rattling noise from engine when under load

[snocross1985]

I have been getting a nasty rattling noise I guess you could call it. Whenever I am driving and rev up past 3000 rpm, it sounds like there are marbles rattling around in the block. It is loud as al get out too. I tried cleaning the MAS because I had this problem before and cleaning the MAS got rid of it. Well I cleaned the MAS with electrical contact cleaner and ran a can of Seafoam as well as disconnecting and reconnecting the battery after 15 minutes to try to reset the computer today. It got rid of maybe 40% of the noise, but there is still some there. I don't know what to do, I am at my wits end. Anyone have any suggestions? I'd hate to think this could caus edamage in the long run so I want to get this fixed. Please help.

 

[Rockey]

What your hearing is detonation. Its a sawtooth waveform that forms in front of the ignition/cumbustion front. There are lots of variables that cause detonation i.e. compression, timing, a/f ratio, intake temperature. Higher octane gasoline will help by giving your engine more resistance to detonation. Try higher octane. If this doesn't help then you will need to look elsewhere. Too much carbon buildup, O2 sensors bad. Its hard to troubleshoot from behind a computer, you may need to take it to a prof. if the simple things dont work.

 

[SportlineXLT]

I've been having the same problem recently. I'm going to have to do a tune up and run some higher octane. No CEL, thank god. Thanks!!! It's always nice to know your not the only one. I got so scared when I first heard the noise, I thought a valve was loose/breaking, until my dad told me it was detonation.

 

[snocross1985]

Well I am running 91 octane, but that is because my diablo chip is burned for 91 octane. I will try calling my chip guy tomorrow to make sure that the chip was burned for the proper octane. Thanks for your help.

 

[Jason94sport]

I get a simliar noise when under load. At about the same RPM, maybe a little less. Sounds like a card in a bike spoke. Only when pressing the gas though. It sounds like it's coming from the rear of the engine. I don't hear it when I'm looking under the hood. But I do hear it from inside the truck. I don't know what it is. All the normal stuff is good. It's not the tranny or drivetrain cause it does it in P & N. I ahven't tried anything better then 87 gas. I fill up my Acura with 93 & at $2.15+ for 93, I'd rather not use it in the X too.

 

[snocross1985]

Turns out my chip requires 93 octane, not 91. I added some octane boost to the tank and the noise went away 100%. On my next fillup I will be sure to use Mobil 93 octane and hopefully this sound stays away.

 

[MrShorty]

You have missed the third common cause of ping on the early 4.0 OHV: vacuum leak. In particular, the lower intake manifold bolts come loose and allow a small leak through the gasket. Usually you can just tighten the bolts down and she'll be good to go. On occasion the gasket actually needs to be replaced.
Beyond that, there are some less common causes of engine ping. Give that a try, and if that doesn't get it, then we can try some of the less common things.

 

[SmoothJimmy]

Ping in 5.0 fixed

Had the same pinging problem with my '96 5.0. Tried 89 octane gas and it helped somewhat. Went to get my car smogged last week (out $87.50) but the smog inspector said I should replace a short (2") vacuum hose. I expected he was trying to sell the parts and/or service. He said he couldn't do that. I checked my manual and the hose connects the EVR to the EGR. If there is a leak in the hose, it will prevent ideal EGR, lean the mixture and cause the engine to run hot and PING! I pulled the hose and found it cracked. Replaced it with a new hose and voila! no more ping. I might even try 87 octane again.

 

[Jason94sport]

My noise isn't pinging. It's something else. I filled up with 93 yesterday & the noise is still there.

 

[bates]

This is a good thread, I have ping issues as well, to the point where I have pulled my octane shorting block out, adjusted my crankshaft position sensor, and I still have the problem. I'm gonna try some of these fixes though. So so far the list is:

-Loose lower manifold bolts
-bad O2 sensor
-carbon buildup
-replace vaccuum line from EGR to EVR (what dia. of line? is there more than one dia.?)

I never had this problem until I had the heads changed, I think maybe the new ones were decked or something, which would give me a higher CR, hence my ping problem, but it comes only after the engine has been running for a while, like on the highway. So it may be a carbon buildup issue, or a vaccum leak somwhere.

 

[brsvo]

Dentonation

I had dentenation and tried most of the things dicussed. Went to a friend that is a top notch Ford mechanic. He plugged a CD into the computer in his shop and went to dentenation problems and Ford says to do a fuel injecter clean. We did this plus new spark plugs and the problem has been solved.

