Blue smoke after pass

[Button9595]

I have a 1990 7.3 idi that has occasional blue smoke issues. It's happened while doing the same things every time. It's always when getting to the summit of a mountain pass. The whole way up the pass, there is plenty of power and absolutely no smoke. Once I reach the summit and let off the go pedal a bit to maintain my speed, the truck sputters as if there is air in the fuel lines and there's a bunch of blue smoke. When I let all the way off and begin to slow down there is no smoke and the truck runs fine. If I start to accellerate again no matter how much throttle I give it, it also won't smoke. It only smokes blue when trying to maintain freeway speed after going up a mountain pass.

It's kind of complicated to explain and I hope I did it well enough. Any insight as to what's going on would be greatly appreciated.

 

[Thewespaul]

Well sounds like you answered your own question there, air in the lines is what I would check first. Otherwise timing would be a good thing to check, how old is your ip?

 

[Button9595]

I can't figure out why air would get in the lines just from going over a pass. And would air in the lines cause blue smoke? I assume the ip is original and the truck has 142k miles.

 

[nelstomlinson]

I have a couple of old IDIs that give off blue smoke whenever I give'em the gas. No smoke unless I'm accelerating. That sounds different than your experience.

Your rig doesn't burn oil, right? So it just about has to be unburned fuel? Could it be that the injectors dribble when hot, or something like that?

 

[retiredinhomer]

I can't figure out why air would get in the lines just from going over a pass. And would air in the lines cause blue smoke? I assume the ip is original and the truck has 142k miles.

CDR maybe?

 

[nelstomlinson]

CDR maybe?

Good thought. Could it be that the blowby from climbing the hill pressurizes the crankcase, then the CDR starts burping oil into the intake at the top? Why only then?

 

[retiredinhomer]

How fresh is your air filter?

 

[Button9595]

That would make a lot of sense actually. I put in a new air filter the other day. The old one was very dirty looking. I haven't gone over the pass since changing the filter, but maybe I will next weekend just to see if that fixed it?

 

[hesutton]

If your fuel parts (IP and injectors) have that many miles...... it is certainly time for an IP and injectors.

Blue smoke on deceleration is common when injectors start to leak.

Ideally, you pull the injectors and test them.... but without an injector pop tester, not really feasible.


I'd give Mel at Conestoga Diesel a call.

Heath

 

[Button9595]

I briefly looked to see if I could locate the CDR valve and I noticed there's a hose coming out of the back side of the valve. This hose on my pickup is basically crumbling apart. Any idea if this could be my issue?

 

[hesutton]

I briefly looked to see if I could locate the CDR valve and I noticed there's a hose coming out of the back side of the valve. This hose on my pickup is basically crumbling apart. Any idea if this could be my issue?

CDR bolts to the rear of the intake and the hose is on the bottom. It runs from the CDR into the valley pan. Not a hose on the back side.

Heath