cooling problems wit underbelly Rad

monkslayer · Wannabe Joined: 22 Mar 2015 Posts: 4

Hi guys,

I really could use some help at this point. I have installed an underbelly rad on my 1970 bus (with a Toyota 4Y-E engine). However despite all the successes posted by others who have chosen this approach, I can't seem to nail it.

My temps keep rising and also once my fan kicks in, it constantly runs. Strangely enough i tried to drive without the scoop for a short run and the fans cycled on and off. I'm completely lost.

Any ideas to help me fine tune my cooling setup will be really appreciate.

trev · Posted: Wed Jul 27, 2016 8:58 am Post subject:

Do you have a constant fall in the piping to and from the radiator or are there any humps in it that could be air locked?

Which end of the radiator is lowest? Front end or rear?

Is your fan on the front or rear of the radiator? Are you sure it's sucking/blowing the right direction?

For your ducting, is the outlet after the radiator the same size, bigger or smaller than the inlet before the radiator?

monkslayer · Wannabe Joined: 22 Mar 2015 Posts: 4

from the radiator it is a constant fall, but on the return line(outlet) i do have a slight angle as it aproaches the expansion tank but flow seems ok viewed through the expansion tank.

the rear end of the radiator is lowest.it is slanting with with the front end being the higher part within the chassis.

my fan is on the top of the radiator in a sucking direction.

the piping is of equal diameter all through( 40mm).

Any clues?

trev · Posted: Thu Jul 28, 2016 8:33 pm Post subject:

Is there a bleed point at the top (front) of the radiator? I have mine tilted the other way: front end is lowest with rear end highest, the pipes come off the rear end so there's no possibility of getting an airlock, it bleeds itself out to the reservoir

monkslayer · Wannabe Joined: 22 Mar 2015 Posts: 4

Yes there is no point at the radiator. I usually do the bleeding from the engine point by just loosening one of the pipes to let air out until i get a steady stream of water.(i know pretty crude, but only option i have till i install a bleader screw;-))

monkslayer · Wannabe Joined: 22 Mar 2015 Posts: 4

Problem solved. Installed a bleeder nipple in line to better bleed it.discovered that I had still a bit of air.also switched the piping and had the water rising at only one point, and that is when it is flowing back to the expansion tank. Finally, installed the radiator switch on the return line to sense cooled coolant back from the radiator and not to(which was always hot thus explaining why my fans were always on).

Now,did a test drive and my temps are stable and my fans didn't come on when on the highway.

Cheers

trev · Posted: Sun Aug 21, 2016 5:19 pm Post subject:

result!! well done and thanks for coming back to update us. This thread might be useful for someone undertaking a conversion project in the future Happy

jp · Posted: Thu Sep 15, 2016 11:38 am Post subject: