The cylinder head and gasket is design so in the head, every cylinder gets the right amount of cooling. So the further back cylinders have biger holes in them because the flow resistens over all is higher as in the front. But your block sees all that coolent flowing in the front and for each cylinder it gets less and less untill the last one sees just the amount that goas to the head. (But still hase a big volume) Further more the back side of the last cylinder sees next to nothing other then some convection! Most older inline 6 have that issue!! BMW owner here! We have the cab heater back there, and you can put two T´s in that and its return with a small hose between as a restrictor! Your 6th cylinder crosshatch will appreciative! 😉

Yep, definitely impressed with it. Keeps temps lower and from rising nearly as much. And mostly peace of mind from popping a freeze plug.

I got one myself. Installed fit was loosey goosey and leaked like a siv. Called Fleece. They knew what was wrong instantly and overnighted the proper Oring. Oring showed up at 10 the next morning. After calling at 430 the day prior.

My 2004, UK built 12V, P-pump truck engine has the bypass as standard

Been thinking about trying one of these sometime... thanks feller 👍👍👍

I saw firsthand how my 1996 Cummins could’ve benefited from a bypass. Pulled the head at 355,000 cylinder 6 cross hatch was mostly gone. When I pulled it again at 494,000, 6 was glazed, 5 had little crosshatch, 4 still had quite and bit and the front 3 were still looking good. This was on a truck that had a fairly easy life, good oil, changes, towed very little. Power was about 100 hp over stock, and EGT very rarely exceeded 1100. We are wrapping up a rebuild and plan to put a bypass on.

I put one on because I tow heavy equipment , big difference

Great Video Rob. I agree 1000% anything to help cooling is a PLUS 👍👍👍

Did that on my truck for a better piece of mind since the coolant doesn't properly reach the rear of the engine. Have had it on for a few years now and am very happy with the product. Have a 200* thermostat for a 2012 in my 2nd gen and never see over 200* at all! Love it!

Just did my 4th gen with the head off when doing head studs, got the plug out with about 4 foot of 3/8 extensions and a sledge hammer from underneath. It wasn't a hard job at all, a person just has to know what they're doing and they'll be fine!

Great info thanks for the video

Thanks for the video. 👍👍

I have done a fleece coolant bypass on my buddy’s 91 1st gen Cummins w250 and me and him had to beat the fire wall to give it clearance and it was a nightmare lol 😂 but it’s doable.

Enjoyed the video and your experience and explanation of the benefit of running this. Also picked up on your comment about running extra clearance on the two rear cylinders. I would like to know those extra clearance numbers for a 5.9 12 valve vs cylinders 1 through 4. Thanks for all the details you give us in these videos.

@CUTTERUPROB

Жыл бұрын

Awesome, thank you!

Just installed one, truck complete. Dropped exhaust and trans crossmember, wasn't fun but is possible.

6:00 When I have to pull a head, I mod the head gasket. I open up all the holes by a small amount. Then on the back I open those just touch more. I drive my truck to extreme limits every day every light. On the interstate holding 3500 to 4000 rpms following the fastest drivers a 1/4 mile back watching for brake lights. Pass them every now and then to keep the pushing. Need my decoys. 😁 I have never used one of these. I am a pretty extreme case, I think that says it all. and for 300 bucks I would say the money is better spent on head studs. Next truck you build skip it and mod the gasket and do head studs.

Fixes at least 4 known/common issues in the Cummins. 1.) Remedies the overheating that occurs in cylinders 5 & 6. 2.) Deletes/bypasses the heat exchanger on the side of the block that's known to fail & could introduce coolant to your transmission = expensive disaster. 3.) Replaces the freeze plug at the back of the block that's known to blow out. 4.) Deletes the hoses & piping that connects the heat exchanger, heater core, & water pump: it's known to leak.

Keep EGT below 1200 and don't allow coolant temps over 230F and you won't have a problem with the factory setup. If you want to spin 3000+rpm get a coolant bypass so you don't blow freeze plugs but I would not say you need one for making a lot of towing horsepower. I have boat loads of guys in the 400rwhp range that tow hard and often that have run millions of miles without coolant bypass. Besides adding complexity and more things to fail I don't see any issues with running one if somebody wants to.

