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Appreciate the advice pvdiag. Do you think the battery tender/jump pack should be necessary? Am I asking for too much when I want to start unaided below 0F? I see videos on Youtube of people camping in the bush and their 7.3 starts right up at -15 or whatever temperature.
Aside from that, I hooked up Forscan to my truck and I logged some data while starting the engine. I was just guessing my rpm from the tach earlier, according to Forscan my 6.7 starter turns 200 rpm. Battery doesn’t drop below 10.5 volts. IPR goes up to 32% then settles at 8.5% for idling. ICP builds up to 2800 psi then settles around 490 psi for idling. I don’t know if any of this is helpful. Engine was at the ambient temp of around 80F.
I decided to run another buzz test and #5 was noticeably quieter. I don’t recall that from the last time I buzzed them months ago. I ran the CCT and it complained about #8 being out of balance. I also noticed that the idle was smoother during the test than after it finished. As far as I know these are the original injectors with 350k+ on them.
Okay, I’ll have to order a diesel compression tester because nobody has one within 300 miles of me. I’m a little skeptical because you would think low compression = low power? I’m having no issues with power. No noticeable blow-by so no concerns with the piston rings… although I’m aware there’s other places to be losing compression… but I feel like I would have noticed low compression while hauling my camper up mountain grades.
I’ll still check it out, this is just my thinking on it.
It doesn't take much compression loss to make it very difficult to get a diesel engine to ignite on a cold morning. They are 900 lb of cold iron. The other factor is you have some injectors that have been in there for a long time, but I wouldn't condemn them without first making sure the foundation is good.
3 and 8 typically fails in CCT,even If everything is ok.
One injector differ in Buzz test no good.
People shims out the solenoid armature plates but it is a band aid action.
If everything else is done and in proper functioning,it leans out to the injectors.
Tired injectors typically acts out when cold and can run smooth when warmed up.
You got it backwards.
Big number is the hot weight.
OP has already 5w40.
I’ve heard mixed things - local diesel mechanics have told me that synthetic oil is no good for the 7.3 but everyone else says you need the 5w40 for cold winters. I don’t know what to make of that?
It doesn't take much compression loss to make it very difficult to get a diesel engine to ignite on a cold morning. They are 900 lb of cold iron. The other factor is you have some injectors that have been in there for a long time, but I wouldn't condemn them without first making sure the foundation is good.
Alright, when the compression tester shows up I will check it out and see. Where am I likely to be losing compression if there’s no blow-by?
Originally Posted by FinnishStroker
3 and 8 typically fails in CCT,even If everything is ok.
One injector differ in Buzz test no good.
People shims out the solenoid armature plates but it is a band aid action.
If everything else is done and in proper functioning,it leans out to the injectors.
Tired injectors typically acts out when cold and can run smooth when warmed up.
I have a set of stock flow injectors from FFD ready to go in if necessary, along with Ford gaskets and glow plugs… I heard that FFD was a good bet but it seems my info was out of date and the quality has gone down over the years. I guess we’ll see.
You might wonder, why spend big money on injectors before knowing if they’re needed… well I had the chance to pick them up while traveling to the US. Shipping to Canada would have cost me ~$700 in freight, tax and duty.
Through the rings. My main experience with no-start diesels is with old VW Rabbits. The ones made 1977-1980, the blocks were made of an inferior grade of iron that was too soft and the last half inch of piston stroke at the top of the cylinder walls would wear out faster than the rest and the compression would go from around 375-400 psi down to 350 psi. At that point it wouldn't start, even at 40 degrees above zero. They would start and run all day long if you dragged them behind another car, or rolled down a long hill and bump start them, but then as soon as they sat overnight no start in the morning again. They would start if the engine would turn over faster than the starter had any hope of achieving. The only cure to get normal service back was an engine rebuild. They cured that problem in 1981 with a harder engine block. Then they would go forever, but the early ones would do good to make it to 60,000 miles. In that case, the compression was still good enough to run normally and develope the fire breathing 48 HP that they were designed to generate and they didn't feel any loss of HP once running.
That's why I'm saying you have to know the engine is good before moving on. With 300,000 on an engine block such as the 7.3, which has a reputation for going a million miles without needing any rebuilding, you stand a very good chance of having good compression and not needing to do anything to the engine. But with diesels, you need that good compression or you're just not going to be able to trust that anything else is going to fix the no-start.
Alright, the consensus here seems to be I should do a compression test, but also that injector 5 buzzing differently means it should be replaced? I may as well do everything all at once… compression test, injectors, glow plugs
Appreciate the advice pvdiag. Do you think the battery tender/jump pack should be necessary? Am I asking for too much when I want to start unaided below 0F? I see videos on Youtube of people camping in the bush and their 7.3 starts right up at -15 or whatever temperature.
I dont think you are asking too much to start unaided at or below 0F. That was my objective since I am too cheap to keep my block heater plugged in for long periods of time.
I learned a lesson on my e99: the stock alternator is horrible at recharging the batts at low rpms. If your driving profile when it is cold is not at speed for extended periods, then your batteries never get fully charged from one drive to the next. Letting it idle for awhile to let it warm up doesn't give the kick in the pants the batteries need after a couple of glow plug cycles and super cold start. Also, unless you isolate the terminals (with those knife blade switches for example), these old dogs have some measure of current draw that doesn't help matters. For me, as the cold weather dragged on, the starting got worse.
Once I added the tender (as well as upping my cable/wiring game, going with the Prestolite IdlePro (I think that is it)) I moved away from plugging the heater in around 0F for an hour or so to not bothering until it was <-20F. By my observation, a successful and relatively quick cold start results from that starter spinning at speed right away. That 1 or 2 second lag before the starter gets going as fast as it can (in the cold) is a guarantee for those longer cranks.
The same goes with the jump box, if you havent been able to get the batts on a tender. You need that "hole shot".
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