300td cold compression check - Page 3 - PeachParts Mercedes-Benz Forum

guru · #31 03-05-2007, 12:52 AM

Fuel issues considered to date are as follows: filters and primed, did the soda bottle by pass with fresh dino diesel, again opened the fuel lines at the injectors and have lots of fuel on each. still no go. she will not give more than a sputter, even on either at 100 degrees with a block heater.

Seems to me that the injectors are suspect, but there should be SOMETHING as we all on planet earth seem to agree that we have enough compression, and with either going in we should get a rumble even if there is nothing coming from all injectors.

i'm all for solving this as a fuel issue, any suggestions will be respectfully considered.

bgkast · #32 03-05-2007, 03:40 PM

I would pull the injectors and have them pop tested and balanced. The local injector shop around here tests them for free and charges around $70 for adjusting them. They are likely gummed up from all of that un-headed WVO.

Glad to hear that the marvel mystery oil may free rings that have been stick from un-heated veg oil. There are going to be lots of these cars left for dead after bad alternative fuel experimentation soon.

guru · #33 03-05-2007, 08:07 PM

I mentioned that I have fuel at all injectors but I'm wondering how much pressure to expect. Should I start to suspect the injection pump? I've read here to eliminate all other possibilities, as they are $ and durable. Any opinions about pulling the injectors first.

barry123400 · #34 03-05-2007, 11:56 PM

Did you do the compression check through the glow plug holes? Have you had an injector out? You said the glow plugs where gummed up I thought when you removed them? Quite a lot?
What I am driving at is perhaps the pre chambers are gummed up. You might want to pull an injector and have a look. You may have already done this.
If you are concerned about the injection pump pressure. When you have the injector out just move a pump line around to get the injector re connected and see if it sprays a pattern when you crank the engine.
Most of us are pretty new at getting to deal with cars that have been on unheated vegatable oil. So there are unknowns about exactly what to expect and look for. We have heard of a lot of stuff reported in the prechambers before on site I think. I am not sure if vegatable oil was even thought of or mentioned back then but the individual had to clean one or more of them out I believe. I does not take much time to pull an injector and have a look. Another ideal that was mentioned to me as well about rings. Adding a quart of transmission fluid to the engine oil after you get the engine to run helps to further clean out rings as well. This could very well be true in my opinion. Thought I would mention it for thought and comments by others.

guru · #35 03-06-2007, 05:44 PM

Thanks for the suggestions...I have removed the injectors previosly and the pre chambers were gunked up. The mm oil cleaned them out as far as I can see, with injectors and glow plugs removed.

I took the injectors out last night and found a clue Dr. Watson...all lines were full of fuel, (clean and clear) the IP was wet at all elements, the injectors were full of fuel also, BUT the opening of the nozzles was dry on all five.

The operating theory is now
1. all injectors are clogged, and/or 2. the injector pump is'nt giving sufficient pressure to make them work. I'll open up the injectors soon and report back.

bgkast · #36 03-06-2007, 05:50 PM

I recommend taking them to an injection shop. Like I stated above they will likely test them for free.

greasybenz · #37 03-07-2007, 01:15 AM

guru, where in SF are you located? i can come over and try to get that car running.

I hope you didnt buy this car from a guy in redwood city (he is a scammer)

guru · #38 03-13-2007, 12:52 AM

Hey greasy pm me, and I'd love to take you up on your offer to come by.
I'm in the outer sunset, sf.

guru · #39 03-15-2007, 02:35 AM

Over the last week or 10 days I re-removed the injectors and the tips were gunky again. When I cracked open the old injectors a few of them were hella gunked, one looked heat scorched, and all looked to be clogged. The injection pump looked good as it spit bursts of fuel from all elments. I soaked the motor again by squirting mmo down each cylinder 2x each day, keeping the block heater plugged in while I waited for new Bosio nozzles. Put it back together, cleaned with new heat shields, bled the fuel system to the injectors and she roared to life. Drove up and down the coast for a smoky half hour, giving as much pedal as she would take. The smoke cleared up and she runs strongly, shifts smoothly and starts up instantly. She cruises like a dream.

