Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #31  
Old 04-17-2010, 06:06 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
Quote:
Originally Posted by KnightOwl View Post

(PS, this is my dads rig and i am trying to help him as he obviously to old and cannot use a computer)
That's funny. Half of us here have a foot in the grave yet we aren't too old!

Try pulling back on the manual shut off lever to see if it makes a different. The brown line should not have been clamped on the shut off valve. If it was, it's not OE. Do you have fuel coming out of the return hose heading back to the tank?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #32  
Old 04-17-2010, 06:14 PM
Registered User
 
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
What I would do is establish the presence or lack of presence of adaquate fuel supply and pressure reaching the injector pump. This is done by taking a short length of clear plastic tubing from the return valve on the injection pump to a container with some fluid in it to submerge the open end. Fuel should be coming out the return valve without a lot of air bubbles when cranking the engine.

If so and the level is rising in the container then you have enough volume and pressure to service the needs of the injection pump. I do not think there is any easier test that can be so conclusive. In my opinion you have to establish this is happening first before looking elsewhere.

You either have a flow of fuel without a lot of air coming through or you do not. Some form of systematic troubleshooting is always better than the alternatives. Kind of one step at a time.
Reply With Quote
  #33  
Old 04-17-2010, 06:51 PM
junqueyardjim's Avatar
Registered User
 
Join Date: Apr 2005
Location: Cicero, Hamilton County, Indiana about 30 miles north of downtown Indianapolis
Posts: 2,623
Geepers, this thread is over a month old

Only three things can stop a running diesel. Engine failure such as in a lack of engine oil, or starvation of air or starvation of fuel. The first two are unlikely in this case. That leaves us with starvation of fuel. Is there enough fuel in the tank? Take off the hose at the "see through" filter and see if fuel is coming out. That way you can check the problem either way, back to the tank if no fuel is coming or forward to the IP if fuel flows. Pretty simple in my way of looking at it. Poorly adjusted valves or low compression will not stop a running diesel. Though it may cause it to be a hard one to start.
__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!
Reply With Quote
  #34  
Old 04-17-2010, 07:20 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,281
A couple of you people are long on declarative statements and short on conceptual physics... particularly diesel engine theory.

Once you have a valve system which has worn to the point that, upon heating , the valves do not seat.. then you do not even have a diesel because you do not have the 20+ to one compression ratio you need for igniting whatever fuel is introduced into the bore.
Reply With Quote
  #35  
Old 04-17-2010, 07:28 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
One question on applied physics: Has there ever been a case on this board of a diesel which was driving down the road, coming to a stop due to inadequate compression as the result of maladjusted valve?
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #36  
Old 04-17-2010, 08:47 PM
layback40's Avatar
Not Banned
 
Join Date: Nov 2009
Location: Victoria Australia - down under!!
Posts: 4,023
It looks like the frustrations are boiling over a little !! Time for every one to take a deep breath.

Maybe sit your dad in front of your computer & you do the key pushing & let him do the reading. Let him read this if it helps. I am sure he is an absolute gentleman!!

I said before that if you have a stuck shut off, sometimes by placing some tube on it & blowing, sucking, blowing into the tube you can unstick it, it has worked for me in the past. Only use breath pressure, not compressed air.

Because the motor is cold, the issue of valve clearances and compression become important. With a cold motor everything must be right to get it to start. Thats why we have people with several different ideas. I was waiting for some one to ask about Glow Plugs.

You need to prove you have fuel flowing in the return line. Maybe first with the primer pump (if this is a 617). Then when cranking.
Please let us know if this is happening. Then we can move on to the next thing.
__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
Reply With Quote
  #37  
Old 04-17-2010, 09:34 PM
Registered User
 
Join Date: Nov 2004
Location: Nova Scotia, Canada.
Posts: 6,510
Quote:
Originally Posted by junqueyardjim View Post
Only three things can stop a running diesel. Engine failure such as in a lack of engine oil, or starvation of air or starvation of fuel. The first two are unlikely in this case. That leaves us with starvation of fuel. Is there enough fuel in the tank? Take off the hose at the "see through" filter and see if fuel is coming out. That way you can check the problem either way, back to the tank if no fuel is coming or forward to the IP if fuel flows. Pretty simple in my way of looking at it. Poorly adjusted valves or low compression will not stop a running diesel. Though it may cause it to be a hard one to start.
Bad fuel enters the realm of starvation of fuel. You can get a batch of it at anyplace anytime. Very infrequently at large truck stops in my experience. I never have.

I make a real effort not to ever fuel at low volume retailers of diesel fuel unless in a bind. Although with all the half ton diesel trucks sold over the last ten years or so things are much better.
Reply With Quote
  #38  
Old 04-18-2010, 02:11 PM
Registered User
 
Join Date: Mar 2010
Posts: 30
Quote:
Originally Posted by kerry View Post
That's funny. Half of us here have a foot in the grave yet we aren't too old!

Try pulling back on the manual shut off lever to see if it makes a different. The brown line should not have been clamped on the shut off valve. If it was, it's not OE. Do you have fuel coming out of the return hose heading back to the tank?

