IP expert HELP needed - 85 300DT - PeachParts Mercedes-Benz Forum

ckamila · #1 11-26-2008, 08:18 PM

1985 300D Turbo, 80K on rebuilt engine - Idle has small shake that increases with rpm to about 1200+ then smooths out a little, but always a little off. Just sounds different than other diesels, no smoke, fuel economy poor - getting only 20 on the highway, I suspect the IP....

I can get my hands on a 81 Turbo IP that has been bench tested and was wondering if i can slip it in. The only physical differences i notice is lack of electric box on block side (behind injector #1) and the banjo bolt coming off the ALDA does not have vacuum line branching off to transmission transducer (blue flying soucer) which i can grab from my old 85 pump. Both of these items i believe are 85 additions. The part number is the same, almost, for both

1985 Bosch # RW 375/2200 MW 28-3 (with a 3 superscript) RIV possible
1981 Bosch # RW 375/2200 MW 28-1

Compression even, and in the high 300's
Injectors popped and balanced
Replaced 1 engine shock, both motor mounts
Timed the IP, twice
New tank screen, pre and spin-on filters
Cracking the injections lines one-by-one gives sames results
Diesel purged
Chain stretch @ 2 degrees via marks on cam tower and reading the balancer

Has anyone out there replaced turbo IP without pulling oil filter housing? i have IP, and if needed, oil filter housing gaskets. Any help is welcomed! Any other ideas???

Diesel911 · #2 11-26-2008, 09:06 PM

I have a feeling people are going to ask when the last Valve Adjustment was done, when was the last time the Injectors were tested an if the Cylinder Compression was checked. Possible problem areas that should be checked before you suspect the IP.
You might want to PM ForcedInduction concerning the IP interchange.

I found this on an 84 SD at Junk Yard. Apparently IP had been removed without removing the Oil Filter Housing by removing the Shuttoff Valver first (which I found on the ground next to the car). The OIl Filter HOusing was still there but the Oil Cooler hoses had been removed I guess to make room.
I have not done this or seen it done but am going by the evidence/observation of how the car appeared.
If you try this method please Post on if it works or not!

The 81 turbo IP; I thought 81 300Ds were non-turbo engines?

barry123400 · #3 11-26-2008, 10:09 PM

Just for the chance of it being low . I would also check the injection pump base fuel pressure as well. You are also quite sure air is not leaking into the fuel system as well? I agree it could be the injection pump but could as easily be something else.

This is the specific area that tests like the milli volt method applied properly really shines. You have to do it properly though with no short cuts. Also remember with very low fuel supply pressure to the injection pump the pump elements seem not to fill in an even fashion. This seems to result in poor idle and poor fuel economy...For the time and effort a simple test in my opinion.

Oh yes I am certainly not a pump expert either.l.

ckamila · #4 11-27-2008, 12:07 AM

Quote:

Originally Posted by Diesel911

I have a feeling people are going to ask when the last Valve Adjustment was done, when was the last time the Injectors were tested an if the Cylinder Compression was checked. Possible problem areas that should be checked before you suspect the IP.
You might want to PM ForcedInduction concerning the IP interchange.

I found this on an 84 SD at Junk Yard. Apparently IP had been removed without removing the Oil Filter Housing by removing the Shuttoff Valver first (which I found on the ground next to the car). The OIl Filter HOusing was still there but the Oil Cooler hoses had been removed I guess to make room.
I have not done this or seen it done but am going by the evidence/observation of how the car appeared.
If you try this method please Post on if it works or not!

The 81 turbo IP; I thought 81 300Ds were non-turbo engines?

Diesel911 - Forgot to add valves to the laundry list of items i have gone through in the last 12 months - checked and adjusted to spec, done cold.
Please see post - did compression, did pop and balance injectors too.

Going from the FSM the Bosch part # showed "starting" in 1981 as i recall
Isn't the ALDA added for the turbo models - could be wrong

further searching shows 82 - 85 models are turbo's

ckamila · #5 11-27-2008, 12:09 AM

Quote:

Originally Posted by barry123400

Just for the chance of it being low . I would also check the injection pump base fuel pressure as well. You are also quite sure air is not leaking into the fuel system as well? I agree it could be the injection pump but could as easily be something else.

This is the specific area that tests like the milli volt method applied properly really shines. You have to do it properly though with no short cuts. Also remember with very low fuel supply pressure to the injection pump the pump elements seem not to fill in an even fashion. This seems to result in poor idle and poor fuel economy...For the time and effort a simple test in my opinion.

Oh yes I am certainly not a pump expert either.l.

Hi Barry - How would one measure the supply pressure to pump - are we talking volume or psi?

Diesel911 · #6 11-27-2008, 01:46 AM

Quote:

Originally Posted by ckamila

Diesel911 - Forgot to add valves to the laundry list of items i have gone through in the last 12 months - checked and adjusted to spec, done cold.
Please see post - did compression, did pop and balance injectors too.

Going from the FSM the Bosch part # showed "starting" in 1981 as i recall
Isn't the ALDA added for the turbo models - could be wrong

further searching shows 82 - 85 models are turbo's

Sorry, I should have paid more attention when I read your thread!

barry123400 · #7 11-27-2008, 01:58 AM

Quote:

Originally Posted by ckamila

Hi Barry - How would one measure the supply pressure to pump - are we talking volume or psi?

Actual pressure under load. 0-30 pound cheap liquid filled gauge. From what I can tell so far a permanent installation might be benificial. As flow increases with load any abnormal restriction has more pressure dropped across it leaving little operating pressure for the injection pump.

