Hello All,

I have a 1995 f350 with a 97 7.3 in it with 250,000 miles.

I was driving along a couple of months ago and started to blow white smoke. I did not worry too much as it stopped after a minute and did not return. This was in the middle of a long drive. It would go ok to happen intermittently over the coming days with seemingly no rhyme or reason.


Well one morning after an hour drive it started BILLOWING white smoke. It was so bad I had to get off the road as I was afraid I was a hazard to other drivers. I parked it for 12hr and trailered it home. When I drove into the trailer it didn't smoke. When I drove off the trailer at home it didn't smoke.


So, I proceeded to pressure test the degas bottle. I could hear a leak somewhere in the engine but could not narrow it down. Sounded like the passenger side. I did the easy thing and pulled the oil cooler. All Orings were intact and the core pressure tested fine. I put another known hood oil cooler on it and it behaved the same way with the audible air leak on pass side. I had also drained the oil prior to pulling the oil cooler and I was getting a stream of water coming out of the drain plug. It did the same after the new oil cooler. I also pulled the water pump and looked for cavitation leaks on the front cover. I only found a small nick and I will post the pics of that. Did not seem like a leak.

So I called in reinforcements (a local diesel mechanic). Before he arrived I put the water pump back on. When he arrived we pressurized the degas bottle and it was not leaking anymore!!!! We pulled the glow plugs and barred the engine over and got liquid shooting out of cyl 7. But after we pulled the injector to look over the cup we found nothing. We sucked out the cylinder and it did not fill up with anything.

The truck sat for three days with pressure on the degas bottle at TDC and it dropped to 5psi and held there for the next two days. I also barred the engine over to BDC on cyl 7 and left it for those two remaining days and it did not lose anymore pressure.


Conclusion: I believe my base issue is coolant migration to the oil. The coolant gets into the oil and slowly it gets pumped through the High pressure oil. This is what caused my white smoke issue as coolant in the oil will make high pressure stuff so funny things. But how it's getting to the oil I cannot tell.


So... anyone up for the challenge!?!? This issue is very elusive and a down right dog. I cannot seem to figure it. Hoping someone has a EUREKA! moment.

 

Sounds like a cup issue? I would pull all 8 injectors and inspect. I believe the pressure needs to hold at either 12 or 17 PSI for the cooling system.

 

What about something that is rare to the 7.3L which is a head gasket issue?

A recent thread on a SD 7.3L coolant issue is linked below.

Link: https://www.ford-trucks.com/forums/1...d-gaskets.html

Very unlikely, but if you are grasping at straws, perhaps this will lead you to the solution.

 

So I am relatively new to the 7.3 community, but I have been learning as much and as fast as possible (I spend alot of time reading forums and watching videos). So take this with a grain of salt I guess.
From what I understand, white smoke (or any smoke for that matter) is due to the extinction of a flame. The engine producing white smoke would typically mean that there is some excess fuel being "semi-burned" causing the smoke you see. Now, based on what your post said regarding the leaking air noise, technically, I guess you wont need excess fuel to produce the white smoke. In your case I would guess its due to not enough air going into the engine. The leak will cause a reduced amount of air, potentially causing a reduction in the amount of fuel being burned. Now since we are some Diesel boys, we got no spark plugs. So we combust with just Fuel and air. Since you arn't combusting everything, your temperatures may be lower, causing the same white smoke you see.

I guess long story short is check your temps and look for low temps. I know that's usually the opposite of what you expect, but that's my guess? I could be totally wrong but good Luck either way!

 

Well I'm pretty sure the whole issue is the coolant migration to the oil. Looking more and more like a bad front cover but while I had a small nick in the front cover behind the water pump I poke around with a pick and knife blade and could not discern a hole. But now the system is holding pressure much better. So maybe I had a small hole and I accidentally closed it up with my scratching around. That's the only thing that fits all the pieces together.

and as for the white smoke I think that's because the coolant got into the oil and caused the injectors to act crazy. So two problems are actually one. One is the prob and one is the symptom.

 

Analyze your oil at Blackstone or the like if you think coolant is in it.

White smoke to me with Diesel is incomplete combustion. Blue is burning some oil. Black just overfueled.

 

Is there a sweet smell to the exhaust?

I agree with you that there could be a leak on the front cover somewhere. A head gasket is possible, but would normally show low compression in at least one cylinder. Which could be leading to your unburnt fuel/white smoke

 

The truck I posted a link to above would have a bit of a "miss or shimmy" when at operating temperature and idling. We attempted to locate the issue for months looking at everything other than a head gasket leak/failure. Turned out the coolant was not leaking when the engine was cold, but when warm the coolant was leaking into the combustion chamber and extinguishing the combustion sequence.

Again, this is very, very rare for a 7.3L to happen to.

I am with Hit Man X on getting the oil analyzed from a reputable source like Blackstone or Lab One Inc. I recently sent off for my first UOA ever and had results in just under 8 days from dropping it off at the mailbox.

Sounds like you are on the right path to success by being sure about removing or adding possible failure points.

 

Honestly when I smelled the exhaust it smelled heavy with fuel. But then again it smells heavy on fuel all the time. This time did seem worse though.

 

We pulled the head and found a sloppy wrist pin and a badly cracked cylinder wall. Cracked all the way up the wall. The piston was messed up too and I do not know why it happened. Replaced it with a bus motor.

 

Are you running a tuner?

 

Yes. A php with canned tunes. But I don't got rid, and I do not tow at all. Seemed to me unlikely it would damage such a reliable engine so quickly.

 

I wonder if a former owner may have used ether to start it and caused the damage.

 

Honestly I hadn't thought of it but it is possible. It ran like a champ for me for 6 months and only had 130,000 miles on the motor. I know this because I bought the complete wrecked truck from him and I k ew the guy beforehand and the truck.
Ran great... until it didn't.

 

Ether doesn't have any octane . Has been used for years . On our trucks the worst that can happen is starting the intake on fire . An engine that runs at 400 or so LBS of compression can handle it .