VO conversion - engine failure - PeachParts Mercedes-Benz Forum

Mike Hauser · #1 11-02-2005, 03:42 PM

I have posted a while ago that my car, an 84 300SD with a VO conversion kit would no longer start (the thread was lost in the hard drive crash last month). I tried a few things that I will post later but was unsuccessful in my attempts. I'm getting to the point that I want to know what killed my car. If it can be fixed along the way that's a bonus.

I have just the last few days found 3 more cars with similar symptoms as mine had when it was still running. The symptoms were:
- poor idle or not able to idle on diesel (fine, even good on VO)
- white smoke (only confirmed in one other car)
- severe loss of power on diesel (probably on VO, too, but much less so it seemed great in comparison)

The cars are 300SDs: 84 (mine, Greasecar, self-installed), 82 (home-made conversion), 83 (Greasecar, by authorized Greasecar installer) and a 300D wagon (around 82, Greasel). The wagon died some time during the summer.

I have thought for a while that the Greasecar kits don't supply a lot of heat for the engine to be ok in the long run with the temperatures in Massachusetts and could cause trouble because of it in the long run. Greasel is worse from looking at the parts of their system. I don't know what temperature the fuel actually gets to but the heat exchange system doesn't look beefy enough on either system.

Does anyone have similar experience or know of other cases? Or maybe insights as to what could be the cause and/or the fuel heating issue described above?

boneheaddoctor · #2 11-02-2005, 03:47 PM

What sort of time frames have these vehicle been operated on WVO and these kits.....basicly how long in time and how many miles?

Mike Hauser · #3 11-02-2005, 03:52 PM

Here's a list of things that I have done or had done to the car:

Shop:
new glowplugs
bench tested all injectors, replaced #1 because of unsatisfactory spray pattern, other 4 were good
valve adjustment

myself:
restored stock fuel system configuration - diesel only
all clear fuel hoses to see air - small leaks but no major bubbles
installed pressure gauge between fuel filter and IP - around 6-8 psi fuel pressure
changed fuel and air filters
inspected fuel screen in tank - ok
drained tank and filled with fresh diesel (not full, around 2-3 gallons)
changed hand primer pump on lift pump
removed and cleaned lift pump (before fuel pressure reading above)
inspected and cleaned IP overflow valve - ok

This engine is fairly new, it is a 3 year old factory replacement engine, installed by PO (I have the car since Jul. 2004). It's been leaking some oil into the driveway as a testimony to poor installation and the engine oil had gotten alarmingly low at some point before I noticed it. The oil pressure was always ok, though.

boneheaddoctor · #4 11-02-2005, 03:58 PM

Time and milage these vehicle were used on WVO is important for this reason.....500 mils and you have poor filtering issues...50,000 miles you might have mechanical issues

Mike Hauser · #5 11-02-2005, 04:00 PM

The owner of the 83SD claims 12,000 miles, conversion about 1 year ago. Mileage of engine around 170K.

I'm not sure about my car because the odometer never worked while I had it. Best guess: 15-20,000 miles, perhaps 10-15,000 actually on VO. Conversion in Oct. 2004. Engine is new 3 years ago, perhaps 50-60K on engine but really unknown.

The 82 SD is relatively relatively new conversion, around May-June 2005. Definitely doesn't get the fuel hot. 200K miles.

No idea about miles on the Greasel wagon, conversion was done about a year before it died.

boneheaddoctor · #6 11-02-2005, 04:02 PM

OK.. now we have the critical info.....you'll have a lot of good answers tonight...

I'm not a WVO expert, but have been researching it....does sound like it can be related to WVO temps that were too low casuing polymerization and slow clogging of injectors as a result....but thats just an educated guess...few hours and you will have answers from people with first hand knowledge and experience.

Mike Hauser · #7 11-02-2005, 04:07 PM

It's definitely not filtering issues with clogged filters. I had those in the past and know how they feel like. The owners of all cars either use the same grease as me or are pretty competent filterers by now.

