Question about 1990 Ford Bronco

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Engine knock... I have a 1990 Ford Bronco. At idle the engine runs fine. At freeway speed it runs fine. But when I head uphill (especially on back roads) it has a knock. If I push the pedal harder and get it to drop down a gear, then the knock stops. When the knock occasionally starts on the freeway, you can floor it, get it to drop down a gear, then left off and let it catch overdrive again and it stops. I just installed a new oil pressure gauge and it idles at about 55 psi.

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  • jacob_falls Feb 09, 2009

    I ran octane booster and one of the slick50 engine treatments. It got better, but still just as bad uphill. I dont understand why its only doing on hill...??

  • Anonymous Mar 12, 2014

    when getting on the freeway the engine starts knocking

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Oil pressure might actually be a bit high for idle. High or low oil pressure in an older engine tends to be indicative of some serious issues. Oil pressure that is too high tends to be a clue that you have serious carbon build up. That aside, have you tried running a higher octane fuel, or perhaps adding an octane booster to your normal grade? Pinging can become knocking in a badly worn engine. One recommendation: At your next oil change try substituting a quart of marvel mystery oil or lucas engine oil treatment in place of one quart of your normal oil. Both have some pretty good track records for helping to free up sticking valves and break up carbon in older engines. I'm an old timer myself, and I personally swear by Marvel for older engines. There is no "rebuild in a can" but Marvel comes close. Give those a shot, let me know what happens.

Posted on Feb 06, 2009

  • Randall LaClaire Feb 09, 2009

    When a vehicle is going uphill then engine is under a heavier load to maintain the same speed you were traveling at, or even to maintain a lower speed. The heavier the load (the more power the engine must provide to maintain or continue to try to maintain the same amount of power to the drive train) the more the stress on several components. Some worn or damaged components won't really be symptomatic until they are stressed hard. Think of it like a smoker's lungs: They are worn out, but it's not apparent when they are just walking around the mall. Only when they try to run up a steep hill does the wheezing and discomfort due to the smoke damage begin. Same with an old man's lungs even if he doesn't smoke. Your vehicle's engine isn't exactly like the human body, but it has much in common.

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