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#16
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Torque is a measure of how much work the engine will do at a given RPM. It's why diesel pickups can tow HUGE loads and get good fuel economy on the highway but can't pass a Yugo without some serious tuning. Power to weight ratio and gearing also come into play for the final driving experience. Suffice to say, in the grand scheme of things, diesel powered cars are slow. Especially the old IDI style diesels. You can cruise all day on the highway and sip the gas doing it, but you're not winning any races. |
#17
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#18
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I should mention this engine is not in a Mercedes car anymore, it's been swapped into a Toyota 4Runner. But I know others that have done this and still have retained close to the mid 20 mpg.
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#19
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Torque is a measure of twisting effort. Horsepower is twisting effort over time and is, by definition, a measure of WORK. Horsepower is a calculated variable (there is no such thing as a horsepower meter - if you see a meter reading HP on a dyno it's running thru a calculation and posting the result) and keeping the equation in mind helps make it clearer - HP= torque x RPM/5252 (a constant that corrects for the math). The RPM adds the time variable and so turns HP into the idea of twisting effort over time. To use an electrical analogy, volts = torque and KW hours (calculated from volts, amps, and time) = HP. Dan |
#20
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Wvo run in a container same as a purge. Where did you install this very low pressure electric fuel pump and why? Just a booster pump at the rear of the vehicle? I know your lift pump is still in the system.
I agree with 30 years in on the 617s the mechanic should be fine. How did you configure the injection pump shutoff? There have been cases where it remained lets say half on. The engine would run but not produce much power etc. At least for the moment the poor fuel milage is no longer a major focus. Finding out why the engine does not hot start is more important. After a vegetable oil test and remember you have to get enough of the vegatable oil into the secondary fuel filter to displace the diesel fuel. Personally I would dump the contents of that filter and fill it with the vegetable oil. If that does not provide some indication then you are almost forced to get a gauge on the fuel pressure in the base of that injection pump. Or this may become a very long drawn out drama. Basically establishing some form of baseline on what is working and what is not has to be engaged. Just not by the financial painful process of guessing. Years ago when presented with situations that I was not sure what exactly was going on. I would do a tune up. In some cases this lead me to the problem. Or along the way I found out what was really working and what remained questionable. When you get frustrated as I imagine like myself it has occurred with many others. Your brain seems to cease logical functioning normally. Best to leave a problem for a time or change the approach to it. Getting emotionally upset about it is also very non productive. I have had countless times where I worked on a problem for hours and got nowhere. Left it for a day and solved it in five minutes. Plus you have to look at the very bright side. You do not have some elusive intermittent problem you are chasing. It is remaining constant. Last edited by barry12345; 02-01-2017 at 11:53 AM. |
#21
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I forgot to ask. Was this problem with the engine present in the donar car? Or just surfaced after the engine was moved? Or do you not know?
If it was not present in the donar car the injection pump is certainly not the issue. Providing you have not moved the timing. Installed a new timing chain etc. Plus the problem was present from the first time you reused the engine. Just thought it may not have occurred to you. Also if there is too much blow by contained or produced by a hot engine there is a chance the pressure will keep the injection pump shut down. Easy check by just leaving the oil filler cap off in an attempted hot restart. Highly unlikely but no stone should remain unturned. This one is quite a reach though. |
#22
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Perhaps if you're using Imperial or British gallons to do your MPG conversion, but not US MPG. |
#23
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__________________
85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked |
#24
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Funola is pretty good on these fuel systems. All I know for sure and that is very little. My chasing fuel system issues is far cheaper than chasing women. |
#25
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I agree that it is hard to see how a bad IP would start cold but not run correctly when hot. For "runs bad hot", I would suspect rubber parts and I don't think there are any in the IP itself.
Since this engine was retrofit into a Toyota, insure there isn't something installed wrong. Recently, someone posted a similar problem (you?) where they plumbed the valve cover vent tube (they termed "PCV") to the air filter oil drain. That caused pressure to build up in the crankcase, which pushed the IP fuel shut-off valve outward thus choking off fuel flow (how a diesel is stopped). Otherwise, suspect the suction side of the lift pump, like a collapsing rubber hose (starves fuel) or cracked hose (sucks in air). Also insure you get free fuel flow from the tank, since your is very different. Perhaps you have a sealed tank that is building a vacuum thus starving fuel flow. Post 19 is spot on. Given a torque curve vs rpm, one can calculate a HP curve. Max HP usually occurs at high rpm, say 5000 rpm. Most people don't drive around like that w/ the engine screaming, especially 4 Runners, so unless you are kid with a "tuned" Honda, you probably care more about max torque and diesels are best at giving high torque at low rpm. Worst is a 2 cycle engine, since they require rpm to breathe correctly. Those who recall the 1970's, remember motorcyclists rev'ing their 2 cycle "ring dinger" engines constantly at red lights so the engine didn't die.
__________________
1984 & 1985 CA 300D's 1964 & 65 Mopar's - Valiant, Dart, Newport 1996 & 2002 Chrysler minivans |
#26
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I'll make this short, no it wasn't me that posted about (pcv)
A 10 min drive and up to temp, stop to fuel up and the motor will turn over but will not fire. I changed most of the fuel lines that were dry and cracked or swollen. Valve adjusted, compression test was done before buying but trani was blown. Installing two new crush washers on the check valve on return helped power. Since MBZ where gravity fed and I'm syphoning from the Toyota tank a low psi pump is there to help the transfer pump out. |
#27
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10 minute drive is not long enough to heat up the injection pump to cause restart problem from a worn pump. After refueling and it won't start, what do you have to do to get it started or do you have to get a tow truck?
__________________
85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked |
#28
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Well I've also driven it for a hour and same thing. If I leave it for a hour it will start. I've been told there is a cold start and a hot starting mode. How would this work?
Sent from my SM-G530W using Tapatalk |
#29
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On the mechanically injected diesels, there's no difference in starting mode. There are no sensors and nothing to tell the injection pump whether the engine is hot or cold.
If you drive for an hour and the engine refuses to restart unless sat for an hour, check for pressure in the tank. If no pressure in the tank, check for air in the fuel system. Also worth checking the valve clearances. If too tight, you may not be able to build enough compression to restart when the engine is hot. With a hot engine with good compression, it should restart easily even without glowplugs if it is receiving and pumping fuel. Air in the system, or pressure/vacuum in the tank can cause starting issues. |
#30
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I have read of very worn IP's that would not restart when the IP is fully hot, pouring water all over the IP to cool it off and will get it to restart, confirms that it is indeed a worn IP. Another confirmation of a worn IP is run a thicker fuel such as veg. If it restarts with a hot IP on veg and not on diesel, it also confirms a worn IP.
__________________
85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked |
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