What would you do? Truck Needs Engine?

[Seamus]

130K is low mileage for this motor. Known issues are always a lifter, or a gummed up valve from the DI system. So if a a valve is slightly stuck open it will have low compression. I will bet 99% the bottom end it perfectly fine. To do a lifter, heads are coming off anyway and and when you see the back side of those valves you will not believe it. Get a second opinion. An AFM delete with a new cam and lifters and walnut blast the backside of valves and it will go over 300K easily.

 

[2015Yukon]

Incorrect cam timing will cause low compression numbers also. So if it does have a stretched timing chain and did spin a lifter, it still would all be fixed by a proper afm delete kit with cam... Assuming it didn't send a ton of metal through the system.

 

[tooleyondeck]

+1 for having another shop (preferably a performance shop IMO) look at it. If you do end up needing an engine swap, go ahead and upgrade to an L86 6.2L and delete the AFM before install and you’ll be good to go for the long run plus gain value with the better engine.

 

[adamztrucking]

Your 2015 Yukon SLE (130k miles) shut off while driving, and after towing it home, you got a P0335 code (Crankshaft Position Sensor). The dealer now says you need a new engine, suspecting a stretched/skipped timing chain or a spun lifter. You've been quoted $8.7k for a used engine, but you might be able to fix the timing chain or lifter and do an AFM delete yourself to save money.

Key considerations:
- Get a second opinion on whether it's just the timing chain or lifter.
- Weigh the cost of repairs against the trade-in value ($10k if engine were fine).
- If the truck is in great condition, fixing the issue could add long-term value.

 

[BigDogYJ]

Unless the thing has been abused and way over due OCI I’d be suspicious of the low compression diagnosis without further info. What’s a spun lifter? I know they can collapse or rotate. Or maybe a wiped cam lobe?

 

[okfoz]

Look at any service manual from 50 years ago and it will give instructions on how to rebuild an engine, rebuild a steering pump, rebuild a steering box, rebuild an AC compressor, rebuild just about everything. Look at new service manuals and they have "Replace engine" Consider this, if you have a tech rebuilding an engine, charging at $100 per hour to rebuild an engine, financially it makes more sense for the dealer to simply buy a new engine, a new AC compressor, a new steering pump or box, and charge the customer. Then pay the mechanic $20 per hour for the job. That mechanic can be doing other things and making the dealer more money.
A small mom-pop shop might be more inclined to rebuild an engine because their labor is not as high and for them it is not as drastic of a hit to simply rebuild it vs buy a new engine.

 

[okfoz]

Unless the thing has been abused and way over due OCI I’d be suspicious of the low compression diagnosis without further info. What’s a spun lifter? I know they can collapse or rotate. Or maybe a wiped cam lobe?

A spun lifter happens because the guides that keep it from spinning are apparently plastic now, instead of the old days that used a steel or cast iron guide. A spun lifter would trash the cam, a collapsed lifter usually does not trash the cam it just runs like garbage. Low compression might be from the valve not completely seated, I imagine a spun lifter could do that, In my experience a collapsed lifter does some funky things and it does cause a slightly lower compression, probably because it does not completely open the valve correctly causing some extra gunk to build up on the valve and spark plug especially if it is a collapsed exhaust lifter (I had that happen).