Why fabricate a header coolant tank?
In order to keep the level of coolant higher than the top of the engine a coolant tank needed to be added to the cooling system. The IQ engine sits quite high in the front of the IQ due to the drive shafts passing underneath it, and because the radiator is in a fixed position lower than the engine there was a chance of running the cylinder heads dry of coolant and possibly seizing up the engine.
As long as the coolant is at the correct level ABOVE the top of the engine it should be able to circulate and do it`s cooling thing.
The first tank I made it was a little on the small side and only held about 10 oz of coolant. Luckily this was only on the car for just a couple of runs. I decided to make a larger one with double the capacity capacity also with an external sight glass tube so I can easily check the coolant level without removing the cap to look inside. This should help the circulation of coolant around the cylinder head and avoid seizing it up.
This is how I made it...
Old Version too small
I was a little hasty in making the first header tank, being so close to getting the engine running I rushed into it without much thought about capacity and how to check the coolant level.
Original Header tank
1.5" round tube 8" long with single 1/4" connector. The top cap part was taken off an old damaged radiator, the rest was just fabed from some scrap sheet.
Making it larger
I had to re-use the Radiator cap, so I cut the cap housing off the top of the old tank and then cleaned up the edges in my lathe so they were nice and flat.
Larger tubing
I used some 2" dia 1/8" wall round tubing cut 10" long. I measured out the capacity which showed 20 oz exactly, which is twice the capacity of the old one.
Fabricating the cap
With the old cap turned down to the correct size and a small adapter place made to fit the 2" tubing it was all ready for welding.
Welding up the cap
Couple of welds and one end of the header tank completed.
Adding the fittings
I chose to use AN6 fittings as they are easy to work with and give a good seal.
Welding up the bottom
I used 2 of the AN6 weld on fittings, one was used for the Sight tube and the other one on the bottom take off which connect to the top of the radiator.
Comparison Tanks
The new and old header tanks side by side. showing the difference in size old one is 10 oz and 20 oz for the new one, keeping the same cape pressure.
It fits snug
I managed to get the new tank in the same place high in the engine bay. in fact the hood just clears the top of the radiator cap.
Modifying the Radiator
The old radiator cap housing was cut off the R1 radiator and a blanking plate welded in place. This was the highest point on the radiator so I drilled a 3\8" hole and then added a 6AN weld on connector then welded it in place.
Radiator finished
6AN fitting bung welded up. The radiator was pressure tested and was leak free. This fitting will hook up to the underside of the header tank, this should allow air to rise to the highest point away from the engine block.
Mounting the tank
A couple of 1/4" tabs were welded to the side and bottom of the tank in order to attach it to the inner suspension pillar wall.
All the fasteners are stainless, so a couple of M8 and M6 Allen head bolts were used.
Done.. but not finished
I decided I didn`t like the 6AN fitting as they just did not look right.
I decided to modify them once again using push fit fitting that will allow me to use some clear tubing to see the level of the coolant better.
Another modification..
I will drill out the weld in 6AN connectors and drill and tap a 1/4" ntp thread to allow the new push type fittings to be used. These are smaller and look better than the 6AN elbow s I had intended to use.
1/4 ntp fittings
Close up of the push fitting connectors, I will use some clear PTFE tubing as a sight glass to check the coolant level.
Engine Ice High Performance coolant
I use Engine Ice coolant, its Blue in color so it should be easy to see the level. I have used this product in every vehicle I have and it works just like it says, and I need all the cooling I can get for my R1-IQ
Update! Here it is finished
The 6AN bungs were drilled out, then tapped with a 1/4 npt tap so the new fittings could be screwed on.
Sight glass/level viewer
So here it is finally completed. I can now see the coolant level, and make sure the top of the engine block does not run dry of coolant. This will go back in the IQ once the drive gearing has been machined up. Will have to see if the PTFE tubing and the push fitting hold up to the high temps and pressure of the cooling system.
New header tank is completed.
Making this Header tank was a nice little project, I guess should have researched more before wasting time building the original tank. But at least it served a purpose briefly wile I was getting the engine running. I will post a couple more photos of the new sight glass setup once its back in the IQ.