73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: c10dude75 on March 10, 2016, 11:44:03 pm
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Hi everyone I got a question my 350sb when I put it in drive and speed up real fast it starts making a loud clunking noise but only happens when you try to accelerate fast if you slowly ease into it not so bad. But yeah if in park it revs up fine but if try to step on it seems to stop accelerating and starts making a loud clunking noise kid I bought it from said it was due to a sticky lifter and idk I think it might be fuel delivery related like maybe to much or to little or timing is off I'm not sure I know at idle when first start its fine then slowly starts climbing in rpms longer it sits maybe something up with the carb might be reason it makes that noise when try to step on it? It's a summit 600cfm 4barrel but yeah if you have had this issue before please feel free to share thank you.
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is it something that seams to increase with RPMs?
is it a noise you hear just once each time you try and accelerate?
could it be a tick more of a clunk?
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Maybe if you could get a recording of the noise it would help. Just a short video with sound. Don't hold the phone/recorder/camera too close to the engine when you do this, just close enough to get good sound quality, might need to repeat a few times until you get a good sound check.
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Had no idea could post a vid clip in here have to totally do that. but I work the next couple days so going to have to wait until Sunday though. But yeah it more of a clunking rather than tick and its pretty loud and it's when you accelerate quickly if you put it on slow you don't hear it so much but soon as go over like a quarter thottle you start to hear it.
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Hmmm...maybe vids can't be posted here....that would be news to me, every forum I frequent has that option. And all of them are entirely cost free. :o Maybe the folks that know can shed some sunshine on the availability of posting videos?
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you cant host a video on the site but you can host one on photobucket or youtube then link it to here.
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Oh I see. Yeah I guess a short YouTube vid be the only answer then that's to bad cant post vids in here
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you cant host a video on the site but you can host one on photobucket or youtube then link it to here.
I meant posting the link and having the video show up in the post, not having the site host the video. Sorry for the confusion. I use Photobucket for all my videos and pictures.
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Yeah I got what you were saying 👌I'd still have to make it and post then copy link and throw it in here.
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Kinda sounds like the bearing problem Philo-beddo had. Is there any vibration? Have you checked u-joints and made sure the slip joint in the driveshaft is greased?
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Reread your first post of the problem. it revs fine from idle sitting still with no noise...is that correct? But if under load it makes noise?
That sounds like a connecting rod problem, maybe.
BUT, it could be a LOT of different things unfortunately.
I knew a guy once that had a similar problem, under fast acceleration/heavy load he got a clunking noise, simple problem, worn out engine mount. Driving down the road it seems the engine would sort of float under load until bumps in the road would cause the frame to move up and hit the safety cage. This caused a nearly constant clunking sound when under load. Not so much cruising.
If you believe it is internal like what the PO told you add some Sea Foam, Marvel Mystery oil, or some other kind of oil and gas system cleaner about a week before changing the oil or sooner. YMMV with these however since they may do more damage, fix the problem, or do nothing at all. :o
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Alright thanks, yeah I put some marvels in there to see what that would do and nothing. also took valve covers off and intake on the top of them there was some chocolate milk looking oil which was thinking intake manifold gasket prob no good anymore but yeah truck came with a full gasket kit so 1 less thing I got to buy. but anyway when I had the covers off everything looked clean no sludge nothing so I don't know. guess I could take 1 spark plug wire at a time till that noise goes away then that give me a better idea of what side of the motor and cylinder the noise coming from.
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truck came with a full gasket kit so 1 less thing I got to buy. but anyway when I had the covers off everything looked clean no sludge nothing so I don't know. guess I could take 1 spark plug wire at a time till that noise goes away then that give me a better idea of what side of the motor and cylinder the noise coming from.
May as well rent a compression tester at your local discount auto store. Average around 40.00, get all your money back when you return it.
If that fella thru in a complete gasket set, I think you may have some major issues....just thinkin out loud
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Yeah I have no idea ill have to do more investigating to see what's going on. And thanks yeah I should go rent a tester. Dude said motor got 100k on it his friend that had it before paid 3,000 for the truck then sold to him cus needed money then I picked it up for 1,500 so if motor is bad I'm not to worried bought it as a project to give me something fun to do you know but if its not too messed up ill keep it in there for now but yeah will see how it goes 👍
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Hi everyone I got a question my 350sb when I put it in drive and speed up real fast it starts making a loud clunking noise but only happens when you try to accelerate fast if you slowly ease into it not so bad. But yeah if in park it revs up fine but if try to step on it seems to stop accelerating and starts making a loud clunking noise kid I bought it from said it was due to a sticky lifter and idk I think it might be fuel delivery related like maybe to much or to little or timing is off I'm not sure I know at idle when first start its fine then slowly starts climbing in rpms longer it sits maybe something up with the carb might be reason it makes that noise when try to step on it? It's a summit 600cfm 4barrel but yeah if you have had this issue before please feel free to share thank you.
