This is quite long because I have 3 years on info to relate. I have an 85 bronco 351w HO, 200,000 miles with original Holley 4 barrel carb. I have had a stalling problem with it for the past three years and it is getting to the point I can no longer drive it. I have had it to several dealerships and garages and I have done alot of work on it also, but no one can find the problem. For the past couple years, on cold days - only in the winter, the engine would die on me when I hit the gas. It would lurch forward into the first lane of traffic and cut right off. After driving for a few miles, it would work OK. Now, After the most recent visit to the ford dealership it runs OK cold - about 3 minutes, but it dies when I accelerate when it is warm or hot. It will sputter a little and die. Judging from the tach, the rpms are all over the place. Sometimes in drive it will idle around 500 and other times 1000. It runs rough in idle, but smoother the higher the rpms go. Here is what I did:
1.had carb rebuilt
2.put on a new Holley 600 carb- no difference so I put the old one back on
3. Checked vaccum hoses and hooked up two loose ones.
3. changed all gaskets under carb and cleaned the egr valve
4. set vaccum advance to specs
4. new gas tank, installed inline filter, new fuel pump
5. new plugs, rotor, cap.

A month ago, the engine overheated and sounded like fireworks went off in the front. was able to limp it home and changed thermostat and waterpump. When I changed the plugs the front two, left and right were coated with white powder, the second ones were fused to the block and took forever to get loose. They had white deposites but were also pinkish. third back look brand new like they never were used and the last two has black deposites on them.

When driving, the engine has good power and does not stall until it drops to idle it is worse when it is cold and wet. Also I noticed recently that when it is cold or running pretty strong, the oil pressure is on the high side of normal, when it's running poorly, the pressure drops to the low side of normal.

I need ideas because my parents want me to sell it because they say it is too dangerous to drive, but I got sort of attached to it over the past 6 years and want to keep it. What else can I try?
Thanks Dan

 

[font size="1" color="#FF0000"]LAST EDITED ON 19-Jan-01 AT 12:44 PM (EST)[/font][p]Sounds like you have some serious problems. My guess, and its only a guess based on what you say about the plugs, is that not all cylinders are running evenly. The plugs fused to the heads could mean a lean mixture in those cylinders causing preignition (very hard on engine), the ones looking like new could mean there's coolant getting into those cylinders.\

Based on these two things, I would suggest getting a set of head and intake gaskets (approx. $50 for all). Pull the intake and check for any sign of damage around the water jacket ports and around cylinders 2 and 6 (could be a vac leak around them causing them to run lean which causes excessive heat due to preignition). If there is no sign of damage around the water jacket on the intake gasket, I would pull the heads to see if there is a coolant leak into cylinders 3 and 7. It will be obvious because the pistons in these 2 cylinders will also look just like new (shiny with no black).

Sound to me as though you have both a vac leak at the intake as well as a coolant leak around cylinders 3 and 7. This is probably not what you wanted to here but its better to tear the top down now before you do some serious damage(if it hasn't happened already).

RCC

PS: keep us posted as to what you find out.

 

Thanks for the ideas. I hadn't thought about a vac leak in the intake. I'll check it out this weekend. I wonder if that is what causes the car to backfire when I shut off the engine? Also I could be off here, but could timing have anything to do with it? Once again , thanks for the ideas.

Dan

 

Dan, Your engine can run hot if your timing is out. It can also make the engine diesel out a little when shutting down. This in combination with a possible vacuum leak can make a type of backfire when shutting down. It would be more of just a "pop" sound than a loud bang. Since your engine did run hot enough to fuse the plugs, it is very possible that you could have head gasket damage. Gasket damage reguardless of if it was before or after the over heating escapade. Heat up that was caused by possibly being out of time. Constant backfire does not help either. I too, have played the carborator game before and then relized it was some type of vacuum leak. It can be a costly way to learn but you got to start somewhere. Good luck.

Jakegypsum // Ford fleet, soup to nuts.

 

I think I corrected some major problems today. While searching for a vac leak around the intake, I used up a can of carb cleaner, but I noticed when I shot it behind the engine, the engine reved up. I saw there were holes in the crossover pipe in the back. Don't know if that is the right name for it, but it goes from one side to the other. When I shot the carb cleaner on the pipe the engine sped up. It was so rusted it broke in half when I took it off. I went to the junkyard and got a replacement and now when I spray the carb cleaner on it, nothing happens. I didn't think that would affect the vac system, but maybe it does. I also, as an afterthought replaced the sparkplug wires. The old ones still said motorcraft 1985 on them and were cracked up and split something aweful. Now the Bronco accelerates great when hot or cold, no hesitation whatsoever. It's still a little rough at times, but this is the best it has run in years. I'm hoping this fixed it, but if it starts to act up again, I'll run a compression test to see if the head gasket is going bad. Thanks again for the ideas.
Dan

 

Well, I spoke too soon. The Bronco is acting up again. I did a compression test today and all but the back two on the drivers side read 130 on my gauge. The back two read 120. I have no idea if that is good or not. The idle is still all over the place. Now I just discovered a large oil leak that is running off the exhaust pipe partly burning and then going on the floor. It made about a 3" round puddle in 2 minutes. I'd put in a new long block, but I don't know if it would help.