WITCH Coolant bypass SHOULD you USE ON YOUR 12 valve Cummins.

Few options for doing coolant bypass on your 12 valve Cummins.
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[@dustindd789]

You can also get a bypass from Cummins. I put it on my 12v in a f350. As for hose routing I just ran it strait over to the heater core. Doesn't overheat and the heater works fine

[@CUTTERUPROB]

Oh yes. I should have talked about those as well. There for a industrial application. I am pretty I have a couple I will have see if I can find one to post some pics of

[@buckshot927tx]

Awesome man I’m glad you mentioned this. I’m installing a 12 valve in my wife’s Excursion. Do y’all know the part number for the factory Cummins coolant bypass?

[@nathanialholdridge9507]

@@buckshot927tx 3925226

[@buckshot927tx]

@@nathanialholdridge9507 thanks man!!!!

[@maxx597]

LOVE your shop,keep up the 12 valves mods

[@bdjm8595]

Straightforward solid info, thanks Rob!!!

[@bib4211]

Thanks for all your informative content and I hope you keep doing this for a long time! Cheers from Holland (Netherlands)

[@highmellow8071]

I enjoy your videos last week I put a block off plate on my 12 valve

[@CUTTERUPROB]

Right on

[@jimkillen1065]

I bought the fleece unit i think last year , i guess it worked ok . But when winter got here and i was trying to sort out why my truck is not heating up . What a can of worms . First off the thermostat in the fleece unit is stuck open . So i built a right angle needle valve half inch to i stall and that fixed the by passing . Now trying g to find a decent 195 that works . The new Mishimoto was stuck closed . All the other pieces of crap thermostat ran at 145 degs . All so is there a coolant sealant you use with a Mishimoto radiator. Thanks for the videos

[@maxx597]

damn, it would be cool to have your shop nextdoor

[@ruthlessronniethemechanic5639]

I ran a open port atyle and i plummed it into a fleese coolant filter with a regulator to slow down the flow. works beautifully temps are stable. Pyro temps went down a bit thinking due to the bypass setup

[@justsaynrush9689]

I literally just finished popping my rear freeze plug. I watched a video on a guy using a puller and looked like a good idea, which it is if like in most videos they do with the engine on a stand. I ended up using 48" of 1/2 in. ratchet extension w/ 1/2X 3/8 adp. on the end. First removed trans cross member then used where cross member mount to frame on dr. side as a rest and it actually came out pretty easy. I'm 68 and know little about metric bolts and spent way less time punching it out than looking for the right bolts and not being able to reach the back of the block.

[@123suzukisamurai]

Excellent again

[@mattweisgerber8598]

Plum in from the top rear of the eng a 5/8hose to the suction side of the water pump and use only one original t stat. The engine will be more consistant in temp from front to back. Also aiding in maintaining 190 degrees more evenly from front to back instead of over complicating it with two which the one will force cool coolant in the front of the engine.

[@CUTTERUPROB]

I will playing with a bunch of different combos next summer.

[@jamescharron8550]

I have the NPT port bypass on my 4bt, I use it as the coolant feed for both turbos in my compund setup.

[@CUTTERUPROB]

Sweet. One of these days I should do some 4bt stuff.

[@claytonleckie9924]

Looked at one of the Amazon China knock offs for the bypass but did spend the money and ordered a fleece kit today some things can't be cheaped out on

[@jimmungai1938]

With that fleece kit with the thermostat cadet be used on my 91.5 give you three guesses was under the hood this is six in a row jim from Kennerdell a Pennsylvania

[@CUTTERUPROB]

They don’t

[@1BigCountry143]

Can you install a fleece coolant bypass for a manual transmission on a 48re automatic transmission? I dont want to bypass & disconnect my transmission heat exchanger. Let me know thanks.

[@MrHuntertaylor]

Can you please do a video talking about the cummins bypass housing! I like the idea of not having a thermostat in a non accessible location. Thanks man I love all the videos

[@CUTTERUPROB]

I can yep

[@MrHuntertaylor]

@@CUTTERUPROB thank you! All of your videos are great, I'm building my 95 3500 C&C service truck and want to do things that will make this ole girl last a lifetime. I appreciate all your info you've given us through your KZbin channel!

