1985 300D loss of power after 20-25 mins

My wife has been driving our 85 the 35 mile trip to work everyday and has had the same problem twice now in the last couple days. After about 25 mins of driving at 70 mph, the car would lose power like a clogged fuel filter. I drove it today and it started to do the same thing after about 30 mins of driving when I floored it up a steep hill near our house at about 55mph. The fuel filters are both fresh with a new priming pump and the air filter is clean. The loss of power is temporary. The car feels fine again after slowing down or stopping. I have not bench tested these injectors yet but the car has wonderful, smooth power until the above problem occurs and consistently gets greater than 25mpg. It runs at 80-90* C consistently as well. We are running it on veggie oil. I also have not checked the fuel tank strainer. Please help! I already ordered Monark nozzles for it and will install those and clean the fuel tank strainer next weekend. Any ideas??!! Brandon Pensacola, FL 1979 300D "Red" 1985 300D Turbo "Blue"

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Body and Interior Specific Aid

Chassis Model Number

W123

Cover all the basics first

The majority (80 percent) of these type of power problems are due to restricted fuel flow or air in the fuel system. I would go after the tank screen first. Be sure and check the tightness of ALL your fuel hoses and clamps.

The other 20 percent turn out to be a mechanical problem. Worn lift pump, injectors, timing chain, injection pump, turbo, etc.

Report back on what you find. Kent

basics

Good morning Kent,
I spent the weekend under both cars troubleshooting and working. On the 85' (the one that has the loss of power), I pulled the fuel strainer to find it was about 98% clear. I replaced all the fuel lines as well and found that my braided line was rotting a little but not bad enough to let air in I think. I have not had the chance to run the car yet since I'm waiting on an intake but should get the parts today.
Considering the good condition my strainer and lines were in and new fuel filters and a relatively new bosch priming pump, do you think it could be something else? One of my diesel mechanic friends suggested it could be the wastegate on the turbo sticking open after the motor heats up all the way and at high rpm's. Possible? Probable in your opinion??
Thanks much,
Brandon Oswald
Pensacola, FL

1979 300D "Red"
1985 300D Turbo "Blue"

97 300d with the same problem

Brandon,
Mine is a non-turbo 97 300d with about 2500 miles running on a two tank veggie system. I am having the same problem and getting it checked out today or tomorrow. My problem occurs after about 20 minutes as well. I notice minor sputtering at a constant rpm and especially on hills where it revs higher than normal and has a problem shifting to accomodate the hill. When I switch to diesel everthing works normal and when I switch back to veggie everything works normal for about 10 minutes. After noticing the problem, on idle I can feel it running rough every so often. I just changed my veg filter and all other filters have a recent change. I am not doing the mechanical work myself so I will be interesed to hear what you find out.

Thanks,

Dave

power loss

Brandon.my 82 300cdt did the same thing.After changing all fuel lines under the car,removing the lovecraft conversion kit and putting it back to the stock spin on filter, replacing the turbo,adding a rebuilt injector pump with new injectors and doing a valve job and timing chain to the tune of about $4500 it turned out to not even be an engine problem.It was the transmission all along.good luck.

Joe.

just a follow up on my 97.

just a follow up on my 97. it looks like a very tiny amount of air is getting into the veggie line. I guess it takes a while to develop, hence the 20 minutes for the sputtering.

Dave

transmission problem

Joe,
Thanks for your reply and that really sucks what you had to go through to find the real problem. What was the issue with the transmission? When mine starts to lose power, it refuses to shift and then when it finally does shift it is really hard.
Thanks for any input you have.
Brandon
1979 300D "Red"
1985 300D Turbo "Blue"

Sputtering, etc.

Dave.

I'm driving a '98 MBZ turbo and I have the same problem of sputtering and loss of power when climbing hills. I have then removed the filter and opened the 'water outlet valve' on the 5 micron filters I am using. Out comes little specks of carbon looking stuff. I figure the WVO is not getting filtered down to 5 microns correctly and the minor sediment floating in the oil concentrates on the filter element. After a while (too much sediment accumulated) I notice the engine 'starves' for fuel. Anyway, that may be the problem, your not cleaning your WVO down to the proper micron cleanliness.

