Air in coolant line on 6v92

[wal1809]

I read and re-read the whole thread.  Other than the fluctuating fluid level at run and start up how do you know you have air in there.  Did I miss this?

[vwb11356]

I don't think it is air in the coolant now.  I just have the level that rises.  I do not seem to build pressure.  I checked it with a prssure gauge on the schrader valve and it has about 1psi all the time when running.

[luvrbus]

Do you still have a shut down problem ? and you should have more than 1 # of pressure more like 4 or 5 lbs

[wal1809]

I would say fluid is getting restricted and lowering the level at the point you can see it, raising it elsewhere in the sytem.  Pressure finally takes over the restricting problem, allowing the fluid to move bringing the level back up.  What in this system could open and close creating a fluctuation in the level?   A large air pocket, a restricted automated valve perhaps?

[dickegler]

Hi All,

I wasn't aware there is a high coolant sensor, or code.  Is this DDEC I only, or am I missing something.  DDEC 2,3, or 4 only lists code 43, low coolant level.  Is there some other type monitor on this engine?

Just trying to clear the waters.

Dick Egler

[Busted Knuckle]

OK first off it's been so long since I worked on a "9" I can't remember what they look like!
OK, OK maybe not, but it's been a while! And I never worked on a NJT "9" that had a  DDEC.
So far I ain't bat'n to good am I?
Well I do have a little insight or experience in this area.
Our first Setra '89 model S215 W/8V92 DDEC in it had similar issues as what your having prior to us purchasing it.
We listened to the head "tech" at the company that had it and were skeptical of a coolant sensor causing the shut downs. But he said "can't be that we already tried that!"
Well I just happened to have one laying on the desk that I needed to send back to Setra as they had sent the wrong one to me for a customers bus. (the customers bus had a 60 Series in it!)
So we took a gamble and took the sending unit (little black box like Jr describes, not the actual sensor!)  with us when we went to look at it on a Sat. and first thing I noticed was that the sensor it had was the same as the one I'd put on the 60 Series. So 1st thing I did was asked if we could "test drive it." They said sure, but you ain't gonna get far before it shuts down and you'll have to wait until it restarts to bring it back.
I told them I'd take that chance. So as soon as we rolled out we found a large church drive to pull off at and unhooked the sender and hooked up the one I'd brought and left it hanging. We drove it for 30 miles or so with no issues. Went back and stopped and took our sender off and hooked the original back up. Just as I pulled into their lot it shut down.
They came out and met us as we got off the bus and told us "see that's what it does to us, if ya buy it you'll have to have it towed home.
Well long story short after the deal was made I switched it and drove it home 138 miles with no issues there. (others yes, but not there!)

OK now after we had it a little while I noticed the coolant low it the sight glass on pre-trip so I added some. While loading a passenger or someone told me yer bus is leaking anti-freeze!
So I went and checked thinking I had a "leak" but it was just coming out the overflow.
So next morning it was down again and I added some again. A little while later it was running out the overflow.
So after 3 or 4 times of this I decided to go ahead and start it and see what happened before adding any. After checking the oil, coolant, belts etc.  I started it and finished doing my pre-trip just before taking off I took one last look at the coolant level and there it was right where it was supposed to be.
So I always waited to add after that and seldom had too. And anytime dad or another driver would drive it the first thing they would do is add coolant, and then complain it was "leaking" later!   (yeah they never listen to me! )

And we've have a newer Setra ('95) with a 60 Series that does the exact same thing!
So if it's not actually showing bubbles it may not really be a problem.

My guess is shut down is a faulty sensor or sender!
YMMV
 BK  

[Busted Knuckle]

Hi All,
I wasn't aware there is a high coolant sensor, or code.  Is this DDEC I only, or am I missing something.  DDEC 2,3, or 4 only lists code 43, low coolant level.  Is there some other type monitor on this engine?
Just trying to clear the waters.
Dick Egler

I'm with Dick on this! Not aware of high coolant sensor. But I once thought I was wrong, only to find out I was mistaken!
YMMV (and Dick posted this while I was typing my book!)
 BK  

[dickegler]

wal1809,

I have an extra coolant level module that BK is talking about.  I would be glad to send it to you to try out.  I think I have a sensor too.

Let me know.

Dick Egler

[vwb11356]

OK.  I have found there are 3 codes that I know of that are related to the sensor.  

Code 13 that is a Coolant Level Sensor (CLS) Low Pg 134 of the DDEC I Manual

Code 16 that is a Coolant Level Sensor (CLS) High Pg 148 of the DDEC I Manual

Code 43 that is a Low Coolant Pg 148 of the DDEC I Manual

I think the 13 and 16 have to do with a "bad" Sensor.  It tells the sensor either "open" or "shorted".
I misunderstood the 16 fault and thought it meant "high level".

The 43 is that the actual Shutdown fault.  

I do not have a sensor connected and think that the shutdown I am getting is caused by the the wiring or the module as described by BK.  Someone connected the signal to the +5v.  I think this may work for a short time , but the sensor dwg shows it as a Pot.  This may need some resistance to make it work.  I am going to order a module and sensor.  In the mean time I am going to try to get the correct resistance across the line and see what happens.

[vwb11356]

Dick,

I could use the sensor and module.  Let me know how to contact you.

Thanks
Vince

[dickegler]

Vince, sent you a pm

Dick Egler

[NJT5047]

I've got some 'wet' and 'dry' readings off of a Robertshaw low water sensor used on DDEC coolant tanks.  
The sensor has 4 pins, but only A, B, and C are used.

Dry with meter on 20 ohm scale.
A to B = 7.3
A to C = open

Dry with meter on 2000 ohm scale.
A to C = 1570
A to D =   216
A to B =  inf

Wet with meter on 200 ohm scale.
A to B = 156

Wet with meter on 2000 ohm scale.
A to C = 1598
A to D = 1604

Omitted readings were either infinity or open.  
Robershaw low coolant sensors are used on both 2 and 4 stroke DDEC units.   Should be pretty common.  

HTH, JR

[niles500]

Man I hate to keep repeating it - BUUUUUUUUUUTT - replace the cap - FWIW  and HTH