First off, thanks a lot for dedicating your time into this thread fella's, we really appreciate it. Wish you many good luck and blessings for your kind help and efforts.

On a second note, the return line that starts from the spin off fuel filter and goes back to the tank, when i pull that off and crank it we do get fuel passing through. Not a lot at a time but it is pretty consistent and can fill a standard cup in about 2-3 minutes of cranking if done so (my guess).

As for the kill switch that is mounted on the valve cover. The funny thing is about 6 months ago it wouldn't work and at times it did... So about 6 months ago we did some test on it. It seemed it would always work on low rpms pretty much every time. Then when we where at HIGH pretty much MAX rpm's the kill switch would NEVER work. But we just left it at that. Just remembered that. Could that have anything to do with it? So your suggestion is to play with the kill switch back and forth while cranking the engine and see if the injector finally squirts?
Reply With Quote
  #39  
Old 04-18-2010, 02:15 PM
Registered User
 
Join Date: Mar 2010
Posts: 30
PS, i am also confused about the clear plastic blow testing trick. Does anyone have pictures?
Reply With Quote
  #40  
Old 04-18-2010, 02:43 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
Quote:
Originally Posted by KnightOwl View Post
On a second note, the return line that starts from the spin off fuel filter and goes back to the tank, when i pull that off and crank it we do get fuel passing through. Not a lot at a time but it is pretty consistent and can fill a standard cup in about 2-3 minutes of cranking if done so (my guess).
Not sure how much you should get while cranking but the fact that you are getting any at all is an indication the IP is getting some fuel. You should also get some fuel out of it when pumping the primer pump if all the air is expelled from the system. I'd give that a try.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #41  
Old 04-18-2010, 03:35 PM
Moderator
 
Join Date: Jul 2001
Location: Woolwich, Maine
Posts: 3,598
Personally, I have never experienced a running Diesel that stopped, but my father in law did. He had the vent line to the fuel tank plug up and the car ran until the lift pump at the injection pump could not get enough fuel from the tank to keep the engine running. I take it you have already removed the fuel filling cap and therefore you likely don't have that problem. When it happens the cap is difficult to remove.

While I get the theory of valve clearance leading to poor compression, I would expect that problem to manifest more as an "analog" failure, meaning there would be a steady decrease in performance before it quit, vs. a "digital" or "binary" failure where it runs on one compression stroke and then fails the next. A chain slip or break fits the failure mode better than a slow degradation of a vital clearance, from what has been described so far.

So, I think you still have a fueling problem, and would start there. Mechanical problems are still possible, but I would work the fuel delivery system first and not assume the injection pump is the problem, yet. And, from your pretty loose descriptions of what the various parts are and what they are connected to, I think it is likely you are doing things and then are unable to communicate what you did because you mix up the terminology. I hate to be a prick about that but we can not help you if you tell us the injection lines are connected to the glow plugs.

I am on business travel and don't have access to a manual so I am hesitant to dig into this too hard. But let's try to get the terminology down, and the fuel flow path, first.

The fuel is delivered to the in-line filter connected to the body of the fuel injection pump. The in-line filter is sometimes clear and sometimes white, and usually has a 90 degree bend in the flow path in and out. The rubber hose connected to this is connected to a hard line on the driver's side inner fender. To this point the fuel is gravity fed. So, if you disconnect the in-line filter and fuel doesn't flow like a cow peeing on a flat rock, your problem is upstream.

If you have a strong, steady flow, the problem is downstream. The next step in the process is to a low pressure pump that runs fuel to the main filter and then to the high pressure part of the injection pump. When the shut-off valve shuts the system down when you turn the key to "off" on the dash, a vacuum actuator applies atmospheric pressure to the top side of this device, which has a diaphragm in it. This causes a mechanical valve to close the feed to the high pressure fuel circuit, I believe (and someone with a manual at hand can verify this, or refute it). Thus, running the hand pump or cranking the engine to turn over the low pressure side pump, will make the system act like it has fuel even though the high pressure side is shut down. Which means making observations of the low pressure side can only be applied to the conclusions you draw about the condition of the low pressure side, and does not prove the high pressure side is getting fuel.

So, I would have a qualified person actually check the shut-off mechanism that is attached directly to the aft end of the fuel injection pump, not the valve cover. It is a plastic doohicky with a hard plastic vacuum line running to it and the vacuum connection is made with a rubber sleeve. No hose clamps - it is about 1/8" in diameter. It sounds like someone may have dorked around with this item, but that is hard to tell because it is not clear what you are writing about is the same device. There are plastic things with vacuum lines going to them on the valve cover - they are part of the engine management system for emissions and the cruise control on some models. They are NOT the fuel shut off.

There is a cadmium or zinc plated lever with a red decal that reads "STOP ENGINE" or the like on the side of the injection pump as well, and this is a manual override to shut fuel off. It feels like it operates by squeezing a viton or similar rubber compound hose until the flow of fuel stops. I don't know how it works though and suspect it just overrides the diaphragm mechanism in the shut-off valve. But, that device is also not mounted somewhere else in the engine bay. And it requires an inordinate amount of pressure from your finger to work.

