Low compression #2

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Apr 29, 2010 | 05:50 PM

royt911

Thread Starter

Junior User

Joined: Dec 2008

Posts: 73

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From: Enola

Low compression #2

I have an 84 F150 302 automatic with a carb. I ran it today with a new module in it. It got hot and overflowed the radiator reservoir. The spark plugs looked OK but I checked the compression in each cylinder. Here are the results.
1: 125-130 psi
2: 30 psi
3: 125 psi
4: 125 psi
5: 130 psi
6: 140 psi
7: 147 psi
8: 135 psi
Now I cranked the engine for about 6 or 7 seconds and did not push down the gas peddle.
I posted my Ford Ranger earlier that also has an issue with number two.
Any idea what the problem is and is it OK to drive it like this for a while?

Apr 29, 2010 | 06:34 PM

dustybumpers

FTE Legend

Joined: May 2008

Posts: 56,542

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From: In my own world

could be carbon under the valves, sea foam will clean that out, could be a burnt valve, or on 1 of my trucks, the pushrod came out from under the rocker arm. try sea foan 1st, then pull the valve cover to see what's going on.

Apr 29, 2010 | 07:23 PM

Franklin2

Moderator

Joined: Jan 2001

Posts: 56,992

Likes: 2,741

From: Virginia

You can take an old sparkplug and knock the guts out of it, and then weld a air compressor fitting on it. Or you might be able to buy an adapter. Turn the engine till #2 is at top dead center, plug in the air compressor into the fitting you made and screwed into the sparkplug hole, and see where the air is coming out. If it comes out of the exhaust, you might have a exhaust valve problem. If it comes out of the carb, you might have a intake valve problem. If it comes out of the crankcase breather, you might have a piston or ring problem.