300td cold compression check

[guru]

Hey everybody I'm new here but already want to say thanks for the information this site has given me...priceless.

I have just gotten cold compression values between 150 and 170 on all five cyliders of a recently aquired 1980 300td with 300k. I am trying to get her up and running but so far not much more than a smoky sputter.

brief PO history;
sat for months, PO said he put SVO in tank without any conversion, it smoked badly and he got a ticket from CHP. He topped it off with dino and was "cleared" by CHP (fix it ticket) it ran fine and was parked because he got a new ride. I don't know how long ago that happened. He also tried to fix leveling hose when it blew, it blew again.

recient developments:
I had her flat bedded to SF as I couldn't get er going at his place.
fixed fuel issues with a new primer pump, in line filter, and bled system to injectors. 5 new glow plugs as old were dead, new plugs getting power and feel hot to touch. so now she sputters a bit and gives off a smoky blowby that smells like wax/veggie oil. When I did the compression test the new plugs were all pretty gunked up with a black...gunk. I have a block heater and spin filters on the way.

MY Q's
Can I hope for her to fired up with cold compression that low? (35F out side now)
Is the gunk my main issue at this point? Solutions?
Will the heated block get her going or is there more to my problems?
When she fires (not if!) how long can I run her without damaging suspension pump?

I'm new to benz and diesel so please no suggestion is too simple for me.
Thanks
guru

[vstech]

ahh. no.
that's pretty low. I would pull the valve cover and set the valve clearances, and test again.
maybe pour a tablespoon of Marvel mystery Oil in each injector hole, and let it sit for a week. then test again.
John

[winmutt]

Originally Posted by vstech

ahh. no.
that's pretty low. I would pull the valve cover and set the valve clearances, and test again.
maybe pour a tablespoon of Marvel mystery Oil in each injector hole, and let it sit for a week. then test again.
John

what is this marvel mystery oil you speaketh of, o one with too many cars?

[vstech]

it's an additive that has been attributed to turning a geo into a ferrari... really it's just a chemical additive that cleans junk from combustion chambers, etc. in cold temps, it's gonna be quite thick, so it's gonna have to sit for quite a while to be effective. available at wallyworld and most any auto parts store... not really a reliable repair tool, but perhaps in this case with such low compression, it's worth a try.
my guess is the WVO has gummed up the rings and letting compression blow by. maybe even try a can of diesel purge after the MMO and see if it can clean up anything.
but certainly do check the valve clearances first.
John

[barry123400]

I think your compression rings are carboned up from the unheated vegatable oil. The same gummy stuff that was on your glow plugs got down there and baked on.
I agree that you should try the marvel mystery oil for a soak first. Let it work for a few days adding a little more each day. I do not know what that marvel mystery oil is actually but I hear it reffered to fairily often.
I too have an engine that was run on unheated vegatable oil. It did not get as far down into the mud as yours has. Thats primarily because my car broke with another problem first and he walked away from the car. If that had not happened I imagine it would have been fed the same diet until the engine did not have enough compression to start at all. In your case I think he tried until he burnt the glow plus out.. Usually they total the starter.
I might pull the injectors to see if the prechambers are gummed up as well. Expect buildup on the nose of the injector and make sure those holes at the bottom of the pre chamber look clear.
I hope the mystery oil softens up the carbon around my rings as well so I do not have to take more drastic measures. Mine did start with block heater applied for a couple of hours. The engine had not run for at least a year as well. Glow plugs were fine. It would not start otherwise and it was not cold.
Before that I drained and changed the tank fuel. Still had to start on the vegatable oil in the pump and run through a little of that first though.
I guess I could have power bled the pump out by loosening the injector lines and cranking for quite awhile.
I was able to pump up the new fuel with the hand pump. So the bulk of vegatable oil in the lines and filters was mixed with the diesel fuel in the tank as it was driven down the return line. Keep us informed as to how things go. I hope these situations are salvagable. I have mine sitting at present and will not be going near it again for a few months yet. I have been waiting for other victims to post attempts at cures and pick the best ones out. Although I have done little research myself yet.
More information on this problem is on various vegatable oil boards. It is one of those things that has to happen to you to really appreciate. Unfortunatly my car is a real fairly low actual miles car. I also suspect this carbon cannot be just driven out. It will have to be broken up and expelled or dissolved before those upper compression rings can work well again. Unless they are already damaged somehow. I would not be concerned about any smoking tendencies the engine has at present.
My engine also at present has the most actual blowby I have ever seen in a running car. And I remember well the old cars years ago that went though a quart of oil every fifty miles. My blowby is primarily combustion gasses rather than oil burning. It is pretty clear but has a lot of pressure behind it.
There is sort of a bright side . If the cars had not been burning unheated used or new vegatable oil we would never have got our hands on them cheap. Plus I suspect your injection pump is still good. That is also another large plus. It is the second most common reason unheated vegatable oil burners become surplus in my opinion. I personally have no bias against running vegatable oil as long as it is done properly.
Your compression numbers do not alarm me at this point. Might if that carbon does not come out though. I suspect the compression rings are cemented in as far as the lesser taper of the lower area of your cylinder wall allows. I will be watching your thread.

