Rattling sound while accelerating?

[chengny]

And now I also notice it sounds like theres a knock in the engine while idling. And the rattling seems to come in the first little bit I press the accelerator at idle and then it goes away.

Oh Jeez dude, I didn't want to bum you out but that's what I meant when I said this:

There are other - more serious - reasons that will cause an engine make the sounds you describe, but eliminate the simple stuff first.

What is your oil pressure at idle?

Does the sound get worse when the oil is warm?

Get under the truck while it's idling and making the noise - and check the area around the flywheel.

While idling, pull the plug wires one by one and noted whether removing a particular wire causes the noise to stop.

 

[Skweegle89]

I hope it didn't detonate itself into submission, but you can do stuff yourself to diagnose your problem without getting raped by a mechanic. Follow chengnys instructions and report back. You might also find a nick place to park it where you can work on it, as it will probably take a few days to figure this out. Also, don't start it anymore unless your doing on of these tests as its not going to get any better on its own. I know it's tempting to fiddle with it, but you won't do it any good at this point. You have to diagnose the problem before you can fix it.

How about a little history on the truck? Is the motor original? Has it been rebuilt since you have owned it?


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[hambo]

I hope it didn't detonate itself into submission, but you can do stuff yourself to diagnose your problem without getting raped by a mechanic. Follow chengnys instructions and report back. You might also find a nick place to park it where you can work on it, as it will probably take a few days to figure this out. Also, don't start it anymore unless your doing on of these tests as its not going to get any better on its own. I know it's tempting to fiddle with it, but you won't do it any good at this point. You have to diagnose the problem before you can fix it.

How about a little history on the truck? Is the motor original? Has it been rebuilt since you have owned it?


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Okay I'll try that and see what happens.

And now I also notice it sounds like theres a knock in the engine while idling. And the rattling seems to come in the first little bit I press the accelerator at idle and then it goes away.

Oh Jeez dude, I didn't want to bum you out but that's what I meant when I said this:

There are other - more serious - reasons that will cause an engine make the sounds you describe, but eliminate the simple stuff first.

What is your oil pressure at idle?

Does the sound get worse when the oil is warm?

Get under the truck while it's idling and making the noise - and check the area around the flywheel.

While idling, pull the plug wires one by one and noted whether removing a particular wire causes the noise to stop.

I just bought the truck about 6 weeks ago. 1987 chevy r20 converted to 4x4 with a tbi 454. Sm465 trans and np205. The engine has almost 138k on it with a new top end meaning new intake manifold, headers and whatnot. I dont know how in depth he went if he put in new valves or anything else. The top end just looks new. I havent gone through the stack of parts receipts he gave me.

 

[hambo]

And now I also notice it sounds like theres a knock in the engine while idling. And the rattling seems to come in the first little bit I press the accelerator at idle and then it goes away.

Oh Jeez dude, I didn't want to bum you out but that's what I meant when I said this:

There are other - more serious - reasons that will cause an engine make the sounds you describe, but eliminate the simple stuff first.

What is your oil pressure at idle?

Does the sound get worse when the oil is warm?

Get under the truck while it's idling and making the noise - and check the area around the flywheel.

While idling, pull the plug wires one by one and noted whether removing a particular wire causes the noise to stop.

I just went out and started it again, and now I cant seem to recognize a knocking sound, just the rattle when I rev it. I checked the flywheel and that didn't seem to be making any irregular noise. Also, my oil pressure gauge just stopped working, I just noticed it when I went to check it. Also, the truck has failed to start 2 times this week. I had to get a jump and. Had to be hooked up for like 10 minutes. It started a few times in between with no issues. And my battery is good and im pretty sure my starter is too. Could the random no starting be related to this rattling/knock issue?

 

[Skweegle89]

I just went out and started it again, and now I cant seem to recognize a knocking sound, just the rattle when I rev it. I checked the flywheel and that didn't seem to be making any irregular noise. Also, my oil pressure gauge just stopped working, I just noticed it when I went to check it. Also, the truck has failed to start 2 times this week. I had to get a jump and. Had to be hooked up for like 10 minutes. It started a few times in between with no issues. And my battery is good and im pretty sure my starter is too. Could the random no starting be related to this rattling/knock issue?

Did the gauge fail or do you just not have any oil pressure!? That's a pretty important observation. The very first thing I would do is a compression test, as this doesn't require the truck to run and will give you the most important information. I would certainly not drive it anywhere, because your going to end up stranded with a hefty tow bill. Go through your receipts he gave you and define new "top end". Have you checked the condition of your oil yet?


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[Skweegle89]

When, in relation to your motor issue, did you last know for sure that you had oil pressure?


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[chengny]

Also, my oil pressure gauge just stopped working, I just noticed it when I went to check it.

This is key. Investigate whether the gauge actually stopped working. Find out if it is working and is telling you that you have no oil pressure.

 

[hambo]

Did the gauge fail or do you just not have any oil pressure!? That's a pretty important observation. The very first thing I would do is a compression test, as this doesn't require the truck to run and will give you the most important information. I would certainly not drive it anywhere, because your going to end up stranded with a hefty tow bill. Go through your receipts he gave you and define new "top end". Have you checked the condition of your oil yet?


