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Discussion Starter · #1 ·
Hi Everyone. It has been a while. I moved from Florida to TN, bought some acres with a huge house up near Knoxville with a large house, and ended up needing a truck for supplies. had to buy a truck and of course I went out of my way to get a project. I ended up with a 2004 4x4 6 seater from the scrap yard for $1200. lol. New motor and tranny, Body work, rewired. I still have some metal work to do but it runs perfect.), Did the same thing with the house. I spent the last year rebuilding it. I spent about $25k-30k just in material for the work I did myself. You can imagine the hours I put in there. Then I got the Corona and I got sick for a long time last June and I'm still recovering to be honest. I ended up buying a car a couple weeks ago(Challenger SRT8), and I have a motorcycle. Between working full time, moving, rebuilding the house, mowing acres, and having a 2 year old(yeah, had a baby at the start of this move, lol), I've been a little busy.

Needless to say, my Bronco isn't being driven in the snow. It has seen very few miles in the last 2 years. With all I've had going on and how many vehicles I have. Probably less than 1000 miles. Now, it starts right up and runs great. The issue is that it sat long enough for a knock to develop.

Now, it sounds like it is coming from the passenger valve cover or from the passenger side of the top end under the intake. If Ford's EFI system wasn't shaped in the worst possible way, I'd just pop the valve cover off and check it out. I thought I'd ask here first.

On a positive note, my vehicle has none of that pollution stuff on it and the wiring has been thinned out, I also replaced the exhaust header gaskets a few weeks ago, so they will just come right off. No breaking and cursing. I honestly need to reseal the engine anyway and I have the stands/picker/room to do it and I already have a full engine gasket kit. I bought the extension and torx bit for the intake bolt that is in the center. The Bronco leaks a little oil but it doesn't smoke.

I lost one of the plugs on the back of the head once, so I checked those. It wasn't as loud as this is and sounded different, so I really don't think it is an exhaust leak but I stupidly didn't sand blast, check for cracks, and paint my headers when I had them off so I don't know for sure. I didn't notice anything obvious like black spots or cracks though.

Symptoms: Loud knocking at top that reduces by 75-80% when warmed up and driven 20 miles but returns when cold next time. It is pretty loud. It is worse at constant lower speed and when you rev then let up.

Whats been done: Oil change with marvel mystery oil in it for 50 miles to see if it would break it up(went from 10w30 to 20w50 at change, cut and inspect filter for metal, pull plug wires one at a time to listen for changes, check for exhaust leaks. The oil looked used but no metal at all, filter was clean inside. I installed a new mechanical oil filter under. My idle oil pressure is something like 70 cold and 40 warm with the 20w50. It has great oil pressure and always did.

The guy I bought it from told me that he had the engine rebuilt. It has only seen 10k miles by me in the last 3-4 years(daily driver, 10 mile round trip). It had obviously been removed and painted. It was not sealed very good but the engine has been reliable.

At this point I'm thinking a bad lifter. If I can fix it without ripping the whole motor apart, I will and make the engine resealing a winter project as I have a lot to do still for other things.

I assume my options are:

1) Use Berrymans/Sea Foam in the crank case, run it for a bit, then let it sit, change the oil(back to 5w30), and see if it quiets down.

2) Take the engine out, and just rip it all apart. This will take me a long time. I've got a lot of things in the fire.

3) Take the upper intake off, see if one of the lifters looks bad or if anything is obvious under the valve cover(turn it over and look for play in one), if it is obviously a lifter, take the intake off and change the lifter out. I can take an extra day off and do this. Then I can just change the motor mounts, the two freeze plugs I couldn't reach and the oil pan gasket later on without removing engine somewhere down the road.

Is there anything else I should be considering? Timing or anything? I can't say I have a huge amount of experience inside of Ford engines, I assume this is all more or less the same as a small block Chevy.

Also, does anyone know if there is a spacer to make the valve cover removable without removing the entire upper plenum? I'd be OK installing a hood scoop if I had to.

Gimme whatever guidance ya got. I miss driving it.
182382
 

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1986 Bronco Eddie Bauer 5.0 bone stock
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465 Posts
Is it a knock or a tap? Bad PCV valves can sound like a sewing machine, maybe check that 2 dollar part?