Since you brought up filtering: the grease I use is from a Wendy's restaurant and partially hydrogenated. Possible that the IP is all clogged up from waxes in the oil.

I also forgot to mention two things about the car:
it gets fuel to all injectors although timing is unknown
it won't start on starting fluid (if I am doing it right, of course. It's a first for me)
camshaft is turning as confirmed by looking into oil filler neck while cranking.

boneheaddoctor · #8 11-02-2005, 04:09 PM

Quote:

Originally Posted by Mike Hauser

It's definitely not filtering issues with clogged filters. I had those in the past and know how they feel like. The owners of all cars either use the same grease as me or are pretty competent filterers by now.

Since you brought up filtering: the grease I use is from a Wendy's restaurant and partially hydrogenated. Possible that the IP is all clogged up from waxes in the oil.

I also forgot to mention two things about the car:
it gets fuel to all injectors although timing is unknown
it won't start on starting fluid (if I am doing it right, of course. It's a first for me)
camshaft is turning as confirmed by looking into oil filler neck while cranking.

Wendys definately has issues of animal fat contamination....they likely have the deepfryer oil and the grill waste ( beef tallow) mixed in the dumpster...was this true during the summer or is this new since fall temp drops.

What is the location....would help to put thsi in your CP so we know if you are in Canada or south texas.

Mike Hauser · #9 11-02-2005, 04:23 PM

I used the Wendy's source since around April or so. We don't have a centrifuge but used some settling to try to get rid of the thicker stuff. That works up to a point...
Ideal would be a centrifuge step at relatively cold temperature before filtration but they are prohibitively expensive.

I'm thinking to first have a compression test done, which should have either devastating results or bring peace of mind for that part of the engine. If the compression is good I guess the IP would be the next thing to look at, first timing and then tear it down and see what's up.

What gets me thinking that it's bad compression is that the car should start on starter fluid even if the IP is bad.

Does this make sense? Any other ideas?

R Leo · #10 11-02-2005, 04:50 PM

Quote:

Originally Posted by Mike Hauser

Possible that the IP is all clogged up from waxes in the oil.

This is a possibility. Raising the temp of the car (heated garage, for example) might fix this.

Quote:

Originally Posted by Mike Hauser

it won't start on starting fluid (if I am doing it right, of course. It's a first for me)

Not even a cough? While not a recommended practice in this situation, starting fluid sprayed into the intake snout should have made it fire. I'd definitely do a compression test; that low oil problem you mentioned may have scuffed the cylinder walls and wiped-out the rings.

Mike Hauser · #11 11-02-2005, 05:08 PM

Thanks for all the answers. I will have a compression check done.

The starting fluid did not produce even a sputter or burned smell or anything. I read a lot of the dangers, too. An act of desperation, perhaps not a smart one but it did produce some food for thought.

The filter changes I did when I first thought that the idle was poor. The valve adjustment and injector test were done not long after after it stopped idling on diesel. I guess the glow plugs were a coincidence, the light no longer came on. The other things were done later in hopes of reviving the engine.

R Leo · #12 11-02-2005, 04:39 PM

Quote:

Originally Posted by Mike Hauser

Here's a list of things that I have done or had done to the car:

Shop:
new glowplugs
bench tested all injectors, replaced #1 because of unsatisfactory spray pattern, other 4 were good
valve adjustment

myself:
restored stock fuel system configuration - diesel only
all clear fuel hoses to see air - small leaks but no major bubbles
installed pressure gauge between fuel filter and IP - around 6-8 psi fuel pressure
changed fuel and air filters
inspected fuel screen in tank - ok
drained tank and filled with fresh diesel (not full, around 2-3 gallons)
changed hand primer pump on lift pump
removed and cleaned lift pump (before fuel pressure reading above)
inspected and cleaned IP overflow valve - ok

So, was all the above done after your engine failure?

If so, you need to do a compression test. With adequate compression of <235psi you should be able to start the engine, provided the timing and IP are OK.

