bluechrome

I need an explanation on the Freeze plugs in a cr Cummins. I'm Not sure Why High boosted CR's Bloe freeze plugs. I understand why High Rpm's Would cause Freeze plugs to blow out due too the water pump Spinning at a faster rate therefore creating higher pressures in the coolant passages, Causing the freeze plug to blow. But what I don't understand is how is "High Boost" Relative to freeze plug blow out? I didn't think the drive pressure's had anything to due with the cooling passages. Are some of the plugs Oil gullys?. I know that in Nathans kit's he has a piece that replaces the freeze to Drain oil for the top charger. So that means that, That paticular plug has to be in a pressurized Oil passage. Right?
Help me Understand this

Raspy

I think it's all about boiling the water in the engine before the t-stat can get opened up during a run. The stat is very slow opening and a sudden very high amount of heat goes into the water jacket while the stat is closed or just barely open. The pressure builds because of very high temps and cannot escape fast enough. Finally the freeze plug blows out.

It's a steam boiler.

bluechrome

I mean I guess I can understand how that can make sense. But, With sled pulling around here there are tons of guys including myself barley get up to 170deg before we pull and havn't had a problem. So far..... My truck can get very hot pullin to

Billm2004

mine was at full running temp before i raced and blew out my freeze plug.

jlibert

Common theories for freeze plug issues.

1. Head gasket lifts slightly under boost, pressurizing the water jacket, in turn blowing out the freeze plug.

2. excessive pressure from the water pump spinning at high rpm's with increasing water temperature drives out the freeze plug.

3. Hot freeze plug in block meets cool water from radiator when the thermostat opens. Combined with excessive pressure from pump spinning at high rpms = freeze plug blows out.

4. Cummins has some kind of defect in tolerances of freeze plugs and/or block castings.

Take your pick. Any one of the theories listed could possibly explain the freeze plug problem.

Diesel Doc

do like the old ford 427 side oilers and tap the freeze plug holes and use a alen drive pipe plug in them.

Sloverado

Man you got to let the motor get a little heat in it before you pull. I make sure the truck is running at full temp for awhile to make sure the t stat is open all the way before I pull. Yes if it isn't open all the way you can build up enough heat and build pressure. I know some still have but that seems to be on more 04.5's and a few 06's. It seems like the 05 for some reason have had better luck with that.

Raspy

The t-stat is never open all the way unless full cooling is required. At idle while at operating temp it is just barely open. The radiator is cool and the stat is nearly closed to force the engine to warm up by restricting flow. Remember, the t-stat's only job is to regulate the water flow based on temp. At idle there is very little extra heat that must go to the radiator, so the stat is just barely open to allow only a small amount of water into the engine from the radiator

It also responds slowly to temp changes and a sled pull or drag race only lasts a few seconds.

T-stat open all the way occurs while towing, or hot weather with air conditioner on and going up a grade. That sort of thing. Maximum flow through the radiator at times of highest temps and heavy load over a period of time. Not idling.

This is my point about the steam boiler. You dump 500 horsepower worth of waste heat into the block and the stat is nearly closed. By the time it can repond the run is over and the temp is way above the boiling point. The water pressure rises as the temp goes up. It would turn to steam if not contained in a closed vessel, but the cooling system can't get rid of the pressure fast enough through the radiator cap vent so the pressure builds higher and higher as the water goes above the normal boiling point. Temperature equals pressure. Finally, the weak link is found. The plug blows out.

Spinning the water pump faster is not a big change, but adding more heat than the system can deal with will push the pressure to whatever level is required to escape. After the plug it's probably the radiator itself, then the hoses or a different plug.

whoops

If a freeze plug goes. What's the damage going to be? Where/and is there more than one freeze plug?

Diesel Doc

there are several freeze plugs. You will loose all of your coolant. A easy emergency plan would be to keep a expanding type freeze plug in your truck just in case

Sloverado

Well I was dumping over 920 hp of heat in mine at operating temps and have not blown a freeze plug yet. Well I guess my 1600 plus egt's at the first 75 feet doesn't get it hot enough to boil over either.

There are many freeze plugs in are trucks. The main won that blows is behind number 6 cylinder by where the trans bolts up to.

12valve

can you hear it when it blows out? or how do you notice?

in case it blows out what do you do? stop the motor right away??

Diesel Doc

you will smell af cooking. yep shut it down