I recently purchased a 2001 F250 SD PSD with 132K miles. The truck ran good and strong for about another 200 miles and all of a sudden while driving developed a "banging" sound and lost power. I originally thought it was just a bad exhaust leak, but since have decided that it is "backfiring" thru the turbo. Maybe this is a bad description, but it's the best I can come up with. Any ideas before I take it to the shop?

Thanks in advance for any help,
CapmJack

 

First off, Welcome to the Forums! Second, have you taken the tubes of and looked at the turbine intake wheel? Check it out, also check the shaft for play as well. That would be a good start, I am sure others will jump in real quick and offer up some more advice. Do you have access to a code reader?

 

I would guess that one of your intercooler boots blew off.

 

Thanks for the reply and welcome. Yes, I have looked in at the turbo wheel and everything looks good. I actually can feel the "backfire" at the turbo intake. No, I do not have access to a code reader. It is obviuos that it is missing on at least one cylinder though.

 

So you can feel air coming back out the intake side of the turbo when idling?

 

Yes, I can feel air coming back out at the same time I hear the "bang". It's not a mechanical "bang" like metal-to-metal, but more a detonation sound. Very loud also. It sounds like one cylinder.

 

I don't know much about it but the only reason I could think of it blowing back at idle given the circumstances you described is a bad valve seat on the intake allowing the compression to force it backwards. Bang might be piston hitting the valve. Not trying to scare you by any means as I really haven't heard this problem before and could be way off.

 

I'm trying my best to stay optomistic about this, but I'm afraid it is fairly serious. I've talked to the local Ford house, and nobody there has ever heard of anything like this either. It's just my luck that I get to have the problem that never has happened before.

 

Well give it a while, daytime is fairly slow on here, there are some very mechanically inclined people on here that may have some idea or know what it is already.

 

Valve sticking really sounds logical. This will completley mess up timing, and it may be possible that you're getting trapped gasses being forced back through the intake valves.

 

If you think it's a sticking valve, maybe a oil change with full synethic would help.

 

I've thought about it being oil related and would like to try the oil change bit. Any suggestions on particular oils?

 

I'm going to call this a bent exhaust push rod. I doubt the cam has gone flat, we have roller rockers. It either just barely opens the exhaust valve or not at all and the pressure comes back out the intake valve when it opens.
Chevy mouse motors would do this whenever one of the exhaust lobes went flat.

 

I guess I misunderstood his description. I thought it only did this once.

Either way, it's either intake valve sticking or exhaust valve not opening. Oil change won't help at all. Do a compression check to isolate the cylinder, then pull the head off of that side. You'll then see what kind of damage you've got. I went through this on 2 vehicles. One was an '84 Bronco II with the 2.8 V6. Loss of power and backfire through exhaust, pulled the heads and burnt exhaust valves is what I found. The other was an '86 S-10 Blazer, bent a rod and experienced the unwelcomed banging.

 

yes i concur with Kwikkordead. i was going to suggest to pull the valve covers and look down and see if you can see anything abnormal. maybe you bent a push rod somehow, and there is WAY too much clearance between the rocker arm and the push rod. it may have started as just too much clearance between the rocker arm and the push rod, and every time the push rod traveled up on the exhaust stroke t o contact the rocker, it stressed it slightly and finally it just gave out, barely opening the valve as a result. i dont think it would throw a code, as there are seven more cylinders contributing to backpressure, and it would not sense a low backpressure code.

maybe a quick way to check to see if it is this problem, and what cylinder bank to start investigating, remove the compressor manifold that is in front of the turbo. both of the intercooler pipes go into it, and it attaches to the turbo compressor outlet by a marmon clamp. remove this, and peer down into the black intake plenums that attach to the cylinder head. swab them and see if you can see any exhaust or combustion byproducts on the plenums. a white pipe cleaner bent at an angle to reach the backmost cylinders would help. however i warn you that unburnt engine oil residue in these and all of the intake from the filter to the engine is normal, it is part of the CCV system. enough to check over for now, i have to go outside before it rains to do some stuff.