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Author Topic: MCI7 8v71 stranded grey smoke increasing with accelleration (injector issue?)  (Read 11463 times)
eagle19952
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« Reply #30 on: September 27, 2012, 08:39:06 PM »

liner ports to me to.....but if you want an in-frame ending park it now.
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Dlsnow
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« Reply #31 on: September 27, 2012, 09:10:11 PM »

I didnt see any missing parts of the liner.  I assume "liner parts" meaning the area betwern the ports...they dont seem to have that shape and there are enoigh of them that I would have noticed some missing while I was in there with the scope.  I will take another look tomorrow.
Im going to pull the other airbox covers and see if they are in other cylinders.
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1972 MCI7 8v71 converted - 1kw solar on roof
sdc53
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« Reply #32 on: September 27, 2012, 11:40:36 PM »

My vote is for cylinder liner ports, too. Some of those chunks appear to have a cylindrical side to them.  Makes me wonder where else they are - in the cylinder itself? Maybe the reason you lost the injector is a chunk went inside the cylinder and destroyed the injector (and probably the exhaust valves too). 
I'd pull as many airbox covers as you can and look for more chunks. It should be immediately apparent if it is port material by comparing what they look like.  Maybe it is from another cylinder?
My mechanic was able to rotate the engine with a breaker bar while I watched for bottom dead center on various cylinders.  I'd take a peek at the cylinder surface thru the ports after the piston has cleared the ports at BDC and see if the cylinder (or piston or rings) is all boogered up.
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Scott
Gladstone, OR
1969 PD4107
luvrbus
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« Reply #33 on: September 28, 2012, 06:44:26 AM »

When you lose a tip always try to find that puppy that little piece of metal will do $$$$ in damage,I have to agree with him that looks to be a old injury to me
« Last Edit: September 28, 2012, 10:07:55 AM by luvrbus » Logged

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Dlsnow
dave
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« Reply #34 on: September 28, 2012, 11:36:13 AM »

Kudos to all who identified them as liner parts - I didnt notice the curve since it is so small.
I washed them up and looked at them closer
lengthwise markings on the smoth shiny side - machining on the opposite side and carbon deposit on the other two
I measured with a dial caliper the machined side of one that is installed and it is the same as the machined side of these pieces (.23mm)
BINGO
So i removed all airboxes and inspected the contents -
so far the 12 pieces came from the left rear cylinder
found one more identicle piece in the right rear
the middle four cylinders (airbox contents) were empty - no metal at least
the left front had a twisted up round wire (see picture below)
so i Barred the engine (rh) to BDC for the rearmost cylinders
 - smooth
 - no scoring
ran the pistons up a bit
 - groove is visible on rings
 - no scoring on pistons
Is it logical to check all of the cylinder liners, pistons?

Also it seems like if one of my liners was effectively broke in two parts i would be able to hear it or it would be locked up (just seems like that to me).

After putting the injector back in yesterday I made a critical mistake - not plugging that oil passage right next to the bolt and washer holding the rack down.
The washer fit right down there
So now im off to spend another hour trying to fish that out - thank God they stick to magnets
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1972 MCI7 8v71 converted - 1kw solar on roof
luvrbus
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« Reply #35 on: September 28, 2012, 11:58:34 AM »

You are beating your head against a wall test each cylinder for compression it only takes a small nick in one of 4 valves per cylinder for that cylinder to be weak on compression but we all do it different that tip went somewhere 

good luck
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B_K
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« Reply #36 on: September 28, 2012, 01:50:24 PM »

Dave trust us on this. If "YODA" aka Clifford or Luvrbus tells you something about one of these ol' relics he knows what he's telling you!

I may only be a "newbie" with slower than dial up connection here lately.
But in a former life here on BCM I was better known as Busted Knuckle and can assure you that of all the advice Luvrbus has ever given, I can count on one hand how many times his info has been incorrect! (and still have 4 fingers and a thumb left over!)

Clifford knows two strokes better than anyone I've ever known. And he knows much about other things too!

