Bottem end going out?

Dustin07 · July 15, 2005

hi folks,

i was on a blazer site and a guy mentioned that his blazer makes a metal knocking sound in the morning when he first starts it, and when he's excelerating or going up hill. someone suggested his bottom end was going out.

for anyone who remembers, I mentioned similar noises in my 99+ 4.8L silverado last december. the noise has gotten worse and i've been to a number of mechanics. nobody has been able to zero in on it. it's definately not exhaust. but it does seem to come from the lower end of the engine, although if i had to say a particular side, i'd say it's louder on the passenger side.

when i park on a steep hill (like when i'm pulling out of my works parking lot, have to stop and a pretty good angle right before pulling on to the road) the noise picks up, almost like at that angle something is looser or something...

Does this sound like a possiblity for my truck as well? i've found NO power loss to speak of, i have about 140,000 miles on it. It's been used for making deliveries and i've been very good about fluid changes. oil never goes past 4500-5000 miles... usually changed at about 3-3300. I have had enough weight in the back to make it squat a number of times, but i use the tow haul and the truck has never complained. i don't think i've had it over it's suggested capacity.

i'm gonna take it to another mechanic, possibly a stealership next week... just wanted to see whatchall that.

if the bottom end were going out, what does that consist of?

tia

JRW68 · July 15, 2005

sometimes you can get away with throwing new rod and main bearings in.... but if you spin a bearing, youll need a new crank or a turned crank. Youll know it when you spin a bearing... itll knock constantly.

As for if thats the cause of your noise, dunno, its possible.... thats a pretty new vehicle to have the bottom end getting loose though... these newer motors, when well maintain, easily break 200,000 miles even if run hard for a fair amount of it.

MrQuadrasteer · July 16, 2005

Get a good mechanical oil pressure gauage and check that first.

Get a FilterMag or similar, put it on the side of the filter then cut the filter open after a 1000 miles or so and see what you're getting. A little is normal, but if it's anything more than fuzz, it ain't good.

The *bottom-end* generally refers to the crank, rods, pistons, cam, timing set, oil pump...

I agree, sounds like you took good care of it

sjspor · July 16, 2005

I'd first check your oil pressure, if your good there with your mileage at 140K, I'd do nothing. You can also have an oil anyalsis done to see if you getting bearing metal in your oil.

My Beretta with 215,000 miles knocks up a storm when its cold. Thats pistion slap, and even though its a 3100 V6, its the same basic design at the 4.8/5.3's Iron Block, Alum. heads with short pistions. I don;t know about under load, the car makes so much noise that I would't be able to tell.

The reality is this, if you had a bad bearing/wrist pin/crank, the sucker would have launched the rod thru the block all ready. A rebuild, has to be 2-3000 bucks, easy. And you should do all of it, heads, timing chain, lower end. I have no idea what a crate motor would cost.

The other option is a junk yard. I know 4 bangers go for 350-500 bucks, because I just put one in my Daughters Saturn.

After you do that, you still have a 140K tranny, A/C, rear, switch gear truck.

Just my .78 cents worth.

MrQuadrasteer · July 16, 2005

Just my .78 cents worth.

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JRW68 · July 16, 2005

I just thought of something... F$%@ worrying about it... trade it in on a new one... now has got to be the best time if you can afford it. But agreed... doing the entire engine is recommended... ussually if you just throw new journals (bearings) in, the top end will go out... and vis-versa. If it is bearing noise.. it can run for quite some time befor it spins a bearing, once a bearing spins its done and generally your gonna need a crank. If it is bearing noise... keep the rpms low, keep fresh oil in it, and watch the oil pressure as mentioned.

Matt99Z71 · July 17, 2005

Get a new one? Crap thats a bad answer, especially if its just your work truck. Theres no reason why it shouldn't go past 200,000 miles. Definetly take Quadrasteer's advice and check the oil and possibly the filter, there would be alotta metal particles if something let loose. But again, under a heavy load, the engine probably would have grenaded by now.

Dustin07 · July 19, 2005

Get a new one? Crap thats a bad answer, especially if its just your work truck. Theres no reason why it shouldn't go past 200,000 miles. Definetly take Quadrasteer's advice and check the oil and possibly the filter, there would be alotta metal particles if something let loose. But again, under a heavy load, the engine probably would have grenaded by now.

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Hey Guys, I appreciate all the replies and i'm going to take your advice on the tests. I've noticed mine is just as loud warm as cold actually, so... hmm.

as far as the rebuild goes... I'm somewhat looking forward to it. I was hoping when that day came i could opt to rebuild with performance parts, I really didn't want to replace perfectly good stock parts until they needed to be

The tranny is actually somewhat new... had it rebuilt at 70K. i think it had issues at 20K.. i remember when i first bought it it wouldn't go into Reverse, twice it happened. Hit, R... nothing, back to drive, then shift to R and suddenly it hits. then no problems ever again until 70K. since then it has shifted nice and firm with no issue.

I have looked at getting a new one, but I only owe under $5K on this one now, so i'll have it payed off within a year most likely (bought it for $21 i think incl tax/license so it's an accomplishment in itself for me ) and my wife would like to get a new car, so my plan is to let her get her liberty (d**n chyrsler) and i'll keep the 'project' going bought this truck originally 4 years ago with plans to show it...lol, so far i've gone as far as installing a K&N filter. then came marriage and house payments. doh!

anyhow, thanks again for the replies guys, i have a laundry list of things to check now and i'll see if i can make some progress by the end of the week.

Dustin