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Author Topic: MCI7 8v71 stranded grey smoke increasing with accelleration (injector issue?)  (Read 12274 times)
Dlsnow
dave
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« Reply #45 on: September 30, 2012, 08:01:18 PM »

an update is in order - title no longer reflects the progress of this issue - and wanted to save you all from reading all the pages to get up to date
1. not stranded anylonger
  found c60 injector missing "crown" tip - effectively dumping fuel at all times
  replaced with c65
  bus ran alot better - a bit of smoke while running
2. smoke still increases with accelleration
  way less smoke - no longer "obstructing traffic"
  doesnt smoke much until fast idle comes in - and while driving
  used to smoke for about 30 - 60 seconds (depending on temp) as soon as it starts but then clears up
3. discovered the bus is no longer getting up to temp
  used to be just fine - was fine after for couple hundred miles after injector replacement
  found faulty thermostats
  replaced with 170F - DD Powercool 50/50 - flushed it out really good - really good
  bus runs at 180 again Smiley  -  and stays there (so far) (just tested today - hope it stays good)
4. isolating smoke issue removed airboxes and found liner parts from an apperently "old injury"
  used scope to look in cylinder - liners are in tact and look smooth and shiny
  heads dont look beatup
  still havent found the injector tip Sad
5. want to check compression - ordered kit from HF - cant wait

So that is where were at now - thanks for hanging in there with my newbie questions.  I havent worked on a 2 stroke since a kid (repairing 50cc mopeds).  This is alot more metal.  I have the original MCI parts and maintenance manuals as well as the electronic version of the DD v71 manual.  So im working "from the book" on this stuff and with all your help will hopefully I get to the root of this issue.  I would really like to not have to repower this thing.  People say if you take care of these old Detroit 2Strokes they will run forever.

Also the bus draws a croud at truck stops - everyone loves to her the Detroit Diesel roar.

-Dave
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1972 MCI7 8v71 converted - 1kw solar on roof
RickB
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« Reply #46 on: October 01, 2012, 07:11:18 AM »

Dave,

Where in central Wisconsin are you?

Rick
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I will drive my Detroit hard... I will drive my Detroit hard.
Dlsnow
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« Reply #47 on: October 01, 2012, 08:05:01 AM »

Wausau area 54403 area code for now...when im through this issue...

Hoping to run to Nashville, Fayettevill AR, Tulsa OK, Dallas TX, Tucson AZ...Quartzsite!

Yes in the bus...
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1972 MCI7 8v71 converted - 1kw solar on roof
luvrbus
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« Reply #48 on: October 01, 2012, 07:24:37 PM »

You will need 2 flare nuts to plug the return and pressure side when you remove the injector or take a old fuel line and bend it or diesel will be spraying every where 

I hope the HF tester works for you I never saw one used before on a DD mine is a Kent/Moore a little pricey but it works goods you can read the test pressure after the engine has stopped it locks in on the highest reading


good luck
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RickB
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« Reply #49 on: October 02, 2012, 06:48:04 AM »

Clifford, isn't the motor supposed to be at operating temperature as well when checking compression?

RB
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Dlsnow
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« Reply #50 on: October 04, 2012, 05:12:45 AM »

I connected fuel line from the supply and return inlet on the head.  The great news is that this stop the smoke almost immediately and there's no more fuel dripping out of the manifold.  So I believe this issue is isolated to that specific cylinder and probably the fuel injector or compression.
 Good question Rick. Does the engine me to be up to temperature in order to test the compression?
 I am currently waiting on the compression tester to show up in the mail Tuesday next week.
 Is there any way for me to test this fuel injector?  I checked it and it is not missing the tip like the previous 1 that was in this hole that malfunctioned.
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« Reply #51 on: October 04, 2012, 06:01:47 AM »

The way I understand the compression test for the Detroit is that the engine has to be running during the test.  So it will probably be warm at least.
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Dlsnow
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« Reply #52 on: October 05, 2012, 09:04:46 AM »

It was too hard to watch the bus just sit out there not making any progress while I waited up my compression tester to arrive.  So I decided to take the fuel injector to a fuel injector shop to have it tested.  They didn't have to test it to see that it was cracked. They said it would pretty much be just dumping fuel right into the cylinder at all times.  They also had the correct c60 injector available.  So I have the new c60 injector and am reluctant to put it in.  I dont want to break it.

