bottom end knock at idle

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bottom end knock at idle

September 27, 2009, 02:05:05 AM

20th anny 5.0

Has had an audible knock since i got her a couple years ago. Sounds a little worse now but my cluster still shows 4 bars.

running 15w40 lately to soften things up a little. Need to pull motor and punch rods , turn crank and rebuild before its too late.

any thoughts on switching up to 20w50 in winter months? I am not really in a position to rebuild it this year but it well needs it soon.

Ive put a about a 80k on her since it came to me with 175k.

nothing over stock going in when i pull it other than something that cant be seen from the outside. Ill probably go with gapless rings and copper head gaskets, shave the heads a little but nothing more than small things to increase power. no dual exhause either but may gut the pre-cats if there is anything in there.

just wondering what you all think about viscosity issues in the winter with this heavy of oil.
No top end noise.

bottom end knock at idle

Reply #1 – September 27, 2009, 10:10:44 AM

I wouldn't go 20w in the winter unless you really want to ruin those bearings.
Thicker low weight oil will not reach the bearings fast enough in the cold.
As for copper head gaskets,complete waste of money if your going stock(not to mention copper is old school technology,mls is the new),just run a good set of felpro gaskets all around.
Just use stock rings as well.no point in going gapless other than hassles that are not worth it for a stock application.
Shaving the heads is really not neccessary if they are not leaking coolant,you would have to shaver them quite a bit to see a notable compression increase so i would say just clean them up well and save your money.
With the money your going to spend in machining and copper gaskets you could almost get an HO setup.

bottom end knock at idle

Reply #2 – September 27, 2009, 10:11:08 AM

Maybe a new oil pump to get ya by...?

Hope ya don't use a Fram filter either.

bottom end knock at idle

Reply #3 – September 28, 2009, 11:27:42 AM

If there is already a noticeable knock, I doubt a new oil pump would help all that much. After doing the oilpan gasket with the motor in car, I would pull the motor before doing that again. Its two seconds long with the motor out of the car, 2 hours of getting mad and using wobblies because I can't get my fingers in there at all. and that was just the gasket. Didn't actually drop the oilpan all the way.

Copper spray is an old hot rod trick for head gaskets that aren't on the car for more then 5 minutes and constantly being pulled apart. Real copper head gaskets, I doubt would do anymore then a stock set. Other then breaking the bolts for your heads rather then blowing your head gaskets, I don't see any other way they could be worth it.

bottom end knock at idle

Reply #4 – September 28, 2009, 11:48:41 AM

Junkyard shortblock? Should be able to get one really cheap.

bottom end knock at idle

Reply #5 – September 28, 2009, 06:40:06 PM

Lots of high mileage 5.0s knock a bit. They will run almost forever like that though. I wouldn't worry about it if it just knocks a bit at idle. It will be fine for years. My buddy had a 90 Grand Marquis that he got with 110,000 miles on it and a knock at idle. He ran it to 180,000 miles over a 5 year period with oil changes every 3000 miles with regular 10W30. The knock never got louder and the AOD died before the 5.0 ever did. 5.0s are kinda hard to kill

bottom end knock at idle

Reply #6 – September 29, 2009, 05:21:42 AM

If it were me, I'd wait till I had a clear weekend and take off a main cap or two and see what kind of shape they were in. I'd also check the crank for wear.