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Okay. I'll go through the receipts and check the compression. I dont know if the gauge stopped working or if I dont have oil pressure. Im sorry I dont have a lot of experience like I said but if I have no oil pressure, wouldn't there be no oil running through the engine and it would seize up?

 

[Skweegle89]

Okay. I'll go through the receipts and check the compression. I dont know if the gauge stopped working or if I dont have oil pressure. Im sorry I dont have a lot of experience like I said but if I have no oil pressure, wouldn't there be no oil running through the engine and it would seize up?

Yes, it would cause an incredible amount of damage and then would seize up. That's why I advised you not to drive it anywhere. Don't apologize for inexperience. I was in your shoes a couple months ago and only know most of what I'm telling you because these guys told it to me.


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[chengny]

Locate the oil pressure sender. I don't know much about BB's but I believe the sender will be located in either of these two places:

1. Above the oil filter mounting boss

2. All the way forward - driver's side. Like behind the power steering pump.

The sender will have a bell shaped housing - one wire connected to it - probably brown.

Pull the sender and check the size of the threaded nipple. Should be 1/4" NPT.

Get a small gauge with the same size connection (0 -60 psi range will be okay). Also get the necessary fittings to allow you to connect the gauge to the engine block.

Start the motor and quickly note the pressure indicated on the gauge.

If it is less than 10 psi - stop. You have insufficient oil pressure to run the engine at all.

If it is over 10 psi (but under 20) - let the engine continue to idle. While it idles, continue to watch the pressure. As the engine warms up the pressure will fall off. If it goes below 10 psi - stop and investigate.

If it initially shows over 20 and stays there - relax. The problem isn't related to oil pressure and your dash gauge is not reading correctly.

 

[GTME94]

Locate the oil pressure sender. I don't know much about BB's but I believe the sender will be located in either of these two places:

2. All the way forward - driver's side. Like behind the power steering pump.

I'm not sure about newer trucks but on my '86 Big Block the oil pressure sender is where Jerry mentioned. Mine has a brass tee with both the oil pressure sender and the choke oil pressure switch. TBI obviously doesn't have a choke but I think they did have a similar oil pressure switch for the fuel pump.

 

[hambo]

Locate the oil pressure sender. I don't know much about BB's but I believe the sender will be located in either of these two places:

1. Above the oil filter mounting boss

2. All the way forward - driver's side. Like behind the power steering pump.

The sender will have a bell shaped housing - one wire connected to it - probably brown.

Pull the sender and check the size of the threaded nipple. Should be 1/4" NPT.

Get a small gauge with the same size connection (0 -60 psi range will be okay). Also get the necessary fittings to allow you to connect the gauge to the engine block.

Start the motor and quickly note the pressure indicated on the gauge.

If it is less than 10 psi - stop. You have insufficient oil pressure to run the engine at all.

If it is over 10 psi (but under 20) - let the engine continue to idle. While it idles, continue to watch the pressure. As the engine warms up the pressure will fall off. If it goes below 10 psi - stop and investigate.

If it initially shows over 20 and stays there - relax. The problem isn't related to oil pressure and your dash gauge is not reading correctly.

I'm not sure about newer trucks but on my '86 Big Block the oil pressure sender is where Jerry mentioned. Mine has a brass tee with both the oil pressure sender and the choke oil pressure switch. TBI obviously doesn't have a choke but I think they did have a similar oil pressure switch for the fuel pump.

Okay thanks for the info guys. Im away from my truck right now and was just going to order a gauge. Is the size 1/4 npt or should I wait until I can check it? Because I dont know how I would check it without having anything to screw onto it. And is the fitting part on the oil pressure sender a male or female fitting? I was planning on ordering a gauge like this: http://www.amazon.com/Milton-1194-P...501700&sr=8-6&keywords=1+4+npt+pressure+gauge

 

[GTME94]

It will be female threads in either the block or the tee. The gauge you linked to is an air pressure gauge. I'm not sure that would work properly with oil. It might be easier to buy an oil pressure gauge from an auto parts store in person or on line. It would have the gauge and plastic tube and fittings all together. That way you can have it up somewhere you can see it instead of having to be underneath to see the gauge.

 

[chengny]

NO - DO NOT ORDER A GAUGE WITH A 1/4" CONNECTION! I was wrong, the correct size is 1/8" NPT.

 

[hambo]

It will be female threads in either the block or the tee. The gauge you linked to is an air pressure gauge. I'm not sure that would work properly with oil. It might be easier to buy an oil pressure gauge from an auto parts store in person or on line. It would have the gauge and plastic tube and fittings all together. That way you can have it up somewhere you can see it instead of having to be underneath to see the gauge.

Okay. Thanks. Yeah, in person is a better idea anyway. I'll go to oreillys this weekend and see what they have. Do they make handheld oil pressure gauges specifically for this purpose?

NO - DO NOT ORDER A GAUGE WITH A 1/4" CONNECTION! I was wrong, the correct size is 1/8" NPT.

Okay. Thanks for the info. I wasnt planning on ordering it until I got the correct size confirmed