I have an old '87 F250 with a 6.9 in it.

We are going to try and fix a few issues with it so we can use it another year or 2 on the farm. So, I have a few questions.

1. It is smoking from behind the intake. With the air filter canister removed I can stick my hand back there and there seems to be a hole about the size of my thumb which moves around with pressure from my finger and feels like plastic. Anyone tell me what this is? What should bein that hole? What is the best way to fix it?

2. The fuel return lines, the part that the rubber hoses slip on to; today when it was running I could pull up an down slightly on a couple of these "things", that have the return lines attached to them, and fuel would run out. Do you repalce these "things" or do they have some type of O-ring or seal that can be replaced?

3. Does these engines need the valves adjusted, like say an inline 6 diesel engine? The engine has about 250K miles on it and to my knowledge the valves have never been touched. If yes, anyone have a thread or link to some directions for pinning the engine and sequence/tolerance to adjust them. I have adjusted valves on big Cat and Cummins engines, but never a V-8.

OK, thanks in advance for your time and efforts in helping me with these questions.
sk

 

when you say behind the air canister, is the hole in the intake? just behind the air opening? or do you mean behind the entire intake manifold?if the hole is just behind the air intake hole that sounds like were the cdr valve goes. and there are "o" rings that will seal off the fuel return leaks there are kits that have all the rings and clamps..ect. in it.there are may threads on here that talk about them,the big thing appears to be, do all of them at once and do them all while engine is cold,after it warms up once the rings "set" and will leak again if messed with

 

1. You're describing the hole for a missing crankcase depression relief valve (CDR valve). This is sorta like a PCV valve oon as gas motor. Soundls like your entire CDR assembly is missing. The CDR valve itself is about the size of a can of tuna fish, and has a tube sticking out the side. The tuna can plugs into the back of the intake manifold and the tube goes thru a grommet down on the valley pan below the intake manifold. Ford dealers still carry the parts.

2. Those plastic caps ("things") snap down onto o-rings on the ends of the injectors. Unless they're cracked, they can be reused. However, kits are available that include the platic caps, the o-rings and the tubing that connects the caps.

3. The valves use hydraulic lifters, and don't need to be adjusted. If you're hearing a lot of valve noise, pull the valve covers and take a close look at the rocker arms. You might have one or two that are wearing out. The lifters seem to last forever - it's the rocker arms that wear out. My '85 has 290K, and this summer, I'm doing a complete valvce job and replacing all the rocker arms.

 

Thanks to both of you for your replies.

Yes Dave, after further research and inspection it appears that the CDR valve is missing. the strap that once heldf itin place is still there, but thats the only sign of it. I drove this truck for 3 years before it started smoking there and entering the cab, that CDR valve must have fallen off out in the pasture somewhere.

SO, is there anything wrong with me using some metal pipe, RTV silicone and rubber hose and aiming that blow-by down under the truck?

Thanks
rz

 

Short answer: No.

Long answer: No, BUT...

The CDR valve does two things that are pretty helpful. First, it limits pressure inside the crankcase that results from exhaust gasses getting past the rings. Venting this pressure prevents oil being forced past crankshaft seals, valve cover gaskets and intake valve seals. Second, it allows any oil in this vented stream to collect and flow back to the oil pan.

Running a direct vent (road draft tube) won't hurt your motor. But as few of the guys on this list have discovered, it will give you a LOT of white smoke out from under the truck whenever it's running. IMO, a new CDR valve and grommet will be a cheap solution.