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Driving Stuff Henry Built
-90 xlt, 351w, e4od, man 1356, 3.55, sag, warn hubs, 35s. -73, 400, np435, d20j twin, 35s
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A small exhaust leak can sound a lot like top end tapping. And can change as the engine warms up & expands. Since you recently had them off it's more likely. To check for a leak use a short section of hose with one end held near your ear. Move the other end along the headers playing "getting warmer/colder" & see if you find anything.
 

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1986 Bronco Eddie Bauer 5.0 bone stock
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465 Posts
A small exhaust leak can sound a lot like top end tapping. And can change as the engine warms up & expands. Since you recently had them off it's more likely. To check for a leak use a short section of hose with one end held near your ear. Move the other end along the headers playing "getting warmer/colder" & see if you find anything.
What he said, and the fact that it gets quieter as it gets warm and louder as it cools only reinforces this possibility in my mind. OR you may have broken the seal on your flange at the bottom of the header maybe? I see long tubes so perhaps the collector gasket? Are they good headers or el cheapos" I had some cheapies one time and it took two gaskets because the flange was so thin.
 

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95 5.8L MAF XLT, Hedman Shorties/MF SS Y & Muff, E4OD, Man hubs, KYB Quads, 31x10.5x15, 304K miles
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Wow, why not start with the Basics and work your way up to the more complicated stuff later. Like you and everyone else said look into the exhaust manifolds/headers cause that sounds like what it could be and it is one of the simpler things to do. Yes there are other things to look into but ya gotta start somewhere!!!!!
 

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'88 XLT. 2" lift, 3G, Saginaw Pump, Headers, High flow 3" cat, 3" exhaust, 6 litre tune, K&N
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I am betting its a bad lifter and/or a bent pushrod from a bad lifter. It is collapsing at lower rpms when there is not as much fluid pressure to keep it pumped up. The motor has been rebuilt and all the new China sourced lifters are hit and miss garbage. Sounds like you have a bad one. I would check the cam lobe when the lifter is out. Roll the pushrod on a super flat surface like a sheet of glass, if its bent you will see it.

Yes, they make phenolic spacers of different heights to raise the top of the intake to clear taller valve covers and to isolate the top of the intake from heat. These require longer bolts as well. I do not know how much lift is required to pull the valve cover off without removing the top of the intake.
 

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1986 Bronco Eddie Bauer 5.0 bone stock
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If you double check everything and still have no luck and need to remove the valve cover, if you've never done it before, removing the upper intake really isnt that big of a chore. The hardest part is getting that one booger of a bolt that is in the middle under the runners, I have a torx socket that fits and a REEALY long extension, and this is the first bolt i remove. Best to make sure everything under there is clean before you proceed though, give it a good once over and blow it all out with an air hose if possible so no chunks fall down in the intake when you remove the top half.
 

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Discussion Starter · #8 ·
A small exhaust leak can sound a lot like top end tapping. And can change as the engine warms up & expands. Since you recently had them off it's more likely. To check for a leak use a short section of hose with one end held near your ear. Move the other end along the headers playing "getting warmer/colder" & see if you find anything.
I actually have a stethoscope. I changed the exhaust gaskets after it started. I believe I checked them and it is more to the inside of the head.

I'll give it another shot and see.
 

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Discussion Starter · #9 ·
If you double check everything and still have no luck and need to remove the valve cover, if you've never done it before, removing the upper intake really isnt that big of a chore. The hardest part is getting that one booger of a bolt that is in the middle under the runners, I have a torx socket that fits and a REEALY long extension, and this is the first bolt i remove. Best to make sure everything under there is clean before you proceed though, give it a good once over and blow it all out with an air hose if possible so no chunks fall down in the intake when you remove the top half.
I bought a impact drill extension and a torx bit to fit. I need to change the valve cover gaskets anyway, I'd prefer not to remove the lower if I can help it but I have the whole engine gasket kit. I think I can tell if a lifter is bad pretty easily at that point and whether I need to go further.
 

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Driving Stuff Henry Built
-90 xlt, 351w, e4od, man 1356, 3.55, sag, warn hubs, 35s. -73, 400, np435, d20j twin, 35s
Joined
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8,753 Posts
I actually have a stethoscope. I changed the exhaust gaskets after it started. I believe I checked them and it is more to the inside of the head.

I'll give it another shot and see.
The stethescope is great for listening for noise under the valve cover, as well as other noises, but a hose works better when looking for exhaust leaks.
 
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