If compression is inadequate, that will need to be addressed before going any further. If compression is OK, next confirm all timing events: Check valve and IP timing.

If IP and valve timing is OK then the problem has to be fuel-related, either a dead or plugged IP.

Some other questions...
...was the engine shut-down on diesel last time it ran?
...is it possible for you heat the engine compartment (or coolant) so that the temp of the engine components is above 60something F?

chocolatesoup · #13 11-13-2005, 09:58 PM

Quote:

Originally Posted by Mike Hauser

I have posted a while ago that my car, an 84 300SD with a VO conversion kit would no longer start (the thread was lost in the hard drive crash last month). I tried a few things that I will post later but was unsuccessful in my attempts. I'm getting to the point that I want to know what killed my car. If it can be fixed along the way that's a bonus.

Mike did yours no longer start after dieing when you switched to wvo. mine did and now i cant get it started. and couldnt get it started while engine was still hot from running. What do i do?

here is my story.

ive just installed a 2 tank wvo
system in my 81 300d. it was running off both tanks with diesel in
both the tanks so i know its all hooked up and will run off both
tanks. I started adding veggie to the 2nd tank that had some diesel in
it. so it maybe has a mix of 20% diesel 80% wvo. i was testing my
system out. warmed up the car and flipped it over to the 2nd tank
shortly later it lossed some power and i went back to the diesel tank
and it gained its power back. i tried it again later while cruising in
a parking lot and it lost power and i couldnt switch back to diesel in
time and it shut down. I could not restart the car off of the diesel tank. i vaccum pumped out the fuel in the line from the selector valve to the IP. Then i re primed the line with diesel and could hear it squirting into the IP.
still wouldnt start.

trying to figure out what the problem is, or how to just get it running off of my diesel tank.

I saw BHANSONS post i think may try that, check my lines. i have one question though as how to check for blocked lines. do i disconnect the return line and try to start the car and see if anything comes out?

TonyFrom... thinks i have air in my veggie side, this may be very true. but i was able to get it up and running on diesel before if konked out. so its on my diesel line and that side seems fine. would that effect me being able to restart my car

Mike Hauser · #14 11-16-2005, 11:50 AM

1983/300CD,
the clear lines I have installed are PVC lines. Not at all the first choice to run the car on but I figured that for a short time they should be able to withstand the diesel fuel and not harden. Perhaps that's not a valid assumption. I will get some of the real stuff to install.

I also got finally got the adapter for the compression tester yesterday and will test the compression when I get to it (over the weekend?).

chocolatesoup,
My car would always run better on VO than on diesel. The problems first started to show themselves on diesel, then later also on VO. It's entirely possible that I have an air leak somewhere that worsened gradually over time. The question is: where? Since your conversion is fairly recent something like an air leak is the most likely. It looks like your problem is on the VO side but could also be in the fuel lines the two systems have in common. A leak that's not an issue on diesel could be a big problem on VO due to the difference in viscosity and temperature.

Mike Hauser · #15 11-16-2005, 12:11 PM

I just had a thought when I was writing the last post and I thought I'd run it by you. Let's assume for a minute that my problems are entirely due to an air leak in the fuel line before the IP.

Facts:
1) the problem was more pronounced when running on diesel on a hot engine.
2) the engine would cold start on diesel long after warm the idle on diesel was bad.

What these two operating conditions have in common is that the fuel is at the same temperature as the coolant (or at least somewhat close).There are no thermal gradients accross seals and the thermal stress on metal sealing rings is reduced compared to hot engine, cold fuel. Fuel hoses should be less affected by thermal expansion than metal seals. Following this theory the culprit would be a metal seal (copper or aluminum) at a banjo bolt or the lift pump.

The only seal where I can't see the fuel afterwards is the seal on the banjo bolt that connects the fuel line to the IP (two seal rings that look like aluminum - non-magnetic). I also used to open this bolt to bleed air out of the system when changing VO filters as it was the only point in the system that both systems had in common. Do the seal rings in a bonjo bolt fail if you open and retighten them too many times?