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1993 k15 burban engine %&*$#!
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whitey79
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Apr 7, 2007, 8:31 PM
Post #1 of 7
(1317 views)
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1993 k15 burban engine %&*$#!
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recently bought this 93 burb and after drivin it for a week we got a weak knockin noise from the engine. after 3 weeks it had got a little bit louder, so i called the service dept. from where we purchased it and they said that the aluminum heads were the cause of the knock. well i'm not an idiot and i told the guy that there was cast iron heads on the motor not alum, and he got all mad and said i didn't know what i was talking about. well last tuesday the knock was horrible along with barely being able to go 50 mph. it almost locked up on me and died when i got in my driveway. i restarted it and it still knocks. rear main is leaking and i checked the valves to see if they were the cause of the noise but they're all within specs for rod movement. it knocks on initial start up but quiets down after a few minutes. then it'll only knock if above 2500 rpm while in park(i don't dare drive it). its a steady knock which resembles a bent or damaged rod, but not during idle. oil pressure is at about 30psi. i did a compression check and most of the 5.7l cyc'swere at 150. 1 was 130 and 2 were 165. best guess i have is the rear main cap is bad, or one of the main bearings toward the back of the block. the people i bought it from have given me the finger basically, and as i've found out the lemon law doesn't pertain to this vehicle. anybody with a similar 5.7l of close year advice is greatly appreciated. i'm a die hard chevy man and i know quite a bit about them, but this is throwing me for a loop. i plan on oulling the oil pan after lunch tommorrow but due to having no garage its cold outside(live in mid minnesota). i've heard about 10 different things so far and only a couple make sense so i look forward to some more. thanks in advance for any help.
like a rock my arse...chevys for life
(This post was edited by whitey79 on Apr 7, 2007, 9:05 PM)
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DanD
Veteran
/ Moderator
Apr 8, 2007, 5:22 AM
Post #2 of 7
(1311 views)
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Re: 1993 k15 burban engine %&*$#!
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Without hearing the “knock” it’s going to be hard for us too advise.
I do believe you’re thinking is on track by pulling the oil pan and inspecting the main and rod bearings. If you don’t see any physical wear or damage; plastic gage the bearings too check clearances.
If you’re not sure what plastic gage is; it’s thread like soft plastic, which is laid on the journal of the crankshaft between the bearing cap and journal. You would then torque the cap to spec; remove cap and then measure the width of the squashed thread.
It’s sold in different diameters; the packaging that the gage comes in will have a graph that you use to determine the clearance. I don’t remember the clearance spec but It’s something like a couple thou?
Dan.
Canadian "EH"
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whitey79
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Apr 8, 2007, 6:04 PM
Post #3 of 7
(1306 views)
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Re: 1993 k15 burban engine %&*$#!
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thanks. i never heard of the plastic gauge tecnique, but it sounds like it'll work. i think the tolerance is .015. most of the rod bearings range from .007-.015.
one other question is anyone have any experiance with using that seal puller tool that looks like an cork screw on a steel wire? i'm hoping that the seal if it needs to be pulled is that its a 2-piece seal and not a single.
like a rock my arse...chevys for life
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 8, 2007, 8:48 PM
Post #4 of 7
(1302 views)
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Re: 1993 k15 burban engine %&*$#!
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This doesn't sound, feel or smell good at all. As Dan said this is a tough call without hearing it in person.
Worn main bearings will knock and get better as oil pressure goes up. Rod bearings should give you a double knock if worn.
What bothers me most is that this caused loss of engine power which if from lack of lubrication this engine is toast. I don't like the compression readings either but these engines would still run ok with about those numbers. How much did the compression go up with a squirt of oil in cylinder?
When you checked the valve clearance what did the sludge situation look like inside? If really sludged up chunks/pieces will plug up oil pump or cake up and starve about any lubricated part in the engine.
If you are sure there is no recourse on this engine by the seller than watch your investment in this engine and cut losses.
I can't know without being there but it doesn't take too much wrong before the most cost effective way out will be a good used, whole engine.
Let us (and the world) know what you find, T
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whitey79
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Apr 9, 2007, 6:06 PM
Post #5 of 7
(1295 views)
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Re: 1993 k15 burban engine %&*$#!
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i drained the oil tonight and it looks like a mild brown(not milky like antifreeze oil mixture) and it has a nice "glitter" to it. found some patchy spots of metallic grey oil on the top of the heads. i'm just going to put a good used engine in mainly due to time consrtaints with needing a vehicle asap. i have a vortec 350 that i'm checking to see if i can make work. which i hope. guy only wants 300 bucks for it, but i don't know if i can swap out the tbi with the efi thats on it. or a local junkyard has a motor with unknown miles on it, but it has a new egr valve, head gaskets, and intake and the compression is 150 all around.
just because i'd like to know and let you guys know. i'm going to tear down that crappy engine and see exactly what it is. i'll roll the rods on glass and the whole 9 yards.
it still boggles me that it idles so dang good yet knocks like a beast. one guess from looking at the oil is that maybe it was running rich and some gas got in the oil and it got foamy and the rod bearings got hot. there was a ton of air bubbles in it when i drained it, but i think that also might've been from doing the compression test. i'll let ya know what i find out though.
like a rock my arse...chevys for life
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whitey79
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Apr 15, 2007, 6:06 PM
Post #6 of 7
(1278 views)
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Re: 1993 k15 burban engine %&*$#!
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the number 8 cyclinder got scorched after the piston dropped. took us about 12 hours but we got the used motor i picked up in it and finished today. had some issues and i'm gonna post them so if others do as i've done it'll give them some forsight when dealing with a motor from a junk yard.
1. make sure that the motor is what they say over the phone. we drove 30 miles and when we got there the engine had 2 cracked exhaust manifolds. which they said were fine over the phone.
2.save all parts for reinstall. ie egr valves and such, vacuum lines, adaptors, brackets, and nuts n bolts.
3. we had to switch the oil cooler lines due to them not fitting into the radiator. it would've been easier if we would have known before we had the motor put in(severe pain in the rear).
4.make sure your ground on the back of the motor is disconnected along with other misc. wire brackets are clear of taking the motor out.
i've been through this ordeal a couple of times, but its amazing how some stuff justs slips out of your mind. hope this can help anyone that has any situations similar to this. have to say its nice that its running great now though. thanks again for all of the advice.
like a rock my arse...chevys for life
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 16, 2007, 1:20 AM
Post #7 of 7
(1277 views)
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Re: 1993 k15 burban engine %&*$#!
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Gave you a tough time as you said.
I just have the luck around me that the salvage yards really check out their used engines with lots of checking them out and known mileage and so on. They are stored indoors with all the data possible about where it came from.
Hope this one behaves for you for a long time, T
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