Romeo

1985 300D Please Help!

After replacing both fuel filters again, pulling the fuel strainer (which was 98% clear), checking vacuum readings, replacing the stock airbox with a high quality aftermarket kit, cleaning banjo fitting for ALDA, adjusting ALDA in small increments, and trying different transmission throttle position cable settings, our 1985 300D is STILL doing the same sputtering and eventual dying after it gets to about 70-80*C.

I also drove it with a guage attached to the boost line that goes to the ALDA. I got 9.5 lbs of boost at full throttle and consistent readings until the engine warmed up but when it started to sputter, the boost pressure dropped correspondingly. I'm not sure, but it looked like it was dropping as the engine spooled down which would indicate to me that the turbo and the wastegate are working fine and are not the culprit.

My wife and I normally run both our 300D's on veggie oil that we thin with 10% Jet A and 5% unleaded fuel, cetane boost, and injector cleaner. We filter it down to 5 microns and run it through a water block before putting it in the tank. I do not believe this is the problem because I filled it up with regular pump diesel on Friday and it is still consistently doing the same thing.

CAN ANYONE HELP?? I'm tearing my &*$^@#* hair out because of how well it runs until it heats up. I don't get it!!!

Should I maybe splice in a fuel pressure guage and monitor that?? Wouldn't air getting in my fuel lines affect perfmormance regardless of temperature?

I feel like I'm missing something obvious but everytime I stand there looking at the engine everything looks and checks fine.

Thanks very much for anything you can contribute,
Brandon and Megan Oswald
Pensacola, FL

1979 300D "Red"
1985 300D Turbo "Blue"

Transmission

I forgot to mention also that when we came to a stop today after test driving, the car was in neutal but the driveshaft was making a banging noise. I got under the car and sure enough the driveshaft looked like it was trying to engage the rear end but was just rotating 1/8 of a turn and contacting it. I had my wife put it in park and it continued to do it there as well. It also got slightly louder as she stepped on the gas. It was idling roughly and I noticed it does this sometimes when the sputtering occurs and I bring it to a full stop.
Think this has anything to do with the sputtering and dying problem?? I does shift somewhat firmly but doesn't seem too bad. Also, when it starts to sputter it won't shift up or down at all.

Thanks again,
Brandon Oswald
1979 300D "Red"
1985 300D Turbo "Blue"

Power Loss

If your intake pressure readings were low after the engine warmed up at 55 mph, then you could have a turbo or waste gate problem or maybe clamps or hoses on the pressure side of the turbo that let air leak out. From what I understand, ou have to have that pressure to activate the ADLA sensor to send more fuel to the injectors. How many miles on the car? Sounds like you have checked the fuel system for restrictions and possible air introduction, but the description sounds like air getting into the fuel when the temp changes. Those air leaks are hard to find because there is vacuum on the hoses and no pressure to force the fuel out. Do you have a boost pump back at the tank?
I am curious now!
Al

Check for exhaust restriction

You did not mention if your 85 has a trap oxidizer. If so I would consider the possibility that it is causing a restriction after heating up. If no trap still consider the possibility your exhaust system.

small air bubbles in fuel supply

--------------------------------------------------------------------------------

Thanks for all the replies and I'm truly sorry for anyone experiencing something like this. I feel like we've replaced all the parts on the car except the one that is causing the fuel starvation symptoms.
I put some pump diesel in our 1985 300D yesterday and it ran ok the rest of the 20 miles home after dying on the way into the gas station from the same sputtering as I've previously described.
We looked back last night and realized that we had not tried running the car with the gas tank full since these issues have surfaced. We're trying that today.
In addition, I started the car last night in the dark and held a flashlight to the clear inline filter before the injection pump while I revved the engine. To my surprise (and hopefully a specific diagnosis) there are obvious bubbles that go through the filter when I rev the engine fairly high. They are probably only about 2-3mm in diameter but I'm sure at sustained high speeds or hills these could build up and cause my injectors to vapor lock. Is that a fair analysis?? Like the previous post, my hair is about to be gone as well except I don't have a beard to turn gray.
Thanks to anyone who donates their knowledge.
Brandon Oswald
Pensaocola, FL
1979 300D "Red"
1985 300D Turbo "Blue"

power loss

I converted my 82 300sd in May and have been thrilled. I recently read about the power loss some people were experiancing and have just now began experiancing the same problem. I changed the rear fuel filter to no avail. I am in the process of looking for air leaks and will let you know. Thanks for the information. Lets stay in touch.

