Cummins 4BT & Diesel Conversions Forums banner
1 - 6 of 6 Posts

·
Registered
Joined
·
13,168 Posts
I'll see if I can help. First off, the plumbing for the aftercooler coolant is metal piping, not rubber. See diagram below. Whether or not they will fit with you custom ac bracket is unknown. Here is another photo from the top. Here is a list of the stock parts and prices from the Cummins store. If those hose parts seem expensive that is because they are high grade silicone rubber.
1 5337075 Hose coupling (old number 3907167) $29.10
2 3914855 Aftercooler tube $73.40
3 3937613 Hose clamp 5 required (old number3918163) $4.83 each
4 3918611 Hose $16.57
5 3918608 Hose elbow $40.35
6 3928909 Hose elbow $45.96
7 3937613 Hose clamp (old number 3934496) $4.83
Human body Gesture Font Auto part Circle

And in the head diagram you'd need part #1 which is 3905639 which is $160.48. That part press fits into a space which normally has a freeze plug.
Font Engineering Gas Cylinder Auto part

You may shop and find better prices. Cummins is never cheap.
 

Attachments

·
Registered
Joined
·
13,168 Posts
Parts can be found a lot cheaper than the Cummins store prices I posted. For example, part #2 3914855 is on Amazon for $25 Amazon.com: Aftercooler Tube 3914855 for cummins diesel engine : Automotive On part #6 3928909 I didn't find many sources cheaper unless you go overseas. You might contact this one in China. They show it but no pricing. Most of the US sources are in the $45 range. https://www.cumminssale.com/?s=ETFH004 Sort of depends on how quick you need it. That hose part was also used on 6bt engines and even larger models with the aftercooler. Komatsu industrial would have it since they often used Cummins engines but doubt they would be very cheap.
 

·
Registered
Joined
·
13,168 Posts
Well, the aftercooler on the 4bt and 6bt had fairly limited use. On a 4bt you only gained 15 HP and the aftercooler and related part could add a lot to the cost of the engine. It showed up more in industrial engines than road models. You could go to the local Onan dealer and probably find those parts since the were found on generators. Of course Onan is owned by a little company named Cummins. LOL. In reality, the water/air aftercooler is more efficient at removing heat than the air/air intercooler. The intercooler is just a heck of a lot cheaper. All the latest model Ford diesels use water/air type. The big secret that Cummins didn't use is having a separate radiator system for the aftercooler. On the Fords, the secondary radiator is larger than the main one for the engine. That sucker is over 4 feet wide. If you had room in front of your engine radiator to put one that large or larger and run a secondary circulating pump then it could be better. There are also 2 different models of the aftercoolers for the 4bt. Yours is the one we'd commonly see on the CPL 0857 that came in road vehicles. Below is the diagram of a better unit used on industrial engine. That one used the HX30W turbo instead of the H1C on the road engines. Although I've never seen one used, there is even an intake heater for the aftercoolers shown in the second diagram.
 

Attachments

·
Registered
Joined
·
13,168 Posts
From my reading on the water/air units, the water absorbs the heat quicker than air so it removes it faster. The Cummins system using engine coolant is not the best idea. In theory you only get down to what engine coolant temp is. The secret of the water/air is to have a separate radiator about as big or bigger than the engine one and a separate circulating pump. As for your concerns about the stock Cummins aftercooler, it isn't the best of units. Most water/air systems have a better heat transfer unit than that one, but that one was fine for its original purpose. There are many aftermarket water/air heat exchangers that are far superior to that unit. You can see why most go with air/air intercoolers. Doing the water/air tends to be much more expensive when done correctly and a bit more complicated. The Cummins version was the cheaper way out and it wasn't cheap. You definitely need boost and egt gauges. Those are a pure necessity. Your power plans will kind of dictate what you need to do for air cooling.
 

·
Registered
Joined
·
13,168 Posts
Doc, that's the way is with most people. A good water/air system can be done but it won't be cheap. The Cummins 4bt units were OK but there have been major improvements over the years, Have to remember that design is over 30 years old. The one used in the Ford diesel pickups is vastly better and there are aftermarket replacement parts that even improve that one. It's all a matter of how much power you plan to make and how much money you're willing to spend. Some of the upgrade kits for the Ford run over $5000. Of course when your dealing with an $80,000 or more pickup that might seem small.
 

·
Registered
Joined
·
13,168 Posts
Very true Dougal. You only need 2 basic components. A secondary radiator and a circulating pump. The rest is just plumbing. On the Ford trucks they have a second belt driven water pump for that purpose. The electric pump used on the Ford Mustang Cobra is one commonly used for swaps. The radiator will just be how big can you fit in the vehicle.
 
1 - 6 of 6 Posts
Top