 

[Skeets'91EB]

My noise isn't pinging. It's something else. I filled up with 93 yesterday & the noise is still there.

Depends. You should at least try a seafoam treatment and see. Using higher octane only covers it up, so it could be that you just have a lot of carbon build-up. If cleaning the mas and a few seafoam treatments don't work, then you know to look elsewhere.

I've got the same problem too, and I'm hoping it's nothing above seafoam. I dont want to start looking at the bigger things like timing chains and rebuild issues.

 

[Jason94sport]

Sea foam was a waste for my engine. My truck didn't need it. Took a whole can & it only smoked a little bit. I have no idle or RPM problems. Runs smooth. Made no difference.

 

[Rhett]

This is a good thread, I have ping issues as well, to the point where I have pulled my octane shorting block out,

Pulling the octane shorting block is not something you want to do because your truck will lose power that way. At least I wouldn't want to do that..
Works ok but I personally would want the power. OHV's need all the hp they can get...

-replace vaccuum line from EGR to EVR (what dia. of line? is there more than one dia.?)

1991's don't have EGR. The only way you would have EGR is if it was added in when they changed the heads--but they would also have had to change the upper intake manifold and computer to add EGR properly. If they added EGR but didn't also reprogram or replace the PCM (computer), your truck will run poorly.

I never had this problem until I had the heads changed, I think maybe the new ones were decked or something, which would give me a higher CR, hence my ping problem, but it comes only after the engine has been running for a while, like on the highway. So it may be a carbon buildup issue, or a vaccum leak somwhere.

Not all OHV heads are the same. I know the heads on a 91 OHV engine are not the same as the heads on a 98 OHV engine. And so the compression ratio is slightly different. Do you know what year truck your heads were taken from? If they simply put 2001 OHV heads on your 91 block, with 91 computer, that could cause a problem--the computer thinks you have 9:1 CR, for example, but you might have 10:1...

Regarding your pinging: You probably already know this but when you engine is cold the computer will richen up the mixture to warm the truck (rich = less chance of ping), and the O2 is turned off. As the engine warms up, the O2 starts firing signals and the computer leans the mix. Leaning = more chance of ping. If your comp. ratio is right, you are on the right track with O2 sensor, and vac leaks (unmetered air = more chance of ping). You might also check your fuel pressure regulator...

If your timing and PCM isn't set up for your heads CR, then you can run all the injector cleaner thru it you want and it won't help. You'd have to get the PCM reprogged for the heads. Or go back to the same build heads you had before. Find out what heads you have on there and re-post...

 

[Rhett]

Sea foam was a waste for my engine. My truck didn't need it. Took a whole can & it only smoked a little bit. I have no idle or RPM problems. Runs smooth. Made no difference.

Well, my truck needed Seafoam, and it didn't smoke at all. Not a bit. Didn't ping afterwards though.

I assume you Seafoamed thru the vac port on the THROTTLE BODY (not any other vac line). I also assume you have no vac leaks and that you have re-torqued the lower intake manifold bolts already. Also make sure your wires and plugs are in top shape. Do you have a timing chain slapping around back there? What about the metal shield around the catalytic converter? It's only tack welded and can bang around in there under acceleration.

 

[Jason94sport]

Everything is tight. No leaks. Unless it breaks I'm not worried about it. I gave up. I just turn my stereo up a little louder now

 

[Rhett]

Don't give up, pinging can be solved! By the way, you are in Boca. I was there not long ago, I went in that big mall there on Glades Rd. Pretty nice to visit but it was expensive there.

 

[Jason94sport]

My problem is not pinging. My truck doesn't ping. It's some other noise. I live down the block from that mall.

 

[MrShorty]

Alright, Jason, yours isn't pinging. Fate has put your posts in a thread about pinging. A couple of thoughts on your noise.
since it makes the noise in P or N, 1st suggestion would be to get a stethoscope and poke around with it to see if you can see where the noise is. A couple possibilities I've thought of:
I've heard of cracked flex plates making rattling noises.
fuel injectors normally make a noticeable clicking noise. I've heard excessive noise from the injectors can point to a bad PCM ground.
loose parts (heat shields come to mind).
I'm sure there are other possibilities.

 

[Skeets'91EB]

Mine isn't pinging either, cuz it's more of a metallic sound. But I'm still a little unsure cuz it only occurs when the engine has a load and around 2,000 rpm. I'm going to check the manifold bolts in the next day or so.