Should i alter it?

**psh** · 13-10-21, 10:54 AM

I am going to replace the corroded thermostat housing on my SBC, with a Billet Aluminium “Swivel” type housing and noticed that they come in a choice of various outlet angles. So while looking at my current setup, I noticed that the hose from the housing goes up hill and them back down to the “header tank” connection, which I have never liked as the “high point” could trap air.

So my question is ,should I take this opportunity to get rid of this “high point” and have the hose leave the housing horizontally, and then down towards the header tank ,which I could achieve by fitting a 90 degree housing ?.

The cooling system on my car works well ,but some people have commented on the fact that the hose leaving the housing is quite easy to compress and does not appear to have any water pressure and that my header tank and its connection is below the level of the housing, as not being ideal. , is this something I should be concerned about?

**skinnymathew** · 13-10-21, 11:09 AM

Doesn't that mean that the thermostat housing becomes the high point?

**kdavies3** · 13-10-21, 11:10 AM

you could add a bleed nipple in the high point.

**jon1d** · 13-10-21, 12:24 PM

Ideally you need your expansion tank to be your highest point which will push out any air on fill up. If the pipe is the highest point will have trapped air. As Kevin says fit a bleed nipple at this high point or install the 90 degree from the thermostat housing. You need space in your expansion tank for the coolant to expand as well so 2/3 full max. Looking at the photo your expansion tank might be almost level or just below this high point . you could lower the height with angle hose.

**psh** · 13-10-21, 01:57 PM

Originally Posted by skinnymathew

Doesn't that mean that the thermostat housing becomes the high point?

No, just been in the garage and using a spirit level and ruler, the highest point in the whole run ,is the bend in the metal part of the hose ,which is 50mm above the top of the housing.

**skinnymathew** · 13-10-21, 02:56 PM

Originally Posted by psh

No, just been in the garage and using a spirit level and ruler, the highest point in the whole run ,is the bend in the metal part of the hose ,which is 50mm above the top of the housing.

I meant if you go for a new 90 degree thermostat housing like you suggested.

**psh** · 13-10-21, 03:11 PM

Originally Posted by jon1d

Ideally you need your expansion tank to be your highest point which will push out any air on fill up. If the pipe is the highest point will have trapped air. As Kevin says fit a bleed nipple at this high point or install the 90 degree from the thermostat housing. You need space in your expansion tank for the coolant to expand as well so 2/3 full max. Looking at the photo your expansion tank might be almost level or just below this high point . you could lower the height with angle hose.

The highest point in the whole run, is currently the bend in the metal part of the hose, (see photo) which is 50mm above the top of the housing and 40mm above the top of the tank, putting the top of the tank slightly above the top of the housing, so I agree it could trap air in the high point of the bent hose.

Glad you agree that by replacing the bent part of the hose, with a straight section leaving the housing horizontally , the high point should now be the top of the tank, which would allow air to be pushed out into the tank automatically during fill up and also any air that gets into the system . This would also mean i would not need a bleed valve in the hose.

The hose coming from the housing runs into the top of the radiator, but is “Tee’d” off and enters the tank at the end at the very bottom, which is roughly 50mm below the top of the housing. There is also a small rubber hose at the very top at the opposite end of the tank, which is connected to the top of the radiator at the opposite end to where the main flow enters the rad.
What is its purpose, anyone know?

I could raise the height of the tank by about 20mm using spacers, anymore and it will foul the bonnet.

Any more than 40mm of water in the tank and it gets belched out the tank , and it maintains this 40mm level all the time, except on very hot days stuck in traffic jams, when it needs topping up a bit.

**psh** · 13-10-21, 03:18 PM

Originally Posted by skinnymathew

I meant if you go for a new 90 degree thermostat housing like you suggested.

I hope not ,because i was thinking of getting one like the one in the link, which looks to be on the same level as the hose.

https://www.summitracing.com/parts/sum-371101?rrec=true

**skinnymathew** · 13-10-21, 06:17 PM

It's tricky because air can collect anywhere in the system if theres a high spot, even if that spot isn't the highest in the system (like air pockets in flooded caves). If you have points like that then they need bleed screws in the right places or you have to fill them whilst under vacuum.