@justsaynrush9689

10 ай бұрын

My question is 1 will it cool the back 3 more and 2 will it help keep overall temps lower?

@bcbloc02

10 ай бұрын

@@justsaynrush9689 Probably effects the back 3 some but it probably also starves the front head side some by changing the coolant path. Overall capacity is dictated by the radiator so no it won't help overall temps.

@JC-gw3yo

7 ай бұрын

I tend to agree with you. Cummins engineers are no dummies

@ericbevan6542

5 ай бұрын

400 isn't a lot of towing hp

@bcbloc02

5 ай бұрын

@@ericbevan6542 It is if you actually are producing and using it. You pretty well have to be in 2015 or newer pickups to have enough cooling system to handle that level of power. We have a 2010 ram and 2012 Ford super duty that both have tuners and are in that mid 400kind of range and they both will go into derate working at their max power levels after awhile because the cooling systems can't handle that level of heat for more than a couple of minutes.

You can do these in the truck with the transmission in. It's tight and it SUCKS. Takes a long time vs with the engine or trans out

Fleece is a great company and they take ownership of their products,broke, damaged, etc. Great video Rob, we appreciate the info and 100% correct. 5 and 6 cylinders, even running a dual intake horn should be 20 thousandths over the rest on a lower upgrade engine...in my opinion. Dont want to put you on the spot,but what oversize do you run? Dont have to answer man,just appreciate the info

@CUTTERUPROB

Жыл бұрын

i am not 100% what your asking

2012 6.7 installed on the ground without removing anything but bracket on back of block covering the freeze plug. Yes it sucked! But doable

I installed one when I had my transmission out of my truck . The product is well made . I did have a time when I got the freeze plug in the block . I should have been a bit more careful lol . Any way I finally got the damn thing out . I was thinking that if I ever have change out the oil cooler I thought I would use the one for a 6.7 . Your thought on that thanks . I installed a box of x Matt in my truck on the transmission tunnel and the floor on the passenger and driver side . Several layers on the transmission tunnel . That made the truck a lot quieter, I was shocked how much difference that made on the g56 , dual disc quiet lol Val Air clutch. It works good bit quiet I guess lol

@CUTTERUPROB

Жыл бұрын

you can yes

I have one kind of homemade on my Fummins. Goes from the tstat housing via an inline ball valve to the plug in the back if the block. I have noticed on cooler days my engine won't get up to operating temps. I'm assuming this is due to the constant flow. The fleece tstat on the back of the block the only way to counteract this?

Looking at the design, it would seem smarter to put bigger holes in the head gasket near the back. This should cool the rear cylinders better and cool the rear cylinder head better. I would expect the front of the cylinder head to be the hottest. If the themastat could be mounted above the bypass hose, i would think that the rear thermastat could be eliminated., but something would have to be done about the bypass hole below the thermastat. Just thinking here.

Aside from the additional thermostat at the back of the block, would it be worth while to plumb a coolant filtration system this same way, from the back of the block to the thermostat housing? I’m just thinking cost, rather than purchasing the bypass kit and a filtration system. But also from an effectiveness and efficiency standpoint, what do you think?

IMO, and i've only done one on an '06, PITA with the trans out. Can't imagine with trans in..

Just thinking about doing this on mine since the trans out, have you ever used one from Amazon looking at one now

I can't remember what brand bypass I've got on my 12 valve. It's a super dark purple color. Almost black. I'm on my third hose in about 80 thousand miles. The hose runs so close to the exhaust manifold, it bakes that hose to a crisp. Yes, it's got a bracket to keep it off the manifold. Last time it failed, I replaced it with a hydraulic line that was three inches longer to get it away from the manifold. Hopefully this takes care of the issue. I don't know if the Fleece suffers from heat in this way or not. Fleece seems to be a great company and I'd think they would have it lined out before hitting the market. My truck also has a BD manifold on it which MIGHT be higher than a factory manifold? Something to think about.

@CUTTERUPROB

Жыл бұрын

ya they all have that issue , i run a ptfe hose ss braid and put a heat wrap on mine, seems to fix the issues

can't you just use the the constant flow one and plumb the hose from it in before before the stock thermostat? instead of having another thermostat in the back of the engine?

