FFFFF Engine Knock.

[White97]

So after I replace the balljoints I notice I have an engine knock It's loudest underneath the car. It only does it if you're freerevving in park at or around 1700RPMs, and in between shifts when driving. I don't hear it at all at Idle or WOT.. It also doesn't do it at all if the engines cold, only after about five or ten minutes of runtime. How hard is it to pull the pan? I'm not sure I can afford an engine swap..

For now I think I'm going to try maybe 10w30 and maybe some Marvel Mystery oil or some lucas..Will the thicker oil hurt it? If it's easy enough I could pull the pan and check out the bearings, but I'd need some help for that as I've never torn into a motor that far. I'm just trying to get rid of the knock for the time being. I just started a new job and can't afford major repairs..

[White97]

For the record, it had a ticking sound a day or two before this, but it sounded like it was in the dash and I didn't bother checking out. It still sounds like a minor tick when you're in it, but when you're outside it soudns like a fairly soft rod knock..or knock of some sort.

[gadget73]

Thicker oil is generally a bad idea with the modular engine. If the noise is in fact main bearings, the oil may shut it up but you run the risk of destroying the top end of the motor. Things run longer with a rod knock than they do with wiped out camshafts.

Are you absolutely certain its not some accessory noise? Pull the belt off and start the motor to see if the noise goes away. Can't drive it like this or run it for an extended amount of time, but if you warm it up ahead of time, you should be able to run it long enough to see if anything changed.

[White97]

Ahh I'm an idiot. I didn't even think to pull the belt. Yeah, it's not severe rod knock by any means if thats even what it is.. By any means. It only does it at certain points in engine speed. And only hot so I'm not freaking out about it yet. I'd say even if it was I could get a few more months out of it.. I'll pull that belt after New Years and let you guys know how it reacts.

[White97]

I do know my idler pulley is shot, and so is the belt..So I gotta do those anyway but I doubt thats the noise.

[91waggin]

In this case, when he says "thicker oil" he said he meant 10W-30. Is 10W-30 really going to hurt a mod motor?

[Lonnie]

What they told us back in the day at Ford school was that the modulars are machined to much tighter tolerances and thats why they went with 5w20. gadget73 is right if you use a thicker oil it may have a harder time getting to where it needs to go.

[johnunit]

What year is this? From (about) 98-01 there was a Timing Chain Tensioner issue, that first presents itself as a tap that sounds like a top-end knock. I've personally seen an engine with a bad timing chain tensioner loose oil flow and lock up from pieces of the plastic tensioner surface clogging up the oil pump. No warning except the knocking noise.

[sly]

I use gtx high mileage 10w30 in my 93 vic since day one of ownership. been almost 5 years now and no wear issues... just more leaks from POS gaskets (needs valve cover gaskets).

[gadget73]

In this case, when he says "thicker oil" he said he meant 10W-30. Is 10W-30 really going to hurt a mod motor?

Ford suggests 5w30 or 5w20 for those. I've been told that really anything thicker, particularly on the PI engines, risks oil starvation to the top end. The cams sit in saddles in the heads, and as far as I know they don't actually have replaceable bearing shells up there, so having sufficient flow of oil is absolutely critical to not killing the motor. I would think that any wear problems wouldn't really be apparent unless the cam journals in the head were opened up to be examined for wear.

Mind you I do not own one of these, and I haven't studied them to any great degree. I'm only repeating what I've been told by others who seem to know what they're talking about. When all else fails, I just default to the factory suggestions for lack of better input. Increasingly I've come to believe that those engineers know what the hell they're talking about.

[White97]

Well we'll see what it does with the belt off. To whoever asked: The vehicle in question is a 1997 Merc Grand marq. It has 161k miles and appears to be the factory engine..The Intake manfiold has an aluminum coolant crossover in the front making me think the manifold has been replaced. There is nothing on the interior or under the hood that leads me to believe it was ever used as a police car.

[sly]

4.6L does not have cam bearings. The oil that fills a small channel in the "saddle" for the cam is the lube for it. But like I said... 10W30 High Mileage in mine and it's got over 200K miles on it and going strong. Only needs valve cover gaskets really.

[marquisman]

but, isent climate an issue as well?

[sly]

true... I live in the warm states. easier to run thicker oil here as the warmth thins it a touch.

[91waggin]

The one I take care of gets 5w-30. Ran 5w-20 once and had to add 3 quarts between oil changes. Wasn't dripping anywhere, so I can only assume it was burning the really thin stuff. I run a 5w-30 synthetic and it doesn't lose a drop.