So save yourself some time $ & grief and follow his advice. He won't tell ya how to do bargain buster projects. But when he tells you how to do it, it will be RIGHT and you won't have to do it over!

Best of luck.
Grin  BK  Grin
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John316
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« Reply #37 on: September 28, 2012, 02:08:31 PM »

Once again, DLS, if Clifford tells you something, you can go to the bank on it. If he says you should test each one, then you should....But, it is your bus. It wouldn't surprise me though, if you don't, that it would cost you way more serious $$$.

Just a thought.
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MCI 1995 DL3. DD S60 with a Allison B500.
Dlsnow
dave
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« Reply #38 on: September 28, 2012, 04:39:26 PM »

well that is a piece of the puzzle
I knew that Cliff loves crabcakes, knows 2 strokes and is dead on with advice
I didnt know that Cliff was luvrbus (im sure I missed this during orientation)

Recovered the washer - still havent found the injector tip - wasnt in any airboxes, didnt find it in the cylinder that it came from with the bore scope or the cylinder on the other side

I am trying everything that you all suggest and the issue keeps getting more and more isolated - thanks to all
Cliff - I would love to check the compression but lack the required equipment

Mechanic will be on the bus Monday for compression test and whatever that may lead to.

and again thanks to all - I cannot express my appreciation enough
sorry I didnt know your username Cliff
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1972 MCI7 8v71 converted - 1kw solar on roof
rampeyboy
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1954 Scenicruiser PD4501-227




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« Reply #39 on: September 30, 2012, 04:48:47 AM »

Could they be broken piston ring pieces?
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Boyce Rampey
Columbia, SC
Scenicruiser 227
Dlsnow
dave
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« Reply #40 on: September 30, 2012, 02:10:42 PM »

Ok confirming for all.  The pieces were definately liner pieces.

Cliff I will definately get the compression tested...I planned on having the local machanic who runs older mci busses do it.  He has been great so far but when i told him i wanted the compression teated he said i dont know 2stroke dieseld (i dont, just learning) and that he wouldnt because they make so much psi that itll knkck you over.  He said about 2200psi.  I didnt challenge him (i know spec says 565psi new and 515 min from manual) over 350 is what im hoping.

So now i need a mechanic who knows 2stroke detroits in central Wisconsin.

I ordered the HF kit for testing compression.  Looks like you replace the inje tor with the plug from the kit.

Is there a way to do this without a tachometer?

Also...WOW the post reply page popped up in record speed. 
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1972 MCI7 8v71 converted - 1kw solar on roof
Dave5Cs
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1979 MCI MC5Cs 6V-71 HT-740 Allison, Roseville, CA




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« Reply #41 on: September 30, 2012, 02:43:21 PM »

Clifford , Were me, I'd put in for for a few more Crab Cakes dude.
As usual you were correct and I'm guessing will be fully right by the time DLS is done with this.
Go for the Clams and bellies too, LOL

Dave5Cs Grin Cool
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sdc53
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« Reply #42 on: September 30, 2012, 05:07:12 PM »

Methinks that if the ports were busted to this point that is would equate to broken rings, too because the head of the piston travels below the intake ports.  The rings need a cylindrical surface to slide on and if most of it is gone, the rings would break passing by the large opening.
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Scott
Gladstone, OR
1969 PD4107
luvrbus
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« Reply #43 on: September 30, 2012, 05:36:38 PM »

He is headed in the right direction with a compression which is a PITA to preform on those engines if he finds the bad cylinder and maybe more weak ones no sense in wasting his time and money to replace the one bad cylinder just rebuild it a simple solution it will save him money in the long run and it could be just a valve   

He sounds like he can do it if he follows the book
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Geoff
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« Reply #44 on: September 30, 2012, 05:52:44 PM »

It might be one hole, it might be that someone overheated the engine and all the kits, heads and injectors are ready to fail.  So the first hole went out-- the rest are ready to follow. With all due respect, the engine may be gone.  That is why you have to follow DD failure analysis prodedure which means you test it when it runs, then start taking it apart to see what the total damage is.

--Geoff
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Geoff
'82 RTS AZ
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