Hello, two weeks ago I bought a 1997 F150 4.6L Romeo with an automatic trans. I got it for a steal because it has 320k miles with the odometer frozen and the engine is making noises. The first thing I did when I got it was change the oil and filter using motor craft oil and filter, also adding a quart of marvel into it. Now I've also changed the plugs with auto lite platinum, air filter, wires (car quest), replaced the shift linkage and most recently replaced the missing bulbs in the instrument cluster. My biggest issue I want to address though is the engine noise. When I first start the truck it knocks three or 4 times loudly. After that goes away there is a tick that is evident at all rpms. From the cab it sounds like an exhaust leak, but from outside it sounds like the valve train. Last night I did the injector test. On cylinder 4 I think (passenger toward the cab) when I unplug the injector it turns into a loud knock. Does this tell me anything? I plan on pulling the valve covers tonight or tomorrow but it's also the first time I've torn into an engine so I am doing as much researching as possible before hand. Thanks.

 

Take it to a knowledgeable mechanic for diagnosis. Impossible for us to diagnose it.

Maybe take the belt off and run it for a few seconds to see if that changes anything. I wouldn't expect it to. Get a piece of hose or stethoscope and try to find where the noise is coming from. Could be some major mechanical issues such as rod or main bearings. If it's a bearing, you may be able to hear it better under the truck. Good Luck!

 

If it is the traditional knock at start up, it's a rod bearing before oil pressure has come up.
It may well be cylinder 4 causing the knock.
I would be cautious about putting a lot of investment in such a high mileage motor until you see it has enough life left to be worth the effort.
I would evaluate the oil pressure to get a read on bearing and oil pump condition.
Be sure to use a Motor craft 820S oil filter for drain back control.
The wrong filter can cause bearing knock before pressure is built even on a good engine.
I would run 5w30 oil in such a high mileage engine.
What good oil pressure looks like is 75 at cold start, 50 hot running on the road and 25 +\- at hot idle. These levels are on my 257,000 mile 02 4.6.
Low pressure at hot idle of 10 psi is getting near the low limit for bearing and oil pump wear. Then it's time for some additive like STP to get some extra life out of the motor at that point in condition.
Good luck.

 

Hello bluegrass and thanks for the quick reply. It is the traditional knock at startup. But the ticking sounds much different. I don't think the ticking is a rod. It I guess it's possible. I have done the stethoscope trick with a screwdriver and a hose. The screwdriver had me somewhere around the transmission. The hose sounded like it was coming from the passenger cat conv. I had guessed if it was valve related it would resonate through the exhaust, but I haven't ruled out the exhaust itself yet. I am using the 820s filter and motor craft 5w-20 synthetic. As for oil pressure are you suggesting my next step should be to install an aftermarket oil pressure gauge? everything I've read says if it's a rod it will get quieter when I disconnect the injector. Are you suggesting it could still be a rod knock?

 

I wouldn't waste any money on a 350K mile engine and very little time.

the 4.6 2 valve was used in several diffefrent ford vehicles through 2014, yes same engine in E vans and crown vics
I'd just look for a newer low milage engine and wait till the old one fails.
I bet it will run quit a bit longer yet.

my bought 99 with 140K (5.4) makes tons of noise, I have removed the oil pan and looked at all the con rod bearing and main bearings, they all look like new.
I have also changed all the cam followers, a lot of them were not working properly but the noise is still there.
it now has 175K miles and still makes a lot of noise but still rens great otherwise.
it's so rusty now when It does finally die, it'll get a proper burial at the scrap yard.

 

And throw a can of STP in the oil.

Also check for loose spark plugs, they need to be torqued to 28 ft/lb to prevent loosening and blowout. Autolites are not the right plugs for your engine, you should be using Motorcraft. Yes, it does make a difference, Autolites are not the right heat range.

 

My Mark VIII 4.6 DOHC engine would knock at startup if it sat for a while. It was the cam chain tensioner. It took a few seconds to pump up. That noise was common on that vintage engine-1995.

 

Ok. I never said the engine had 320k miles. I was assuming it's been rebuilt or replaced at some point. Is there any way to tell? I'm not just going to call the engine screwed because there is a ticking noise. I am asking for advice on how to further troubleshoot the noise.

 

Also I read on here that both motor craft and autolite platinum were ok for the 4.6. Is that not true? What kind of stp? I already have marvel in the engine.

 

I wouldn't assume that. Those engines will last that long if taken care of.

 

Marvel thins out the oil. You want to thicken it if it's knocking.

You didn't read on THIS forum that Autolites were okay on a 4.6 or 5.4 2 valve engine. They aren't causing the noises unless they are loose, but they aren't the right plugs.

https://www.f150online.com/forums/19...ml#post4872726 Post #6 by jbrew

Plenty more posts but that's a representative one.

 

my sons 03 screw has 325000 miles on it, makes a little noise all the time, still runs great and has plenty of power

these engines are noisy, if you get one that's not, you're lucky

and though many will say motorcraft on the plugs, I've run others and had to problems, I've been working on these trucks since 99 and owned them since 2002 and never found a problem I could blame on a sparkplug.
I do buy the motorcrafts when I change them though.

 

I've had two 5.4 engines, a stroked version of the 4.6, and both were/are quiet but i only put 105k on the 2000 and my current 2002 5.4 only has 142k miles.

 

Then there was the guy that got 1.3 million miles out of a 5.4 in a 97 E-250 van.

 

yea there are many mod motors out there with 500K+ miles on them

there is a video on youtube of 2 5.4's out of e series delivery vans with some insane amout of miles on them. In the video they tear them down and measure things out and determine they were still good to go.
both engines were still running fine when pulled.