Cummins 4BT & Diesel Conversions Forums banner
21 - 35 of 35 Posts

·
Registered
Joined
·
2,556 Posts
I see 190/195 under normal interstate loading and it's pretty consistent summer/winter, here the ambient temp swings from 10* to 110* and I drive 70-80 mph temp is influenced much more by engine loading that ambient temp. Just a thought but when I first finished my build I was running a pair of electric fans and they would not keep up when the truck was under high load at low speeds, in the end it was the fans inability to move enough air through radiator/IC due I "think" to less then ideal venting of the engine compartment adding side and top venting to the hood helped some but the issue remained to some extent until I ditched the electric fans. I now run a 20"x10 blade mech. fan that is fully shrouded with a electrically controlled fan clutch.
IIRC you said your radiator is side mounted and the fans blow out through the side? If so I might try experimenting with flow direction as well as how the outside airstream affects flow, you could go back to 1930's aerodynamics and do a "tuft test" with yarn and tape, some minor spoiler/ scoop setup might well make a difference.

I could see the coolant being 10* warmer than the head is externally at least until things are truly heat soaked ant that would be after prolonged operation under load.
 

·
Registered
Joined
·
283 Posts
So I’m at about 3000 miles on my truck now and I’m still working out some bugs. My latest is water temp. I have my water temp sensor in the rear left side of the block. I believe this is the recommended location. My truck is complexly custom and has a side facing radiator. The radiator is very large with two very powerful Spal fans.

Most of my driving has been below 55mph. At those speeds, the water temp remains very low. (170’s) Recently, I have been driving faster due to solving some other issues. On several recent trips, I have been up to 60-65 mph. At those speeds, the temp gauge will slowly climb up to about 230. If I pull over and let it idle, it will cool back down to 170 in a matter of a minute. But if I continue above 60, it will climb up again.

I don’t know if it’s important, but it has never over heated. When I say overheated, I mean it has never blew steam. I have a recovery tank and the level never changes. It would seem like 230 would have to boil. One time I ran it to 230 and pulled over and pointed a temp gun at the radiator outlet. It was like 150. I wish I had pointed it at the inlet, but that’s not as easy to access. Can the coolent be 230 in the block and 150 coming out of the rad?

Do you think running the rear block at 230 will damage it? The motor seems to be running fine. For background, my 4BT has a HX30w with the fuel turned up some. At 62 mph, my EGT is running 1100. (RPM’s are around 2300)

Any ideas or comments welcome.
Any images you can post of the side mounted radiator?
 

·
Registered
Joined
·
936 Posts
Discussion Starter · #23 ·
Any images you can post of the side mounted radiator?
Dont have great pics of it. Here is one from early in the build.

Motor vehicle Gas Auto part Automotive fuel system Automotive exterior


Finished view.

Wheel Tire Vehicle Sky Car
J

Ive just learned that a temp gun is very inaccurate when pointed at shiny metal. Of course, my stainless radiator tubes are somewhat polished.
 

·
Registered
Joined
·
2,556 Posts
If it's drawing engine compartment through the radiator what is the compartment air temp during prolonged operation, can't be ideal but don't know if it's high enough to be an issue
but knowing for sure would be useful and if it's excessive looks like room for some form of "ducting" could be tested.
 
  • Like
Reactions: SUBRUTUS

·
Registered
Joined
·
13,272 Posts
What Eggman said about the electric cooling fans bears true for most diesel applications. They just don't move enough air. The one exception to that was the fan used on the Lincoln MK VIII. That thing moves a tremendous amount of air and has been used on 4bts in past swaps. One member commented that thing sucked the squirrels out of the trees when it comes on. Seems like that things takes a 60 AMP fuse when in full operation. It sucks a lot of current. It is also quite large.
 

·
Registered
Joined
·
936 Posts
Discussion Starter · #27 ·
If it's drawing engine compartment through the radiator what is the compartment air temp during prolonged operation, can't be ideal but don't know if it's high enough to be an issue
but knowing for sure would be useful and if it's excessive looks like room for some form of "ducting" could be tested.
It’s not really drawing air out of the engine compartment. It’s drawing air from under the truck. But of course, that’s where heat goes from the engine. I tried running the truck with out the engine cover. You would think the heat would go out the bed then. Didn’t seem to make much difference on the radiator. I would like to measure the temp in there.

