom]

Any possibility the owner could trade it in before the engine dies? A newish Cobalt should have some resale value.

 

[jk_636]

Originally Posted By: slacktide_bitog
That oil filter looks good! I know the Ecotec filters have a bad reputation for buckling, so that one did great! When is the next oil change going to be?

Will you pull the valve cover again soon?

I would love to pull the valve cover and take a look inside but this vehicle is in Texas and I am not; and I would need more than a week of vacation to tear into this engine, but it would be cool to see what it looks like under there. Perhaps next time I am down we may take a trip to harbor freight and run a bore scope down there and take some pictures.

Originally Posted By: UncleDave
Sounds like timing chain guide and tensioner rattle the slipper and guides are most likely wasted. Id also guess the cam faces are galled and opening up clearances.

You've already recovered some "lease on life" but the damage the owner did through neglect was permanent and all you can do now is drive it till it dies and or open it up and fix it all. Given the abuse It suffered when it dies It isn't worth the surgery -when it finally kicks the bucket I would pick either a reman engine or a wreck that shows no sign of abuse.

XW-40 something may quiet it down a bit.

Great C&Ps thank you.

UD



Something 40w is a good idea UD. I will discuss that with him before the next oil change is due in 4 weeks. Now that I'm almost certain that the sound is from the tension on the chain and not a lack of lubricant getting to it, something 40 weight may help provide a bit more protection.



Originally Posted By: JLTD
Chunks. I see chunks....good they're coming out but bad if they lodge in the wrong place.


Isn't that nasty. If you zoom in it looks like the oil filter has chickenpox made of sludge.

Did you see the original filter photos? If the oil screen wasn't completely blocked before I don't see it happening now (fingers crossed!)


Originally Posted By: andyd
Any chunks in the drain pan? Judging by the filter, the process is working. Apparently the pickup screen is clear enough so it hasn't starved. I would rinse and repeat. Please post next filter pics.


Not sure about chunks. I will ask when I speak to him next.

Rinse and repeat is pretty much the idea. Monthly motor flushes, oil and filter changes and substituting 20% MMO in the crankcase is the treatment plan for the rest of the time it is alive.

I will continue to post updates!

For those who have not seen the original thread, I have linked to it here to give you an idea of where we began to where we are now:

https://www.bobistheoilguy.com/forums/ub...ing#Post4818556

 

[jk_636]

Originally Posted By: Oldtom
Any possibility the owner could trade it in before the engine dies? A newish Cobalt should have some resale value.


This poor Cobalt was already wrecked by the first owner who had it for about a year, has a bent rear axle and a few other problems. I don't know how he would get in trade, so we are trying to keep it alive as long as possible until he can afford something else.

 

[Oldtom]

Based on the limited resale value, sounds like he should drive it till it dies.

 

[Snagglefoot]

Here is another good cheap cleanup oil.

 

[jk_636]

Thank you for the input Snagglefoot.

I have had him using Supertech since it was the cheapest oil with a decent all around additive pack, readily available at Walmart; but I have not priced out GTX so I'm not sure how comparable the price point is.

I know this isn't the PCMO forum, but I wonder how the cleaning power of Supertech paired MMO compares to Castrol GTX?

Supertech:

http://www.pqiadata.org/SuperTech5W30.html

Castrol GTX:

http://pqiadata.org/Castrol_GTX_5W20.html

 

[WyrTwister]

Thanks for the update .

 

[Triple_Se7en]

Originally Posted By: Snagglefoot
Here is another good cheap cleanup oil.




Sludge protection and sludge remover are two different animals.

 

[pbm]

That Castrol GTX has a nice additive package....Calcium, Boron and Moly...I like it....and the 5w20 is just shy of a 5w30 for those who like their oil on the ticker side...