Checking a 400
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Joined: Feb 2004
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Checking a 400
This may seem like a question that could not realy be answered by anyone not in presence of the vehicle but....I'm looking at buying a 77 F250 400 / C6. The current owner had no work done to the truck and has owned it for about 4 yrs but was told it was rebuilt by the previous owner with a few mods added (Headers,Intake,Carb) . What are the signs it might need a rebuild you might see on a test drive???? Thanks in Advance.....
More Turbo
Joined: Sep 2003
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First of all does it make a puff of oil smoke on startup? valve guides or seals.
How about at full throttle? Blue smoke here means the rings are shot.
Drive it at least 20 miles at highway speeds. Notice a big rumbling/bubbling noise coming from the engine compartment on the passenger's side? A gallon of antifreeze blowing out of the engine? Head gasket put on backwards.
It's a pretty bulletproof engine otherwise.
R.
How about at full throttle? Blue smoke here means the rings are shot.
Drive it at least 20 miles at highway speeds. Notice a big rumbling/bubbling noise coming from the engine compartment on the passenger's side? A gallon of antifreeze blowing out of the engine? Head gasket put on backwards.
It's a pretty bulletproof engine otherwise.
R.
Elder User
Joined: Jun 2003
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From: Houston/Hope BC
ALWAYS pull/inspect plugs and do a compression test before buying anything used. Hold the corner of a dollar bill to the tail pipe while idling. Bill gets sucked back into pipe = bad EX valve(S).
Posting Legend
Joined: Sep 2001
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Elder User
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oil pressure should be pretty high on the factory guage or read more than 50-60 psi on aftermarket guage while driving after it's warm. If it idles at less than 20 psi or runs down the road with less than 40 psi, suspect worn out bearings or pump.
Look for obvious things like smoke and old man engineering on all the little things like carburetor return springs and fuel filters. Make sure it's got an air filter in it. Look at the rear main area to see if it seeps or pours. Check the trans, don't buy one that is slipping or takes forever to change gears from drive to reverse, unless you are willing to replace the tranny.
For the most part, these engines are bulletproof. They can be killed, but in stock form they usually last at least 100K miles before anything major breaks.
Be wary of the timing chains on old fords, the factory used plastic gears for years. By now they are mostly ruined and waiting to fail.
The worst part about 400 and C-6 will be the gas mileage. Good luck breaking 10 mpg with it.
Look for obvious things like smoke and old man engineering on all the little things like carburetor return springs and fuel filters. Make sure it's got an air filter in it. Look at the rear main area to see if it seeps or pours. Check the trans, don't buy one that is slipping or takes forever to change gears from drive to reverse, unless you are willing to replace the tranny.
For the most part, these engines are bulletproof. They can be killed, but in stock form they usually last at least 100K miles before anything major breaks.
Be wary of the timing chains on old fords, the factory used plastic gears for years. By now they are mostly ruined and waiting to fail.
The worst part about 400 and C-6 will be the gas mileage. Good luck breaking 10 mpg with it.
