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Author Topic: Re-engining an MCI8 with a Detroit Series 50  (Read 19375 times)

« Reply #30 on: September 05, 2006, 07:54:05 PM »

I certainly didn't mean a slight when I spoke about "amateur" status.   I'm an amateur road racer and I've held or tied lap records at two tracks.

I could tell by some of the comments that you hadn't glommed onto the installation manual

The bleeder tube from the Thermo housing is a good thing but it only works as advertised if you have the tilt.

You can still generate air in the system even with two radiators, but not if they're "fresh"  Configuration of various goodies in the system can do it also.

Remember the coolant is "close" to boiling, so it don't take much pressure differential to "spontaneously" develop aeration.

Pump becoming 'air locked" is an extreme situation.  You can get the engine in trouble long before you lock the coolant pump. 

It may be that the loss of cooling capacity with aeration prompts people to jump to the conclusion that the pump is air locked. 

My guess is something would break, due to the nature of aeration and the engine's response to its presenced, long before the coolant pump air locked.

I compliment you on your approach and presence of mind.  You've got most of the "battle" won.  Just alot of diligence and hard work in front of you now!

Onward and Upward

Clarke Echols
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« Reply #31 on: September 05, 2006, 08:58:50 PM »

I am not familiar with any "installation manual" for the S-50, but I have a copy of the EPQ (end-product
questionnaire) which specifies a long series of tests that are required to be performed and passed, or
the warranty on the engine is void.

I haven't noticed any "tilt" on the S-50 in my Neoplan which was installed in a repower by Stewart &
Stevenson in Denver, so I don't have an opinion there.  However, it is critical that all air
be rapidly removed from all coolant passages in very short order after starting or you can expect very
big trouble.  The amount of heat generated by the high temperatures inside the cylinder make it
imperative that there be no possibility of gas bubbles forming against the cylinder surfaces at
any time during operation.

The tests call for a clear tube in the radiator hose going to the top of the radiator with a piece of
string or yarn to demonstrate fluid flow through the radiator.  The surge tank must be above the
engine with a bleed tube from the de-aeration port on the engine upward to the tank.  There
are some other details as well, but my memory is fading and the book isn't readily at hand right now.

You should be able to obtain a copy of the manual from any DD dealer or parts department.  It
is well worth studying and understanding.  Experience has demonstrated to my satisfaction that one
can avoid a lot or problems by simply understanding how your equipment works so you can
recognize when things aren't as they ought to be.  I repair a lot of stuff operated by "mechanical
bozos" who never bothered to understand or try to understand, even though they no doubt could
with some effort.  It's a very expensive "easy way through life".


« Reply #32 on: September 06, 2006, 08:04:59 AM »

For the record, I didn't refer to the installation manual when I made my comment about installation manual.

Actually,  I was quoting "hearsay."  At the same time, just because it's "hearsay" doesn't mean it's worthless information.

At the time I posted, I happened to be on the telephone with Bob Sheaves, discussing the point with him.

This was probably the (innocent) impetus for the "amateur" comment.  Bob, while workding for DD, was an engineer on the original S-60 design (Big Brother to the S-50) team and probably has an "idea" of whether or not it is BETTER to install the engine at a slight nose up angle.

Bob is currently working with Freightliner, helping develop cooling systems used in Export versions,  like the land train picture shown in another thread.  This was the truck application he was working on when "we" gave "his" seminar on "All you never wanted to know about cooling and were afraid to ask!" at Rickreal in July.

When I've commented that things can happen very quickly, look at it from Bob's perspective.  Trying to make it work, rather than trying to "get by" like a less than knowledgeable converter,   In new truck installations they've blown 5 Mercedes engines in a little over a month. 

To ressurect a topic routinely raised about "band-aid" fixes to cooling systems augmented by misters . . .

Bob's open minded, because he understands all the competing factors.  A cooling system can be designed to employ a mister system.   If it isn't designed, from the start, to employ a mister system,  it isn't a good idea to rely on one because other attributes of the system can prevent the engine "realizing" what a mister system can do- at exactly the point one needs it.

Onward and Upward
Greg Paciga (S.Ga)
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4 years and I'm almost there. N.J. Transits Rock!


« Reply #33 on: September 06, 2006, 03:49:40 PM »

Well I must comment here. This has been one of the most enlightening posts I've read. I have spent the last hour reading each and every opinion posted here. VERY GOOD READ!!

 Each and every one.

Now...Fred Hobe tells me my 6v92T is one of the weakest he's ever seen. Even though (according to the wheel odometer) the rebuilt blue "reliabuilt" engine only has about 30K mile on it. I'm thinking that maybe it's just the down sized injecters that N.J.T. had installed on all of thier replacment power plants to try and conform to air standards.

But I haven't had the time or money yet to send it to the local experts to re-rack the engine and actually check the size of the injectors.

Good read guys
Greg Paciga (S.Ga.)

Don't think your going to do a conversion overnight. I did and 4 years later I'm still only 85% done. LOL Smiley Smiley

Why?? Because I did it right. Check out my any of my 900+
pics posted on Community webshots.com
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« Reply #34 on: September 06, 2006, 07:10:05 PM »

But I haven't had the time or money yet to send it to the local experts to re-rack the engine and actually check the size of the injectors.
Greg Paciga (S.Ga.)

Greg, sounds like you have a "ceramic" engine. If it is an ex-NJT with a blue engine, it is the most emission cleanest they had prior to the DDECs. It does have small injectors, but you may find some power increase by running the max gov speed up to 2100 RPM. It's probably set to 1800 RPM. That alone will make a noticeable difference in power once you get going. The "blue" engines had ceramic liners. Yours may have steel in them now...depending on whether NJT was responsible for the last major. Silver color was also Reliabuilt, purple was in-house NJT, and blue is the very low emissions ceramic cylinders.
Didn't I see that you're coming to Timmonsville? I've never seen a "real" blue!
See you there! JR

JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.

Ayn Rand
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73 MC7 with Series 50 and 10 speed

« Reply #35 on: October 13, 2006, 10:43:59 AM »

The installation manual I found is DDC pub 7SA747 of May 04.  It is for Construction, Industrial, and Marine applications, not for mobile applications.  Still has a lot of good info.  It is a 433 page pdf.  I will be glad to share it with anyone interested.  It also applies to S-60s.

Actually, my S 50 engine is hard to get up to normal 190 deg operating temp.  I have changed the thermostats and seals, which helped a little.  It only runs at around 140 normally.  The only time it gets up to 190 is when we are on a long pull.  I don't understand this behavior.  I have 2 gages, and both show about the same temp.  Any ideas? 


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The Quest is But The Beginning...

« Reply #36 on: October 13, 2006, 10:53:26 AM »

Here is a link to a newer version of the same PDF....somebody had posted this in a thread a few days ago, but I cleaned it up

S60 A&I  7SA747 0405.pdf


Edited:   Sorry,  Niles500 was the somebody I couldn't remember who posted this link on another thread  I jus' modified it a bit   Roll Eyes
« Last Edit: October 13, 2006, 07:58:51 PM by eglluvr » Logged
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