Yesterday I was fidling with the cdr valve and ended up pushing on my top radiator hose, it was full of air, so I look in the radiator and I the level was down to where I could see the core part.. So I top it off and fill my overflow tank halfway.... This morning I go to a friends house and when I get there I hear all this noise, look under, there is a big gushing of antifreeze spewing out from the pitcock valve.. So what do you guys think could cause this? I am thinking either the radiator cap blowoff psi is too high (mines 13psi) or the cap is stuck.. But maybe there are a number of other reasons that I can't think of.. I am also not sure if the coolant is even flowing.. I have looked in it several times and never see any flow but don't know if the radiator is just too big or something.. I am going to change the thermostat while I am at it since I have one and now that I have no antifreeze I figure I will kill 2 birds with one stone.. But is there anything to bleed the antifreeze around the thermo? I heard that when you change you antifreeze you can create an air bubble where the thermostat is and then that air has to get super hot to get the thermo to open..??

 

Cap pressure is 13lbs.......but a new cap slightly lower would not hurt. You will not see any flow........as for super hot coolant part BS... see below re the check ball... that is what releases air as you fill the coolant.... so it has to work.

CAUTION:
The specified/required thermostat does not contain an internal bypass, since the bypass is located in the cylinder block. Whenever the thermostat is replaced, it is mandatory that only Motorcraft E5TZ-8575-C or Navistar 1807974C94 thermostat be installed.

CAUTION:
Do not attempt to repair any thermostat. It should be replaced if it is not operating properly.

Check the new thermostat before installing it for correct opening temperature. Before suspending in boiling water, with a flashlight check where the rubber and the flat metal flange meet for bad seal. Tstat should start to opening barely at 180-192f, fully open 200-212f, allow to cool and check for rubber seal again.

Removal: Disconnect batteries, drain 4+ gals A/F, remove: as required, fan belt, alternator set aside, alt bracket, remove filter support from fuel filter then e/block. Disconnect upper rad hose at rad, remove tstat bolts and housing. Clean both faces, depression and holes in block, ensure check ball in goosekneck is clean, free and rattles "do not remove".
Installation is reverse proceedure, I do not use sealant on gaskets and faces. REMEMBER the tstat pellet(copper end) goes into the block. I do use a "very small amount" of sealant on the edge of the tstat face when installing into the recess, now go for coffee, allow sealant to setup, this has saved me from tstat slippage when the gasket and goosekneck are installed. Replace all items in reverse order......

Manifold bolt torque......... 20ftlbs

Need more pics etc.. click on my name and email me.......

 

Ah, I see.. That thermostat sure sounds hard to change.. I'll do it all though.. Something just can't be right though.. I don't understand why that thing blew. And for some reason I never have anything in the overflow tank, it sucks it all down..

 

Didja tighten the petcock? It just might be loose?

 

I can't touch it till after wednesday because I don't have the time.. I looked at it last night but it was dark and I couldn't see anything.. I might be able to glance at it today when there is light..

 

[QUOTE=PLC7.3]
CAUTION:
The specified/required thermostat does not contain an internal bypass, since the bypass is located in the cylinder block. Whenever the thermostat is replaced, it is mandatory that only Motorcraft E5TZ-8575-C or Navistar 1807974C94 thermostat be installed.

QUOTE]

I've never heard of this is this the same for the 6.9? got any pics of the differnce I had problem with my 6.9 blowing the water out of the burb bucket every one said bad head....

 

Well I finally got time to mess with it. All I did was screw the petcock back in and it's fine. Now.. HOW IN THE HELL DOES THAT HAPPEN?? The only thing I can think of is maybe when I changed the antifreeze 2 years ago, I left the petcock open and something clogged it...until now.. But I am doubting that theory very much... You guys got any ideas?

 

460429freak.... that has been gospel since i got my truck in 93, but it is applicable to all back to the first 6.9. Parts guys will fork over anything to get you outta the store..... I will admit there is one aftermarket tstat out now that is almost similar...... however it comes with a rubber sleeve which must be removed....... I find the oportunity to miss those instructions not worth the hassle if you burn up an engine. Also some parts persons just do not know the difference between IDI and PSD cooling systems and usually sell PSD tstast when specific IDI ones are needed.

Runred was the rubber seal still there or are you face to face with the plastic....