Ok, First a short history of the problem. I got the Bronco and it drove fine just around base (I am in the Navy stationed in Iceland). the first time i take it off base, I get to about 35MPH and it looses all power, engine is making a slight noise like it is struggling, I can't get my power back without shutting off the truck and letting it sit for a bit then starting it back up, then same problem. I replaced the spark plugs, wires, rotor, dist. cap. The distributor is a newer optical pickup(not sure of brand). I tested the coil according the manufacturers specs and it seems fine. I checked the timing and it was way off, i adjusted the timing back where it should be and it seemed to run fine but was hard to start. The "hard start" problem just got worse with each time i started the truck. It almost sounds like the battery is dying but it is not. Timing gear and chain are new. The engine is a 289 bottom with 302 heads. I drove the truck for 3 days before buying it and it ran fine. I am at a loss as to where to go next and any advice would be much appreciated.

 

I'll go out on a limb here - but the symptoms (timing way off, hard starting that gets worse when timing is corrected) sound like bent pushrods caused by the timing chain being installed a tooth off.

 

How about the model year of your truck? Are we dealing with fuel injection or a carb?

 

sounds like a timing chain problem. When i replaced the stock timing chain and gears on my '82 302w i found that it had been coated with plastic for some reason and some of the teath were worn and on top of that the chain had way to much slack in it. After doing some research it seams that ford thought it was a good idea to coat the timing gears with plastic to cut down on friction. Over time the teeth become dry-rotted and brittle, causing many problems.

 

He said that the timing chain and gears are new, so they would be metal.

Knowing that they were recently replaced, and judging by the symptoms, there is a good chance that the installer put the timing chain in wrong, a tooth off probably - so it runs but the timing was way off. Then when the timing is adjusted to specs, it bends pushrods because it is so far off and you get the exact symptoms that he is describing.

It's just a possibility, but I have seen it happen.

 

My truck is an 84. The engine is carb'd, 289 block w/302 heads. I am not a mechanic by any means of the word so if my terminology is off bare with me. The truck ran great shortly before i bought it, and after the new timing chain was installed. The distributor, plugs, wires, rotor, cap are all new. I havn't touched the carb. It ran great for the first week or so that i had it, then ( i never did anything mechanical to it), i was on the road and got to around 35MPH and noticed the problem. It was so bad Monday morning that it would not start. I retarded the timing back a touch and it started right up. It had almost no power at all under normal driving conditions. It almost sounds like it is missing but i have no idea how/where to start looking. I drove it to work this morning and it got me here but ran like crap. The timing chain and gears are all metal. When i changed the plugs, the old ones all looked fine and after putting the new ones in i checked them and they look fine also. The distributor is new, it is unlike any that i have ever seen though. It is optical rather than using a magnetic pick up. Could this be failing? Since the problem began i have also replaced all the vaccum lines, I wasn't sure if this would help but was worth a try. This is just agrivating the hell out of me. I drove the truck when it was running like it should and it acted like a new truck. I just don't know what could be causing all this when i didn't change anything.
Thank you all for your help.

 

Pardon my stupidity on the subject but;
would very low oil pressure cause the problems i am having? I had to take the truck to the mechanic today and he called me this afternoon asking if the oil pressure had always been low. The guage didn't seem to read low to me (could be broke) and i didn't ask if he was looking at the guage or if he hooked something up to the thing to test it somewhere.

 

I told you what I think the problem is.

 

Would low oil pressure be a symptom if there was a bent pushrod?

 

No. Low oil pressure would not really have anything to do with how the truck runs, unless it was so low that it started knocking and you do not have that problem.

Venis123 here said timing chain as well; even though they were thinking that a plastic gear went bad, the point is that they saw timing chain as the issue (as in jumping a tooth.)

It could be a lot of things, but your symptoms as reported here add up to the timing chain being off. Since it is new, it is possible that it was put in wrong. You do not necessarily have bent pushrods, but the way that your symptoms are getting progressively worse suggest that. A timing chain being off can certainly bend pushrods, especially when the timing is brought back to where it should be.

I would tell your mechanic that the timing chain was recently done, and you started having a lot of problems after you put the timing back to stock.

Good luck and let us know how things turn out. Hopefully it will be something easier than the chain and/or pushrods and they don't have to get into the engine.

 

when it's hard to start are you getting spark from the coil?

 

I'm with everybody else check the timing chain installation. Make sure firing order is correct before having engine work done.

 

True that, check the firing order. Good call - sometimes we overlook the simple things. Two wires off, and it will still run, but run poorly.

Since a mechanic has your truck, I am sure that he will check the firing order. That's about the very first thing I would do if someone brought me a truck with your symptoms.

 

PS - I could give detailed but simple instructions for checking to see if the timing chain is properly positioned - in a nutshell bring the number one piston to TDC and see if the rotor is pointing to the corresponding spark plug. It should be relatively close. If it is very far away then your timing chain is off.

Also, you said that it had a new distributor. That could have been put in off as well.

 

Check it out everybody. He stated that the truck ran great AFTER the timing set and distributor were installed. No work has been done to the truck until AFTER it started running badly. Sounds like the timing is advanced too far though. Was the distributor loose when you checked the timing? You can't always go by the pointer and timing marks on old engines. Timing covers and harmonic balancers are different for different years, and the outer ring on old harmonic balancers can slip. Also with an aftermarket camshaft, sometimes you can't use the factory timing marks.