sound of rod bearings.

[rcsavage]

im hearing a new noise in my 3.0 i have to turn the radio off as well as the air conditioning to even hear it. its kinda like a thump noise. it is very intermintent. like 1 or 2 a minute. sometimes if i turn on the air conditioning, it thumps instantly. my dad suggested maybe backfire. when it thumps i can feel it though the car. it not very strong. i almost have to listen for it to reconize it. so what do the experts think? bearings or somethine else?

edit: just saw a post and it reminded me. could i be feeling the effects of oil in the plug wells?

 

[shelby_sho]

Doesn't sound like rod bearings at all. A rod bearing makes noise because there is too much clearance between the bearing and the crank journal. Every time the crank spins around the rod will knock against the crank.

You could be feeling a misfire at idle. If so, plug wires and spark plugs would be a good place to start. I'm not sure that oil in the plug wells is all that serious. I had some oil for > 60k miles without any misfire problems. If you do go to the expense of replacing the wires though, you would probably want to re-seal the plug wells.

 

[rangerj]

The thud you are hearing could be a dead miss due to a bad plug or plug wire or failing coil. Oil in the plug wells could also cause this, as stated above. If the plugs and plug wire have more than 60K on them they are due for replacement. Check the plug wells first, than start pulling plugs and check their condition, gap, etc. Also check for any fault codes in both the KOEO and KOEO modes.

 

[ViPER1313]

This is what a bad rod bearing sounds like - http://www.bdcforum.com/upload/shoknock.avi

 

[rcsavage]

ok thanks i have some new wires so i guess ill buy some plug seals and make sure it gets fixed. should i replace the plugs also? if so, what plugs should i use. Viper1313, as i understand it that was an engine that spun the bearings so i was thinking maybe mine were in the begining stages.

 

[rcsavage]

ok i went to check codes and i got 15, 85 on the koeo test and 21, 77, 74 on the koer. i looked them up on sho phoenix project but it doesnt mean much to me. also, i heard a new noise today that is like a light tapping and this happens very quickly. this is the noise i hear is the sign of rod bearings correct? anyone know of a good shop in or around Boca Raton Florida?

 

[93superSHO]

ok i went to check codes and i got 15, 85 on the koeo test and 21, 77, 74 on the koer. i looked them up on sho phoenix project but it doesnt mean much to me. also, i heard a new noise today that is like a light tapping and this happens very quickly. this is the noise i hear is the sign of rod bearings correct? anyone know of a good shop in or around Boca Raton Florida?

Don't worry about the codes they are non-essential. You need to pinpoint where the tapping is coming from( top of the engine or bottom of the engine). Go to an auto parts store and get a mechanics stethiscope or just use a long screw driver and listen to each valve cover front and back on both ends of the cover and the oil pan.

The tapping noise could be a bunch of things- injectors, cam chain/tensioner, sticking valve, cam lobe hitting shim(valve lash needs adj.), rod bearing.

Save some money and try to pin point it yourself, Does the noise occur when engine is normal temp, cold? Does the noise increase/decrease with the speed of the engine? When was the upper/lower 60k done? I have worked on an SHO that had a bad timing belt tensioner that made a tapping sound similer to a sticking valve(the belt would hit the cover).

Hope these idea's help.

 

[rcsavage]

ok thanks alot. i try to pin point it more but i can hear it in the car and hear it very litte(because of the sound of the engine) when i open the hood on the drvers side. thats the side with the chains isnt it?

 

[rcsavage]

the noise happens up to about 3000 rpm but i probably just cant hear it over the engine. it sounds like its coming from the chain nearest the firewall. i listened to the front also and didnt hear it. i went to the passanger side and listened and just heard a squeak so its probably just a puley. if it were the rod bearings, where would i listen to hear it. and if its the chain/chain tensioner, what does that require replacing?

 

[93superSHO]

To check the lower end of the engine you need to listen thru the oil pan. It will be a lower tone of tapping. I doubt it is a rod bearing. From what you have said, it sounds like you have a bad or going bad cam chain tensioner. I have seen this several times on higher mileage engines and an engine with 50,000 miles. On the tensioner there is a guide/wear pad on it (it uses oil pressure to control tension, oil sludges up and does not drain out properly, the result is the tensioner puts excess tension on the chain wearing the pad down to the point where you get the chain to "jump" on the pad). To check this you will have to take the valve cover off and remove the tensioner( it sits upside down on that head IIRC. They are NOT interchangable, if it is bad you will have to get another one for that side. Hope this makes sense to you.

 

[rcsavage]

ok thanks. they dont happen to make these new any more do they?

 

[SHOblime]

If your motor has a chain you are in bigger trouble than a possible misfire...

 

[ohfosho]

If your motor has a chain you are in bigger trouble than a possible misfire...

you do know that the SHO motors have a timing chain on the drivers side of each head right? they arnt really a normal wear part (well the tensioner pad 'should' last the full life of the engine, if it has been well maintained), these arnt really timing chains...but they keep the twin cams over each seperate head in spec with each other. the timing BELT is one the passeger side of the motor.

 

[SHOblime]

hehe right after I made that post I realized that I just had my valve covers off, too... I thought he was talking about the timing belt at first...

 

[rcsavage]

until i can find a new tensioner, is it ok to drive it around? the only time i have coming up is in march when im doing a valve adjustment. will it hurt anything if i keep driving. obviosly i know that if it gets louder it getting worse at which point ill stop driving it.

 

[93superSHO]

You should be alright. Try to take it easy on it if possible, keep fresh oil in it( I'd change it at 2000-2500, I know it sucks) I replaced them on a SHO that were making noises for 10,000 miles( I don't recommend waiting that long). The chain started to wear into the metal on the bottom of the pad. When it is really bad it will sound like a constant rubbing sound. They are still floating around in dealerships. I bought both sides from my local Ford dealer( tell them what your looking for- camshaft chain tensioners for bank #1) Mine came from a dealer in Ohio. I was told that a dealer in Wisc. had one and Texas had one. They cost me $83.44 each.
I am NOT 100% positive that is the problem however from what you described it sounds like that is the problem( based on my experience with these engines)

ALSO, If you can't find one I can get you a good used one from a local connection

 

[rcsavage]

ok see if i can get one. if not ill pm you. thanks for all the help.

 

[ManySHOs]

you do know that the SHO motors have a timing chain on the drivers side of each head right? they arnt really a normal wear part (well the tensioner pad 'should' last the full life of the engine, if it has been well maintained), these arnt really timing chains...but they keep the twin cams over each seperate head in spec with each other. the timing BELT is one the passeger side of the motor.

I refer to those as timing chains. If you adjust the sprocket or alter which teeth the chain lies on, you've changed the timing. These chains can stretch over time. When I built my 3.2 I installed new Ford chains with tensioners that were in great condition.

Ian

 

[JSIL1]

This is what a bad rod bearing sounds like - http://www.bdcforum.com/upload/shoknock.avi

First off: Sorry for reviving the dead..now on to important issues


I am looking at a 91 SHO with what I would consider to be the same noise as in this video.

What would I be looking at in terms of repairing it?

The noise was there from the moment the engine started and was loud as S@%t.

 

[platoribs]

I'm prolly not your best source of information here @ SHOForum, however I have heard it said that if you got a bad spum bearing you will have to either fix that journal/connecting rod/bearing by removing the crank and having it machined and install oversized bearings, or replacing the entire rotating assembly.

If you can find a decent, low mile boneyard engine you will probably be saving money over the proceedures above.