84 300SD not starting anymore
 

Around thanksgiving, both the people and weather of eastern kansas treated my SD most unkindly. First, it got down to about 10 deg F. The car refused to start. I didn't have the time to deal with it, so I had it towed to a shop. After a few hours, the shop got it running. They told me they had in the block heater and just recharged the battery and started it in the warm shop. Upon getting my car back though, I found that a piece of interior wood was broken off, my oil pressure gauge now pegged at 3 whenever there was power to it, and the crankcase vent hose from the top of the valve cover to the air filter had been torn in half and miserably covered over with some green hose that looked like garden hose. This enraged me, especially since the discovery occured in rural Oklahoma when I smelled oil while the heater was on. Anyway, the car drove fine for a week. It got cold again in Kansas and it stopped starting again. Mid-December I met a mechanical engineer/mechanic who helped me out (for a price). We replaced the battery, the starter (the old one tested weak), the secondary fuel filter, and even put a few more gallons of diesel in it, and it still wouldn't start.

Starting it got a little harder over the past few months. I don't know when the last valve adjustment was done. However, once she is running, she runs great, and doesn't smoke. Last time I tried starting her, there was some white smoke coming out the tailpipe, so she's getting some fuel. Tomorrow the mechanic is going to stop by and we are going to crack the injector lines. I'm already up to $320 that I owe him so far, and I'm not made of money. He doesn't have a compression tester for diesels. Does anyone here have recommendations as to what I should do next?

P.S.: It has been in the 40's and 50's around here during the day, and usually the car didn't have problems starting. I also had a few emergency situations over the summer (fuel leaks) that necessitated burning some canola oil. The secondary fuel filter looked ok though when pulled. Also, I would add a little bit of Phillips 66 Jet-A to diesel every once in a while...car ran smoother.

How about the simple stuff first - fuel filters and glow plugs? Have they been ruled out?

checked a couple things
 

I was out of town when the mechanic replaced the secondary fuel filter. He said he pulled it off and it was full of diesel and looked ok. He also primed up the new filter with the hand pump on the IP. The glow plug light will go on when you turn the key, but we haven't hooked up an ohmmeter to them yet. I'll be meeting up with him at 1pm central tomorrow, I'll post on what I find out.

If your oil pressure needle was not pegging above 1000rpm's or so in the past, something was wrong. They all peg above idle on 617's unless something is wrong.

You may need this thread link.
 

You may need this thread link.

ShopForum > Technical Information and Support > Diesel Discussion
Organized MB DIY links
http://www.peachparts.com/shopforum/general-information/135055-organized-mb-diy-links.html

Since it runs great once it's running, you can forget about bad fuel filters or bad injectors.

Your problem is one of four possibilites, listed in order of the most likely culprit to the least (I'm eliminating the starter and the battery since they were recently replaced):

1) Failure of one or more glow plugs.
2) Valves that are seriously out of adjustment......allowing one or more valves to remain slightly open.
3) A timing chain that is very elongated resulting in very late valve and injection timing.
4) Low compression.

the oil pressure gauge used to work fine...just like it did on my other MBs. I can't say at what engine speed it would peg since my tach is dead. It is now ALWAYS (when its running) pegged at 3 and that was after I took it to the shop that tore the crankcase vent hose. Right before thanksgiving, I drove the car from Kansas City to Fort Worth, stopping and spending the night in Wichita. The car stayed in an unheated garage without its block heater, but started up on the first try with minimal fuss in the morning. The mechanic today told me that he was cranking for 30 seconds, and he could tell it was hitting a couple cylinders, just not starting. If I can't get it to start by Saturday (at least 50 degrees tomorrow, and it should be 65 degrees by Saturday) we'll see about a valve adjustment.

whunter: thanks a ton for that link.

Little tidbits continue to emerge.;)

What was the temperature in the unheated garage that night?

From your post, it sounds as if you are back in Kansas. You did not mention the status of the glow plug light. Are you even getting one? Have you checked the fuse inside the controller?
If so, are you doing a complete glow cycle? In other words, turn the switch to ON and wait till you hear the controller relay "click" under the hood, then turn to START/CRANK.

Brian,
The garage was probably in the upper 40s. On the return trip to the Kansas City area, the car was left overnight in a parking lot in Wichita. When I got to it in the morning, there was frost on it, so it was below freezing during the night. Whenever its gone below freezing I preglow three times before cranking. Started right up then, too.

Bah, I want this car to work. I'm tired of people looking at me funny driving my big diesel sedan during the summer and my SL in the winter.

Well, the upper '40s won't tell us much. But, the "below freezing" certainly will. If it started fine under these conditions, then you likely have decent compression.

So, the first thing to check is the condition of the glow plugs. Get yourself an ohmmeter and check each plug, via the wire from the relay, to ground. You must have less than 1.2 ohms. Anything above this value means that you must replace the plug. Make sure the controller is working and that the plugs are actually receiving 12V.

Some of us will simply replace the full set of plugs, once age has crept up on them and starting issues arise. But, if you are frugal, you can test them first.

Since you have no idea when the last valve adjustment was done, it's time to pull the valve cover and, at the very least, measure the valve lash on all the valves. If they are seriously tight, then you have to get them adjusted back to spec.

Just do it.

Well crap.
 

I cracked the injector lines today and saw a little bit of fuel dribbling at each line. It may be interesting to note that it took a couple cranks before fuel came out on a couple lines. The glow plug relay is working, and the voltage from each glow plug relay wire was at least 10V. I unfortunately did not have an ohmmeter available. I will tomorrow. The engine turned much faster than it used to, but it didn't sound like it was firing at all. From the exhaust pipe, there was white smoke, but I felt a rhythmic puffing, like a vacuum; much like the feeling of a running gas engine misfiring one cylinder. My mechanic doesn't have a diesel compression checker, he recommended the local "expensive" shop for that. He expressed some concern that my oil was jet black and that there could be a problem with the rings; also I should change the oil as soon as I can get the engine running. I've always used Rotella T 15W40. Maybe something lighter for the winter? Now I'm staring at spending a bunch of money for a compression check and/or valve adjustment, right?

I apologize for any nonsensical wording in the above paragraph. I'm in emotional distress over my car.

Step 1: Fire the mechanic. He knows nothing about a diesel engine

Step 2: Go back and reread post #11.

Step 3: Follow that post.

Step 4: Report back here with findings.

Ditto!
 

I agree with Brian on this. Relax and we can help you through this.

Your comments tell us that your mechanic knows next to nothing about diesel engines. Black oil tells you that the oil is doing its job and suspending soot particles.

Also, he has monetary gain in mind with this continuing saga of unable to start. We, however, have nothing to gain from this and are only trying to help you out. He may also be just trying to cover his lack of knowledge to prevent embarassment on his part. We do not know your mechanic so this is not anything personal against him.

Once you sort out the glow plug problem, you should have little trouble starting. You have not answered any of the questions about the status of the glow plug light or checking the fuse in the controller.

sorry, forgot to answer the glow plug light question. the glow plug light is working fine. the relay correctly clicks on when you turn the key to 2, and after the light goes off, the relay stays on for about 20-30 seconds, and then it clicks off. I have not checked the 80A fuse inside the relay, I'll try and do this soon. I will update with progress.