Check for a cracked flexplate. Remove the inspection cover and use a bright flashlight to look up at the steel plate between the engine and the torque converter. Cracks around the center of the flexplate are a common problem. Post a pic of the "chocolate milk" looking oil and where you found it. A compression test is a good idea to determine general engine condition.
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maybe a stethoscope will help too. I used to use a long philips screwdriver but a stethoscope is much easier and less deadly. Plus it's not too expensive. http://www.tooltopia.com/otc-tools-4491.aspx?utm_source=google&utm_medium=cpc&utm_campaign=paid_search_google_pla&scid=scplp6824168&gclid=CIXZkOCFvcsCFQYNaQodIE8DIQ (http://www.tooltopia.com/otc-tools-4491.aspx?utm_source=google&utm_medium=cpc&utm_campaign=paid_search_google_pla&scid=scplp6824168&gclid=CIXZkOCFvcsCFQYNaQodIE8DIQ)
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Thank you yeah ima take a look tomorrow at some of the stuff that you guys have brought up also will be taking some pic's see if can get a video to help but yeah I live in oregon so hopefully not raining tomorrow that and it's my only day off so ill try do as much as I can
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Chocolate milky looking oil on the dip stick I think I might of cleaned little bit of it up before that's why not as much but like I said found some coating inside top of valve covers. but yeah Couldn't get under the truck far enough to check for cracks in the plate also since I was under there was curious if stock torque converters are sky blue / baby blue or if that's after market. But yeah was raining a lot today wasnt able to do much there was a few breaks in th weather but barely enough time before it started raining like heck again.
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https://m.youtube.com/watch?v=WrMHzjXZ-Rg
The link 🙌 I guess it's more of a knocking been a while since i have drove it but yeah sounds bad.
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The Youtube video is locked as private and is inaccessible to public view.
My concern with "chocolate milk" is moisture. If there is significant water in the oil it will whip into a mayonnaise like consistency and appearance. "Chocolate milk" could be a high accumulation of condensation in the oil from rarely running the engine to operating temperature combined with poor oil and filter change habits. It could also be a large accumulation of water that hasn't been whipped yet. Either scenario degrades lubrication of the rotating assembly - the second scenario being a worse case. If the rotating assembly has been starved for adequate lubrication, you maybe hearing bearing knock. Remove the oil drain plug just long enough to drain about a quart and check it for water before you run the engine again.
Factory torque converters are not painted, suggesting it has been replaced.
Edit: Look at the thread: Crankshaft (http://forum.73-87chevytrucks.com/smforum/index.php?topic=32797.msg278430#msg278430).
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So add a flush and oil change to the list and see what that does huh? and here's the link again I check it and it says public maybe I was still in my account when I copied link don't know but try this again https://www.youtube.com/watch?v=WrMHzjXZ-Rg should work this time 👌
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yeah i would be kinda concerned with the choco milk oil, i had something similar on my motor and it all started because the po didnt tq the intake bolts down and the gaskets didnt seal. When was the last time you changed the oil? i barely drove my truck at all when i got it (less than 5 miles) then i changed the oil after letting it sit for a few days, and i had half a quart of water come out before any oil because of the leak in the intake. I decided to pull my motor out and put a rebuild kit on it, and its probably one of my best ideas because i found my crank in pretty bad shape, and thats when i noticed the intake issue. The intake gaskets were all swollen because they werent tqd down all the way. Attached is what a photo of diluted water will do to the crank... I just pulled the crank out today and found a very spun bearing, but my truck would idle fine and rev up fine while in park but knock when it warmed up and i hit the gas. Just food for thought...
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try and let it sit for a day or 2 or 3 before you change the oil if you can, that will give the water and oil time to seperate, and any water will come out before the oil.
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never changed oil since iv had it which was last summer but yeah it sits and I start it up few times a week but yeah prob should dump that crap out of there. But yeah sounds right on what's going on with my truck so we'll see what happens in the end. Soon as I get another paycheck ill get some fresh oil in there and stuff see if it makes a difference.
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Alright so took another peak in some different areas under the truck and I came across the 2 piece bearing of the drive shaft I don't think that spine should be hanging out like that. Then I looked up and found this form http://www.plowsite.com/archive/index.php/t-10025.html pretty much saying that it can cause loud clunking under acceleration. I Think that might be it
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that will be ok. thats where the shaft will slide when you hit a bump. it should give it a couple inches in each direction
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Have u checked your engine and trans mounts?
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Yeah got around to looking at the flexplate and engine and trans mounts it's been to rainy I can only go so far under cause front sits to low the long tube headers would be no joke on my throat not much room so have to wait until its half way decent outside so I can lift the front end and check up on the stuff underneath. But yeah anything else that you guys think it might be let me know thanks👌
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^ I mean haven't
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Ramps....
