1986 Bronco XLT "BUKNBUL"

9254 Views 88 Replies 10 Participants Last post by sackman9975, 9 d ago

sackman9975

Discussion Starter · Mar 22, 2022

Well it's time....I'm going to start a build thread for my 1986 Bronco that I acquired back in March of 2021. This will be virtually a Ground Up Build.

Originally, I was going to purchase a new 2021 Bronco but then decided, it really isn't what I truly wanted.

I started my search for a Bullnose Bronco mainly with the idea of finding something along the lines of my first Bronco I had when I was 17. With a little help from @MS88Bronc and a quick call to say "hey get on Facebook and look to see what I tagged you too", I was able to get this project that you all are about read on.

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Immediately I contacted the seller and worked out a deal offering him exactly what he wanted. Wired the money and BAMM I got EXACTLY what I was looking for!! Had it shipped from Texas and when it got here it was better than expected! I don't think this thing has EVER been off road. The under body is so clean (minus the oil leak) and everything is as solid as it came off the factory line.

Now I've had this truck for a year now and only put maybe 30 - 40 miles on it. Leaks oil like no other but that's ok. Why? Because I got plans for this thing!!!

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Currently as factory, it comes with the 302 FI with the AOD transmission. Has 3.55 open diff and BW1354 transfer case.

I recently did a barter deal with a guy here in Michigan for some parts. I told him I needed parts off his parts truck which was a 1996 Bronco Eddie Bauer with the 351W/E4OD. After working on his truck for 2 hours, I was able to score the 8.8 (H9), all the wiring from the truck and the computer.

So my plans are to make this truck 351 MAF / E4OD using the OBD2 system. I have a 351W in my garage that I had built years ago that's bored .030, E303 cam fully balanced. It moved my last 95 Bronco pretty good on Speed Density. But I've been thinking of maybe doing something different (stroker) with it....not sure just yet.

During the past year I have removed the billet grille and push bar and put a new grill with Ford Emblem, new bumper guards on the front, removed the crappy running boards and found a dash pad from a swap meet that was in MUCH BETTER shape than what it came with.

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Removed the fancy 1980 steering wheel wrap only to find a MINT steering wheel!!

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So I'm hoping I can find time to get this project completed in about a year. From drivetrain to paint, this will be my FOREVER Bronco. It WILL NOT see a Michigan winter, I can promise you that!!

Now.....Let the fun begin!!
In queue I have new Warn Premium Hubs, a set of Chrome Nerf Bars, a working clock, 4.10 gears and rebuild kit for the 8.8 LS.
I have 2 E4OD transmissions in my garage, one being from a 96. The 96 trans I was told only had 40k miles on it back in 2004 but it's been sitting for 16 years with me. I'm on the fence if I want to rebuild the 96 E4OD or just pick up a factory unit from Monster. I'm certain the seals are probably shot. I think for an extra $1000 from the rebuild kit price, it may be worth the headache. I have rebuilt a few transmissions in my life and they have all worked, but never an E4OD...plus I'm fairly a busy guy. So time is valuable too.

I need to source a few more parts for my project.
Manual Transfer Case linkage from a 91-96
E4OD Steering Column linkage from a 90-91
O/D Button with housing and pigtail from a 90-91
4.10/4.11 gears or a D50 Pig.

My plans for the PSOM is to either one of two things. Either tuck a working PSOM behind the dash and cable drive the existing speedo or integrate the guts from the PSOM with the face of the Bullnose Speedo. Still waiting for a junk speedo to try and see what I can do.

Going to document as I go. Going to be plenty of work including electrical integrating the 86 wiring with the 96 wiring. My goal is to be able to drive it this year, while sending it in for paint during winter of 2022/2023.
I can't wait to cruise this thing!!

Going to start pulling the H9 axle apart probably this weekend to start the rebuild of it.

In case you want to see how it was when I got it, I did a couple of "unboxing vids"

Stay tuned!!

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sackman9975

Discussion Starter · #81 · 2 mo ago

Well, after some due diligence I have come to the conclusion that there is an oiling system problem with my engine.