I bore scoped the cylinder again and the liner looks shiny and has no scoring or dull spots.  I dont see any marks on the head and the piston top does t have marks.

One thing i noticed when the c65 injector was being installed is my mechanic didnt measure or adjust the distance from the base to the top of the spring.  Forgive me not knowing the right terminology.  I thought you needed to use a dial caliper to ensure the timing was the same as the others.
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1972 MCI7 8v71 converted - 1kw solar on roof
Oonrahnjay
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« Reply #53 on: October 05, 2012, 11:51:33 AM »

  It was too hard to watch the bus just sit out there not making any progress while I waited up my compression tester to arrive. (snip) 

     I don't have an engine like yours so I've only been following this on theory so sorry if this is wrong, but it appears to me that you have two problems -- 1) an injector issue, and 2) a mechanical engine damage issue -- both of which could result in total engine damage to your engine if not repaired. 

     This sounds as if you've fixed your injector issue (I hope that the problem that this fixed was the only injector issue you had) but I would be *very* careful about running that engine until I'd found out where those broken pieces came from and I would be sure that I wasn't further damaging the engine by running the engine to "test" the injector.

     Again, sorry if I've missed something, but it appears to me that your engine could be very susceptible to further damage.   BH  NC   USA
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Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long
6-cyl, 4-stroke, Leyland O-680 engine

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« Reply #54 on: October 05, 2012, 02:28:50 PM »

His damage is done the tip probably took a valve out on exit, Disnow I am having a few doubts about your mechanic lol buy your the correct timing pin a dial indicator will work but is a pain 

You don't just match a injector timing to another injector do those all the same buy yourself a 20 dollar timing pin ,when you loose a tip they blow black smoke like crazy not the grey smoke that comes from fuel with no compression that cylinder is burning no fuel


good luck
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Dlsnow
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« Reply #55 on: October 05, 2012, 05:56:11 PM »

Right-Makes more sense to blow black if it is dumping fuel althlugh this started at the same time as my thermostats got stuck and the bus wouldnt get up to temp.  New stats and it gets up to good now.  Not sire if this is a factor.

Ill wait on installing the new injector until after i test the compresion.

Im done with the mechanic after seeing what a healthy injector looks like.  The one he put in didnt have a nipple on it and probably didnt work from the get go.

Question on the injector tool...I see two kent moore options...should i get the one for n60 with 1.460
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« Reply #56 on: October 06, 2012, 09:15:24 AM »

Just a thought here... Is there any chance these metal pieces were from a previous issue that someone could've missed?

Rick
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eagle19952
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« Reply #57 on: October 06, 2012, 09:49:47 AM »

Just a thought here... Is there any chance these metal pieces were from a previous issue that someone could've missed?

Rick

Lets hope not.
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Dlsnow
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« Reply #58 on: October 06, 2012, 01:37:48 PM »

the pieces were definitely liner port parts and were part of an old injury. 
they measure the same width and have the right markings - confirmed liner port parts
I checked each cylinder with scope through the airbox's to confirm all of the current liners are in tact - and all are - all have a nice glaze, all pistons rings have a visible groove - no scoring...
I am certainly no diesel mechanic and this is the only diesel engine I have worked on (full disclosure) - so when I bought the bus I had a reputable DD mechanic look it over (worried he would say it was junk) he said it (the engine) was in good shape and had been well maintained (as least since last rebuild) but he didnt know coaches at all.
So fast forward to now -
  Im waiting on the compression tool - tuesday arrival
  trying to figure what to time this new injector at - 1.460 or 1.470 (manual says 1.460 for c60 and also says 1.470 for coaches with c60) - cant find a 1.470 DD timing tool though

What to do now - will there be a difference?
Do i need to time only the injector i have out or all on this side?
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1972 MCI7 8v71 converted - 1kw solar on roof
thomasinnv
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« Reply #59 on: October 06, 2012, 01:44:05 PM »

To do it right you need to have all injectors matching and run the rack and time all injectors on both sides.

Sent from my PantechP9070 using Tapatalk 2
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There are three kinds of people in this world....those that make things happen, those that watch things happen, and those that just wonder what the heck is happening. Which one are you?

1977 MCI Crusader MC-8
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