Won't stay cool..

Camo · Post by **Camo** » Sat May 25, 2013 11:23 am

Hi folks,

I am slowly getting there with the Moss but I am having trouble with the cooling system.
I am after advise and I have my own theory and will explain and show pics

The rad is not a V8 one, no idea what its from but it seemed large enough so I built things around this one. The hose outlets have to go forward for space reasons but don't think this is the issue.
The issue is the filler cap is lower than the thermostat and that hose as per pic. I can obviously take off that hose and fill from there which I have done.
Problems are that the engine doesn't circulate the water at the right time. the engine will get very hot, rad and pipes remain cold. I then have to turn off the engine before it overheats. The fans don't cut in as the temp sensor has cold water sitting there and of course the rad is cold anyway so the fans would not have an effect on the engine water temp !

I then take the hose off, release the pressure and the thermostat is open so there should be flow (think the water level too low or air block) I can fill it up with some water again, re attach and start the engine, eventually after a few goes at this the water starts circulating and the rad gets warm, fans kick in etc.
Next problem is the rad doesn't seem man enough to keep the engine cool, or the fins are too blocked to allow enough air flow through (they are push fans) I didn't notice that the fins were a little crapped up but can't shift some of it.
I just think I need a better rad and maybe fit a filler in the top hose at the highest point so I can bleed out any air ?

Any suggestions welcomed.
Thanks
Stu[/img]

DaveEFI · Post by **DaveEFI** » Sat May 25, 2013 1:47 pm

Sounds to me like an airlock. What I'd first try is installing a bleed valve at the highest point.

As regards the rad, an SD1 Vitesse type is pretty low and will cope with quite a bit more power than a Vitesse in the UK. Provided it has a decent airflow through it.

Ian Anderson · Post by **Ian Anderson** » Sat May 25, 2013 1:52 pm

Do you have your heater connected?
If so turn it off /cold so it stops the water circulating through that circuit. Basically engine heater bact to pump to engine. So it never sees the rad. If you do not have a heater where does your pipe work go? Try vies gripping the small pipe to stop the flow and force it through the rad.

Also have you checked if your thermostat actually opens? If ir is crocked closed you will never get water flow

Ian

ChrisJC · Post by **ChrisJC** » Sat May 25, 2013 3:41 pm

You need to have some kind of bleed from the highest point. Otherwise it will just fill up with air.

The rad doesn't have to be at the highest point, but the bleed does. If you can't get your header tank high enough up, you can use an expansion bottle instead.

Basically, you fit one of these to the highest point:
http://www.ebay.co.uk/itm/Moroso-Radiat ... 0927392306
Note that is outrageously expensive - cheaper ones are available.
Then you need a rad cap that has two seals, one to seal against the inner part of the neck, and has a pressure relief, and an outer seal to seal against the top of the filler neck. Then stick a small bore pipe from the filler neck to the bottom of the expansion bottle which is open to the atmosphere (and partly full of water!)

The idea is that when the engine warms up, the air will be expelled into the expansion bottle. As the engine cools, water will be sucked back into the engine from the expansion bottle.

This automatically purges any air, and keeps the system topped up.

And it gives somewhere to fill it up right at the top!.

Note that the expansion bottle only has a single pipe, compared to a normal header tank which has to be at the top, and has two pipes, one from the highest point, and one to the bottom rad hose. The expansion bottle is open to atmosphere, whereas a header tank is pressurised.

Also the expansion tank system needs the right sort of radiator cap. If you use a normal one, it will probably suck air back into the system when it cools down.

Chris.

Camo · Post by **Camo** » Sat May 25, 2013 5:00 pm

Thanks for the replies, It does have a heater and the hoses are fully heated, no way to turn it off though, its a very basic car at the moment !
I spotted one of those at JJC and thought that was the best solution, and yes that price is outrageous ...
I will have to get a better rad and use the hose filler at the highest point, I don't have a header tank or expansion bottle currently, car was now running crap too, got dirt in the float bowls I think, won't run unless the choke is on ?
Had it running ok'ish but don't know how long it had sat collecting crap ..

Cheers,
Stu

ChrisJC · Post by **ChrisJC** » Sat May 25, 2013 5:29 pm

Camo wrote:I don't have a header tank or expansion bottle currently,

Hmm, it might well just blow off a hose or split the rad then if there's no expansion mechanism......!

