I think I'm screwed....Crank Bearing?

1985GT50 · Apr 16, 2010

So a friend of my wife is married to a true 'car guy' (which I am not quite yet) who has rebuilt a number of fox bodies into 10 sec range draggers. I put my 85 GT Automatic up on his lift to investigate a horrid squeal. He said he's 99% sure it's a thrown / spun / busted crank bearing that would require a rebuild, which, per my aforementioned not-car-guy status I not prepared to tackle. The weird thing is, it runs fine other than running hot. His interim ideas were running lighter weight oil and adding some motorkote crap. This, however, won't change the blow up that's coming.
So, what else could it be, and am I screwed? Spent $2000 on the car....don't really wanna drop the coin on a rebuild relative to the total project value.
Thanks for your thoughts.

Codye3m · Apr 16, 2010

i would get a second opion, if i was you

90lxcoupe · Apr 16, 2010

could you elaborate a little more then "horrid squeal"

1985GT50 · Apr 16, 2010

squeal elaboration

well, best i can describe it:
it has a similar sound to a belt / pulley but every one has been independently tested and that ain't it. when we put it on the hoist he listened to the flywheel / torque converter / tranny hookup thinking it may be something in there. he said the sound is 'clearly' coming from above the oil pan, not the trans area. the sound only happens when the car is warm, and is most noticeable between 1000-2000 rpms. it will whine in park when idling (if warm- not just started cold) at ~1200 rpms. when i put it in gear and the tac drops to ~800 it goes away, and i don't hear it when i'm on the gas at any speed. it's coasting / in park when it's maddeningly loud. it's an intermittent squeak that really sounds like jumping up-n-down on an old spring bed. it's quite high-pitched, and one interesting thing is that when i shut the engine off it hangs on for 2-3 seconds whining down in pitch. the noise stops a few seconds after the engine is cut off......that's about as descriptive as i can be....thanks for your thoughts.

87GT Drop Top · Apr 16, 2010

Did you try running it with the belt off?

Tanus · Apr 16, 2010

what he said^, pull the belt and start it up before you do anything.

also Id run thicker oil opposed to thinner oil if it is indeed a bad bearing, actually your regular oil but with a bottle of lucus.

capri debris · Apr 16, 2010

Sounds like the throw out bearing or pilot bearing is going bad.

old_blue · Apr 17, 2010

if it is intermittent then I dont think it is a spun bearing. My camaro did that and it was all the time. Also check the all pulleys. The pulley bearings on my tensioner went out and it sounded like what you are describing. Replaced it and all was good.

1985GT50 · Apr 17, 2010

i did run it with the belt off, and the noise persisted. at points it seemed like the noise was coming from the main drive pulley. how important may it be that the noise only kicks in after the engine is warm? seems like if it was any metal-on-metal it would be constant.

1985GT50 · Apr 17, 2010

tanus...i've heard both ways on the oil. someone said lighter oil to be sure it gets into the smallest gaps, but that thicker would 'dampen' the noise....i dunno. can anyone describe the pros and cons of either better than i understand?

7upstang91 · Apr 17, 2010

capri debris said:
Sounds like the throw out bearing or pilot bearing is going bad.

My thoughts exactly! This would be alot cheaper to do than a rebuild, even if he thinks its coming from this area.

1985GT50 · Apr 17, 2010

maybe I'm wrong, but i thought that automatics didn't have a pilot bearing. am I wrong or do I have the wrong term?

capri debris · Apr 17, 2010

I missed the part about it being an AOD.... so it's not the throwout bearing or the pilot bearing. My bad.

So now my second guess is perhaps the torque converter has ballooned out and is rubbing the sheet metal plate between the engine and tranny. I had this happen once, used to have pics of how bad it rubbed the block plate.

1985GT50 · Apr 17, 2010

no prob...thanks. do you mean the thin sheet metal protector plate on the front of the flywheel or something between fly & torque conv? the metal shield where you can see the 3 fly bolts/gear rotate was bent in and rubbing the flywheel, but very little. bent back. not it. sounds like you're talking about something internal that would require a tranny drop? referring to the t/c ballooning out, I assume that means it's bad, not just loose or out of place.

5.0ina66 · Apr 17, 2010

As far as using thinner oil to quiet engine noise, I don't know what they're smoking. You want THICKER oil to quiet it down, partly because it raises the oil pressure.

1985GT50 · Apr 17, 2010

5.0ina66 said:
As far as using thinner oil to quiet engine noise, I don't know what they're smoking. You want THICKER oil to quiet it down, partly because it raises the oil pressure.

to clarify, thicker will quiet the noise because its density dampens it more, but thinner will actually work its way into smaller gaps more easily, thereby improving the noise level because it will be better lubed (assuming that's the problem). correct?

5.0ina66 · Apr 17, 2010

1985GT50 said:
to clarify, thicker will quiet the noise because its density dampens it more, but thinner will actually work its way into smaller gaps more easily, thereby improving the noise level because it will be better lubed (assuming that's the problem). correct?

Nope. Dampening has nada to do with it. Neither does the possibility that thin oil will get into the nooks and crannies.

Fords that are knocking due to wear often suffer from low oil pressure and too-big clearances on the bearings.

Thicker oil raises the oil pressure, which gets more oil where it's needed, and that helps most knocking engines. Thick oil also takes up the gap in too-big clearances, and that helps as well.

The rule of thumb is the bigger the clearances, the thicker the oil you'll need to make any kind of oil pressure. You'd need thick oil. If it's not beyond help, some nice straight 30wt or something ought to make a difference.

HotFox · Apr 17, 2010

take the trans out of the equation....pull the convert bolts, push converter back the start engine and see if noise is gone. If not....my guess is? Nothing comes to mind in the engine that would cause the noise that you are describing. I can tell you I dont feel it is a bad main or rod bearing.

Scott

1985GT50 · Apr 18, 2010

HotFox said:
take the trans out of the equation....pull the convert bolts, push converter back the start engine and see if noise is gone. If not....my guess is? Nothing comes to mind in the engine that would cause the noise that you are describing. I can tell you I dont feel it is a bad main or rod bearing.

Scott

alright....makes sense. what's the easiest way to do that? i am assuming i have to drop the trans?

HotFox · Apr 18, 2010

No you do not have to drop the trans. There should be a little tin cover just behind the oil pan that bolts to the bell housing that will give you access the the converter, not sure never played with a auto in a mustang. There are 4 bolts, you will need to rotate the engine around to gain access to each one. The reason I am thinking this it the pump that drives the trans in just behind the converter and could make noise from what you are describing.

Scott

I think I'm screwed....Crank Bearing?

1985GT50

New Member

Codye3m

Member

90lxcoupe

1985GT50

New Member

87GT Drop Top

Member

Tanus

New Member

capri debris

Member

old_blue

1985GT50

New Member

1985GT50

New Member

7upstang91

1985GT50

New Member

capri debris

Member

1985GT50

New Member

5.0ina66

Member

1985GT50

New Member

5.0ina66

Member

HotFox

1985GT50

New Member

HotFox

Similar threads

I think I'm screwed....Crank Bearing?

New Member

Member

New Member

Member

New Member

Member

New Member

New Member

New Member

Member

New Member

Member

New Member

Member

New Member

Similar threads

Privacy & Transparency

Privacy & Transparency