Join Date: Sep 2013
Rated Cap: None
Bear with me, this is a long post, but worth the read. First and foremost, $9,000 is entirely too much money. The 5.7L is a great engine, but has its limitations and is a bit small to be in a 1-ton (1500 is 1/2-ton, 2500 is 3/4-ton, 3500 is 1-ton), meaning it worked harder than a 7.4L or 8.1L would have. Be careful. Check this unit out carefully. Dirty oil, oil smells like fuel, trans fluid smells burned or smells like coolant, engine blowby, walk away.
A good test for engine blowby is to pull the oil filler cap and oil dipstick at idle. It will not hurt anything as long as they are replaced before driving. If you see what looks like steam/smoke or oil coming from either, my usual advice is to walk away, but check the PCV valve first.
Smoke blowing from the oil filler or dipstick tube usually means the piston rings and cylinder walls are badly worn, and engine compression is blowing past the piston rings into the crankcase and blowing oil back up into the cylinder head. Pressurizes the crankcase excessively, causing front / rear main oil seal leaks.
Such symptoms mean the engine is effectively worn-out. You either live with it or rebuild / replace the engine. The only other explanation for these symptoms is a stuck PCV valve, which is also a simple test. Remove it and shake it. If it rattles, it is not the problem. If it doesn't, it should be replaced and the symptom rechecked.
Another thing to check for is cooling system problems. If the coolant recovery gurgles at any point, especially on shutdown after running at operating temperature for awhile, walk away. This can likely indicate a cracked cylinder head or weak / blown head gasket.
The 96+ Vortec 5.7L engines were known for blowing intake gaskets for awhile, and are also known for fuel injection system leaks (look up GM Vortec CSFI 'spider' fuel injection). It can only be diagnosed with a leakdown test (engine not running). Factory specs are 62 psi startup, 58-60 psi running, 55-58 not running, and should not drop when not running. A leak in this system can flood the engine with fuel and dilute the oil, which will wash down the cylinder walls, causing excessive wear from insufficient lubrication. Which lead to blowby and crankshaft bearing wear even without excessive engine hours.
This should all be checked both with the engine/trans cold and at operating temperature after a test drive. All of these potential issues can be worse when cold or warm.
Reason being that low miles mean nothing with bumper-to-bumper California city rush hour traffic. Engine hours could be sky-high, meaning lots of idling. You can press and hold the trip odometer stalk to get the current hour reading, but don't take the result as gospel -- GM trucks, including cutaways like this, are known for the engine hours mysteriously resetting for no apparent reason. Heavy wear on the rubber pad on the brake pedal means a lot of braking, meaning a lot of stop-and-go low speed driving, which presumably means excessively high engine hours for the miles.
My own experience for example - In 2016, I bought a 131,000-mile 2005 Chevrolet Impala 9C1 (police package) on PublicSurplus. Bidding was at $700 and had been for two weeks (30-day online blitz).Three hours away and I didn’t have an easy way to make the trip to see it in person, so I took the listing info of "Runs good, was turned in for newer vehicle" at face value and sniped it for $1,180.00 in the last 5 minutes. Sounds like a good deal, right?
When I arrived with insurance and registration paperwork in hand expecting to drive my new used car home without issue, I was walked out to a car with a 2-years-expired state inspection sticker and a dead battery from sitting so long.
When the hood was opened for jump starting, the oil was quite dirty and the oil fill cap had a blob of orange paint on it. When the engine fired, I discovered why -- it knocked worse than a diesel. I'm lucky it made it home, and my $1,200 government auction deal more than doubled in price when I found a salvage yard with a clean low-mile engine for $1000, that they would install for $725. A couple other necessities aside, I was on the road with essentially a new-looking car for about $3300. The only reasons I did so...
1) I wasn't sure the car would make the 3-hr return trip with the engine knocking so badly to get a refund.
2) The maintenance records supplied with the car indicated a great deal of work in the previous 30,000 miles, including a new dealer-installed transaxle and power steering unit, among other things this model was known for.
So what happened here? GM's venerable Buick 3800 Series II engine shot to hell at just over 130,000 miles? Transmission failure at 110,000 miles? These 3800s are usually 300,000-500,000 mile engines if taken care of.
Police usually work either 8-hr shifts, 5 or 6 days a week, or 12-hr shifts -- 4 days on, 4 days off. Much of those shifts are murder on vehicles, due to lots of idle time spent waiting for speeders followed by full-throttle to catch them, idling while securing accident / crime scenes (prevents dead batteried from emergency lights running), or anything you can think of in between. What it amounts to is revolutions on the engine that don't show up on the odometer, only the hour reading, if the vehicle has the ability to record it.
When you look at it from this perspective, 12 hrs a day, 4 days on, 4 days off (assuming the unit wasn't rotated between officers), that's 192 hours a month of engine run time. 192 hours a month x 12 months = 2,304 a year x 9 years (2005-2014) = 20,736 hours on the engine. 131,000 miles across 20,736 hours = 6.3 mph average.
The car had no tachometer but I can safely assume 1800 rpm at 60 mph due to lower transaxle differential gearing (it got about 20 mpg highway and I drive conservatively). 20,736 hours at 60 miles per hour = 1,244,160 miles. And the transaxle had failed at 110,000 miles, or 17,411 hours. Which was technically 1,044,715 miles worth of runtime at highway speed.
So in reality, my 131,000 mile Impala's engine had over 1.2 million miles worth of revolutions on the bottom end, and it still ran, even though the selling agency's maintenance schedule SUCKED - the records showed oil changes between 6,000 and 8,000 miles -- three to four times less frequently than it should have been. A true testament to the 3800's durability, but the point it is that the odometer can't always tell the whole story, and it's really no surprise that the engine was shot when I got it. This is, of course, all best guess, as I did not know the true hour reading on this car, but I'd wager it was pretty close.
I'm not telling you this story to scare you off of what could be a perfectly good bus -- rather, simply bear this in mind and try to get as accurate of an hour reading as you can, as this model is known for randomly resetting its hour reading due to a design flaw. Most route buses average 3-18 miles per engine hour, a few average 19-30. Any higher and it has likely reset at some point. Perhaps the selling agency would be willing to help in figuring a realistic estimate if the hour reading is not accurate.
Not to mention the engine and transmission could well both have been replaced at some point, which changes things a bit - this thing likely came from a government auction -- and government auctions mean government maintenance / replacement (usually means dealer replacements). Don't assume anything -- ask for records. Without records, check everything you can.
If engine runtime can be assumed or shown to be anywhere between 3,000-5,000 hrs, and major service or replacement of the engine and transmission cannot be proven, I'd be thinking about a timing chain replacement. 3,000 hrs at 60 mph is 180,000 miles at 60 mph. 5,000 hrs at 60 mph is 300,000 miles. Food for thought. Just my $0.02.
You might web search the VIN to try to find the original government auction listing, which won't always give a wealth of info, but could help.
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