This is key info right here. The clicking noise that I posted about in posts 74. It's still clicking even after new lifters and a new oil pump. The lifters have to be bleeding off. There has to be a hole/leak in the oiling system "straw".
The compression numbers show cylinder 5 with lowest compression and cylinder 1 with lowest compression. They're the last set of lifters to get oil as show from this diagram.

These were my numbers. Both ends of the oil flow for lifters are lowest numbers.
1-100
2-135
3-100
4-105
5-95
6-115
7-105
8-110

When I put in a new set of lifters, they were already pumped up and right after install, I tested the compression on cylinder 5 and got 170 psi. Once the engine ran for 2 minutes, I was right back to 95psi. So that tells me that if the cylinder can get 170psi, the compression chamber and rings are sealing good.

With the headers turning cherry red, I have to assume that the 3.5 inch stroke isn't taking in 3.5 inches of air as the lifters are opening the valves very late due to the oil pressure to the lifters. After some due diligence on this lean issue, I replaced the fuel rail, return fuel line as it had some kinks, put in 24 lb injectors, fuel filter and still having a hard time starting and low compression.

After watching this video, I understand the oiling system a little better. Focus on 4:30 - 7:00.

Engine is coming back out. I'm hoping that this oil leak is noticeable. There is a possibility that the guy I sold my last Bronco to, when he wrecked the truck that the impact could have jarred lose an oil plug???
I want to keep this engine if possible. If I can't find where this internal leak is, I'll be focusing on a stroker motor to go back in.

Stay tuned...

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sackman9975

Discussion Starter · #82 · 1 mo ago

Well, it all makes sense now.

Day 1 of driving this truck after the motor install, I bent all the pushrods. I started hearing noises then. The engine even made a grinding noise and shut down. I was able to get it restarted, and get it home.

Replaced the pushrods. Ran great after. Had a slow decline in performance until it no longer would fire up.
There were times that I was hearing a "free wheeling" while cranking like the sound of a 4 cylinder engine that lost it's timing belt. Then it would turn over just fine....

The compression was low on cylinder 5 at 95psi, then new lifters it immediately went back to 170psi. Ran great for a couple minutes then wouldn't start again and compression was back to 95psi.

Headers were turning cherry red.....

Well, here's the answer to this mess!!

I tore the timing cover off today.
I grabbed the timing chain and felt the cam gear move. The bolt had come loose. The gear was slowly backing itself from the cam creating a gap from the oil pressure port from the cam thrust plate. This is why the lifters were clicking!! The cam dowel pin came out with the cam gear. The cam is damaged on the front and won't allow the dowel pin back in.

Now, I have to replace the cam. I've been running this E303 for the last 15 years. Really love the sound and the performance. I will probably get another, but am shopping around. Need to get this truck running before the May 6 swap meet, I want to drive it!!

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MS88Bronc

· #83 · 1 mo ago

I see now why this happened. This all happened because the cam bolt that holds the cam gear tight backed off - that started the whole problem. The cam bolt backed off and the dowel started backing out of the cam, and when it backed off just enough for the dowel to slip completely out of the cam, it spun the gear enough to gouge that first semicircle mark and it stayed there for a while. That took your cam a few degrees out of phase with the crank, reducing performance with late valve openings and lower compression (not to mention the lower oil pressure not pumping up the lifters). Then, as the bolt backed out a little more, the dowel jumped out of that gouge and started spinning all around the cam, leaving the marks around the camshaft end. Theoretically, you COULD just drill out that dowel hole in the cam end JUST ENOUGH to deburr the opening so you can get the dowel back in and reassemble. Then put the thrust plate and timing set back on (it's probably fine) and reinstall the washer and cam bolt with red loctite this time. I bet that would get you driving TOMORROW.

I understand that the gouges in the cam end make you want to replace it, but I'm not sure you truly need to.

Just a thought.

