Bad Knock...Ohhh how much will this cost?

T

The Dan

New Member

Jul 16, 2003

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Orange County, CA

Apr 4, 2006

#1

• Apr 4, 2006

• #1

Looking for opinions on what potentially is the problem with my 306 that has maybe 1500 mi. on it. I statrted it up a few days ago to go on a cruise and then it happened, out of the blue, without warning. Knock Knock Knock. It isn't a lifter knock, it is like a VERY solid and rattling KNOCK KNOCK as if someone is hitting the inside of the block with a ball peen hammer. Not terribly hard or violent, but a good solid sounding knock. I don't know if something has come loose internally or what? At first, due to the rattly noise, I thought a motor mount or something on the outside was loose, but have found nothing externally, so I convince it is an internal problem. The car will statrt and run, but obviously not wise to let it run this way due to possible collateral damage from doing so. I pulled the valve covers and all rockers are solid and push rods are tight. Just looking for some ideas before I really start to disect this motor, which upsets me to do since it is such a fresh engine.

All ideas appreciated.

 

R

rufusbooth

New Member

Jan 16, 2003

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Manteca, CA

Apr 4, 2006

#2

• Apr 4, 2006

• #2

My recommendation is to first drain the oil and look for metal shavings. From what you describe you are most likely going to see some. It sounds like you have a spun bearing in one of your rods. The easiest way to confirm is to yank the oil pan off and try to move the bearing caps. Most likely you will find a loose one. If not it would behoove you to remove the main and rod caps one at a time for inspection.

Sorry about the bad news.


Cheers,

Rufus

 

M

mustangdave

My rearend needs a stud and two nuts.

Founding Member

Feb 26, 2002

2,976

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56

North Carolina

Apr 4, 2006

#3

• Apr 4, 2006

• #3

Definitely agree. Most likely a rod problem with the bearing or cap, although I wouldn't rule out the crank. I had this happen and made the mistake of running it too long and trashed my block, crank, rods,etc... Don't run it anymore until you at least pull the pan. Sounds like a rebuild; sorry. Where did you get the engine?

 

spirockp

5 Year Member

Mar 26, 2004

465

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NJ

Apr 4, 2006

#4

• Apr 4, 2006

• #4

Hows the oil pressure? That can tell you a lot! My 302 started to sound like a diesel it was knocking so badly with very little oil pressure. It truned out that because of missed matched pistons it made the crank go out causing a bad knock. Don't ask where I got the motor from.

 

Dark Knight

Founding Member

Feb 1, 2000

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Chandler, Az.

Apr 4, 2006

#5

• Apr 4, 2006

• #5

I'd check for a header gasket leak, they can get pretty bad and sound like you broke something.. I know..

 

T

The Dan

New Member

Jul 16, 2003

319

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Orange County, CA

Apr 4, 2006

#6

• Apr 4, 2006

• #6

Well, not what I was hoping to hear, but not surprised to hear it. Looks like I've got a job ahead of me.

Ford Performance Solutions in Anaheim built it. Don't know if it is too fair to say that if it is a soun bearing that it is their fault, anything can go wrong when building for high HP.

It is not a header gasket leak, I checked it for blow and it is sealed. I only have an oil pressure light, but the sender is new, so I'm sure it would trip if the pressure was too low. It has a balanced and blueprinted pump from Precision Pumps, so I'm confident it has good pressure.

Listening to it I would have to support the bearing idea, just hoping that wasn't going to be the problem...wishful thinking

 

302 coupe

Founding Member

Mar 2, 2000

1,952

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36

Macon, Ga.

Apr 4, 2006

#7

• Apr 4, 2006

• #7

put a real oil press gauge on it, and a real temp gauge too if you haven't already. When it comes to idiot lights....the name fits.

 

dennis112

15 Year Member

May 15, 2005

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Amish Wonderland of Central PA.

Apr 4, 2006

#8

• Apr 4, 2006

• #8

Remove the oil filter and carefully cut it open. Look for lots of metal shavings. Post pics.

You can take a long screw driver and hold it against the block and put your ear against the handle. This can help confirm that the knock is inside the block.

If you have a rod bearing or a wrist pin going bad and you want to determine which cylinder has the knock, try removing plug wires one at a time and listen for the sound to go away.

 

spirockp

5 Year Member

Mar 26, 2004

465

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NJ

Apr 4, 2006

#9

• Apr 4, 2006

• #9

The low oil pressure wouldn't be from a bad pump. It would be caused by too much play between the bearings and the crank for example. The clearence between a good set of bearings and the crank would be much smaller than a bad crank and bad bearings causing lower oil pressure.

