I have a strange sound upon cold start with my 1994 with 302 engine. Everything is original.. well besides plugs, wires, maintenance stuff.. 260,000 miles. About a month ago it started to develop this slight knock or tick or something. On another site I have been talking a guy who has been quite helpful, but we have not been able to know what this is. Was hoping that maybe someone here would have any ideas. What happens is, the engine has to be cold.. during high idle, it does NOT make this odd sound.. as soon as it drops down to regular idle, this sound is present until the engine gets to operating temp... after that, quiet as could be, and remains that way until it cools down and I do another cold start. Our current thinking is it may be a slight exhaust, or possible AIR tube leak on the back of the heads. I have done my best to examine everything, but can not come up with a conclusive answer so looking for any other opinions or thoughts. Has anyone else experienced this? I have determined it is not rod knock.. I have taken each plug wire off, one by one and ran the engine, doesnt seem to make any difference at all. I also removed the serpentine belt, started her up, no difference.
Anyone have any ideas? Truck runs great, has never used any oil, had the pan off 2 years ago and factory crosshatching is still on the cyl walls, engine appeared to be extremely clean inside. Take a look at this video and if you have ANY ideas, PLEASE respond.
Thanks guys and gals!!
Here is the link to my video...

 

Good possibility it is an exhaust manifold leak. Once the manifold is heated up, it closes so no leak and no noise.

 

What are you using for oil and filter?

 

thats what me and another guy I have been talking to think. Just doesnt quite sound metalic enough we dont think for something internal, but could be. I have owned this truck since new, it has only gone over 3,000 miles 1 time without an oil and filter change, dont beat on it. She is rusty, but I have taken excellent mechanical care of her. I just find it very hard to believe its something internal, but it could be.. just doesnt quite sound like it. With the AIR tubes on the back or the heads, they are difficult to see as well. I have done my best with a mirror and spotlight, things look ok as far as I can tell. Could be a checkvalve back there I suppose. The EGR tube that runs down tot he exhaust did have a crack in it, about the same time I started hearing the sound, but thats not it. I temporarily put exhaust tape on that and its sealed off for the time being. It seriously has me stumped. The next think I think I will do is just do a quick torque check on all the exhaust manifold bolts. I dont see any black exhaust soot anywhere, but worth a shot.

 

Have used Pennzoil 5w-30 its entire life, nothing else. I tried bumping that up a tad to 10w-30, no difference. Ran some lucas oil stabilizer through it (that crap is like syrup) dumped it out after 100 miles, ran another round of 10w-30 for 300 miles, drained that and now I have switched to Pennzoil Platinum Full Synthetic 5w-30. Wix filter.
I "think" I may have discovered the issue. half of the exhaust manifold bolts on the drivers side certainly were not tight to spec. Pulled them out, checked them over, reinstalled or replaced and torqued. the only ones Im not sure how you take out... would be the 2nd and 3rd I believe from the front, has a bracket attached, and one in the back that has a bracked attached for the dipstick... they are extremely rusted, how do those come off? It "looks" like there is a gap between the bolt head, on the inside of the bracket and the manifold. Anywho, started it up cold after doing the drivers side, the sound has diminished a bunch! So if I can get those others, maybe it will be gone. Havent done the passenger side. Im very tired today, and its starting to heat up again. Might tackle that tomorrow... but it would appear I am on the right track. Like I said, there has only been 1 time I have ever gone over 3000 miles in 18 years without changing oil and filter. Went almost 5000 that time, and that was probably 16 years ago.

 

Interesting, that yer truck is a '94 302 without a Mass Air Flow sensor setup. What month was it built on the door jam sticker?

Adrianspeeder

 

LOL, why interesting? Whats going through your mind?
I will run out and take a look.. I cant remember what month it was made. I think july, but cant remember...

 

3/94 was the build date. I must be thinking of one of my other vehicles as July... I dunno.

 

Just when I think I have Ford figured out, always find something different. First '94 302 I've seen without this...



Nothin' to do with your exhaust leak, just sticks out to me.

Adrianspeeder

 

Glad that seems to be fixing the problem, although I am shocked that the bolts are not frozen in the block. Especially at that age.

 

I didnt think that setup came out until 1995???
I got the bracket cut off.. now have to rig up a support for the oil dipstick tube, but it was broke anyway.. what a pain! the bolts that held the bracket on WERE literally welded onto the bolt. anyway, got them out and replaced. I havent run into a single manifold bolt that was difficult to back out. a couple didnt have much of a head left, like dime thin, obviously leaking for quite some time. giong to tackle the passenger side tomorrow. Half of them were not anywhere near tight to spec and the front one was sticking out, so were the two with the bracket. Its helping, but not solved. Perhaps the passenger side will cure it, or maybe (I bet) it needs new gaskets. At least I dont think its anything internal at this point. Much relieved.

 

I am pretty sure that setup didnt come out until 1995. Maybe late 94? I bought her new, so I know for a fact its a 94. Pretty sure I have seen this discussion elsewhere and the setup you show came out in 95. Hmmmmmmm.

 

Or.. perhaps my truck is super rare being its the first 94 you have seen with my setup.. make a deal.. say.. ummm.. $50,000 and its yours. :-) I have the title right here.. ok, ok.. $45,000 but I get visitation.