95 F150 4x4 5.0 auto trans

My engine only has 136k miles and has developed a pretty bad knock. I'm crossing my fingers that it's a loose exhaust manifold or something else but it sounds pretty bad at times especially when I haven't run the truck for a while, seems to quiet down once it's warm 5-10 minutes after it's been started but it never goes away completely. Would a rod knock do that?

I've had experience with exhaust manifold leaks before but they seemed to be more of a ticking noise than a knocking noise. I did notice that few of the exhaust manifold bolts were loose, finger loose, when I first bought it couple months ago so I tightened em up...didn't knock at all when I bought it. Could tightening the loose manifold bolts have caused the manifold to not be torqued correcly and start making the noise? I'm not seeing any loss of power or any other adverse performance.

What can I check? I would assume a mechanical oil pressure gauge will give me some further insight, no?

I suppose it won't be the end of the world if I have to put a $400 junk yard engine in it, they give a 60 day warranty too. Hopefully it won't come to that, though.

 

quote
seems to quiet down once it's warm 5-10 minutes

Piston slap?

Boy sounds are a tough thing for me because of shooting guns and rock bands, and at times an unhappy women. You will have to try to isolate its location using a listening device, maybe a wooden dowel, or rubber hose. I suggest that first determine the speed of the sound, is it engine speed or half speed. Hook up a timing light, if the noise is every flash then its half speed and of course noise twice per light is engine speed. Once you determine noise speed that will help to direct you.

 

A rod knock would become louder as it warmed up or at least stay the same. last post sounds more likly piston slap from bad wrist pin. does knock speed up and get louder with more revs?

 

It does speed up with revs but it doesn't get louder. In fact, it's less pronounced when I rev it. I can hear it again more clearly as the engine idles back down.

 

Mine sounds the same. Everything was ok before tearing down the heads, new head gaskets, and completely cleaning the engine. Afterwards, it sounds like a diesel. Sounds ok for the first few minutes and then get's worst. After getting above 1K Rpms, completely unnoticable. Trying to find a suitable donor motor so I can rebuild "Ol Blue...

 

It could be loose torque converter bolts.

 

That could be true because the guy put a junk yard tranny in it about 6 before I bought it so those bolts could have been unbolted and bolted back in. How can explore this possibility more?

 

pull the tranny inspection cover plate on the bellhousing. Very easy to see.

 

Thanks, I'll check it out tonight. I get the feeling that it's one of the exhaust studs and/or manifold loose. One of the exhaust manifold bolts was missing and/or broken off in the head when I got it but there was plenty of thread left to put another bolt in so I did, it was then that I noticed 2 of the studs on that same side were were finger loose so I tightened them. I'll check as many of the manifold bolts as I can tonight too. Is there a way that I can pinpoint whether it's the exhaust manifolds other than by tightening all the studs I can get to and praying?

 

I spent $12 on a Mechanic stethoscope at the parts store. Well worth the money. You can also use a piece of garden hose or equivalent and listen around the heads, oil pan, tranny. A stethoscope is wonderful tool!

 

Since it quiets down with revs I am sure you are looking at an exhaust manifold leak. You may have to pull them and have them planed down if they are warped. Try to tighten and replace bolts first if that doesn't fix it you will have to remove it or them and check them for warpage.You could also put in gaskets. hopefully the missing bolts just fell out and aren't broke off but either way they need to be replaced. good luck but better then rod knock or bad rist pin.

 

Its easy to tell which manifold is leaking have someone give the engine a few quick revs while you listen at each side of motor you should hear pretty easy which one is leaking. if its cloudy or getting dark you should be able to see small back fire flames also at the exhaust leak after they let off the rev.If the manifolds have been loose for a while they are very likly warped a gasket my be enough to take up the gap. easier then removing the whole manifold from the truck and shaving them. hope this helps

 

Hello, question for you if you don't mind? I have been reading through a ton of forums and cannot find any answers to my problem, or even anyone explaining it like mine. However I came across this and it is exactly what is going on with my truck, same exact symptoms to a tee. This motor has been driving me nuts trying to figure out where the noise is coming from. Engine runs excellent but the sound is driving me crazy. Just wondering if you ever found out the issue because it's the same one I'm experiencing. Any help would be appreciated. I know this was an old thread but hopefully you recall. Thanks!

by the way I have a 1995 Ford F-150 with the 5.0 180k

 

I did eventually find the problem. The 1st and 2nd cam bearing's were toast.

The engine is still sitting in my garage. I only found the problem when I pulled the water pump to have it exchanged for my rebuilt engine. I pushed on the timing chain and the cam moved over a 1/4" inch. When I pulled the cam, it was noticable.