tested the heater core

[johnjem]

to test the heater core on a 4905 up front in the heater box i removed and cleaned it up to be sure there are no leaks i was going to run some air in it what would be a good psi ?without blowing it up??johnjem 4905

[TomC]

It should be able to take 50psi easily, since the system works at around 10psi.  Good Luck, TomC

[makemineatwostroke]

John most shops test at less than 5# of air no way would I use 50# of air on a 7# system

[Sojourner]

As per makemineeatwostroke quoted.
Fill a pump spray bottle with half teaspoon of liquid dishwashing soap and water to spray over radiator for continuous small or large bubbles. If you don't see flowing bubbles now, then wait a few minutes later to see if more tiny bubbles presenting.

Never go over 20# psi.....brass and copper is soft metal and will flex to cause crack or leaks if over working designed pressure.

Check your manual for correct radiator cap's pressure spec.

I suggest to borrow a Stant tester to pressurize the whole system while you at it.
Example: (older version is great) http://www.stant.com/brochure.cfm?brochure=578&location_id=183

Some of new cars are going for much higher pressure now.....testing at 30# psi. This is new on me.


FWIW

Sojourn for Christ, Jerry

[gmbusguy1]

the 4905 cooling system runs at 4 to 5 PSI

Chris

[TomC]

I apologize for the wrong information, just called Atlas radiator in Norwalk, Ca that works on only industrial radiators, and they test all their radiators and heater cores at 15-20psi.  Good Luck, TomC

[Sojourner]

Thank you TomC for the update.

Sojourn for Christ, Jerry

[Paso One]

Typically guys the system is tested at the Rad cap pressure as it should never exceed that if the rad cap is working correctly

[johnjem]

Ok i got it. I ran a test at 7 psi had found some pin holes i didnt go any higher on psi didnt want to make them pin holes any bigger,next step how or best way to seal the core??any ideas?? johnjem 4905

[belfert]

Personally I would look for a new core if you have pin holes.  I was having overheating problems even with a Series 60 that runs cooler than a 2 stroke.  I sent my radiator out for cleaning and when it was rodded out there was evidence of stop leak being used.  The pressure test found a number of pin hole leaks.  The choice was between soldering shut the bad passages or a new core.  There was a chance of more pin holes developing with the repair.

I choose the new core and my overheating problems are over.  The temp sits right at 195 on all but the steepest grade and I only gained 5 degrees then.

[Sojourner]

About pin holes in core....Bar Leak or any radiator stop leak would work temporarily however being a bus with long coolant line runs and big engine mean allot of coolant capacity. Think you are still going have many problems using stop leak.

Very common after many years those radiator and heater cores get pitted as well fins between cores are loosening to be less effective heat transfer. I go to your good local radiator repair stop and have them install new core assembly using your old tanks. Then you will be trouble free plus increase BTU output.

FWIW

Sojourn for Christ, Jerry

[roadrunnertex]

The drivers heat,defroster core on the P8M4905A coaches are the same core as the 4104,06,07,08,s and the Scenicruiser PD4501.
The one on my P8M4905a was leaking also and I had a radiator shop repair the core.
The BTU rating on the drivers heat/defroster system is 40,000 BTU's.
It will keep the front of the bus nice and warm on a cold night.
jlv

[JohnEd]

What Belfert said!

John

[buswarrior]

Yup, get a fresh core.

Do you really want to have to take that thing out again anytime soon?

happy coaching!
buswarrior