After 2 months of soaking, resoaking, and chasing down problems and learning, I brought my first diesel benz back to life. "Thrilled" doesn't seem expess the satisfaction. The neighbors clapped when she roared up the block, the same ones who laughed when she arrived by flatbed. Thanks to all who gave their $.02, your advice has been priceless. The Marvel Mystery Wagon will need some attention to her saggy rear, front shocks, a purge etc. I thank you all in advance for the knowledge I am sure to seek.

barry123400 · #40 03-15-2007, 09:58 AM

I cannot really relate how happy I am that all your trouble has been worthwhile. It just makes me feel good. I almost want to clap as well. Headstands and backflips will have to suffice though.

The fact is that besides your increasing everyones knowledge there is now positive proof some of these vegatable oil burners can be turned around at reasonable cost. I suspect yours is the first so called documented case of back from the brink. Anyways congratulations are in order and with this under your belt a 616/617 type engine will never intiminate you either.
Another thing I suspect is the bosio nozzles might require a 500-1000 mile period to totally develop a good needle seating pattern so running may even get better with a little time. Just guesswork though on my part.
With every answer comes questions to a simple mind like my own. I now have to wonder if some of the engines that have run diesel fuel over the years might benifit to some extent from an attempt to clean out the rings?
If the site members that have rebuilt these engines at one time or another could quote how much carbon etc was found in the ring lands upon dissasembly it might provide a clue.
I am also almost convinced from talking to old timers that for some diesel engines water ingestion turning to steam is an old concept that can work in some cases. Depends I guess if the rings are worn or just jammed up enough that they cannot present a good scraping edge because their mobility is no longer there or severily limited. Meaning they are unable to tilt a little to present a good scraping edge to the wall on stroke reversal as well. I also even am starting to wonder if a good soak down or other treatment might be benificial as a kind of tuneup at higher milage. A microscopic examination of an old rings edges might put this to bed.
Sorry about wandering around so much but both for my own call it self centred reasons. Plus what I have read about amounts of blowby on some of these engines it stared me thinking quite awhile ago about the rings. In many cases they may not be worn out. Thanks again for posting what you have experienced. It will help a lot of us over time. It has helped me already.

vstech · #41 03-15-2007, 10:36 AM

YEAHYYY! glad to hear it's going well for (what I feel honored to hear) the marvel mystery wagon. glad the MMO tip helped. also glad that injectors were the final problem to overcome on your first experience into MB Diesels!
John

barry123400 · #42 03-16-2007, 11:42 AM

Bump.. I think this thread is important as we will stumble upon cars that have used unheated vegatable oil from time to time. Knowing that some problems can be undone at reasonable cost may impact our not walking away from an otherwise good car. Best of all they should be cheaper to purchase.

I already aquired a beauty far cheaper that if it had it been running well or at all come to think about it. I suspected it might even require a new used engine originally. It will not.

GRIESL · #43 03-16-2007, 02:35 PM

Way to go, dude! It took some real hutzpah to revive one of these diesels. I have a very important question, though. Have you checked your compression since this? If there is hard evidence that the Marvel Mystery Oil can loosen up carbon junked rings, then I'll be shooting that stuff down my injector holes right before I go on vacation and let it do its thing for a week. I just replaced the head and there was a lot of carbon on the valve seats and stems. So there's at least good evidence that carbon and sticking is possible (I've got a little bit of blue smoke at idle). What do you think?

rrgrassi · #44 03-16-2007, 02:56 PM

I'm sure Lovecraft would say that won't happen with HIS conversion...

Good job on getting back on the road!

Do you have pics of the gunked up injectors?

barry123400 · #45 03-16-2007, 02:58 PM

Griesel, another gentleman did a controlled experiment reciently. He kind of proved the marvel oil did dissolve the build up on his injector to some extent. A week sounds about right for an initial soak attempt but watch your ambient temperatures. Chemical reactions slow or stop when too cool. Always best above 70 degrees.
The chances of hurting anything seem very small at this point. Thats with what little knowledge has been aquired to this point. It is also thought that a quart of transmission fluid in the base oil might help but again no recorded results or attempts by members on site to my knowledge. That would also be a really long time related approch if it does help as well. My feeling is the two combined might be of some value.
Still waiting to hear from guys that have rebuilt these engines about how much ring action impairing products where present that they had to clean up.