Engine noise

[MFerioli]

Hey guys,
I have a '90 3.0 with 113,00. it recently started to make some noise, sounds like a rattling from within the engine. It does it at idle and it does it when getting on the gas in higher gears. Seems most pronounced when the engine is under load, like when going up a hill on the highway in fifth and stepping on the gas, or in any other situation where I have lower rpms in a higher gear. It doesn't sound like a ticking, definitely more rattly than anything else.
Just wondering if it could be anything other than a bearing/pin deal on the rods.

Thanks,
Mike

P.S. The information on this site was a huge help in replacing my slave cylinder and bleeding that pain in the ass clutch. Thanks to all that contribute here.

 

[Wicked_Sludge]

this is almost assuredly detonation that you are describing...though it usually doesnt occure at idle. the 3.0's are somewhat notorious for it. there are several likely causes: id start with a good tune up (fuel filter, plugs (set to the correct gap!), wires, rotor, cap, air filter). have your base ignition timing checked (it should be 10 degrees, and dont forget to pull the spout). the last step is cleaning the cumbustion chambers to remove carbon deposites. this can be done at home with a product called seafoam (comes in a red and white can)...but if none of the above helps, i would take it to a shop for water injection.

spark knock, detionation, pinging, are all cause by the same thing: the air fuel mixture is exploding rather than burning, causing the piston to jar against the wrist pin and the connecting rod to jar against the crank. its VERY bad for your engine and its vital that you avoid situations that cause the noise. downshifting to a lower gear on hills is REQUIRED with this motor (4,000 RPM is nothing to a vulcan). if all else fails, you can always retard the timing a few degrees. this will cost you a small amount of power, but it will save your engine from a premature death.

 

[bikerboy]

Wicked nailed it on the head!

 

[MFerioli]

Thanks for the reply, I will begin to gather the parts for a good tune up. I do already down shift, stay off the gas, and try and maintain high rpms to avoid the noise as much as possible. I noticed you mentioned that it doesn't usually occur at idle, thats what concerned me that it may be something else, but I will definitely do the tune up first and go from there. I'm sure it could use it anyways.

People seem to think seafoam should only be run for a short time, it doesn't anything about that on the can, why the short time suggestion?

Just curious, you seem pretty knowledgable, are you a mechanic by trade? Or just a well seasoned enthusiast?

Thanks again for all the input.

 

[Mutant Pony]

Plain old rod knock WILL knock at idle and get louder under load. Does it have oil pressure? Has it ever had a head gasket problem? A mechanical oil pressure tester will show a spun rod bearing by a bouncing needle.
There is also a possibility of carbon knock. It is a condition where the carbon in the engine builds up so much that it causes an obstruction between the piston and cylinder head, hence the knock at idle. It also raises the compression causing detonation. Big repair shops have a "top cylinder cleaning system".

 

[MFerioli]

Oil pressure guage always reads in the middle. Don't know if it has ever had a head gasket issue as I am the second owner. A top cylinder cleaning sounds pricey. How effective do you think seafoam really is? Maybe I'll do a tune up first, check results and then run the foam to see if it makes any difference.

Thanks,
Mike

 

[Mutant Pony]

Any good cleaner sprayed into the intake at a slightly increased idle will remove the carbon. I've used carb clean on older stuff. You may end up with a new engine code but, it is just from the cleaner. You will have to divise a way to spray between the mass air flow sensor and the throttle body.
Your oil pressure gauge uses a sender for a light (idiot gauge). If it has 5lbs of oil pressure, it reads half gauge. That is why you need it tested with a mechanical gauge.
A head gasket problem in the past may have caused bearing damage.

 

[Wicked_Sludge]

you know, the longer i think about it, the more the noise at idle doesnt sync up with detonation.

i think mutant is on the right track (bad news since the engine will likely have to be opened to repair the problem). detonation is just such a common problem with high mileage 3.0's, i had it stuck on my brain.

i am a mechanic by trade (as are a lot of members on this forum)....who sometimes jumps to conclusions thats why it pays to have more than one mind on a particular problem.

 

[MFerioli]

Well thanks for all the replies, I'm going to do a tune up anyways, we'll see what happens. Can I get motorcraft parts to replace all the electrical? I assume it would be fine to just use the OE stuff.

Can bearings be changed with the engine in by just dropping the oil pan?

Thanks,
Mike

 

[Wicked_Sludge]

most guys on here will tell you motorcraft or autolite plugs are the only way to go. personally i run champion in my truck and havnt had a problem. really any double platinum plug will work.

i prefer napas belden 8mm wires.

i also reccomend using a motorcraft PCV valve and nothing else. aftermarket companies like to take short cuts and sell "one size fits all" PCV valves...so most of the time they are not metered properly for the application they are being used for.

 

[MFerioli]

can bearings be changed by dropping the pan?

How much carb spray would you run through the intake? a whole can?

Thanks

 

[Psychopete]

can bearings be changed by dropping the pan?

I am not saying it's impossible, but I will say that the likely hood of finishing it in such a state is likely not going to happen.

The biggest issue is the rod bolts and the crank shaft, it's a V design. It's isn't like you can just undo the rod caps, mains and drop the crank. If you attempt such a thing w/o condoms on the rod bolts, you'll scratch the crankshaft. Plus it's essential to keep everything CLEAN.

I will say that I know of a person who changed a bad rod bearing in a 3.8L Taurus with no machine work ultimately had the engine fail within 2 days (in the car, but they only replaced one and didn't have a cross member right in the way). If you have a bad bearing for some time, it's likely the crank is going to have some light scratches or gouges.

People already have lots of problems ONLY changing the oil pans gasket going that route, I can't even comprehend the nightmare you want to unleash on yourself.

Ultimately, the answer from me is, save your self the trouble and pull the engine (basically, no). IMO, an engine crane is essential to a DIYer.

IMO

Pete

 

[MFerioli]

Thanks Pete,
That is the kind of info I was looking for. I don't have the ideal setup, just a driveway in the cold northeast. So I guess I'll do my tune up, make an effort to reduce carbon and drive her nice. Maybe it won't get any worse, maybe I'll get lucky and its detonating a bit. One can always hope right.

Any other suggestions for carbon removal would be great. Wish I had one of those scopes to stick in the plug hole and check things out in there.

Mike

 

[Wicked_Sludge]

as for the seafoam:

its not a spray, its a liquid...you feed the engine through a vacuum line. make sure you feed it slowly enough that you dont stall the motor. the can has instructions on how to use it. after youve gotten the seafoam into the motor, you shut the engine off and let it sit for 5-10 minutes so the seafoam can penitrate any carbon build up...then you fire it up and go drive the shit out of it (high RPM and high heat are what shocks the carbon loose). of coarse if you have a spun rod bearing, high RPM isnt going to help that situation...but thats something that isnt going to clear up on its own and will only get worse (rapidly) anyway.

 

[MFerioli]

My engine rattle is interesting. I was listening more closely today, noting the sound at different rpms and loads. When in high rpms and in 2nd or 3rd, the engine seems smooth and quiet. When in fourth and stepping on it is when it will rattle, its kind of a non synched rattle, it almost doesn't seem to sync with the motion of the pistons. When revving the engine in neutral, I get no noise at all. Some days there seems to be a noise at idle and some days I dont really hear anything. I will almost always hear it when going up a hill where the engine starts feeling more load.

Just figure I'd post my observations. Thanks for the tip on the sea foam, I read a can once but only saw the part about adding it to the oil. I was confused a bit because i could'nt see how that was going to help carbon build up.

Thanks again for all the back and forth, off to put in some new plugs on this cold MA night!

Mike