What are your thoughts on the bypass that doesn't have the thermostat? Is having it open all the time okay?

@CUTTERUPROB

Жыл бұрын

They do the same job. But you have to have a why to restrict flow to keep the engine temp in the engine. If you full flow them the engine will run cold

I definitely would put one in!

So if the tractor trailers have no thermostat cab you get away without putting a thermostat in the bypass?

What about running the billet freez plug with the threaded bung and running a restricted hose end where it connects to the thermostat housing so it's not a constant flow in a 1/2" line.

@CUTTERUPROB

Жыл бұрын

you can do that as well

@JU57US

Жыл бұрын

I was going to do exactly this, but then scrapped the idea of drilling/tapping my rear billet freeze plug because I will be running a coolant loop from the back of the head up through the head on my air compressor and then into the front of the head by the thermostat. So, it's pretty much doing the same thing.

Quick question is it possible to tap a hole for the turbo drain compound setup while the motor is still in the truck........like punching a hole in and not drilling it to avoid shavings in motor through the oil pan

@CUTTERUPROB

Жыл бұрын

Yep punch a hole like you said an weld a plug in

I was wondering about if you could do a closed loop from the temp sensor location to the water pump inlet on a 93 12 valve just to promote coolant flow? Do you think this would work?

@CUTTERUPROB

9 ай бұрын

You sure can.

Hey Rob, my brother and I had put one in his 08 6.7, afterwards the heater didn’t make as much heat as it used too. Is that a common issue on these kits. Also, truck burnt in a shop fire so I can’t look and see if we screwed something up.

@CUTTERUPROB

Жыл бұрын

for the most part no , but i find i like to purt a 195-200 stat in the if your dont have one in

Just installed on my deleted 2016 6.7. Live in high heat Florida. My temps have gone from 194to200 down to 184 sometimes 178 while stopped at idle. I installed for long hauls and wanted the circulation for longevity. I plan on going up in HP as well. Are those temps to low though?

@CUTTERUPROB

Жыл бұрын

Nope that about what they do

I have a general question not related to this video. I recently watched a video on the Diesel Podcast where the fellow being interviewed stated that Dodge introduced intercoolers in the early nineties strictly for emission purposes to lower combustion temperatures. Increased power was a byproduct but the intercoolers were added to reduce emissions. I plan to install a 12 valve in a truck where it will be quite difficult to include an intercooler. I'm wondering if you think it's a bad idea to run the turbo directly into the intake like the early first gen Cummins even though the engine I'm using had an intercooler from the factory? Thanks

@CUTTERUPROB

Жыл бұрын

You can run with no cooler. Just keep an eye on egts.

@RuggedArtistry

Жыл бұрын

Thanks Rob. Happy Holidays!

@brentmcmahon8188

Жыл бұрын

You will lose power I waited until the they put 5 speed and then the intercooler and I bought a 92 with these up grades.

I have a 1993 5.9 12 Valve Cummins. Does anyone know if a 1994 - 1998 Fleece Coolant Bypass will work for me? If not, is there any way I can modify it to make it work?

I am currently in the middle of finishing a 2004 f350 6.0 to 12 valve cummins swap. I was planning on using the 3/4in plug to run a line to the degas bottle on the ford 5/8 and then running the stock from the degas bottle to the 6.0 radiator. The line to the radiator is 5/16 i believe. Do you see a problem with this set up? I think is would promote cooling to the back of the head better than stock. It might take longer for the engine to warm up possibly. Any input would be greatly appreciated! Edited for clarification.

@CUTTERUPROB

4 ай бұрын

You want your degas bottle to be on the non pressure side on the system. So rad side. Then run the the small line from the pressure side.

@PopsHowTo

4 ай бұрын

@@CUTTERUPROB Thanks a bunch!

On my first Gen I’m considering just putting an NPT plug in the block where it feeds the heater core and then running a hose from the rear expansion plug (using one of those aftermarket bolt-on expansion plugs) directly to the heater core inlet. Would this be a bad idea?

