2001 F350 7.3 dually automatic 4X4 171K miles
I coud use some help diagnosing my truck. It blows white smoke out the tailpipe upon start up. Once it warms us it seems to go away. It burns oil, about a quart every 1,000 miles or so. It idles rough and I have noticed a loss of power and drop in mileage.

I've had two shops look at it and have gotten conflicting diagnoses from both. One said the #2 cylinder was bad - failed compression test (it was around 200 lbs. while all others were in the >300 lbs. range). I had another tell me the #2 injector was bad and the ICP sensor was bad.

They want $1K to replace the injector, $2200 to replace all four on that side. I don't want to (can't) put that kind of money into the truck if the rings and/or valves are bad. I've asked them if they could help diagnose it further, i.e. check to see if the rings and/or valves are bad. They don't want to. Just want to replace the injector(s) and the ICP and "go from there". If the rings are bad I will probably just park it for a better financial day and then put in a short or long block.

I think I'm going to have to take over diagnosing myself from here. I don't have the Enginuity software so it was probably worth it for them to diagnose the injector/ICP.

How would you recommend I proceed? My thoughts were to do a compression test. However, if it turns out to be bad how do I know if it's the rings or the valves? I realize a leak down test is used to diagnose the valves (I believe) but I have no idea how to do one and don't know if I have the tools/equipment to do it. Any advise would be greatly appreciated. Thanks.

 

Welcome to the site..

Cylinder leak down works for valves and rings. 171K isn't alot of miles on a 7.3, but always possible a comp issue.

One indicator for a ring/s issues is excessive blow by either at the fill cap or the outlet at the left valve cover to intake. You may notice it if excessive with the intake extension hose removed, or blocking the small elbow and then check the flow out of the fill cap. You may also notice a lot of oil residue in/around the inside of the intake hose going into the turbo wilh excessive blow by. You 'may' notice it pushing out of the dipstick as well, or collected residue there. Diesels don't have a PCV so some blow by is normal.

If they checked the comp and read 200lbs thats too low. But you may want to check it yourself to varify their reading before condeming the cylinder/engine. If it's a failing injector, you can as a test,, swap 2 out on that bank to varify the injector/cylinder. They would need to be re oringed on the final install. If an injector is removed, the oil that runs into the cylinder 'must' be removed before cranking the engine. The injectors can fail 2 ways, the electrical/solenoid side, or the mechanical side. If the mechanical, usually you can tell looking at the 'exhausting' oil out of the injector manifold will show a weak volume flow. If you swap a 'known' good injector into a bad/weak hole, with no improvement, chances are their reading was a good one..

With a diagnostic scan tool, a injector 'buzz' test can help pinpoint a failing injector/circuit on the solenoid side, cylinder 'balance/performance' test can help with with injector mechanical issues as well as compression.

If you need any 'as you go' help, let us know..

 

Thanks Hayapower. I appreciate the help.

I do have oil residue at the turbo intake. I know because I couldn't keep the connecting hose from blowing off when I'd step on it. I'd have to pull over to the side of the road and put it back on, clamp it down as tight as I could, only to have it blow off again the next time I stepped on the accelerator with any force. At one point I had to wrap a buch of duct tape around it to keep it on. I've since put a new boot on and it seems to be holding but there seemed to be quite a bit of oil in/around the connection when I'd have to fix it.

I don't "notice" a lot of blow by but, then again, I don't know what would be considered excessive either.

Is there any possibility that the bad injector could have resulted in the bad compression that the first shop saw?

I had never heard of a cylinder 'balance/performance' test. Is this something that can be conducted with the Enginuity software? I'm at the point where just to further diagnose the issue the shop wants another $600 (on top of the $350 I already owe them). At that point all I will know is a) I have a bad injector (know that already supposedly) and b) whether the compression on that cylinder is really bad or not. For ~$400 I could buy the software myself. If I did would the 'balance/performance' test help further pinpoint what all the issues are? Is this the same as a contribution test?

Thanks.

 

Just a side note, there should be negative pressure on the intake side of the turbo. you might want to look for some kind of restriction in the intake system unless you are referring to the engine intake.
Also the turbo itself could be going south.

 

Are you popping the CAC tube off, the large aluminium tube?

Being that your saying its loosing a quart of oil every 1K is suspect especially if nothing showing up on the ground, and dry bottomside. But like Hanky stated, the turbo seals could leak and cause the oil loss internal to the engine, could also explain the smoke but not the only cause,, but one possiblity. But it wouldn't explain the rough idle if a turbo bleed. The buzz and cylinder contibution tests 'should' have already been run or done for you as part of the diagnosis for a rough idle condition if the shop had adequate equipment. Maybe they did and didn't explain it to you?

Maybe a better bet would be to buy/rent a compression gauge and 7.3 glow adapter (about 150.00 to buy) and check the condtion of all the cylinders done through the glow plug holes. If the cylinder/s comp out ok, then look into the injectors (valve covers would still be off from the comp test), and eliminate other area's that would explain the oil consumption like comp., external leaks ect.

