Engine Knocking and Smoking! - Ford Mustang Forum
 
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post #1 of 7 (permalink) Old 02-19-2010 Thread Starter
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Engine Knocking and Smoking!

I have a '91 5.0 that is stock and I am trying to figure out what is wrong with my engine. It has started to knock real bad when I accelerate and when it does I get alot of smoke out of my exhaust. I know the oil is not low because I just changed it this weekend. I was at an auto hobby shop and had my timing checked and it was adjusted back down because it was high but it wasn't able to be adjusted back to stock settings. I am just trying to pinpoint and issue but am not really sure where to start. Any suggestions?

Thanks,

Chris
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post #2 of 7 (permalink) Old 02-19-2010
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Time for another engine. Even if you fixed one thing or two that are bad... who's to say in one or two months 3 other internal engine problems won't present. Rebuild it or buy another engine is my opinion, or maybe another car if that is an option.
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post #3 of 7 (permalink) Old 02-19-2010
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HI
I think it is most likely that the engine is done in particular if you are getting a lot of white/blue smoke and the oil level goes down over time. However, you could also just have put in their bad fuel, or (I did this once in my 67) managed to put diesel in the gas tank. Diesel will make the engine knock so loud that you would think you have blown a couple of cylinders.
I hope my comments help. If you can add more details, like the age of the engine and the mileage it would be helpful.
Good luck!

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post #4 of 7 (permalink) Old 02-19-2010
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If the oil isn't low, then it's either gas or coolant making the smoke.

What's the oil pressure like? It can be full of oil but if it's not being pumped then it'll knock.

Did it sound like rocks in a coffee can? That'd be detonation and it's usually caused by too much timing, too low of octane, or carbon deposits.

Is it a clank/clang that speeds up and slows down with the engine? That's probably a rod knocking and if it is, you better stop driving it because you could vent the block eventually. It also means a rebuild is in your future because it's beating a bearing to death.

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post #5 of 7 (permalink) Old 02-20-2010 Thread Starter
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The oil level per the gauge is never the same. It is always changing, probably a bad gauge because I have changed the sending unit and it still does it. I know that I am losing oil because I usually have to add a quart or two in between oil changes.

As far as the fuel part, this problem has been around for a while but it just started getting worse. I use 89 octane for the most part. I have tried 93 and it seemed to help some but the knocking was still there.

The engine is probably the original 91 enging with 165,000 miles.

Does any know a good price to have a short block rebuilt?
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post #6 of 7 (permalink) Old 02-20-2010 Thread Starter
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Quote:
Originally Posted by EagleAutosports View Post
If the oil isn't low, then it's either gas or coolant making the smoke.

What's the oil pressure like? It can be full of oil but if it's not being pumped then it'll knock.

Did it sound like rocks in a coffee can? That'd be detonation and it's usually caused by too much timing, too low of octane, or carbon deposits.

Is it a clank/clang that speeds up and slows down with the engine? That's probably a rod knocking and if it is, you better stop driving it because you could vent the block eventually. It also means a rebuild is in your future because it's beating a bearing to death.
I guess I would need a mechanical guage to really tell if the oil pump is going out or not. Right?

The knocking is only really present when I accelerate. If I was to guess I would say it sounds like rocks in a coffee can but if it was detonation, would it still smoke like it does? Also, I noticed that while driving, when I accelerate in gear, it knocks. But if I take it out of gear and and rev it up while driving, there is no knock. Does that make sense? Is there some reason why it would not knock while out of gear as opposed to being in gear?
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post #7 of 7 (permalink) Old 08-04-2010
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My 2000 GT does the same thing one person told me it was a rod. I parked it and saving to fix it. Any one know how much I'm looking to spend ?
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