UPDATE: General DP Question (air leak in fuel line)

[Spizzer]

We just took our Cat C7 out for a few days in the mountain. After a long climb up the pass and getting to our CG, the rig smelled hot, like something was burning, even could smell it in the bedroom. All guages were normal during the drive.

After three days we went to head back home and it took a lot to get it fired up. Cranked and sounded like it was trying to catch, but would not run on its own. After a long crank, it finally caught enough to lite of and run, but there was a BIG cloud of whit/bluish white smoke! During the trip down the pass it ran fine but when we got home (40 miles) I could smell the hot smell again. My first thought was a head gasket, but coolant and oil are perfect. Upon more inspection I found the fuel line going into the primary filter a bit loose and I can tell Diesel fuel has been leaking out at the input line is dirty compared to the output. I assume that since diesel can get out, air is being sucked in when it is running.

My question is: Is the diesel going to be like a gasser and if it is running lean due to air in the lines, will it run hot? Exhaust temp would be high causing something that normally doesn't smell hot to smell hot, while the radiator keeps the overall temp down showing no abnormal indication. Air in the lines would certainly explain the hard start. Once it was warmed up it starts normally.

I am due for filter changes, so am going change them out and fix the loose fitting to see if the problem goes away. Thought I would ask the question in the meantime.

thanks for your thoughts,

jeff

Okay, all!

I changed the filters and took apart and redid the lose fitting. Primed the bejeebers out of it, and then tried to start it. It cranked and fired up like normal!! No smoke, either. So relieved.

Next step is to take it for a long ride and see if the smell has gone away, too.

Thanks for all the advice. I will update you on the next phase.

jeff

[Spizzer]

Okay, all!

I changed the filters and took apart and redid the lose fitting. Primed the bejeebers out of it, and then tried to start it. It cranked and fired up like normal!! No smoke, either. So relieved.

Next step is to take it for a long ride and see if the smell has gone away, too.

Thanks for all the advice. I will update you on the next phase.

jeff

[wolfe10]

With a "hot rubber" smell, check your belts. Suspect you have a serpentine belt and a separate V belt driving just the water pump.

Particularly if one of the accessories (A/C compressor, alternator, fan hub) are starting to seize up, they will cause the belt to slip and burn.

Also, if the separate water pump belt is loose, it can cause this-- it is on a manual, not automatic tensioner.

Bottom line, with a burned rubber smell, I would not drive until diagnosing it.

[Spizzer]

rgatijnet1 wrote:
I'm guessing that you may have been close to an engine fire and the "hot" smell that you experienced was from diesel spraying on to some hot engine components.

I pretty sure that is not the case. The loose fitting I have is on the back side of the RV radiator so not near the engine. ALso, the hot smell I have seems more like a rubber or something. Not a fuel smell.

jeff

[Spizzer]

WILDEBILL308 wrote:

I would fix the loose fitting change your filters and go for a test drive. I would also check the front of your CAC (this should be done at least annually) as Britt subjected.
Bill

Thanks, Bill. That is my plan....should tell me a lot. And while I have the engine cover off to change the secondary, I can check carefully for anything that looks like it got overheated.

jeff

[Spizzer]

slickest1 wrote:
I would check your oil for signs of water in it or check your radiator for signs of oil fuel.
It sounds like a head gasket to me.

I did check both and they appear perfectly normal. Levels haven't changed, and they are clean. I sure hope you are wrong about the head gasket!

jeff

[Spizzer]

wolfe10 wrote:

lfeather wrote:
Generally, a lean fuel/air mixture will run hotter than a rich fuel/air mixture.

In a gasoline engine where you need a stoichiometric ratio-- yes.

But a diesel can run on a VERY wide range of fuel:air.

As stated, in a diesel, less fuel, less fire, less heat.

Thanks, Brett. Didn't know that about the differences.

jeff

[Spizzer]

Ivylog wrote:
Air in the fuel will keep the injector from building enough pressure stopping the injector from spraying the fuel resulting in loss of power and ruff running... Cooler temps. White smoke is a sign of water. Drain the fuel in the filters into a clear container to check for water.

Thanks, Ivylog. Thanks for the thoughts. I will check the filters for water.

jeff

[Spizzer]

wolfe10 wrote:
Also, check the front of the CAC and make sure that the fan has not pushed diesel and then dirt into the front of the CAC. THAT would smell!

Brett,

My primary is on the rear of the Radiator and CAC, to any leaking diesel is being blown away. I Don't think the diesel is the source of the smell.

jeff

[Spizzer]

Rickieblue wrote:
The only symptom you may experience if it is sucking enough air, that the vent back to the tank can't handle, is that it will stumble and surge under load and run kind of ratty with no power, and alot of times it will run pretty much normal but when you bring it back to idle it will gallop and stall or just gallop till the air vents out and then will seem fine. Hope this helps..............Rick

Thanks, Rick. It does help. Good info.

jeff

[rgatijnet1]

I'm guessing that you may have been close to an engine fire and the "hot" smell that you experienced was from diesel spraying on to some hot engine components.

[WILDEBILL308]

Spizzer wrote:
We just took our Cat C7 out for a few days in the mountain. After a long climb up the pass and getting to our CG, the rig smelled hot, like something was burning, even could smell it in the bedroom. All guages were normal during the drive.

After three days we went to head back home and it took a lot to get it fired up. Cranked and sounded like it was trying to catch, but would not run on its own. After a long crank, it finally caught enough to lite of and run, but there was a BIG cloud of whit/bluish white smoke! During the trip down the pass it ran fine but when we got home (40 miles) I could smell the hot smell again. My first thought was a head gasket, but coolant and oil are perfect. Upon more inspection I found the fuel line going into the primary filter a bit loose and I can tell Diesel fuel has been leaking out at the input line is dirty compared to the output. I assume that since diesel can get out, air is being sucked in when it is running.

My question is: Is the diesel going to be like a gasser and if it is running lean due to air in the lines, will it run hot? Exhaust temp would be high causing something that normally doesn't smell hot to smell hot, while the radiator keeps the overall temp down showing no abnormal indication. Air in the lines would certainly explain the hard start. Once it was warmed up it starts normally.

I am due for filter changes, so am going change them out and fix the loose fitting to see if the problem goes away. Thought I would ask the question in the meantime.

thanks for your thoughts,

jeff

I would fix the loose fitting change your filters and go for a test drive. I would also check the front of your CAC (this should be done at least annually) as Britt subjected.
Bill

[slickest1]

I would check your oil for signs of water in it or check your radiator for signs of oil fuel.
It sounds like a head gasket to me.

[wolfe10]

lfeather wrote:
Generally, a lean fuel/air mixture will run hotter than a rich fuel/air mixture.

In a gasoline engine where you need a stoichiometric ratio-- yes.

But a diesel can run on a VERY wide range of fuel:air.

As stated, in a diesel, less fuel, less fire, less heat.

[Ivylog]

Air in the fuel will keep the injector from building enough pressure stopping the injector from spraying the fuel resulting in loss of power and ruff running... Cooler temps. White smoke is a sign of water. Drain the fuel in the filters into a clear container to check for water.