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Iver · 08-14-2005, 09:09 AM

Need some help understanding the readings from my new X-Monitor from BD. I have an 05 Ford Excursion PS 6.0 Diesel. I put the monitor in because I was told in no uncertan terms through this site that the gage that is stock is worthless "by the time it moves from normal your tranny is cooked". Took the advise seriously ($700). I spent the bucks for this vehicle to have an engine that lasted into my old age and I can no longer remember how even spell engen.
The tranny temp and pyro I understand and have the alarms set conservatively. But the boost reading runs all over the place, from .03 to 18 depending upon how heavy I am with my foot at the moment. Other than "nice to know" information, what do I use this for? Is this information only useful if you have one of those aftermarket performance chips?
Another related question: When I was into sailing it was common practice to let the diesel cool off before shutting down and then give it a short throttle up just before shutting it down. I was told this was to bathe the cylinders with oil and just a good practice. Is this a good practice with the PS or not necessary.
Thanks for the help. Please, in your response, keep the explaination to the "Diesel for dummies" level because a mechanic I am not.

Porky Pig · 08-14-2005, 10:20 AM

Quote:

I was told in no uncertan terms through this site that the gage that is stock is worthless "by the time it moves from normal your tranny is cooked".

Hey ... that sounds like me!

The boost gauge is your friend ... this article explains it better than I can.

Quote:

When I was into sailing it was common practice to let the diesel cool off before shutting down and then give it a short throttle up just before shutting it down. I was told this was to bathe the cylinders with oil and just a good practice. Is this a good practice with the PS or not necessary.

I don't think blipping the throttle is necessary ... but getting your EGT down to 300 (pre-turbo installs) before shutting down is helpful. However, there is a school of thought that thinks this is a bunch of bunk. I'm still in the 300 club.

Tinsel Loaf · 08-14-2005, 12:49 PM

When towing I always do a cool down before shutdown. I never shut off the engine when doing a rest stop less than 15 minutes, otherwise I run the engine for 15 minutes before shutdown expecially after a hard pull. The stock idle is to low so I did a mod to increase the idle. You can get the idle mod information from the dieselstop.com. Also the parasitic heat from a shutdown hot engine is bad for the tubro bearings among other things like transmission. The rev before turning off the key is not necessary.

Iver · 08-14-2005, 02:06 PM

Thanks guys for the help. Porky the article was just what I needed. Now I can really use the information given from the gages to see what is going on.

You guys are great ... well, not exactly great but good ... well, that may be going too far ... perhaps adequate is the right word ... now, come to think of it you are probably barely meeting average and I am too generous ... yea, it is true that I, in my magnificance, tend to take the marginal and promote it to my level.

Chaplain Kent · 08-15-2005, 01:16 PM

Porky- thanks for the article, I thought I understood those gauges but learned something new.

Saddletramp · 08-15-2005, 05:40 PM

Hello Iver,

As a retired engineer with 35 years experience with the design, manufacturing and service of diesel engines, I understand perfectly well what you, your engine, and transmission need for monitoring temperatures.

Those who advise you to not shut your engine down until exhaust temperature cools to 300F are entirely correct. That probably will be the only use you will find for your exhaust temp gauge, despite the admonitions of the gauge salesmen. The reason for that is if you shut the engine down when the turbo is too hot, the oil will actually burn in the bearings forming coke, which is very abrasive producing wear and at the same time reducing bearing clearances. I have seen turbos that were so coked that the shaft would hardly turn. It turns at 40,000 rpm at full load normally. If you see 1200F, that is cherry red hot, if you could see the part in the dark. If you resist the urge to add special chips to your fuel system electronics that increase torque and horsepower, and have an automatic transmission you will probably rarely, if ever see that high of exhaust temperature. Cool-down on my Ford diesel never takes longer than 5 min. of idling, it just seems longer. Idling any longer than necessary is not only wasting fuel, it shortens engine life. For some reason truck drivers have for years let their diesel engines idle for extended times. This is a very wasteful habit. Many fleets using our engines had us program our electronics to automatically shut the engine off after 5 min. of idling. This added thousands of miles to the useful life of their engines. Also be sure to adhere to the advice that you NOT goose the "gas pedal" before you shut it off. That just accelerates the turbo and then shuts off the oil supply to it.

As for your transmission temperature guage, you want to watch the the upper end of that scale. Don't ever allow your trans. temp. to exceed 200F if the sensor is installed in the oil sump. Some mechanics install the sensor in the line going to the cooler. This will raise red flags unnecessarily. It should be in the return line to the transmission, or the sump. Mine is in the pressure oil galley on the side of the trans. case, sensing oil to the clutches.

If you pull long mountain grades in hot weather you will find that an investment in a supplemental transmission cooler will be more useful to you than a boost guaqe, which in my case would just block my view of traffic when mounted on the front pillar.

I hope this information is useful to you and anyone contemplating purchase of additional instrumentation.

Saddletramp

Iver · 08-15-2005, 06:00 PM

Saddletramp, et al:
Thanks for the imput. I am sure others will benefit also.

Regards and happy streaming.
Iver

Iver · 08-19-2005, 02:43 PM

I began to pay attention to the shut down temp. and discovered that it took awhile to get it to come down. It was a warm day, for here, but nothing like one could expect elsewhere. Then it dawned on me to turn off the a/c. Guess what ... it dropped immediately well below the majic 300 degrees. A good lesson for anyone with a diesel and no gauge.

Thanks

Saddletramp · 08-29-2005, 10:33 AM

Hello Iver,

What you found is very logical. Air flow picks up heat from the condenser core then passes over the intercooler which cools the engine's intake air with air hotter than ambient. Lower ambient to the engine's intake air will make a dramatic reduction in exhaust temp.

Saddletramp

Iver · 08-29-2005, 02:00 PM

Saddletramp: With the desel engines on sailboats there apparently was a possible problem with it running away ... not being able to shut it off. The solution was to stop the air intake and starve it of air which shut it down. I take it that this is problem is not possible with these engines ???

Saddletramp · 08-30-2005, 09:17 AM

Hello Iver,

Purely mechanical fuel systems that utilized scroll fuel pumps controlled by a rack could run away if a plunger stuck in it's barrel due to contaminated fuel. In that instance the governor could not move the pumps to control speed and they would run away if stuck in the fuel-on position. The only way to stop them was to block the air supply.

In order to meet more stringent emissions regulations, diesel engine manufacturers have had to move to electronic fuel systems, which do not have those mechanical parts that could bind. One hesitates to say it is absolutely impossible for an engine to run away, but it is vastly less likely to ever happen to your engine.

Saddletramp