[@jaythacker5160]

I tried the Fleece bypass on my 2012 cummins street truck and the dang t-stat in it stuck open, I called them and tried another t-stat and it stuck open as well. So I took the kit off and just used a block off plate on the back freeze plug. On my 2008 race truck I'm just using an electric water pump. In both instances I was doing it to prevent blowing freeze plugs at high rpm. I'm running a coolant pressure sensor in my race truck so I can monitor if the pump ever dies (which they are know for) otherwise you'd overheat in a hurry.

[@CUTTERUPROB]

i have used atleast 50 of the fleece bypass and never has a issue with one. the one i had in my dd truck has been in there for years ( witch reminds me i should put that back in lol ) the electric pump are but for dyeing so be good idea to have a gauge

[@jimkillen1065]

Yea i also have a fleece doing that and it throught me for a loop trying to figure out why my truck was running cold . Till i felt of the hose and realized this thing is by Pass in stuck open . So i finally took a SS half inch valve made for swedge lock fittings and right angle. Cut off the swedge lock ended and welded on the half inch pipe fittings to replace the 90 deg fitting by the thermostat housings. Basically i can throttle the flow or stop it completely. Works good . I only open when i towing and need the flow to help cooling .

[@bib4211]

Hey Rob , would it also be possible to put a standpipe in the 20 millimeter hole you talking about on right side of 6th cylinder in the head and run a hose to the front fitting that's under te alternator bracket (close to the lower coolant inlet) On the 12 valve with automatic transmission I got there was a heat exchanger connected for the automatic transmission!

[@CUTTERUPROB]

I don’t see why not

[@clintjackson2783]

Dows anyone know if a Fleece coolant bypass will work for my 1993 5.9 Cummins 12 Valve? I only see a Fleece bypass for 1994-1998.

[@jim5870]

I've heard it said that its good to add an extra .001" piston bore clearance for #6 cylinder to help it handle the occasional high heat moments. True? False? Thanks BTW

[@CUTTERUPROB]

yep that is common

[@davewhipple4815]

I have a 12 valve first gen what do you think of bypassing the heat exchange

[@CUTTERUPROB]

I have lots of time with no issue. But you do want to let them warm up if your live were it gets cold

[@farmerboyfpv3637]

Could you run it out the bypass through a davco 382 to heat wmo? Or atleast good or bad idea?

[@CUTTERUPROB]

FOR SURE YOU COULD

[@tnhotrodder]

8:48 minutes into this video, you mentioned a way to actually do the job on a 12v without being either a magician or pulling the engine to fight the rear freeze plug removal and bypass install by just putting a tee onto the temp sensor npt in the head and spacing the sensor out an inch. That seems waaay easier. My goal is strictly to cool the #6 cylinder better. Where is the smartest, neat and clean way to reroute that hose back to? Is it possible it would ever flow too much and the head be starved for more flow?if so, is there a size hose you recommend to cool #6 but not starve the head? As in could it slow down water distribution somewhere important or create an air pocket at the top of the head ?

[@CUTTERUPROB]

Ya you can add it to the back of the head. I prefer it in the block as the heat comes right from the 6cyl. But the I have done them off the head. Thats how I have done it for ford conversions I have done for the heater core. But if you run it full flow and have a heater core hooked up the engine will run cool

[@nordic95]

Im buiding a 2004 5.9 cummins now for my 2500 quad cab auto trans. I want to run the fleece bypass kit but im concerned about eliminating the torque converter cooler on the motor. I reached out to Fleece and they just said it has to be eliminated. Anyone have any ideas on how i may add a "T" or something and still run the cooler if at all possible?

[@CUTTERUPROB]

you dont have to you guess have too re route the cooling line

[@branmanhosmaniac3489]

I have a few question (skip paragraph to ignore my little introduction) but i need to ask an overly viewed topic, but since I removed the trans heat exchanger, can I tap into the line that supplies coolant to the heat exchanger and go unregulated flow to cylinder 6? This is a topic that has many similar questions, but I guess I don't understand the coolant t flow enough to make sure I'm doing the right thing. 1) In the bypass kits, is the flow going from the hose into the block, or from the block into the hose? 2) If the trans heat exchanger was removed, instead of plugging the line up top, can I tap in there instead of the thermostat housing or upper rad. 2.5) If I can tap into that, is it safe to plug the bottom port for the heat exchanger without creating a deadhead scenario? AS OF RIGHT NOW, the truck is stock and I plan to do mild towing, but my purpose is to prolong the life of the engine with a lil preventative maintenance. Also, may be a dumb question, but if it's ran unregulated flow, what do u mean use an orifice? I'm not familiar with that term, any sort of example I can look up to truly understand what it is, as I don't feel I need that much flow. Please answer this if u get the chance, it's been bugging me for a while, im ready to purchase and install!!!

