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Discussion Starter #1
Hey I have a 89 Thunderbird and it makes a knocking sound when the engine is cold then goes away when the engine warms up. Whats should I do. It is the Base model.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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What kind of knock? Like a rattling paint can? Or a heavy metallic thunk?

When? At idle? Accelerating lightly/moderately/heavily? Cruising?

Without the answers to these questions I can only guess. But - first guesses are either a knock related to pre-ignition (try 93 and see if it goes away) or a knock due to oil sludge buildup in the passageways restricting oil flow (sea foam the oil system a couple times then use synthetic).
 

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A lot of older Fords do that from the 3.8L to the 5.0L to the 4.6L. I call it the Ford Knock!

My Thunderbird does it unless I keep the oil filled + 1/2 quart, then it doesn't do it when I start it in the morning. It's just a high mileage engine and I'm sure at least one rod or main is pretty worn.

You can put a couple of pints of Motor Honey in your engine. I do that to mine for the valve seals and that quiets the 'cold knock' for awhile (usually 3-4 weeks or more depending on how many miles I put on 'er).
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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You should be using either 5W-30 or 10W-30. That stuff you're using is too thick. The reason you're hearing the knock is because it's not circulating adequately until it warms and thins.
 

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IIRC, they now specify 5W-20 for the 3.8L engine. I still use 5W-30 in my 95 tbird engine but IMO, going to 20W-50 is FAR too thick at startup and for when the car is warm.
It's your car so good luck with whatever you do with it.
-g
 

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If you're running 20-50w motor oil with Lucas and it's still knocking - you need to open up the bottom end of that thing. I've been dealing with knocks a long time, and if you keep running it like that until it knocks all the time, you will be stuck pulling the crank and turning it.

I've changed only the rod bearings on a few motors with a slight knock and it fixes it if you don't wait.

I'm just saying. If you fix it early, it's easier.....
 

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It could also be there was nothing wrong until it ran cold-starved with the 20W50 in there.

20W50 is for old flathead V8s and Studebakers.

Anything with a 12V system, just about, would work better with 5W30 or 10W30 instead.

If it's so worn that 20W50 is indicated, it's more indicated it's time to find a newer motor out of the boneyard and rebuild it.

RwP
 

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It could also be there was nothing wrong until it ran cold-starved with the 20W50 in there.

20W50 is for old flathead V8s and Studebakers.

Anything with a 12V system, just about, would work better with 5W30 or 10W30 instead.

If it's so worn that 20W50 is indicated, it's more indicated it's time to find a newer motor out of the boneyard and rebuild it.

RwP
You are too old, Ralph..... :D


I'm kidding, I hope you know that :cool:


Oh, to the OP, I've also had a bad oil filter cause cold start problems. You know an oil filter has a valve in it (if it works) that only lets oil go through one way. That way the engine isn't starved for oil when you start it. Grab a new oil filter and try to blow through the center hole to see what I mean. You can suck air, but you can't blow through it (or you shouldn't be able to). You might want to try a new oil filter first.
 

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You are too old, Ralph..... :D


I'm kidding, I hope you know that :cool:
But I AM an olde phart! :diablo:

I'm old enough that a "sick" paint job was one you were in the process of stripping off so you could put a good one on it.

I remember when "fat" with ANY spelling was also bad.

I ALSO remember fighting carburators to get them tuned enough to even idle.

I ALSO remember setting points on a car ... Not fun!

I ALSO remember old heaps with flathead V8s in them in school. Along with Boss 302's and Z28 Camaros. We had a bit of a range where I went to school, in the early 70's.

RwP
 

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Discussion Starter #13
Well then I will change the filter again and use 10w-30. I will look into opening up the bottom and change the rod bearings but I might need some help im kinda a new when it comes to taking apart engines.
 

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The Parts Guy
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Even 10W-30 is going to be too thick at startup. At least step down to a 5W-XX oil. Provided that the oil starvation on startup from using a 20W-XX oil hasn't already done too much damage, your knocking should go away. And don't run that LOS in there...just 5 quarts of a 5W-XX oil.
 

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Discussion Starter #15
The engine has 170,000 miles on it and 2 people are both saying thicker oil is better for high mileage cars and that's why I put it in there. But I just want to see what you guys have to say about that. I haven't been driving it lately till I figure out whats wrong with it.
 

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The Parts Guy
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At thicker viscosity at operating temp may be necessary, but at startup it's evident that a thicker viscosity is causing trouble. If you want to know for certain what is going on, you need to install a real oil pressure gauge.
 

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The engine has 170,000 miles on it and 2 people are both saying thicker oil is better for high mileage cars and that's why I put it in there. But I just want to see what you guys have to say about that. I haven't been driving it lately till I figure out whats wrong with it.
Sure it is. However, it makes it harder to use the hand crank on the front.

Err - What? There's no hand crank on the front?

They WHY are you using information for, as I said earlier, "flathead V8s and old Studebakers"?

I'll suggest that you study up on some of the information at Bob is the Oil Guy ( http://www.bobistheoilguy.com/ ) and get you a real oil pressure gauge. Or at the very least, fix your current gauge to work like one instead of as the factory idiot needle.

RwP
 

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