When working on a 7.3 that comes in with a rough idle, standard practice is to run the 'buzz' test (you would notice an audible difference between weak and healthy injectors on the electro side as the test 'energizes' each injector/cylinder) then a contibution test that measures cylinder 'balance' or performance. It helps to pinpoint a cylinder/s that aren't up to spec. Then of course a comp test to be sure, more so for higher mileage engines. But,with the oil consumption and unstable idle, if you could rent a gauge and adapter might save you a little to find out a cause, or help take the base engine out of the diagnostic equation.

 

Thanks guys. I really appreciate all the help. I'll keep this thread alive and let you know my progress, or lack thereof

I picked the truck up last night. I just can's sink the kind of money they want into it just to diagnose it by process of elimination. I really, really wish I had used the $350 I gave them to diagnose the injector to buy AE. That's how I really wanted to spend the money but just didn't for some reason.

Anyway, they told me they swapped the ICP out with one from another truck while they had it and it ran better but not perfect. I assume they ran a buzz test but when I asked the "counter worker" last night when I picked it up he stumbled around for the words to describe what they did. Of course all the technicians had gone home but he did say that they "hooked it up and it had so many codes they couldn't write them all down".

I think what I'll do is the following:

1. Go buy an ICP myself. Easy installation and see how much of a difference it makes.
2. Take the driver's side valve cover (and all associated turbo/intake connections, etc.) off. I have seen on the internet how you can run the engine with the valve cover off and visually inspect the injectors to see if they are squirting oil or not. I guess this would give me an indication if they are operating mechanically or not. At this point I have to truct the shop about the #2 not working electronically (unless I break down and buy AE).
3. While I've got all that apart get a compression tester and test the compression on all 4 cylinders on that side.

After that I'll re-post and see where to go from there. Is there any need to test the compression on the other bank of cylinders, besides the peace of mind (or further frustration) it might cause?

Also, if I were to just purchase AE I could do the buzz test and confirm/refute the bad #2 injector diagnosis. I could also do the cylinder contribution test. What would that tell me, though? I'm a bit more vague on what that would do for me.

Thanks again for all your help. The two of you have been terrific.

 

Sorry Hayapower. I didn't answer your question about the CAC tube. I don't know what a CAC tube is but it is the large aluminum tube that was popping off. It is held on by a blue rubber sleev with clamps on both sides. When it was popping off (almost any time I was pulling the boat and would start pulling a hill) there was a lot of oil inside. To the point where a fried recommended I carry a can of non-chlorinated brake cleaner to clean out the rubber connector before I put it back on.

 

Some oil in the CAC (Cold Air Charge) tube is normal. Excessive blow by and any turbo seal leaks would add to the volume of oil within the intercooler and tubes. The coupler hose and tube need to be clean and dry, also make sure the tube ends aren't collapsed from over tightening and that the clamps are in the correct position within the lines on the hose.

Checking the base engine for spec comps both banks probably would be job 1 given the rough idle and oil consumption. Doing a comp test on all the cylinders would give you better over all results, just in case there are any other cylinders 'below desired'. But you could just do the suspect bank as a start. Plus if you get a bad reading on one bank, doesn't change the over all outcome for the repairs much.

PM'd some info as well..

 

I have seen where the charge air cooler became filled with oil and caused enough of a restriction to cause the turbo to blow off the connections. They are difficult to clean out, but the turbo was still responsible. It might pay to look a little further into that part of the problem.

 

OK, ran around today basically just gathering up parts/tools. As per another thread I bought the $30 Harbor Frieght compression tester and am attempting to fashion the adapter so as to be able to get it into the glow plug opening. I've found every piece but the adapter that goes from M-10-1 on one end to a 1/8" female NPT on the other. I've looked everywhere here in Houston of the places that are open on a Satruday - no luck. I'm going to have to call a hose & fittings store Monday. I tried calling a couple today but they're all 9-5 M-F.

I also bought an ICP sensor. The shop was adamant about that being bad so I figured I might as well do it now. Tomorrow I plan to fire it up with the existing sensor and then try the new one. I believe there is also a test you can do where you unplug the sensor and if it doesn't make any difference in the way the engine runs it means it's bad. I'll try this before I open the package for the new one just in case I need to take it back.

I'll probably tear everything apart on the driver's side and get the valve cover off tomorrow as well. Hopefully Monday I can find the adapter and check the compression Monday night.

Before I tear everything down and replace the ICP tomorrow I'm going to start it up and visually inspect the blow-by. I've done this before on the oil filler and it didn't seem bad. It's been a while but I don't remember anything remotely alarming or surprising about the amount of smoke coming out of the oil filler tube but I'll try again tomorrow. I also saw a video somewhere where someone did the same thing with the turbo inlet with the CAC (I think it was) disconnected. The big aluminum tuve he disconnected seemed to be the same one I've had trouble with popping off. He disconnected it and then showed a video "smoke/blow-by" just inside the inlet. I have never done this test so I have no idea what to expect.

I'll post again and, agian, thanks.