@CUTTERUPROB

Жыл бұрын

bad idea no ,

@bobbybeyer2127

Жыл бұрын

@@CUTTERUPROB wait so it would be a bad idea or would not be a bad idea?? Sorry I’m still not sure lol

@McCallieOrchestra

3 ай бұрын

Your idea is a good one and a very popular modification done by many for years. If you search somewhere like Amazon for a Cummins rear billet freeze plug, look for one that is already threaded for an NPT fitting. You can then add fittings and hoses to make your own system for far less than the Fleece kit costs. You will just have to tap your thermostat housing near the alternator. The difference will be that Fleece includes a thermostat inside their replacement rear freeze plug. It helps the truck still warmup like factory, then stay cooler than factory by being fully open at around 180 degrees F. Fitting a thermostat inside makes their freeze plug larger than one that is merely threaded for a fitting. The Fleece kit is harder to install due to its larger size. The biggest downside with their kit is that thermostats fail and trying to access theirs after it is installed will be very difficult. For a DIY kit, you can just add a lever style shutoff lever where the line you run goes into your thermostat housing for a simpler, still adjustable setup.

I have a commercial 5.9 that was in a school bus, it has 74,000 miles on it, I’m thinking about putting it in a 1993 4x4 5 speed f-350 idi cab and chassis tow truck, i have been told to sell it and get one from a pickup , why won’t the bus motor work in-the ford ?

@CUTTERUPROB

11 ай бұрын

Depends on the engine. But for easy to start with a pickup engine is easier and saves time and money

So if I put a bypass system in I would not put a thermostat in the rear of motor and that’s all you need. I don’t know how good it cools 5-6 cylinders I just put a 180 thermostat in and Iam hood and put a fail safe 180 in the thermostat houseing and forget it .

@CUTTERUPROB

Жыл бұрын

If you put a bypass in the truck you run a should run a 180 in stock location and the 180 in the rear. I have run these lots of times over ther years and never had a tstat fail in one. But if it does it would be a pain to replace

Will the 5.9 12v and the 5.9 24v thermostat freeze plug adapter fit the same? Because it is $150 difference in price for the 1997 to the 1998. The 1998 is cheaper.

@CUTTERUPROB

Жыл бұрын

the rear parts is the same 12v to vp44 24v

@seanbrossard8178

Жыл бұрын

Great you just saved me $150. And I am going to copper plum the hose with a pigtail to the thermostat housing just have a dissimilar metal issue to deal with. Even if I go with aluminum tubing still have the issue at the thermostat housing. But no hose burning problem.

@seanbrossard8178

Жыл бұрын

P7100? 1997 block 12v

It is not smart to put the thermostat in the rear of motor it is as hard to change as putting in the bypas to start with. So put a fail safe thermostat in the bypass spot and if it fails it fails open and no problem but a regular thermostat in back will fail shut and your new high dollar bypass is back to having nothing !

My problem is my 99 24v wont ever reach operating temperature evening in the summer time with the ac on, and in the winter time it wont make enough heat to have the heater on unless you block off airflow to the radiator. Only time it gets warm enough to open the thermostat is with the ac on and pulling a load. I feel adding this would make my temps drop even lower. I can't figure out why the truck wont get up to operating temps, ive change the thermostat to see if it was the problem. Any suggestion?

@CUTTERUPROB

6 ай бұрын

This will sound like a dick question. But the tstat is in the right way right ?

@StephenSmith-vn7mg

6 ай бұрын

@CUTTERUPROB yes it is. In the heat of summer pulling a load 10k plus with the ac on it will get to close to 190 and maintain the temp but as soon as you stop it will drop quickly back to 140, and stay there until back at highway speed again.

@CUTTERUPROB

6 ай бұрын

@@StephenSmith-vn7mg is the clutch fan Stuck on maybe.

@CUTTERUPROB

6 ай бұрын

@@StephenSmith-vn7mg also make sure it’s not just the stat. I have seen lot of bad ones. I would get one for a 2012 6.7 Cummins

@StephenSmith-vn7mg

6 ай бұрын

@CUTTERUPROB thanks for the advice, I'll get another thermostat and check it with hot water before installing it. You can spin the fan by hand but it does feel stiff to me, I've kinda been leaning towards the fan clutch is bad. Just wanted another opinion before throwing parts at it. I've owned the truck since 2008, it had 120k on it then and it has 480k on it now, and has been like this since I owned it.

What would happen if you took the thermostat out of the bypass?

