Knock Knock Good Morning

[V8GrandMarquis]

Hey guys I have a 1989 MGM with your standard 5.0 EFI now the engine doesn't burn a drop of oil but there is a light knock when I start the car. The knock lasts about 45 seconds to 1 minute until it warms up a bit. I use 10W30 oil and I added some of the lucas oil crap that didn't do much of a difference. Should I be using a higher thickness of oil any advice would be help full. Thanks.

[1990LTD]

http://www.grandmarq.net/vb/showthread.php?t=36488&highlight=knocking

The knock is whats referred to as the lopo knock. Basically the main bearings are worn out and you hear the crankshaft slapping around until the oil gets to the bearing and cushions it. The bearings in a motor don't actually make contact with anything. The crankshaft and connecting rods ride on a film of oil between the bearing surface and the crankshaft. When the bearings get worn away, the clearances open up and the oil runs out when the motor sits, hence the knock until it pumps up again. There isn't anything you can do about it short of rebuilding the motor, so as long as its making some oil pressure I wouldn't get concerned about it. The reason the bearings get beat up in these motors has to do with the firing order. It puts two cylinders at the front of the crank in sequence and over time the #2 main bearing tends to get worn out. The HO and 351 engines have a different firing order that puts the sequential cylinders at the back of the crank where the bearing is larger. Those don't develop the knock.

[V8GrandMarquis]

ahhh ok would you recommend getting a thinker oil?

[ald872000]

I use 10w40 in my vic an now she's pretty quiet

When its time for an oil change switch it up an see if that quiets up your engine

but b/c she's a lopo your gonna hear the famous lopo knock from time to time

=)

[V8GrandMarquis]

I try to let her warm up and make sure the knock stops before I start driving but ill try 10W40

[1990LTD]

I put castrol gtx high mileage 10w30 in last time...will try 10w40 cause it doesnt get terribly hot around here. probably cant hurt.

[Lincolnmania]

use 10w40 in the summertime and 10w30 in the wintertime.......if you were in florida or something i'd say run 15w40 but it's cooler up in canadia

[Pirate]

ahhh ok would you recommend getting a thinker oil?

No, I'd go with blinker fluid.

[pantera77]

My wagon does it, along with burning a ferocious amount of oil. I just run 15-40 and a bottle of lucas (not that I think it does anything).

[V8GrandMarquis]

Ya I tried Lucas didn't do much

[V8GrandMarquis]

Well thanks everyone for your help I though my engine was done for so I guess Ill just run her for a couple of years. (Cross Fingers)

[johnunit]

A local guy (sold me my car and works on lots of them) swears by Shell Rotella T oil (15-40ish) in the summer to quiet these things down. He even warned me that he'd put in the oil when he bought it, and that if I switched oils the light valvetrain noise (which sounds very similar to lopo knock) would get significantly louder. I went with a 10w30 conventional for the winter, and sure enough the tapping became noticeably louder.


Apparently rotella also has good stuff for flat-tappet valvetrains that has been removed from gasoline engine oils for emissions reasons.

[gadget73]

I don't think its got the ZDDP anymore, or at least not in the amounts it used to have. Its good oil though, I run it in my boat.

[johnunit]

from some quick googling, it went down from 1600 PPM ZDDP to 1300. So there was a reduction, but it still probably helps.

Mobil 1 Extended Performance 15W-50 apparently has similar ZDDP content.

[gadget73]

Just for comparison's sake, most of the rest of the Mobil 1 line has about 800 ppm, but the race oil is 1750 ppm. I was curious and looked it up. Not sure how that compares to other brands, but Mobil 1 is what I found the data sheets for easily.

http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf