92 4.0 knock under load
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Freshman User
Joined: Apr 2004
Posts: 32
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From: Portland OR
92 4.0 knock under load
Hello-
I have a 92 AWD 4.0 ext aerostar with 166000 miles on it, I purchased it 1000 miles ago. The Trany was rebulit 800 miles ago (before the first tank of gas was used).
Over the last 450 miles the engine has developed a knocking that speeds up with the RPM. The knocking only occurs when the engine is under load so I am having a hard time locating the knock in the engine. The engine sound good at idle and high RPMs in neutral. When I give it over 1/2 throttle under load the knock disappears but that maybe due to the increased engine noise.
The van is getting 17-21 mpg. The oil pressure is solid at 3/4 on the gauge. Replace the oil with Motorcraft oil filter and 10-40 oil at 166,000 miles. Current indications show 1/2 quart usage per 1000 miles. I have yet to replace the plugs and wires.
There are two other Aerostars in my family and I plan on keeping this one.
My question is: Does anyone know the cause of the knock? How soon is a long block in my future?
This vehicle is slated to be used for towing a 800# tent trailer with a full load of young ones.
Thank you for your input.
I have a 92 AWD 4.0 ext aerostar with 166000 miles on it, I purchased it 1000 miles ago. The Trany was rebulit 800 miles ago (before the first tank of gas was used).
Over the last 450 miles the engine has developed a knocking that speeds up with the RPM. The knocking only occurs when the engine is under load so I am having a hard time locating the knock in the engine. The engine sound good at idle and high RPMs in neutral. When I give it over 1/2 throttle under load the knock disappears but that maybe due to the increased engine noise.
The van is getting 17-21 mpg. The oil pressure is solid at 3/4 on the gauge. Replace the oil with Motorcraft oil filter and 10-40 oil at 166,000 miles. Current indications show 1/2 quart usage per 1000 miles. I have yet to replace the plugs and wires.
There are two other Aerostars in my family and I plan on keeping this one.
My question is: Does anyone know the cause of the knock? How soon is a long block in my future?
This vehicle is slated to be used for towing a 800# tent trailer with a full load of young ones.
Thank you for your input.
Senior User
Joined: Feb 2004
Posts: 467
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From: northwest
mine knocks too. or pings, whatever you wanna call it. it have a 95 just like yours. but my 91 3.0 shorty 2wd did it too.
I put super in it when we went camping and pulled our 3200 lb trailer. no knock or ping the whole trip. got back, ran regular, and it knocks and pings again, no trailer!
i think its the gas.. I would hope I am wrong, but thats all i have narrowed it down to!
I put super in it when we went camping and pulled our 3200 lb trailer. no knock or ping the whole trip. got back, ran regular, and it knocks and pings again, no trailer!
i think its the gas.. I would hope I am wrong, but thats all i have narrowed it down to!
Thread Starter
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Freshman User
Joined: Apr 2004
Posts: 32
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From: Portland OR
Found a possible fix
I've spent time looking for the answer before I posted, I swear. But of course I found a possible solution just after posting. I'll post an updated after trying removing the carbon with the carb cleaner.
https://www.ford-trucks.com/forums/s...ighlight=knock+
Thanks
https://www.ford-trucks.com/forums/s...ighlight=knock+
Thanks
Thread Starter
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Freshman User
Joined: Apr 2004
Posts: 32
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From: Portland OR
TSB works
Well, completed the work per TSB with good results. The 1st can smoked heavily for the whole 3 mile @~3000 rpm run, the 2nd run only smoked ~1/2 mile and the third only smoked down the driveway then was clear.
Make sure your home's windows are closed while draining the cans into the engine. The 1st can was the worst.
The oil still looked good but was changed anyway per TSB.
All the spark plugs were changed per TSB. I don't think there was carbon build up on the plug due to the cleaning. I don't know how long the plugs were in either. They were all light tan and the electrodes were in good shape. The wires were changed as well. The 4.0 designers at ford really try make you mix up cyclinder 5 & 6 plug wires so becareful.
This proceedure only took 6 hours, much better than the days of replacing the engine.
Thanks for your ear.
jc
3 cans of PM-3 (Ford dealer) ~$16
6 Bosch Double Plat Plugs (Local Auto Store) ~$24
1 Bosch Wires (Local Auto Store) ~$35
1 Motorcraft Oil Filter ((Local Auto Store) ~$4
1 Case of 10w40 ((Local Auto Store) ~$25
Total = $104
Make sure your home's windows are closed while draining the cans into the engine. The 1st can was the worst.
The oil still looked good but was changed anyway per TSB.
All the spark plugs were changed per TSB. I don't think there was carbon build up on the plug due to the cleaning. I don't know how long the plugs were in either. They were all light tan and the electrodes were in good shape. The wires were changed as well. The 4.0 designers at ford really try make you mix up cyclinder 5 & 6 plug wires so becareful.
This proceedure only took 6 hours, much better than the days of replacing the engine.
Thanks for your ear.
jc
3 cans of PM-3 (Ford dealer) ~$16
6 Bosch Double Plat Plugs (Local Auto Store) ~$24
1 Bosch Wires (Local Auto Store) ~$35
1 Motorcraft Oil Filter ((Local Auto Store) ~$4
1 Case of 10w40 ((Local Auto Store) ~$25
Total = $104
Postmaster
Joined: Apr 2001
Posts: 3,818
Likes: 3
Originally Posted by jasonbbq
Hello-
I have yet to replace the plugs and wires.
I have yet to replace the plugs and wires.
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