Before I converted,I added a

Before I converted,I added a electric boost pump at the rear.I can bleed air in seconds.It will pump wvo and wmo.

fixed?

brandon,

i was wondering if you fixed this problem? I have the same problem on a 1990 300d and was thinking it could be a tired fuel pump. Let me know.

Mac

Not yet

Haven't fixed it yet. This problem is truly mysterious and frustrating. I have now replaced every fuel line, checked for ANY restrictions, changed the fuel filters, swapped the fuel lines from supply and return a couple times, new primer pump, different fuel, cleaned fuel strainer, driven at all kinds of speeds and loads all to no avail.
When I rev the engine really high from under the hood I can see a froth of tiny air bubbles develop in the primary fuel filter going into the lift pump. I don't think it should be doing this. I have checked and rechcecked EVERY fuel hose and fitting and can find no leaks or even questionable areas. My wife and I are going to take the car to a guy that is an injection pump specialist next week.
I really don't think it's the turbo either.
I just feel stupid with this since usually I'm ok at dealing with mechanical issues. (not so much with electrical)
Thanks,
Brandon and Megan

1979 300D "Red"
1985 300D Turbo "Blue"

bubbles

how about the manual pump.

Air in fuel line

I am writing concerning my 82 300sd. I have double checked all fuel line attachments and filters and am still getting air in the fuel. It can be seen in the filter between the preheater and lift pump coming from the direction of fuel supply. When I switch to return fuel they diminish but then switch back to loop fuel a large amount of air can be seen and then drops back to small bubbles coming through. I need to know of any possible sources and how best to diagnose the source. Any help would be most appreciated. Thanks

Same old song and dance

I just found this thread and have the same problem on my 1984 300TD with WVO conversion. I've tried everything I can think of doing but cannot nail down the problem. The car dies under load when I first warm it up in the morning but then seems to repair itself after it sits. I think it's the WVO producing a lot of vacuum. Recently when it happened, I opened the drain on my water separating filter and it hissed like it was releasing pressure. I have a looped fuel return on the conversion but I think I'm going to change the manual valve to allow the WVO to return to the tank. Will it help? Beats me, but I ready to sell the car!

air in fuel line

For those of you having problems with air getting into your WVO systems: which fuel line clamps did you use? I am running on WVO on an 83' for a year now with zero problems of air in fuel lines. What I did was go to a decent store like NAPA and ask for a bundle of clamps from their bulk supply instead of using those from the shelf packages. These fuel line clamps are wider, and are able to get tight without potentially cutting the hose.

I helped a friend install a WVO kit from one of the popular websites and the fuel line clamps they sent with the kit were the cheap kind that you had to be careful to not overtighten.

If you are getting air in the line and have 'thin' clamps, go out and buy a better set for a few bucks and it should take care of the air problem.

For those of you having transmission strangeness, where is shifts find, and then later hard. It sounds like a vacumn problem. I wonder if you have a bad EGR valve. The EGR valve gets a vacumn once the engine gets hot, could it be leaking a vacumn when it gets open and that impacts the vacumn going to the transmission...thus it shifts hard and the EGR is causing the engine to also sputter? Don't know, just guessing. How about if you disconnect the EGR valve (blocking the vacumn line to still hold a vacumn and see if the 20/30 minute problem does not occur?

Good Luck, Steve H.

