My 8V92 with 220,000 original miles has a new problem. About half way through our recent trip, I started noticing some very small oil spots on the front of the toad. I started looking for new oil leaks that could have caused this and noticed a very small amount of oil in the tube leading from the valve cover breather on the left side. The right side is dry with no evidence of oil. I have rubber hose extenders on the breather tubes so I could watch for this.
I wasn't too concerned as I had been pushing the bus pretty hard up and down mountain roads (hills to our friends out west). I washed the front of the toad so I could have a clean surface to monitor the situation and for the rest of the trip I would get a few drops each day but again, it was a very small amount.
After three days of driving (again I was pushing pretty hard, 70-74 mph pulling a 5200 lb toad). I had a few more drops on the front of the toad but nothing to write home about.
I parked the bus for week. In preparation for leaving the following morning for the final run home, I started the engine. If there were any mosquitoes in the campground, the white smoke that poured out of the exhaust surely would have killed them all. Thank god all my neighbors were out and about.
The smoke did not last long but it sure seemed bad at first. After the bus warmed up, I shut it down, let it sit a few minutes and restarted it with no issues.
The following morning I started the engine and again a nice puff of white smoke. Nothing like the night before but still worrisome.
I ran the last 700 miles home without incident although I was not pulling the toad for this leg.
Next morning, started the bus and small puff of white smoke.
If I didn't know better, I would have sworn someone stole my DD and installed a Cat 3208 when I wasn't looking.
So the signs and symptoms are; oil in the left valve cover vent tube when it used to be dry. The amount of oil coming from the valve cover tube is very small. There is not enough to cause a drip when the bus sits. Right side valve cover tube dry. White smoke at startup when cold but stops after a few seconds. Never had white smoke on startups only a little black which I know is normal. No noticeable performance changes and no smoke on hot restarts.
So the big question is what is going on here and what do I do about it?
Thanks.
White smoke on startup is un burned fuel, not oil. If it hasn't been done, 200,000 miles is the magical number that you should be installing new tips on the injectors and rolling in new rod and main bearings. At 300,000 miles, the blower and turbo should be rebuilt. Every 100,000 miles you should run the rack (if it is a mechanical engine) and adjust the valves and Jake brakes. 2 stroke Detroits will run for a long time-but need preventative maintenance to achieve this. Not like Series 60's that only need there overhead adjusted when power loss is felt. Good Luck, TomC
I forgot to mention the engine is a DDEC II. Does that change anything?
I am intrested in your responses because I have my engine down now to put in bearings (322,000 miles) and found a follower retainer spring broken and deciding on how far to go with overhaul..have the same spotting problem on the toad sounds like a fuel tip problem.I'm far enough apart it would be simple for me to correct..Good luck ..I put new air box drain valves on mine and it stopped most of the problem one was clogged..they can be taken apart and cleaned.
Does an 8v-71 have airbox drain valves? If so where are they located?
on side of block each side below head should have a rubber hose attached that hangs to ground.
I have started to get the same white smoke at start up. Is this new injector time?
Hey guys before rushing out to change injectors we are getting into cooler weather a 10 degree drop in tempature will make a huge difference in the white smoke on a DD 2 stroke on startup and if you think they are bad watch a 3208 Cat or a 855 Cummins fire on a cool morning.If you don't want the smoke plug your block heater in for a few hours
good luck
So it seems everyone feels white smoke on start up is fuel injector related. In my case, I don't think it is ambient temp related as it didn't smoke when in cold weather, was of sudden onset, and smoked as much when back in Florida at 85+ degree ambient as it did in 65+ ambient in NC 24 hours earlier.
With a DDEC, how do I determine which injector may be the culprit or do you just change all of them at the same time?
I gather the oil out of the left side of the breather is unrelated? What is the cause of this and what does one do about it?
Thanks.
Paul, if you have a Pro/link you can do a cut out test for the injectors it just maybe the tank of fuel or low voltage to the ECM will cause a DDEC to smoke on startup.
good luck
Especially with a DDEC engine-if you're getting any white smoke at startup-it is a good indication you need injector tips. Why-because one of the things the DDEC system does is to change the timing when cold to prevent white smoke. While it will be a few hundred dollars for it, you'll get better fuel mileage with the new tips (it might feel a bit less power since the new tips will be tighter and not allowing quite as much fuel through). Good Luck, TomC
TomC you are wrong about a DDEC not retarding the timing for cold weather start up.
good luck
Perhaps this may help ??
I've noticed that DDEC's VERY OFTEN white smoke on startup if the Batteries are low - but when that happens they also stumble at idle and resist throttle up -
but as soon as the engine RPMs increase and the 50DN starts kicking in - the white smoke and stumble goes away
I suggested to Bill Gerrie in Canada that he switch his DDEC supply to the house batteries and it has seems to cure his startup problem
Might it be time for a compression check? Make sure if you do it that they do it at operating temperature or the shop you have do it will be trying to convince you that you need a out of frame rebuild.
The way I read it TomC said the DDEC does change timing??
Luvrbus- I think you read my post wrong-I said that DDEC does retard the timing when cold-more so then mechanical timing-to reduce white smoke at startup. So if you're getting white smoke at cold startup with a DDEC engine, it is a good bet you're in need of either new injector tips or complete injector overhaul. Good Luck, TomC
Anyone have an idea of the expense to replace/overhaul the injectors? Is this something I can do myself? I do have two stage jakes if that matters.
I have replaced injectors on several Cat 3208s as well as small genset diesels so I have a working knowledge of the process on mechanical engines.
Thanks
Paul, you are looking at around 2 grand for parts and another 1000 to 1500 for labor maybe more.
To check to see if they are leaking have a oil sample done if signs of fuel in the oil then change the injectors but I doubt if you find any dealer now days that will just change the tips it is cheaper to replace the whole injector with the price of labor at the dealers.
If you have all the special tools required for a DD and a manual you may can do it yourself but it is not a easy task with Jake Brakes.
good luck
Wow, I had no idea they were that expensive.
I think I'll do the oil sample routine. I did one in April of this year so it would be a good benchmark to help set me in the right direction.
Thanks for all you input.
Paul
I find it unlikely, but don't forget white smoke at start up can also be coolant in the combustion camber (cracked head). Another thing I've experienced is "cold ring stick" where carbon build up in the ring land causes the ring or rings to stick and not allow enough compression for ignition for a few seconds at cold start up. My experience was that only a few degrees difference in ambient temperature would cause this to happen (something like 50 degrees would be no problem and 40 or below would cause a misfire for a few seconds) resulting in white smoke (unburnt fuel). I know carbon was the problem because about 13000 miles after I built the engine it broke a rod and during the re-rebuild process I discovered the ring lands were full of carbon, which I found unusual in such a short period of time. I built the engine again and it was doing the same thing in about the same mileage. The only thing I thought that might have caused this was the big injectors I was running. I never found any chemical that fixed the problem (and I tried many). Carbon is an organic compound. The only thing that I know of that will clean it in a combustion chamber is water. Just take a look in any engine that has the head removed because it had coolant leaking into the combustion chamber (blown head gasket). The cylinder with the leak will be spotless. This was a 6V92
Ken