Engine advice

[Foggy]

IF it's just bad lifters, pay your mechanic to pull the cylinder heads and
replace the lifters... As long as the camshaft lobes haven't been wiped out from
that particular cylinder.... IT'S a very common job.. I've done a few myself.
Yes, it's a chunk of money.. These are very expensive vehicles to begin with
and very expensive to replace..
So it;s just decision time ... the truck market right now is stupid.. worse than
the housing market $$$$$$$$$

 

[wsteele]

We had intelligent scanner connected to the ECU. Cleaned a bunch of old faults.
Truck starts with no problem but, runs rough and with loud tapping noise. Givbe me credit on one thing - I worked on my cars since 1990. Being 66, I just don't have back enough to pull engine heads and replace lifters. But, I do have pretty decent ear for noises and still do all basic mechanical and maintenance jobs myself. Reason I mention this is - I can tell difference between normal rockers chatter and rather loud rocker noise. It's rocker noise, not connecting rod tap.
So, with scanner connected, we ran live data, that showed misfires at cylinders 5 and 6. When RPMs were raised, by pressing gas pedal (giving it gas) - cylinder 5 misfires went down to zero, while 6 stayed unchanged.
I did not do compression test, electrician, who repaired chewed up wires, did, bless his heart. He just was curious and was diligent enough to do so. I don't know specific numbers.
Mechanic, I was hoping for, told me that he is firm, it is stuck lifters. He owned 4 Tahoes, about the only reason I bought this one was his high recommendation. He repaired many of them and says, he knows that problem well. Unfortunately, something changed in his life and he can't promise, when he will do such repair. I, on the other hand, hate for truck to sit in front of my window do nothing. So that's the technical gist to it.

My question is not on repair. My question is - do I sell it as is, or invest more money and fix it? I know, it's very personal decision. I do not see that year on craiglsist for less than $9k and that's with mileages running into 250k-300k. I have 142k truck with everything else apparently working. No, I am not taking it to dealer, thank you.

Question is - sell as is, or fix?

I don't think anyone can answer your specific question of "keep it or sell it".

The problem with not knowing what the compression is, is you don't know if the problems extend beyond the top end (say a stuck lifter). If you spend a couple grand and get your top end rebuilt, but your rings are shot, you will end up getting a reman anyway (another say $5-6K).

If on the other hand, your two "low compression cylinders" are not out of normal spec, maybe just a little lower than the others, or the low compression is related to something in the top end (why a wet compression test tells you more), then perhaps a rebuilt top end turns your truck into a reliable daily driver.

I firmly disagree with the notion that you should swap engine types. I personally don't think that is a good idea for someone who doesn't want to work on their own truck. Just my $.02.

If you will only accept "keep it or sell it", I would say, sell it and get a late model Toyota.

 

[Doubeleive]

location pacific northwest and you are saying there are no reasonably priced engines available? apparently you are not shopping around properly.
there is about 30+ LMG engines on ebay within 750 miles almost every single one is free shipping. prices range from 1900-3000
that is just what is listed on ebay alone. you can search part outs locally on multiple platforms. you probably won't find anything low miles but you will find a running engine.
don't be scared of the internet it wont hurt you.

 

[kbuskill]

Collapsed lifters shouldn't cause low compression, quite the opposite actually.

If the lifters are collapsed then the valves should be shut and compression should be fine unless the rings are shot.

However a broken valve spring will definitely cause a valve to stay partially open and not build compression in that cylinder.

 

[PeteCT]

1. Don't buy lower mileage "swap", buy factory remanufactured. It cost about 2800-2900 shipped to your address (for the engine itself). They usually give you 100k warranty on the engine.

2. If you know how to put 2+2, you can do the work yourself, will take you 1-2 days, plus rent of the equipment ($100 for the engine lift, liquids cost (don't loose transmission fluid).

If shop, swap cost should be no more than $800.

Then, you will have older truck with almost brand new engine.

I bought truck in the same exactly condition and just threw out an old engine and dumped in a factory remanufactured. Drives great, drove around US a few times (added 60k miles), no issues. Just recently started work on suspension, but it has nothing to do with the engine.

 

[Bill 1960]

Since you’re going to be paying others to do the work AND you don’t trust the only mechanic you know = sell. The situation is perfect for emptying your bank account.

This is a great opportunity (maybe) for DIY but not when you’re paying shop rates.

 

[iamdub]

Collapsed lifters shouldn't cause low compression, quite the opposite actually.

If the lifters are collapsed then the valves should be shut and compression should be fine unless the rings are shot.

However a broken valve spring will definitely cause a valve to stay partially open and not build compression in that cylinder.

I disagree. If both valves are closed and no air can get in, there won't be anything to compress other than the volume that was in the cylinder before the piston started moving. It'll just compress and decompress that amount of volume with every stroke.

 

[iamdub]

Since you’re going to be paying others to do the work AND you don’t trust the only mechanic you know = sell. The situation is perfect for emptying your bank account.

This is a great opportunity (maybe) for DIY but not when you’re paying shop rates.

I 100% agree. If it were closer, I, myself, would be inclined to buy and fix it for a quick flip.

Buy for ~$4,000, drop in a known good condition LMG (deleted, of course) for around $1,000 total, sell for ~$7,000 (assuming it's in great condition otherwise) = ~$2,000 profit for two weekends of work.

 

[kbuskill]

I disagree. If both valves are closed and no air can get in, there won't be anything to compress other than the volume that was in the cylinder before the piston started moving. It'll just compress and decompress that amount of volume with every stroke.

This is true I guess. What are the odds of both lifters on the same cylinder being bad I wonder?

 

[wsteele]

This is true I guess. What are the odds of both lifters on the same cylinder being bad I wonder?

Based on all the YouTube videos of AFM lifter collapses I have watched, I think pretty close to zero. It seems to me, the critical valve from a compression test standpoint is the intake valve opening and closing in time. If the intake valve has the collapsed lifter, then it seems you are never are going to get a full charge of air into the cylinder, so compression would appear low. (not enough volume to compress), when in fact everything may be sealing well.

In any case, the mechanics for this case don't seem to be very forthcoming with regard to detailed diagnostic process. I sure as hell wouldn't turn any of them loose on a reman swap, especially for $2K in labor. Yikes.