Cummins 6bt thermostat question

[FellowTraveler]

I've noticed most of the replacement thermostats on the 4/6bt are not "hi-flow" and look like the 6.2/6.5 bypass type thermostats with a somewhat smaller opening for coolant flow. I run the "hi-flow" in my 6bt which looks like the thermostats on the dual thermostat 6.5td but with a bypass valve on the bottom too.

I'm suspect of the smaller thermostats actual opening size creates an a pressure issue in the cooling system and question as to whether or not they actually do contribute to the system pressure rise at upper rpm's which everyone claims pop casing plugs (aka: freeze plugs) on the blocks of the 4/6bt series...

I bring this up because more than a few vendors have tried selling me billet covers to replace the plugs....

 

[ak diesel driver]

What kind of rpm will you be running? I run my 4bt up against the governor quite a bit and no issues. I'm not using the stock stat either as it's only 180*. Just started going thru stats at the parts store till I found a 195 that would fit.

 

[FellowTraveler]

What kind of rpm will you be running? I run my 4bt up against the governor quite a bit and no issues. I'm not using the stock stat either as it's only 180*. Just started going thru stats at the parts store till I found a 195 that would fit.

Going to try and keep it 3.5k rpm max just don't know yet.....

 

[Will L.]

Everytime people have a concearn on cooling systems they want to say "popping out frreze plugs". Bullcrap.

What is the pressure release on the cap- 85psi? 75psi?
Less than 20. If anything happens and they pop a freeze plug, First: their cap was toast. Second: their engine should have been PSYCHO overheated to generate the amount of pressure needed. UNLESS their cooling system is horribly corroded to the point the freeze plugs are eaten away.

Go to a junkyard with you coolant pressure tester. Hook it up on something that is still sealed, and pump away & watch what it takes.

 

[ak diesel driver]

I sense your are holding back Will, tell us how you really feel LOL

 

[Will L.]

I sense your are holding back Will, tell us how you really feel LOL

I would, but I don't want to take up a moderators time of deleting certain words/phrases and getting chewed out. Haha. No wait, really.

 

[FellowTraveler]

Everytime people have a concearn on cooling systems they want to say "popping out frreze plugs". Bullcrap.

What is the pressure release on the cap- 85psi? 75psi?
Less than 20. If anything happens and they pop a freeze plug, First: their cap was toast. Second: their engine should have been PSYCHO overheated to generate the amount of pressure needed. UNLESS their cooling system is horribly corroded to the point the freeze plugs are eaten away.

Go to a junkyard with you coolant pressure tester. Hook it up on something that is still sealed, and pump away & watch what it takes.

I've had no problem with the cooling system and recently one core plug out of all being slightly pitted but the Cummins was stock then.

Since I'm modifying for more tq/hp + higher rpm I've come across all these stories in my research about popping core plugs due to water pump output increase as rpms increase then more talk of getting billet core cover eliminators.

The one common item I did see different are the thermostats.

So in the end it's all BS just marketing to sell high priced billet.

 

[Will L.]

Billet would fit very accurate, but at that point why not screw in style and be done with it. More expensive but 100%.

 

[THEFERMANATOR]

Alot of the issues with freeze plugs popping out is on engines pushing 4 digit and up HP. That kind of stress can push anything to the limits, as well as pop freeze plugs from the block flexxing and moving going through the motions of running. Another overlooked item is everybody thinks the 5.9l cumm8ns block is some heavy piece of iron that nothing can affect. Well it's already been proven that simply pushing on the side of the bl9ck with no head on it can change the cyli,der shape enough to measure on a finite bore gauge. Were not talking much, but the point is these blocks are not some magical creation that nothing can break. Yes the blocks twist, flex, and move as the engine runs, and as the power output goes up, so does the movement. And I could easily see it get to the point of walking a freeze plug out when the block is really being pushed. For the average owner, I don't see it being an issue myself. As to which stat, I always used oem, but that was because I was working at a dealership doing them.

 

[FellowTraveler]

Alot of the issues with freeze plugs popping out is on engines pushing 4 digit and up HP. That kind of stress can push anything to the limits, as well as pop freeze plugs from the block flexxing and moving going through the motions of running. Another overlooked item is everybody thinks the 5.9l cumm8ns block is some heavy piece of iron that nothing can affect. Well it's already been proven that simply pushing on the side of the bl9ck with no head on it can change the cyli,der shape enough to measure on a finite bore gauge. Were not talking much, but the point is these blocks are not some magical creation that nothing can break. Yes the blocks twist, flex, and move as the engine runs, and as the power output goes up, so does the movement. And I could easily see it get to the point of walking a freeze plug out when the block is really being pushed. For the average owner, I don't see it being an issue myself. As to which stat, I always used oem, but that was because I was working at a dealership doing them.

Thanks FERM great info, I going very mild on this one....

 

[Will L.]

@THEFERMANATOR Just wandering, what is oem instruction on installing? All clean and drive till just beyond flush or adding any of the "magic" ie. locktite or silicone.
I have seen more cummins guys (usually big rig) do that than anyone else over the years.

 

[THEFERMANATOR]

I don't know what cummins spec was. I know most machine shops I know of use the black permatex aviation sealer that comes in the white pladtic container with the brush atatched to the lid. Works really well.