[@CUTTERUPROB]

Flow is from block to rad hose. ( block is pressurized) Heat exchanger just plug the lines off Orifice is just a resistor in the line to slow flow down. Hopefully that answers what you need

[@branmanhosmaniac3489]

@CUTTERUP ROB yes, it definitely helps. And I'm gonna ask one more silly question, just to make sure we're on the same page; but when u say coolant flows from block to rad hose, I just want to verify we are talking about flow from the rear plug to the hose that would be installed with a bypass kit?

[@jimmiller4951]

What should I do for a 1991 BT5.9 1st gen to cool the # 5&6 cylinders ?... Oh great video Bud

[@CUTTERUPROB]

Any type of coolant bypass would help

[@jimmiller4951]

@@CUTTERUPROB Thank you but I was hoping you would recommend a specific one ...... haha . Your my go to man ,man

[@CUTTERUPROB]

@@jimmiller4951 keep an eye out for when I am working on SHAE ‘S truck I am doing to do one on his truck. I am not sure what will fit and what won’t.

[@jimmiller4951]

@@CUTTERUPROB , Thank you I am always keeping an eye out for your videos . The key is to find that one person who actually knows what he's talking about and stick with him. Yes Sir

[@bruno3617]

You say the bypass valve that works on pressure at high speeds opens at 70 psi. Since the radiator cap only holds 15 psi in the system, how does that work?

[@CUTTERUPROB]

Block pressure is higher as the holes in the head gasket are small so it build pressure

[@jameshinton2755]

Will coolant bypass help lower the risk of a 53 block cracking or is there something else I can use

[@CUTTERUPROB]

it doesn't make that much difference for that . but it can't hurt

[@corpsmind5920]

Which

[@rickwildman2260]

Posted it to Ramforum for you Rob. www.ramforum.com/threads/for-the-older-cummins-owners-on-here.170511/

[@CUTTERUPROB]

Awesome thanks Rick!

[@willshanahan3689]

You do not need either thermostat, you all ready have one , hose from back of block to brass tee at behind thermostat, thermostat opens coolant flows , about $65 dollars in parts , 638 hp never over heated

[@CUTTERUPROB]

Doesn’t really have to do with over heating. It’s more for keeping the engine stead temp in the colder weather.

[@Cumminsmcgee]

What size is the brass fitting

[@yoanlm1872]

hello, where are you located? I would like you to do a job for me

[@CUTTERUPROB]

I am in Calgary Alberta Canada

[@yoanlm1872]

@@CUTTERUPROB wow too far to take my cummins engine to you, but maybe you could help me with some tips on how to upgrade it. i'll pay you for that if you agree

[@leviwolf5839]

You really shouldn’t use a quarter turn valve u might have never had a problem but a quarter turn valve isn’t really designed for throttling the valve tht is designed for throttling is a globe valve the quarter turn can suffer from premature wear we used for throttling but like I said u might not have ever had an issue I’m a pipe welder and pipe fitting so I’m not jus blowing smoke or selling snake oil

[@CUTTERUPROB]

you are 100% right that the 1/4 turn ball valve is not designed to restrict flow. really should use a needle valve or a orifice to do it. But i have never had a issue doing it on low pressure application ( 40-80 psi ) even in a industrial application when i did my millwright

[@leviwolf5839]

@@CUTTERUPROB it would take a long time to eat the ball away in a ball valve the only thing with a needle I would think I would clog would in not????? By the way really like ur channel u know ur stuff for sure goin to be swapping a 12v in me 96 Chevy and I will definitely be referencing ur videos I’m hope to get one thts pretty good shape just gone the cylinders new rings bearings gaskets I’ve worked on a lot of small block Chevys and been turning wrenches my whole life so I am mechanical inclined but never torn a diesel down