Help!!! collapsed lifters???

[Sarah_Yukon]

Ok to start I have a 07 Yukon Denali xl 6.2 170,000 miles....Ok the car was running perfect right before this happened....I was in idle in a drive thru no issues then all of the sudden huge noise then proceeded by first service/disabled stabiltrack, then check engine light came on about 5 sec later started to flash...so from the little bit I know about cars I knew I needed to pull over turn it off asap...so I have active onstar so I called and asked for my codes....p0300 random misfire ....now to add the little few yards I had to drive it out of the drive thru to parking spot I noticed I had zero brakes!....Also the truck would not stay in idle unless I gave it gas and if it stayed running it was rough...At that time when i was trying to start it I could hear my lifters..I have had this cars codes read multiple times got 2 different extra codes ...one for the MAF one For TPS and always got p0300( but since I reset it only p0300 now ) ...had four mechanics come out take a look all blamed different things...so I gave up and towed it to gm shop ...they come back with collapsed lifters due to low oil pressure "upper end failure" and there reason I have no brakes is there's no "vac" period getting to it ..it itself(booster) is not bad... now first guy that came out said clean your throttle body...So I did that myself and it was gunked up bad!! cleaned it and intake and now the car WILL RUN In IDLE ..were before it would not...so some progress there!!!...My question for you guys is what do you recommend from here im tired of getting/paying for tons of quotes ...they quoted me 3500 to rebuild or 5000 new engine....please help!!! what can I do from here to confirm? Troubleshoot? also regarding the shops low oil pressure as to the reason of failure when this happened my Gage was reading normal and the engine was not hot..truck just had oil change last week!!!....right now all I have is a expensive driveway decoration!!!

 

[ccapehartusarmyINF.(ret)]

sounds like you definatly had some sort of catastrophic failure so lets cover a few things see if we can narrow it down
when ever the check engine light comes on and starts flashing means yer getting a constant misfire and if it wouldnt stay running at idle you were probably having a misfire on multiple cylinders
pull on yer spark plugs see what they look like if yer not sure exactly post pictures of them see if your oil or coolant looks milky i fyou can get it to run at idle does it shake excessively and stand behind yer vehicle does it smell like gasoline ? also see if you can get all the codes its thrown

 

[ccapehartusarmyINF.(ret)]

collapsed lifters would be very noisy and noticeable as well as low or no oilpressure

 

[Sarah_Yukon]

Yes its loud on one side...but pressure says normal to me...my oil level is fine to ...but this shop said low oil pressure let to" upper end failure some lifters have collapsed " now in idle the truck is "missing" like crazy

 

[Sarah_Yukon]

sounds like you definatly had some sort of catastrophic failure so lets cover a few things see if we can narrow it down
when ever the check engine light comes on and starts flashing means yer getting a constant misfire and if it wouldnt stay running at idle you were probably having a misfire on multiple cylinders
pull on yer spark plugs see what they look like if yer not sure exactly post pictures of them see if your oil or coolant looks milky i fyou can get it to run at idle does it shake excessively and stand behind yer vehicle does it smell like gasoline ? also see if you can get all the codes its thrown

OK to answer some of your questions : oil looks normal,yes car shakes horrible like it would if you had bad vac leak,iv cleared codes and only get P0300 (random misfire) ,yes you can smell strong smell of gas if your in front or behind, only thing is prior it would not idle unless you gave it gas but since I cleaned the throttle body/intake it will idle on its own now but still "missing" still shaking ,and you can hear the lifters bad on one side ..and I have zero brakes ..I have not pulled the plugs yet ...ty for your reply!

 

[CrashTestDummy]

Broken DOD lifter can do this. Heck, another Tahoe PPV owner, this time with a 2013 model, had a DOD lifter ROTATE in the lifter bore while he was cruising on the freeway. One second all's fine, the next, his engine is rattling.

This is probably what happened. Pull the valve cover on the noisy side, and I bet you'll find a rocker that's loose, or doesn't move as you spin the engine over. It's a fairly-common issue with these DOD engines.

It's probably damaged a cam lobe, or two, so a cam replacement is in order. It's about $1500 in parts, usually another $1000-$1500 in labor, as the heads have to come off.

If you go this route, go with a DOD-delete kit and a better cam.

 

[Sarah_Yukon]

Broken DOD lifter can do this. Heck, another Tahoe PPV owner, this time with a 2013 model, had a DOD lifter ROTATE in the lifter bore while he was cruising on the freeway. One second all's fine, the next, his engine is rattling.

This is probably what happened. Pull the valve cover on the noisy side, and I bet you'll find a rocker that's loose, or doesn't move as you spin the engine over. It's a fairly-common issue with these DOD engines.

It's probably damaged a cam lobe, or two, so a cam replacement is in order. It's about $1500 in parts, usually another $1000-$1500 in labor, as the heads have to come off.

If you go this route, go with a DOD-delete kit and a better cam.

OK he (shop) did mention if I choose rehaul (3500$) who knows if I need new cam...I'm assuming he meant what your saying....so can you walk me through how to check the rocker? I'm assuming its under where the coils are on that side? This is past what iv ever done on a car so I'm still learning bare with me ...Ty for your reply

 

[FrankU]

I'd try and replace or clean the oil filter that is under the oil pressure sending unit first. Go to you tube for the procedure.

 

[Sarah_Yukon]

I'd try and replace or clean the oil filter that is under the oil pressure sending unit first. Go to you tube for the procedure.

OK will do ty

 

[Sarah_Yukon]

OK update: I called the shop back he did not take any valve covers off only did oil pressure test ..despite my dash gage saying normal...on the TEST no matter the rpms the truck is only getting 3psi oil pressure???! Help me understand this..