WVO woes after driving for 20 min

A second question on your WVO tanks...and the shortage of fuel. How sealed is your tanks? Does all your tanks have a way to let air in while you are driving? if they don't then you will generate a vacumn and eventually the engine cannot pump oil. If you are not sure, try leaving your cap 'loose' and give it a trial drive and see if the problem that happens after 20 minutes goes away.

Be sure and put something around hte openening in case any oil sloshes out while test driving.

Steve H.

Hey Steve, I tried leaving

Hey Steve,

I tried leaving the fuel cap off but it didn't seem to make any difference with the hesitation problem.

Last night I mixed two gallons of diesel with about half a tank of WVO and this morning the car ran fine. I guess it thinned the fuel down enough to flow.

Thanks for all the ideas.

Matt

1985 300D loss of power after 20-25 mins

Hi All:
I've read this tread wuth great interest as I've been dealing with the same symtoms for a while now. I'm also running an SVO mix to complicate the diagnosis. It was driving me crazy cause sometimes it would run fine & others not! I went through all kinds of hair pulling & had pretty much come to the conclusion that I was getting air in the fuel systom someplace but couldn't figure out where. Anyway, I think I fixed it!!! Previously, I changed the Primer Pump 3 times with used ones that I had that seemed ok. They weren't! Out of desperation I ordered Ken's new (Very Solid & Well Built)Primer Pump. NOT the OEM model but the more expensive ($28-) heavy duty one! Well, I put it in last weekend & haven't had the problem since. Before that, It had become a daily issue! I Very Very Highly Recommend everyone BUY THIS PUMP!!! At the very least, it's cheap insurance to avoid all the aggrivation I went through!!! Best car part I've bought in a long time!!!
Have a Great Day!
Yours:
Drew
82 300TD 350,000+ SVO
85 300D 123,000 SVO
99 Subaru Legacy Outback

300D LOW POWER

1984 300D TURBO 147K
NEW ENGINE BY METRIC AND REBULT TRANS, SMOKE, LOW POWER, REPLACE FUEL LIFT PUMP $150.00 NOW POWER IS GOOD, NO SMOKE, FUEL MILEAGE INCREASE DIY 2 HOURS, DONE, WHEN ENGINE CHANGE THEY USE THE OLD FUEL PUMP

1984 300D TURBO LOW POWER AFTER REFUEL TANK

1984 300D TURBO 149K
REMOVE THE 14 AND 17 MM BANJO BOLT FUEL RETURN PLUG LINE ON INJECTION PUMP ENGINE SIDE GOING TO MAIN FUEL FILTER TAKE OUT SMALL SPRING AND STRETCH TO 27 MM REINSTALL AND ON THIS SITE ITS PART NO. DSLCOMPCV $24.00 USED WITH SPRING, POWER OFF IDLE IS BACK THE PART NO IS 0000747284 ITS $29.50 NEW

check this

maybe your car has an altitude adjustment out of whack. That made a friends 116 diesel run either robustly or totally slow and alternate without rhyme or reason- until he got a new altitude thing on the fire wall. Good luck

1982 240D bubbles in fuel line

I'm relieved to know I'm not alone with this issue. I converted to a Kent's single tank system last summer and car ran fine for 4000 miles. Last December car developed dramatic loss of power climbing hills. Filter change did not resolve problem but a diesel purge treatment did. Problem returned after 500 miles only more pronounced (stalled due to fuel starvation). Replaced lift pump, added boost pump and checked all filters including screen in tank all were clean yet problem persisted. With the help of a retired MB mechanic we got the car to run (eliminating bubbles) on a 50/50 diesel/wvo mix by turning off the glow plug fuel heater. This past weekend I upped my WVO proportion and turned the heater back on and car ran OK. On Kent's advise today I checked the operation of the thermostat that controls the glow plug and it runs continuously (possibly supporting my thought that the bubbles are super heated drops of fuel?). Another issue also returned today: After installing the new lift pump and boost pump in attempting to purge the system of air the car would run in the looped mode but would immediately stall when switched to the return mode. With the heater turned on today the car wanted to stall when I switched it to the return mode (with heater on) but runs fine in the return mode with the heater off.

Any thoughts would be appreciated