1800: Air in cooling system

[Phid]

I've just sorted my heater out and plumbed it back in to the cars cooling system - it was previously by-passed. I've poured coolant into the heater core and into the input and output hoses and connected everything up. I've ran the car to temperature but I think air is trapped in the hose running into the heater valve, it being the highest point. That hose is not getting hot.

I guess it could be the heater valve not opening but in order to rule that out I need to lose the air - if it's there. Could I install some kind of valve in that highest hose to expel the air? Does such a thing exist?

When hot the system doesn't seem to be under that much pressure - hoses are easy to squeeze.

Previous owner installed a waterless coolant system (has special aluminium rad) and I'm wondering if this is not helping here. Maybe the water pump is struggling with the slippy coolant and I would be better off with an old school water / coolant mix?

A lot of points raised - any feedback much appreciated.
Thanks

[Ron Kwas]

Phid;

It often takes a while to burp all of the air from the CSys...while expelling air the first time, keep Heater Control Valve open (set to Hot), leave the Rad Cap open (even if there is an Overflow Bottle installed), and help agitate air from the system by repeatedly squeezing top Rad Hose and topping up Rad as air works its way out and level drops. Monitor Temp, Rad and/or OBottle level for several thermal cycles until all air is expelled and Heater Core is working effectively, and level (including in OBottle) remains stable.

Cheers

[JP 1800]

Jacking the front of the car as high as possible helps greatly with removing trapped air.

[Phid]

Thanks for the advice - I didn't have rad cap off nor jacked the car up so will give that a try this coming weekend.

Any thoughts on the waterless coolant?

Would it be the air in the system preventing the pressure getting sufficiently high?

[Faust]

I'm no expert on waterless coolant, but surely the point is that it doesn't pressurise in the same way that traditional coolant does?

When Ed China used it on an episode of Wheeler Dealers (was on a TR6), he got the engine/coolant up to temp and was able to remove the radiator cap as the system was not pressurised.

I'm not a fan of the stuff to be honest: seems to be a solution to a problem that doesn't exist. Coupled with the fact that it's apparently quite flammable (a lot of circuits won't let you on if you're running it) and all the faffing around you have to do to get it installed in your car…

I've also read that it can cause problems with water pumps and hoses - it's more viscous that water so pumps can struggle to move sit around the system and hoses can have reduced flow.

As always, there are mixed reports out there… a quick google will tell you all the pros and cons of the stuff.

Made up my mind a while back... it's never going anywhere near a car I own!

[SwallownAmazon]

Originally Posted by Faust

Made up my mind a while back... it's never going anywhere near a car I own!

Hear Hear. Horrendously expensive and to paraphrase a previous poster why bother?

[swedishandgerman]

I don't know anything about the waterless cooling system but there are a couple of things that I would investigate here.

Firstly, yes - you most definitely need to expel all air which involves running the engine with the front jacked up or on a really steep slope making sure the cap is the highest point. If there's an expansion tank - later version - you need to un-clip the tank and hold it up high. What are the details of that aluminium radiator there? What expansion tank do you have there if any?

All said, you should have some heat from the heater and the off pipe from the back of the head is lower than the top hose.... You say that the hose isn't getting hot. Why is that?

I can't recommend enough thoroughly flushing the block on an Amazon. It's amazing how much crud builds up in there. I recommend by-passing the heater and fixing up a 3-way hose connector with the water running through it as fast as possible for as long as you like. Lots and lots of mank comes out. Is it possible that the whole block is so manked up that it's partially blocked? Not impossible.

Also, there's a metal pipe that runs inside the engine to from rear pipe from the heater to near the water pump. Sorry to say that they do deteriorate resulting in little to no flow to the rear of the engine.

Lastly, there is a choice of caps for the expansion bottle (if you have an expansion bottle). The later type allows the bottle to pressurise higher and if you have an early type cap on a later expansion bottle, it won't pressurise at all! I don't think a late type cap will fit an early type bottle.

Please note that neither type provides that much pressure: even the late type goes up to less than 7PSI before it blows! Don't expect the same kind of psssst that you get from a modern which is about double that. Of course, to properly pressurise, the system has to go through the full cycle of cold to warm.

All said, pressurising the system is not the problem here: the problem is that your heater is getting filled with hot water!

[swedishandgerman]

Originally Posted by swedishandgerman

Also, there's a metal pipe that runs inside the engine to from rear pipe from the heater to near the water pump. Sorry to say that they do deteriorate resulting in little to no flow to the rear of the engine.

No - I think I've got that wrong and I can't picture in my mind which way it goes round: does it go from the pump internally with outlets throughout the head and exits to the heater? Is there an external pipe that returns from the heater to the front of the engine??

Can't remember. Sorry to be confusing!

What I'm saying is that you should check that coolant is actually exiting the back of the head!

[Ron Kwas]

S&G;

"Is there an external pipe that returns from the heater to the front of the engine??"

Answer: Yes, there is...its the one that returns into Coolant Pump 8 on graphic I came up with a while back, for the B18/20 Cooling System:

This pipe "deteriorating" would not result in reduced supply to back of engine...a blockage could conceivably hinter Heater Loop flow which would have symptoms of poor Heater Core effectiveness, but engine supply is internal by way of Dist Pipe...ext. pipe is the return from Heater Loop.

Regarding "Waterless Coolant"...why bother?

Cheers

[Phid]

Thanks for all of the feedback.

To clarify, the cooling system was working fine when the heater was bypassed. Also the engine has been rebuilt very recently (previous owner) so I'm assuming for now it is just air in the system.

The expansion tank is positioned low down to the right of the rad.

I tend to agree with the comments on waterless coolant to be honest. If I can't expel the air I might try draining completely and refilling with old school water and antifreeze. I do wonder if the water pump is struggling to push the coolant sufficiently around to drive out the air. Will try the jacking up and rad cap off first and cross my fingers!