@CUTTERUPROB

Жыл бұрын

You want the stat to hold the coolant in the block so it can get heat soaked. I should do a video on that too.

@worlds_okayest_cummins

Жыл бұрын

@CUTTERUP ROB I guess I should have finished the vid first 🫠

@worlds_okayest_cummins

Жыл бұрын

I was leaning towards the constant flow theory

@McCallieOrchestra

3 ай бұрын

It would then still even out cylinder temperatures further back so the engine should remain a little cooler and be protected from blowing out the stock freeze plug since this one is billet and bolted in place instead of just pressed in. What you asked is the way these used to be done before the aftermarket put a thermostat inside a freeze plug. You can buy a rear billet freeze plug already tapped for NPT threads for $40 to make your own bypass without this second thermostat.

Why does that not fit on my 2017 Ram! I have a tiny Frost plug, and no bolt holes?

@CUTTERUPROB

6 ай бұрын

The big plug is under the cast bracket that bolted on the back of the bolt

@karlmoffat6165

6 ай бұрын

@@CUTTERUPROB I wish I could show you the picture of the back of my motor so you can see what I'm talking about. With the transmission out had to get it overhauled

@karlmoffat6165

6 ай бұрын

Hey brother I found a video of a fleece bypass kit install with the transmission in place and I saw the bracket that you're talking about thank you very much. Karl Moffat

@karlmoffat6165

6 ай бұрын

@@CUTTERUPROB hey brother what is the bracket for and is it okay to remove it I don't need that brace??

Is it necessary does it provides protection and longevity? To upgrade, on my 5.9 CUMMINS with a bypass cooling system I have 75k on my engine??????

@CUTTERUPROB

6 ай бұрын

It help keeps 5-6 cylinders cooled off for sure which can help you from having issues

@maliknolan5711

6 ай бұрын

@@CUTTERUPROB How much does the kit cost? And how much does installation cost?

@CUTTERUPROB

6 ай бұрын

@@maliknolan5711 kit is 350-400usd. Installation you would have to talk to a shop that’s installing it for you

@maliknolan5711

6 ай бұрын

O okay, thanks, man. I'm new to the diesel platform My truck is stock bone 74k , What other health mods should I do

@McCallieOrchestra

3 ай бұрын

You only need a coolant bypass if you are experiencing frequent coolant temps well over 200 degrees or are spinning high RPMs like over 3,000 for extended periods. If your engine is that hot, everything should be swollen to help maintain a good seal so you are actually less likely to blow the freeze plug. But if overheating is an issue, the bypass should help balance the coolant temps throughout all cylinders instead of allowing the last couple to stay hotter, which is a flaw in the original design that is primarily triggered to failures on engines modified with much more power and towing heavy. A racing Cummins like in a sled pulling truck that spins at 5,000 RPMs should have at least all billet freeze plugs if not also a coolant bypass at the rear because the water pump is spinning faster, creating more pressure than the stock freeze plug can hold. Swapping from the stock mechanical water pump to an electric one can help regulate the pressure as another option, but billet freeze plugs are a wise preventative step for trucks run harder than originally designed. This Fleece kit is one of the most expensive options but it is very popular. A stock engine with such low miles that isn't even broken in yet should not need this modification but this kit won't hurt anything and should decrease the wear in your cylinder walls over hundreds of thousands of miles. Only significant drawback with this kit is that when you have to replace the thermostat inside their freeze plug, it is in a very difficult location to perform that task. If the thermostat fails stuck shut, you will be broken down until it is replaced or removed. If it sticks open, you might never even know.

I thought the fleece has a 190F thermostat? it's what I recall seeing in their website as I bought a high temp thermostat to match it @ kzread.info/dash/bejne/gopoqsOwiabKnpc.html

@CUTTERUPROB

Жыл бұрын

It’s just a sbc stat so they could have swapped them around. But this one was a 180

is it a good thing or a piece of shit ?I didn't find the installation video...

@CUTTERUPROB

Жыл бұрын

I run them on all my stuff. I think it’s worth it. My buddy ended up in some hard times so he hasn’t finished the truck yet

@shevilihabibi8895

Жыл бұрын

@@CUTTERUPROB thank you sir !

Good video… would you do this on a 2007 5.9?