Hook up a real oil pressure gauge. The idiot light may only come on with no pressure not low.

 

T

The Dan

New Member

Jul 16, 2003

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Orange County, CA

Apr 4, 2006

#10

• Apr 4, 2006

• #10

Fortunatly I have a Filter Mag on, so that hopefully will have kept any and all shavings, if any, from getting through the engine. I'll try pulling one plug at a time tonight to see if it will go away and go from there.

 

J

jbuening

Member

Apr 28, 2005

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Apr 4, 2006

#11

• Apr 4, 2006

• #11

Similar situation happened to me and one of the nuts on the rod cap came loose. Pulled the cap, inspected the crank, replaced the bearing, and retorqued the cap. Been going strong ever since. There weren't any shavings in my oil or filter, but obviously i changed them both. Hope your's is a similar situation. Mine was a VERY loud rod knock.

 

M

madbrad

Member

Mar 6, 2003

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Albuquerque NM

Apr 4, 2006

#12

• Apr 4, 2006

• #12

Oil pressure can tell you a lot. I lost pressure at idle and found out that i had a bad main bearing.

 

D

D.Hearne

New Member

Sep 29, 2000

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south louisiana

Apr 4, 2006

#13

• Apr 4, 2006

• #13

Spun rod bearing or broken rod bolt. If nothing's obviously amiss, start pulling rod caps one by one. Chances are it's screwed the journal and the crank and rod will need to be replaced.

 

redhotcomet

New Member

Mar 30, 2005

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Western Canada

Apr 4, 2006

#14

• Apr 4, 2006

• #14

I had this happen, similar situation, new motor. What happened on mine was that the wrist pins on 3 pistons locked up and the pistons started scuffing the cylinder bores and took out the rod bearings. So we took another 0.010 off those cylinders, but in new pistons and bearings and its good so far,~7500 miles on it now. Its a fairly stock motor and I dont take it over 6000 rpm, so I think it will hold together.

 

Hack

15 Year Member

Mar 23, 2004

1,945

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Minneapolis

Apr 4, 2006

#15

• Apr 4, 2006

• #15

If a local company built it and there's only 1500 miles on the rebuild, I would start by calling them. They should cover it completely. You should be able to have them tow it to their shop, fix it and you pick it up when it's done - all free.

Don't tear it apart, because they are going to want to look at it first. Once you tear into it, they may use that as an excuse not to fix it.

 

T

The Dan

New Member

Jul 16, 2003

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Orange County, CA

Apr 11, 2006

#16

• Apr 11, 2006

• #16

OK

Drained the oil this weekend. No metal in the oil. Cut the filter open, no metal in the filter. Good news I gues, but what the hay is this noise? I pulled the valve covers and started it and all the rockers looked fine and were functioning fine.

I forgot to mention that I run a main girdle, so because of that I don't think it is a main cap only because the girdle would still hold the cap in pl;ace even if a bolt did loosen up.

Cam bearings, rod cap?????

Taking it to an old school Ford garage by my house tomorrow.

I will win this (insert evil laugh) ha ha ha

 

J

jbuening

Member

Apr 28, 2005

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Apr 11, 2006

#17

• Apr 11, 2006

• #17

The Dan said:

OK

Drained the oil this weekend. No metal in the oil. Cut the filter open, no metal in the filter. Good news I gues, but what the hay is this noise? I pulled the valve covers and started it and all the rockers looked fine and were functioning fine.

I forgot to mention that I run a main girdle, so because of that I don't think it is a main cap only because the girdle would still hold the cap in pl;ace even if a bolt did loosen up.

Cam bearings, rod cap?????

Taking it to an old school Ford garage by my house tomorrow.

I will win this (insert evil laugh) ha ha ha

Click to expand...

My guess would definitely be a rod cap. Thats exactly what happened with my fresh rebuild in the mach. Just one nut came loose and it sounded like the whole motor was falling apart.

 

D

D.Hearne

New Member

Sep 29, 2000

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south louisiana

Apr 12, 2006

#18

• Apr 12, 2006

• #18

Check all rods for a spun bearing.

 

T

The Dan

New Member

Jul 16, 2003

319

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Orange County, CA

Apr 14, 2006

#19

• Apr 14, 2006

• #19

Well, to answer my original question "How much is this going to cost me?",

Answer: $200

Problem: Flexplate bolts came loose.

Easy fix, hard place to get to. Didn't think the price was too bad considering the tranny had to be dropped and replaced to make the repair. Man, feels so good to have it going again!!!

 

geostang351

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Mar 30, 2005

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Danb., CT

Apr 15, 2006

#20

• Apr 15, 2006

• #20

Thats great dude! Way to win the battle!