It is an excellent indicator of when your fuel filter should be changed out as well. Non free flowing fuel filters affect overall fuel milage negativly on these engines. My prime concern is there may be many sub standard old lift pumps out there as well. Under ten dollars for a rebuild kit if required. .

TylerH860 · #8 11-27-2008, 02:04 AM

I wouldn't dismiss your IP before doing some other cheap fixes that could possibly solve your problem.

I'm interpreting the lesson WHunter gave at the recent tech session, so someone might correct me since I have little first hand experience.

Since Diesel is thicker than air, it is possible for air to be getting into the system without a fuel leak. That means it may be a good idea to replace your intake and return lines, the primer pump, and the secondary fuel filter bolt's rubber O-rings. Another very cheap and fairly simple fix is to rebuild the lift pump, but I'm not sure if that would cause your problem.

You might as well try every cheap hour or less job you can before pulling the whole thing.

TylerH860 · #9 11-27-2008, 02:07 AM

Quote:

Originally Posted by barry123400

My prime concern is there may be many sub standard old lift pumps out there as well. Under ten dollars for a rebuild kit if required. .

He beat me to it. Great minds...

first300D · #10 11-27-2008, 10:55 AM

Hi guys did someone write down the part number for the lift pump rebuild kit during our recent GTG ? I know I didn't but would love to have it if someone else did . This is something on my todo list.

ckamila · #11 11-27-2008, 12:08 PM

TylerH860 - Have replaced spin-on fuel filter o-ring, supply and return hoses replaced with Viton (running Bio now, shake was already there though). hose clamps tight, some PO had installed newer primer pump.

TylerH860 & barry123400 - What are my options for a lift pump rebuild kit - dealer only or parts house? What internal items would be replaced?

[Edit]
Looks like these items are in kit:
OM617.912 Lift pump Repair kit
Part# 0000900210 REPAIR KIT
Part# 0010742280 GASKET
Part# 0029976540 SEAL RING
Part# 0000910619 VALVE SPRING

barry123400 - a gauge like this
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98887

What standard type fittings will i need, NTP? Sorry, fabricating test equipment is not my bag.

PS - 2 local indy shops looked at this with 2 different solutions (guesses)
shop A - replace the pump (course they missed the roten motor mounts and bad engine shock)
Shop B - new chain & re-time the IP (engine has only 80K on rebuild)

Stevo · #12 11-27-2008, 01:29 PM

Quote:

Originally Posted by barry123400

It is an excellent indicator of when your fuel filter should be changed out as well. Non free flowing fuel filters affect overall fuel milage negativly on these engines. .

I was on a tug many years ago that had such a gauge in the wheel house, you could see when the filters were getting near to change time. "Ive never see one since on any diesel, I have always wondered why, seems like a good idea.

barry123400 · #13 11-28-2008, 12:17 AM

Lift pump kit should be available from sponsor of this site. Basically two valves and gasket or gaskets I suppose. The pump is not a diaphram pump but basically a piston type pump. Easy to kit I am told.

The harbourfreight pressure gauge is the right type. There is a 0-30 pound unit around pretty well exactly the same. Better range for fuel pressure. Drop our member Yellit a note for the exact description of the fittings he chose and what he learnt. He is friendly and knowledgeable.

I know that he initially found he basically had very low fuel pressure. He used a hose to extend the gauge into the passenger compartment.This enabled him to examine pressure under load. An important item perhaps. Right now he is basically the man in this area.

barry123400 · #14 11-28-2008, 12:38 AM

Quote:

Originally Posted by ckamila

1985 300D Turbo, 80K on rebuilt engine - Idle has small shake that increases with rpm to about 1200+ then smooths out a little, but always a little off. Just sounds different than other diesels, no smoke, fuel economy poor - getting only 20 on the highway, I suspect the IP....

I can get my hands on a 81 Turbo IP that has been bench tested and was wondering if i can slip it in. The only physical differences i notice is lack of electric box on block side (behind injector #1) and the banjo bolt coming off the ALDA does not have vacuum line branching off to transmission transducer (blue flying soucer) which i can grab from my old 85 pump. Both of these items i believe are 85 additions. The part number is the same, almost, for both

1985 Bosch # RW 375/2200 MW 28-3 (with a 3 superscript) RIV possible
1981 Bosch # RW 375/2200 MW 28-1

Compression even, and in the high 300's
Injectors popped and balanced
Replaced 1 engine shock, both motor mounts
Timed the IP, twice
New tank screen, pre and spin-on filters
Cracking the injections lines one-by-one gives sames results
Diesel purged
Chain stretch @ 2 degrees via marks on cam tower and reading the balancer

Has anyone out there replaced turbo IP without pulling oil filter housing? i have IP, and if needed, oil filter housing gaskets. Any help is welcomed! Any other ideas???

I am sitting here wondering if we should open a can of worms. We know you injectors are probably fine. Compression is pretty equal as well.

So if your interested and own a digital voltmeter and want to do and post the results of a simple test do so. Ground one lead of the meter on the head casting or valve cover. Take the second lead and go from one glow plug to the other with the engine warmed up and running at idle. Record the milli volts reading from each glow plug. It will be in the range of 6 to 20 millivolts on the plugs. Post the readings. This will indicate the cylinder or cylinders to examine more closely. Or the particular type of problem with the pump.

ckamila · #15 12-08-2008, 01:56 PM

Looked at the pressure releaf valve spring per a "lift pump" thread - found 85 IP had a 21mm spring, 81 IP had a 20mm spring. Stretched spring to 26mm per thread (without testing first =() ), now it starts a little rougher than before @ 40 degrees. Currently don't have liquid filled gauge (on order from HF) for testing IP pressure between lift pump and IP.

Need to test first before i continue to blindly tweak stuff.