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kd4jfd
Top Member

USA
1152 Posts

Posted - 01/10/2012 :  7:21:15 PM  Show Profile  Click to see kd4jfd's MSN Messenger address  Send kd4jfd a Yahoo! Message  Reply with Quote
I have a '96 BB TC 5.9 Cummins that is loosing about 2 quarts of coolant a day. The mechanic has replaced the cap 3 times and the last time it helped to recuce the loss to about 1 quart. It appears to be blowing it out the cap and overflow tube. The cap is a 10 lb. Any suggestions/helpful comments?

Thomasbus24
Administrator

USA
3291 Posts

Posted - 01/11/2012 :  05:24:09 AM  Show Profile  Reply with Quote
Sounds like a head gasket. A guy can fill the system up, then put a pressure tester on (instead of the cap), then go in a start the engine. I'd imagine you'll see the pressure begin to rise right away. That's how we find 'em anyways.

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wrenchmen
Senior Member

USA
115 Posts

Posted - 01/12/2012 :  12:41:58 PM  Show Profile  Send wrenchmen an ICQ Message  Reply with Quote
If this bus is equipped with Air Brakes, it could also be the air compressor head gasket.
Test in the same manner as above but with the air tanks full and engine off.
Gauge will rise as air pressure from air brake system leaks into cooling system.
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Thomasbus24
Administrator

USA
3291 Posts

Posted - 01/12/2012 :  1:32:06 PM  Show Profile  Reply with Quote
Very good point about the air compressor!
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C.HARDY
Advanced Member

350 Posts

Posted - 01/12/2012 :  2:24:32 PM  Show Profile  Click to see C.HARDY's MSN Messenger address  Reply with Quote
You can rev the engine up with the cap off and see if coolant blows out.

"Hardybusman"
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Crown
Senior Member

62 Posts

Posted - 01/16/2012 :  12:18:46 PM  Show Profile  Visit Crown's Homepage  Reply with Quote
We've had a few of those with leaking head gaskets. We think it traced down, in our case at least, to some new coolant that we were using. Putting assumption on top of assumption, we think the problem is fixed.
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02raptor
New Member

8 Posts

Posted - 01/27/2012 :  05:36:24 AM  Show Profile  Reply with Quote
Are you sure it is the cap? We have had to replace the plastic tanks on those and went to a steel tank.

9 school buses.3 service vehicles.4 Tractors and Me.
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bwest
Administrator

United States
2248 Posts

Posted - 01/27/2012 :  07:15:11 AM  Show Profile  Reply with Quote
There is a test stip that will tell you if there is exhaust getting into the coolant as well.

Bryan
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JustinB
Advanced Member

United States
490 Posts

Posted - 01/27/2012 :  2:47:06 PM  Show Profile  Reply with Quote
The strip will come back in technicolor on most any cooled EGR engine from the past 10 years.

I may not know the answer but I can usually find who does.
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Ron Maden
New Member

1 Posts

Posted - 02/17/2013 :  11:33:43 AM  Show Profile  Visit Ron Maden's Homepage  Reply with Quote
I had one with a bad head gasket on the compressor that caused the same problem. Now the same bus is loosing about 1 to 2 quarts a day with out any signs of leakage.
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IBTMech
Top Member

USA
973 Posts

Posted - 02/17/2013 :  4:38:10 PM  Show Profile  Visit IBTMech's Homepage  Reply with Quote
No external leaks. No unusual drainings from the air tanks. It's going out the tailpipe somehow.

If it doesn't fit, FORCE it.
If it breaks, well, it needed replacing anyway.
Pullin' wrenches for 45 years.
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kd4jfd
Top Member

USA
1152 Posts

Posted - 02/24/2013 :  2:01:00 PM  Show Profile  Click to see kd4jfd's MSN Messenger address  Send kd4jfd a Yahoo! Message  Reply with Quote
UPDATES: The mechanic put a 13 lb cap and it only needs to be filled about once a month.

Also, I got a 'promotion' - moved to a different route with less students and smaller bus with more hours.

539 - Repair work in progress! 349 for sale!SOLD!for sale!sold? SOLD and GONE!
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