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sackman9975

Discussion Starter · #84 · 1 mo ago

MS88Bronc said:
I see now why this happened. This all happened because the cam bolt that holds the cam gear tight backed off - that started the whole problem. The cam bolt backed off and the dowel started backing out of the cam, and when it backed off just enough for the dowel to slip completely out of the cam, it spun the gear enough to gouge that first semicircle mark and it stayed there for a while. That took your cam a few degrees out of phase with the crank, reducing performance with late valve openings and lower compression (not to mention the lower oil pressure not pumping up the lifters). Then, as the bolt backed out a little more, the dowel jumped out of that gouge and started spinning all around the cam, leaving the marks around the camshaft end. Theoretically, you COULD just drill out that dowel hole in the cam end JUST ENOUGH to deburr the opening so you can get the dowel back in and reassemble. Then put the thrust plate and timing set back on (it's probably fine) and reinstall the washer and cam bolt with red loctite this time. I bet that would get you driving TOMORROW.

I understand that the gouges in the cam end make you want to replace it, but I'm not sure you truly need to.

Just a thought.

View attachment 211960

.....and with the cam gear backing away, there was a loss of oil pressure from the thrust plate channel therefore lifters weren't pumping up giving me the crappy compression in all cylinders.

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CrazyBRONCOguy

· #85 · 1 mo ago

I like to stake the cam bolt when I tighten them. I have also put a small TIG spot weld on this before too on stuff that sees continuous high rpm.
Some sleeve retaining loctite (green usually or #640) for the dowel never hurts either.

Awesome to see someone post digging into this to find the 100% root cause too, I appreciate your efforts in doing so.

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White Dragon

· #86 · 1 mo ago

So, I have a question.

Are you going to pop the Heads off & Inspect the Pistons, Valves & Pushrods
while you are in there?
(seeings as the cam gear was spinning)

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sackman9975

Discussion Starter · #87 · 1 mo ago

White Dragon said:
So, I have a question.

Are you going to pop the Heads off & Inspect the Pistons, Valves & Pushrods
while you are in there?
(seeings as the cam gear was spinning)

Well, I did bend all the pushrods back in August, and put in a used set afterwards. I just had the intake off last weekend, they're all still straight.

When it was running, there were no backfires of any sort. Compression in cylinder 5 was at 170 upon new lifter install. That tells me it's sealing up good. I even inject air into cylinder 5 and no leakage was evident.

I have no reason to believe that there is any internal damage at this point. I've already checked all the bearings when I put in the oil pump.

At this point I'm going to ream out the cam dowel pin hole to get it back in there and button her up and hope for the best!!! Fingers crossed!!

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MS88Bronc

· #88 · 1 mo ago

White Dragon said:
So, I have a question.

Are you going to pop the Heads off & Inspect the Pistons, Valves & Pushrods
while you are in there?
(seeings as the cam gear was spinning)

I believe he has the stock style dished pistons in the engine, as well as factory ratio 1.6:1 rockers, so he should be fine because I'm fairly certain that the 351w is not an interference engine.

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sackman9975

Discussion Starter · #89 · 9 d ago

Boy am I slacking.....
Well I ended up rat tail filing out the dowel pin hole in the cam and replacing the timing chain and gears.
The truck is back up and running now and even took it on about a 600 mile trip earlier this month.

Gas mileage was better than expected. At 65mph tops I was getting 14.87MPG. At 75-85mph I got 13 MPGs.
After the 600 mile trip, once I got off the freeway, the power wasn't there....(NOT AGAIN!!!!)

I took it to work the next day and on my way home I had a total shutdown. Coasted into a school parking lot, popped the hood, popped the distributor cap and grabbed the rotor....it was free spinning. Broke the dowel pin on the distributor. I remember looking at that pin when I purchased the distributor and thought something looked funny....the pin was split in half brand new out of the box. It just took 1000 miles for it to break.

I've got some trans issues that are not ideal. During the 600 mile trip, the torque converter kept unlocking. Also, upon initial start up and drive, it will not shift into second. Once I manually shift to second, if I have enough speed it will shift to 3rd and OD. Once it goes through the gears, shifting is there but sometimes it can be a bit harsh. Today I will be getting the computer tuned and hopefully that will correct what it's doing. I know everything is wired correctly so hopefully the tune will correct it. Crossing my fingers today it will be fixed.

On a quick 0-60 run, it's about 7 seconds. Not bad for a non-aerodynamic box.

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