So, if the shut-off valve is in the shut-off position for some reason, either the vacuum lines or control valve for position (on the back side of the keyed mechanism in the dash for starting) are munged up, or the valve itself has had a mechanical failure, you need to work on trouble shooting that device. I would suspect one of the plastic parts of spontaneous and peculiar failure than a metal part. But that is just me. Anyway, if you pull the vacuum line off the shut-off valve you isolate that problem to the shut-off valve if fuel continues not to flow, or to the control mechanism in the dash if the problem is resolved. In the first case, the problem continues you will want to remove the shut-off valve. Which is not difficult, but you need to have an experience person reinstall it, or put a new one in as failing to have it connected properly can be unsafe - engine runaway and things like that. There are some threads in the archives about how to do this correctly.

By the way, the fuel injection pump has 5 little valved connections to hard, high pressure fuel lines on the top (4 on a 240D). These lines go to the fuel injectors, not the glow plugs. The fuel injectors are little pressure relief valves that squirt fuel into the combustion chamber, toward the hot end of the glow plugs.

The injection pump sends out a metered amount of fuel, depending on throttle position and ALDA input, to each injector. If you get 30 mpg, and the machine is running at 3,000 rpm at 60 mph, in one minute the car travels one mile, so it uses 1/30th of a gallon. The injectors have fired roughly 1500 times each in that minute, so each injector spits 1/5th of 1/30th of a gallon divided by 1500. So, don't expect a lot of flow from the injector lines when you loosen them - you should see a dribble. Depending on how much runs out when you undo them, you will have to refill the line by cranking the engine in order to have the stuff dribble out again. Most of us just "crack" the mechanical connection (nut) at the injector and look for a persistent wetness that appears when you crank the engine. The fuel pressure with loosened connection will not reach the level needed to pop the injector, and the fuel will leak past the threads of the loose connection.

If it turns out you are getting fuel, the problem lies elsewhere. It is possible you had a mechanical failure associated with the valve timing, which also affects the injection timing. Any serious mechanical failure that would suddenly affect compression would also be accompanied by a faster cranking speed in your diagnostic efforts using the engine starter - if the cranking speed is still kind of lumpy and sounds like it always did you might be ok, mechanically. A compression test will tell.

I would take the valve cover off to see if the valve train is ok. Check the chain. Look for tensioner parts, like the rail that applies load to the chain to keep it tight. An old chain and lots of miles on the oil, you may have either stretched the chain to the point where it slipped a tooth or so, resulting in bent valves and no compression or the tensioning rail might have failed - same result. Taking the valve cover off will tell if there is a mechanical reason for your dilemma.

Good luck and I hope this helps.

Jim
__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)
Reply With Quote
  #42  
Old 04-18-2010, 09:06 PM
layback40's Avatar
Not Banned
 
Join Date: Nov 2009
Location: Victoria Australia - down under!!
Posts: 4,023
Jim's post is excellent!! You should read it at least 5 times before you proceed. best get your dads mechanic to read it as well !!

As you have fuel flow in the return line, the next thing is the shut off. Its the diaphragm looking thing at the back of the IP. Some times they stick. As I suggested in post 36, you need to try blowing & sucking on a vac hose that is connected to it only. This may unstick it.
If you dont understand where the shut off is, please ask. There is another thread on here at the moment with some one being told to do a similar thing. Their motor will not shut down. Have a look at the pic in that thread to show you the shut off diaphragm location.
__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving
Reply With Quote
  #43  
Old 04-18-2010, 09:28 PM
Moderator
 
Join Date: Jul 2001
Location: Woolwich, Maine
Posts: 3,598
Actually I got the vacuum logic wrong. The normal operating condition is to have atmospheric pressure provided to the shut-off valve, and shut down mode requires vacuum to be applied to the shut off valve.

Jim
__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)
Reply With Quote
  #44  
Old 05-04-2010, 11:23 AM
Registered User
 
Join Date: May 2009
Location: Fremont, NE
Posts: 59
I was always under the impression, running several diesels and doing my own maintenance on my semi engines that when valves wear, they wear tight, as the springs pull upwards on the valves, not loose as to lose compression. Every time I have adjusted the valves on my 300 or my semi, I had to increase the gap between the valve and the cam. You can get to the point that they won't open up enough, and cause loss of power, but I don't think this is the case here of not allowing it to restart.
Reply With Quote
  #45  
Old 06-07-2010, 01:05 PM
Registered User
 
Join Date: Mar 2010
Posts: 30
The thing is, i tried to blow in and out from the rear safety switch (brown tube) behind injector pump. Right now we have the metal fuel lines disconnected from injectors.

The weird thing is, when we crank the engine it squires only from injector #3. The rest of the 4 injectors just sit there (one full of fuel others completely dry). So we know the chain is good and the actual shaft inside the injection pump is moving.

Can anyone describe what is happening? Why only one injector squirts and other sit dry? Thanks

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 02:40 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page