What Eggman said about the electric cooling fans bears true for most diesel applications. They just don't move enough air. The one exception to that was the fan used on the Lincoln MK VIII. That thing moves a tremendous amount of air and has been used on 4bts in past swaps. One member commented that thing sucked the squirrels out of the trees when it comes on. Seems like that things takes a 60 AMP fuse when in full operation. It sucks a lot of current. It is also quite large.
Im using two Spal fans. Spal is recognized as one of, if not thee best, fan manufacturer. I had to run a 75 amp relay on each fan because one relay fails rather quickly. Those fans blow ridiculous amount of air. 90 percent of the time, it doesn’t get hot enough to turn the second fan on.
 

·
Registered
Joined
·
60 Posts
I can’t help but to think you have an over- fueling problem, or not enough air or timing. 1100 on flat ground and especially at such a high rpm does not sound right to me. What are you seeing for manifold pressure under those circumstances?
 

·
Registered
Joined
·
936 Posts
Discussion Starter · #29 ·
I can’t help but to think you have an over- fueling problem, or not enough air or timing. 1100 on flat ground and especially at such a high rpm does not sound right to me. What are you seeing for manifold pressure under those circumstances?
If it was over fueling, wouldn’t it smoke? I have almost no smoke. Boost is around 20.
 

·
Registered
Joined
·
283 Posts
Dont have great pics of it. Here is one from early in the build.

View attachment 134365

Finished view.

View attachment 134366 J

Ive just learned that a temp gun is very inaccurate when pointed at shiny metal. Of course, my stainless radiator tubes are somewhat polished.
That is an awesome build. Food for thought, you can power a pusher fan, from your driveshaft, via a pulley at the flange of the t-case, then a belt, to another pulley to drive another pulley with a fan attached at the radiator.
There are various ways to activate/deactivate the fan manually or by solenoid, or just a clutch fan.
 

·
Registered
Joined
·
186 Posts
If it was over fueling, wouldn’t it smoke? I have almost no smoke. Boost is around 20.
Step 1: I'm old and may have missed it.. but If this isn't a manual temp gauge... suspect the sender or the gauge... EGTs... do you have an exhaust restriction.. or small exhaust? I don't know how you get that engine to warm that much.. the 6bt runs 165.. unless really pulling.. The 4bt is noted to be the same... I will ask a stupid question... Which direction does your water pump turn? I believe they make them that turn left or right????
 

·
Registered
Joined
·
936 Posts
Discussion Starter · #32 ·
Step 1: I'm old and may have missed it.. but If this isn't a manual temp gauge... suspect the sender or the gauge... EGTs... do you have an exhaust restriction.. or small exhaust? I don't know how you get that engine to warm that much.. the 6bt runs 165.. unless really pulling.. The 4bt is noted to be the same... I will ask a stupid question... Which direction does your water pump turn? I believe they make them that turn left or right????
Im not aware of pumps that turn the other way. (on Cummins) If it turned the other way, it would need to have grooves in the drive pulley. (Mine is flat)
 

·
Registered
Joined
·
186 Posts
Im not aware of pumps that turn the other way. (on Cummins) If it turned the other way, it would need to have grooves in the drive pulley. (Mine is flat)
Did you find your answer? If Not.. Take your tranny fluid Temp before it gets to the radiator.. I think i see the tranny cooling thru the radiator... the 47RH should have a radiator with a 1/2 inlet and outlet.. if its 3/8 you may be heating your tranny and that heats the radiator...and coolant..
 

·
Registered
Joined
·
936 Posts
Discussion Starter · #34 ·
Did you find your answer? If Not.. Take your tranny fluid Temp before it gets to the radiator.. I think i see the tranny cooling thru the radiator... the 47RH should have a radiator with a 1/2 inlet and outlet.. if its 3/8 you may be heating your tranny and that heats the radiator...and coolant..
Ive been out of town, so no work on the truck. My tranny has 5/16” lines. (It’s a C6) I’ve stopped a couple times and checked the temp on the pan a few times and the tranny seems to run cool. (160-170) I’ll get some more testing done now that I’m back.
 

·
Registered
Joined
·
186 Posts
Ive been out of town, so no work on the truck. My tranny has 5/16” lines. (It’s a C6) I’ve stopped a couple times and checked the temp on the pan a few times and the tranny seems to run cool. (160-170) I’ll get some more testing done now that I’m back.
Pan is not a good place to check... that is where the cold oil goes from the radiator... check where it comes out of the tranny pump ..... and goes to the radiator... I'm not sure which line it is by I suspect the front one... a digital will show one a lot warmer that the other.. I looked at the picture... that is an awful long run for the stock pump ..
 
21 - 35 of 35 Posts
Top