[GRIESL]

The gunk is not going to be your main problem. Seems like you could fix that by draining the tank (and clean out tank screen while you're down there). I wonder why it smoked with veggie. My car won't blow any fuel smoke when burning bio.

Adjust valves and check compression again, but this time go to a plumbing store and get a little adapter fitting that will allow you to connect a compressor or hand pump to your compression adapter and inject air into the cylinders--just a little at a time is all it takes--if you're using a compressor hook up a levered ball valve to control the flow. Then listen to where the air is coming from (with compression that low you'll here it coming from somewhere). If you hear it coming from intake or if you hold a tissue to the exhaust pipe and see it flutter, then you've got burned valves. If air is heard at the oil filler cap or dipstick (or timing cavity if you have the valve cover off), then it's related to the bottom end of engine i.e. rings, pistons, cylinder walls.

You could also squirt a teaspoon of oil into the cylinder and then check compression. There are differing opinions on this one, but I did it. If your numbers don't go up dramatically, then the problem is more than likely valves, since the oil will seal the rings to the cylinder walls. Good luck!

[winmutt]

Any chance of using this stuff to clean the valve seats?

[barry123400]

Originally Posted by winmutt

Any chance of using this stuff to clean the valve seats?

I can not think of any way to apply it to the valve seats in enough concentration if at all. Both exhaust or intake. One poster mentioned it helps some things by introducing it into the fuel tank. I still wish I knew what this stuff is. A lot of people seem to have experienced positive results. The product has always been marketed as long as I can remember. I suspect it is not snake oil.The newer penatrating oils have a strong acid base. Perhaps this product is an earlier version of them?

[guru]

thanks for the ideas, I'll look into the marvel oil and get it soaking. I'll update the thred as things progress.

[barry123400]

Originally Posted by guru

thanks for the ideas, I'll look into the marvel oil and get it soaking. I'll update the thred as things progress.

Thanks for that. If they will not soak loose one way or another I have been toying with an engineers ideal to blast them loose. All other easy possibilities should be exhausted first.
I do not really have a firm opinion if they would just loosen up over time by driving. Somehow I suspect not.
Also I do not know if coke deposits are hard enough to score the walls.I suspect not. I really like the possibility of the marvel oil softening or dissolving the deposits first if possible.
You might wish to turn the crank 1/4 turn every other day. A better chance of soaking the compression rings on all the pistons. The pistons near the top of the bores possibly have the rings at their greatest distance from the walls because of the cylinder taper.
The other thought is the position is irrelevant. The rings cannot rock a little to allow sealing because they are glued in with coke. If your car is outside remember chemical activity really slows at low temperatures to almost nothing so try to be patient.
I might take an old coke coated glow plug and stand it in a small cap of the miracle oil to check periodically how much effect it is having on the coke. The burnt out plugs might be ideal for this. You cannot see inside the engine. . I would do two separate old glow plugs that way. One I would leave outside to duplicate the rate of penatration of the coke by the oil and the results. The second one I would keep in the house as the increased chemical action at elevated temperatures will show the end result of the miracle oil in the engine well in advance. Plus provide a baseline for what the oil can achieve.
This whole thing should be interesting. I will also try to find out how other people have dealt with this problem if they have at all over the next few days.

[t walgamuth]

after the soaking i would pull the car to get it started. then i would drive it out on the highway for a couple of hours. i would put a quart or so of marvel mystery oil in the fuel along with some injection cleaner. this might well clean the rings out if they are gunked up.

then i would try the compression test again.

tom w

[Johnhef]

if you dont have a good battery and thin oil in it, do that first.

[kerry]

Try an alternative fuel source. Using a soda bottle filled with diesel or diesel purge, put one line to the primary filter and stick the return line in the bottle. This will rule out any fuel problems from the engine back to the tank. You should get a pretty good flow from the fuel return hose backinto the bottle.

[barry123400]

This car like one of mine was on unheated vegatable oil. The one I purchased not running obviously has stuck rings. We had quite a time to get it started. Evidence the previous owner had gone through several starters. It now has massive blowby and is a low milage car. I estimate if driven a few thousand miles more on unheated vegatable oil it would have no longer been capable of self start. Still have a gummed up /carbonized ring problem by the amount of blowby.
This gentleman does no longer have a big compression issue. He has modified that. Joe on this point you are right. His car now has enough to start. Yes he could have a fuel issue. I suspect the previous owner of it used the car until the last gasp. Vendors do tend to not always tell the truth. I just want to hear that he has got his engine running again.

[guru]

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.