Hi all. I have a friend who has an 84 F150 5.0L auto. he says recently it went out on him, luckily he was at home. It starts but you have to floor it in order for it to move at even an idyling/coasting speed. He drove it from the house to a garage where it has sat for about a month. The guy there said the timing chain was out. Huh? I would have thought that if it was the timing chain then it probably would not start at all! If it is the timing, then it probably just skipped a tooth, or a bunch. I have not had a chance to take a look at it yet. Any ideas out there? We would appreciate it, thanks!
It’s not uncommon for an engine to run, but very poorly, if the chain has jumped one cog. A compression test will show all eight cylinders to have uniformly low compression.
Also, the cam gear teeth on these engines were made from plastic. So it would come as no surprise if these cam gear teeth came apart and now the timing chain is running on the what’s left of the cam gear hub.
If it runs, throw a timing light on it and inspect the timing mark. If the chain is really out then the mark will not only be off it will also be wobbling around quite a bit.
Since this is an older vehicle, and IF the timing chain is the problem, then the timing chain cover should be inspected very closely when removed. With age, some of these covers were prone to coolant rot at cover/engine block junctions and will leak coolant.
Depending on the severity, the cover could be resurfaced or replaced if it’s too bad. Hope that helps.