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Yeah I got ramps too just doesn't seem like the greatest idea to do that in the middle of down pours be trying to look for stuff at the same time getting my man parts washed by Mother Nature trying to look for a break in the weather.
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Could be worse, it could freeze the man parts right off... :o
I hem and haw at crawling under my stuff too, gravel drive, mud and no concrete or other solid area to work on my stuff. Gravel and grass. Drop a bolt or something and spend twenty minutes looking for it (not anymore though, I finally bought a strong magnet). I'm really seriously considering using pavers to make a solid, albeit rough, area to park my stuff on to work on it. Then get one of those $700 carport canopies to work under. Maybe lay some plywood down so the jack will roll.
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Haha yeah something like that. I figure when I finally get a house of my very own I'm just going to pave over everything. Grass is over rated haha👌
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I agree now, but 13 acres to pave is a bit pricey. ???
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Yeah that be a bit much ha.
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Well I found a leak 1 of the freeze plugs or casting plugs w/e you want to call them is leaking water on my started which explains why it doesn't wanna start when I put a lot of water in. But anyway yeah think I could fix that without pulling the motor? looks like a tight fit defiantly would have to remove the starter out of the way. and back to the knocking noise could it just be low on oil or cause there's probably water in there so it's not oiling everything up like it should and making that clunk noise? Found more chocolate milk lookin stuff haha
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Take a small bright flashlight and look into the oil fill hole to see if that sludge is sitting on top of the rockers. If so change the oil and filter and keep an eye on it for a few weeks and change it again. As for the clunking/knocking that is never good coming from an engine. But there is always the slim possibility that the sound is being transmitted forwards from something else. Water on the starter doesn't hurt anything, it is after all out in the open anyway. I used to start my old truck when it was under water, in fact my throwout bearing seized and broke the front input housing nose off my sm 465 and drove the truck the rest of the week 4 wheeling and then drove it 100 miles home through St. Louis traffic to north county (all with no clutch and approximately 10.5/1 compression -450 horsepower- for the starter to turn over). And even that didn't kill the starter.
The casting plugs (most often erroneously called frost plugs) can be changed if you have the room. But that is a problem sometimes- getting the room. Maybe someone here that works on them more often than I do has new advice on how to do it easier than the way I know. No matter what, it is not hard, just takes some time. I say not hard once you get to the plug, getting to the plug can be a nightmare on an old engine with stock exhaust manifolds. Broken exhaust bolts will be the most common headache.
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Can't quite make out what that image is. If the white accumulation is the "milk" you are referring to, there is water in the oil and the knock is a rod bearing - damage has already been done. Under these circumstances, changing the oil is futile.
Procure a cooling system pressure tester, fill the radiator with water and pressurize it to 20 PSI, no more. Remove all of the spark plugs and unplug the power lead from the distributor (HEI) or remove the coil wire (conventional ignition). Pump up the cooling system pressure if it bleeds off. After about 15 minutes, have an assistant crank the engine while you watch from the front of the motor to see if water blows out of a spark plug hole on the initial crank. DO NOT stand over a fender or you could be drenched and possibly injured. If water blows out through a spark plug hole either the head gasket has failed, or a cylinder wall is cracked, or a head is cracked. If the cylinders pump clear then there is either a cracked block, a cracked cylinder head, or the intake gasket is leaking from the coolant crossover passages at one or more of its four corners. There are other possibilities, but these are the most common.
Don't waste your time with the freeze plug or any other superficial repairs until you determine what has failed and is causing that knock.
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Shouldn't there be a bolt going through that hole?
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Yes, along with a matching bolt on the front of the crossmember and one down through the top for a total of three bolts retaining the diagonal brace to the horizontal crossmember on the right side.
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So I take it every time I stomp on it while driving that's probably moving around making that noise? cause when I watched my little YouTube video it didn't quiet sound like it was coming from under the hood unless I was just thinking to much into it but like I said revs up fine but when I stomp on it while actually driving I get the noise
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A crossmember popping can make a loud disheartening sound, but normally will just "pop" once in awhile as the frame flexes. The bolts that pop are usually the larger frame bolts passing through the side rail. Actually, it's not the bolts that pop, but the large members suddenly overcoming the clamping friction between them, which allow the frame members to slip. The video you posted sounds a lot more like a large rotating mass that is hammering. That coupled with water in the oil are bad indicators. But, being there you have the advantage in determining where the sound actually originates. If you can reproduce the sound with a helper in or next to the vehicle, perhaps you can narrow it down.
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Yeah thought about tapping a video camera to the hood then maybe under to see what's going on prob get best results that way that's if the camera doesn't fall off and get run over in the middle of the shoot ha.