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  #16  
Old 01-31-2017, 11:42 PM
Diseasel300's Avatar
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Originally Posted by Frankenyota View Post
I know this, the reason I chose this engine was for the torque. But expected more.

HP is how fast you hit the wall, torque is how far you go through.
Think of it another way: HP is how fast you pass someone. Torque is how much pedal you have to give it to keep the speed afterwards (this is why gas engines tend to downshift and rev higher when climbing hills and increasing speed).

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.

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  #17  
Old 02-01-2017, 12:12 AM
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Originally Posted by barry12345 View Post
You do get the odd diesel for whatever reason. Seems to want a little glow plug cycle even warm to fire off. I had a 1.6 volkswagon engine once that displayed that charactaristic. Otherwise seemed fine so I never investigated it.


As for your current problems. I think you have a series of minor tests to do before deciding anything.


What struck me as perhaps not normal was your low indicated fuel milage. Now it is important to know if this car is or was on waste vegetable oil for fuel.

No the engine was not run on VWO.

If not first close off the return line at the injection pump. It will not hurt anything and you could mention what you observe. One of our esteemed members suggests that a small length of clear hose be installed there. This perhaps next if the first test shows nothing useful.

I'll put a clear line back on as the old one was brittle, and I just replaced with a new black line.

That allows you to establish if air is the problem. If the results of the first two tests do not indicate anything to some of the members. I would next run the engine on a can of vegetable oil. The thicker viscosity helps seal the injection pump elements if they are worn. This just to see if the engine will start when hot. Over time many members have developed somewhat of a systematic approach in attempting to narrow down certain issues.

So add a bottle to the fuel tank or run it through a purge system?

As a general statement but of course there are exceptions the injection pumps are usually not the suspect early in the troubleshooting game.


It also sounds like your mechanic friend may not be up to speed on these particular engines and that is not uncommon either. .

He's been fixing the hagins military viehicles which run the om617 in them for 30 years.

Run on diesel fuel these pumps usually last a very long time. Since these cars perhaps are new to you. The odometer may not be correct. Perhaps going back through the file of service invoices can verify the overall milage.

They matched when I pulled the engine.

At your milage in our climate I usually expect to still find the drivers seat still in pretty good condition with no bolster wear etc. Not so much with the true leather interiors. Common issues are the odometers fail and also are so easy to manipulate that when these cars where newer I think a lot where rolled back. Now if some simple testing indicates you need another injection pump.


Used ones acquired certain ways are a fairly safe risk and reasonable in cost. As a general rule these cars were not scrapped because of injection pump issues. You have the injection pump with the visable tang that is useful for checking the pump timing.

In the archives the location will be described. Basically you put the engine damper on the right degrees. Take a small mirror and look for the tang in the port of the injection pump. If not in the center turn the crank exactly one revolution to the same degree setting. Look for the tang in the centre of the port. If not there with either crank position your injection pump timing is off.

I'll look into this.

Driven on the highway at the speed limit I would expect 30 mpg on 3.78 liters of fuel that is an American gallon. With a five speed manual and the original rear end. The car should be peppier than the automatic version as well.

Actually your description of the problem made me have thoughts about your egr valve. Cold starts would work because there would be no burnt gasses and the engine would get oxygen. Hot engine not so much. Performance would aqlso be bad. Since the engine could not burn the fuel properly. Fuel milage would probably be low as well.

ERG was deleted.

Poor injection pump elements if the idle sounded reasonable would to me indicate. Perhaps not enough fuel injected giving low performance but I suspect you would still retain decent fuel milage. If certain simple tests indicated nothing also a semi obstructed exhaust might be present and there is a plug to remove as a test.

Added a 1.0 - 2.5 psi inline electric pump. Installed a new exhaust system.

What I am trying to do is make you keep an open mind. Simply because I do not like how your symptoms add up or do not. To me you have a way to go and it is all cheap except for a little time. Yes it still may be the injection pump but you have no solid indicator it is yet. Excuse my long post as I am not a working mechanic. There are a lot of smarter guys on this site to help you as well. If you own one of these cars you are in the right group as the support is massive.
No problem with the long post. I'm trying to keep a open mind but getting very frustrated.
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  #18  
Old 02-01-2017, 12:21 AM
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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  
Old 02-01-2017, 07:50 AM
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Quote:
Originally Posted by Diseasel300 View Post
Think of it another way: HP is how fast you pass someone. Torque is how much pedal you have to give it to keep the speed afterwards (this is why gas engines tend to downshift and rev higher when climbing hills and increasing speed).

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.
You're off a bit in your definitions:

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
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  #20  
Old 02-01-2017, 11:31 AM
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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.
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  #21  
Old 02-01-2017, 12:03 PM
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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.
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  #22  
Old 02-01-2017, 02:03 PM
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Originally Posted by Frankenyota View Post
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.
I have a hard time believing that the 617 in a 4-runner would get mid 20s, much less 30s. They struggle to hit 30mpg in the original cars they were installed in, they weigh a lot less and are a lot more aerodynamic than a 4-runner.

Perhaps if you're using Imperial or British gallons to do your MPG conversion, but not US MPG.
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  #23  
Old 02-01-2017, 02:24 PM
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Originally Posted by Frankenyota View Post
I know I'm new to this site, and I have done multiple searches but I can not find the info I need. So my questions are:

#1. What's the difference between a 6170704101 IP and a 6170705001 IP?

#2. I'm having a problem starting after the OM 617 engine is hot. Yes it cranks over just won't ignite. The Valves are adjusted properly, the compression is good at a average of 350 with no cylinder more than 10% difference. All injectors test fine at a average of 135.6 bar and spray properly. Glow plugs glow at tip and have a resistance of 0.00 to 0.01 ohm, same with electrical leads. Relay fuse 0.01ohm at 12.9 Volts. Not as much power as I was expecting from this legendary motor plus fuel range is 14 Litres per 100km. I've been given 3 possible trouble area's. Lift pump, fuel check valve or a RSD valve, or the big one, a shot injector pump. Engine was maintained by PO, I have a 3" binder full of passed services. Motor has 425,000km on it. Any extra help would be great, as I've been pulling my hair out trying to nail this down with out throwing money at it.
Can you clarify "won't start after OM617 engine is hot" ? How long does the engine have to be driven for this to happen? Have you eliminated air in fuel as the culprit?
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  #24  
Old 02-02-2017, 09:43 AM
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Originally Posted by funola View Post
Can you clarify "won't start after OM617 engine is hot" ? How long does the engine have to be driven for this to happen? Have you eliminated air in fuel as the culprit?


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.
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  #25  
Old 02-02-2017, 02:41 PM
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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.
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  #26  
Old 02-02-2017, 11:07 PM
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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.
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  #27  
Old 02-02-2017, 11:19 PM
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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?
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  #28  
Old 02-02-2017, 11:23 PM
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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?

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  #29  
Old 02-03-2017, 11:13 AM
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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.
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  #30  
Old 02-03-2017, 11:21 AM
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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.

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