12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

Coolant bypass

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Old 10-19-2014, 07:34 PM
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Default Coolant bypass

Anybody on here know if you can do a coolant bypass on the good ol 12 valve without using the rear freeze plug like maybe teeing off if the temp sensor? I don't have any temp problems but I am getting up in the hp and I know the stock cooking system is only meant to handle around 350 hp and I don't have any current problems with the rear plug and with something like that why fix it if it ain't broke?? I do however have the plate from haisley machine in case it does go. I'm just looking for some ideas to get me by for now until I get time to rebuild it and do it all right
 
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Old 10-19-2014, 11:07 PM
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.I think it is possable yes.i think i know someone that has it done on their 12valve.
i'll do some checking with them,
 
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Old 10-19-2014, 11:31 PM
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in between the last two Bead bolts on passenger side there is a Frost plug in the head .. you would pop that out and NPT thread it and install a 90* Brass fitting with as big of a hose fitting as you would like .. can also use a ball valve as it will make it more difficult to warm up on cold days
 
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Old 10-20-2014, 11:03 AM
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Originally Posted by 4x4manonbroke
in between the last two Bead bolts on passenger side there is a Frost plug in the head .. you would pop that out and NPT thread it and install a 90* Brass fitting with as big of a hose fitting as you would like .. can also use a ball valve as it will make it more difficult to warm up on cold days
I did think about that but I would think it would be too much stress on the plug. Or is it like a thread in plug that I've never noticed ?
 
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Old 10-20-2014, 01:40 PM
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There is no threads behind the plug, you would have tho thread it yourself
 
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Old 10-20-2014, 02:05 PM
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Originally Posted by Just-Another-Dieselguy
There is no threads behind the plug, you would have tho thread it yourself
Thread the plug or thread the hole in the head?
 
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Old 10-20-2014, 02:39 PM
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thread the hole in the head, the plug will go MIA and you will install a npt fitting that you can put your hose onto. and like stated above, you can install a ball valve to shut the bypass system off to help warm the engine up on colder days
 
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Old 10-20-2014, 09:09 PM
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I wonder what size pipe thread that would be cause we have all the fittings and hoses at the shop and I was thinking a thermostat valve instead of a ball valve
 
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Old 10-21-2014, 01:45 PM
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I think its 1/2" Npt ? cant remember .. I will look into it ..
 
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Old 10-23-2014, 05:18 AM
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Originally Posted by JustAnother_cummins_guy
I wonder what size pipe thread that would be cause we have all the fittings and hoses at the shop and I was thinking a thermostat valve instead of a ball valve
The bypass relieves excessive pressure being built up, so you would want to use a pressure valve not another thermostat valve.

If you are worried about it on a hot street truck personally I would pull your current thermostat and drill three 1/8" holes in it.
 


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