Chris.

Ian Anderson · Post by **Ian Anderson** » Sat May 25, 2013 5:52 pm

When you get the engine running again, put vice grip on the heater hose to stop the water flowing around that circuit.

If the resistance to flow is less in the heater circuit compared to the radiator circuit and all the water will go through the heater.

Ian

Post by **katanaman** » Sat May 25, 2013 10:56 pm

That type of radiator has the header tank built into it and should never be filled to the bottom of the cap or what Chris has said will happen. The system you have created is always going to be a pain to bleed but it is doable with a bit of patience, faffing about and a bleed screw in the top hose. Try and find the bleed procedure for something like an old Renault 18. They had this same type of system.

Alternatively weld a 12 mm stub onto your top hose and pipe it to a separate header tank higher up somewhere. Brim your radiator, cap it and fill the rest via the header tank. It would probably be much more reliable ultimately.

unstable load · Post by **unstable load** » Sun May 26, 2013 4:51 am

If your heater hoses are hot and there is no way of turning the flow off, I'd remove them and stick a bolt in each one to block the flow to allow troubleshooting to be done effectively.
If that does lead to solving it and you don't/won't have a heater, then make up a pipe to join the ends together with a small hole to allow some flow to circulate.

You will definitely need to get the air out of that high section of hose, that Moroso remote filler neck has the pipe to attach to your expansion tank already fitted so it or a similar one should cure the problem quite effectively. Alternatively, you could use one of those fittings that mount the electric fan sensors and fit a bleed valve to it in place of the sensor.

To bleed the system, I found the easiest way to be to run the front of the car up ramps or jack the front up and then run the engine while filling it as the air purges out. Back when I was an apprentice, we used to use the front legs of the 4 post lift to do it, and it worked a treat.

kiwicar · Post by **kiwicar** » Sun May 26, 2013 8:27 am

Hi
With regard the rad not offering enough cooling, it would work much better with some ducting around it, so the original partially goes through hhe rad and not over and under it. Put some ally from the top of the front of the rad to the hole in the front of the car and the same from the bottom and sides of the nose cone. While you are at it you could direct come fresh air at the top of the engine from the front of the car.
Best regards
Mike

teamidris · Post by **teamidris** » Mon May 27, 2013 4:01 pm

Top bleed works for me. I have a filler and a bleed pipe at your highest point. But I am rear rad'd.
In this case I would only have a filler at the rad, with a blank rad cap, so that the pressure rad cap was on a header tank. I don't know if you can get a 'blanking cap' for that neck though?

On the air flow the ducting into the rad is important, along with an air box of sorts. It's job is to space the fans from the radiators fins, as the hub on the fan blanks air flow. Blowing works on a ring shaped area of the fins. Sucking the air is better for the fins, as normal air pressure pushes the air making more fins work, but there doesn't look much room for that

I run electric fans both sides of the rad if that helps? The pushers are on the thermostat, the big 2 speed kenlow runs all the time.

DaveEFI · Post by **DaveEFI** » Mon May 27, 2013 4:22 pm

katanaman wrote:That type of radiator has the header tank built into it and should never be filled to the bottom of the cap or what Chris has said will happen. The system you have created is always going to be a pain to bleed but it is doable with a bit of patience, faffing about and a bleed screw in the top hose. Try and find the bleed procedure for something like an old Renault 18. They had this same type of system.

Alternatively weld a 12 mm stub onto your top hose and pipe it to a separate header tank higher up somewhere. Brim your radiator, cap it and fill the rest via the header tank. It would probably be much more reliable ultimately.

If you fill up any system to the top, it will simply squirt out any excess coolant past the pressure release valve on the filler cap as the coolant heats and expands. If it blows a hose, that hose was fooked anyway.

Denis247 · Post by **Denis247** » Mon Jun 03, 2013 11:31 pm

ChrisJC wrote:You need to have some kind of bleed from the highest point. Otherwise it will just fill up with air.

The rad doesn't have to be at the highest point, but the bleed does. If you can't get your header tank high enough up, you can use an expansion bottle instead.

Basically, you fit one of these to the highest point:
http://www.ebay.co.uk/itm/Moroso-Radiat ... 0927392306
Note that is outrageously expensive - cheaper ones are available.
Then you need a rad cap that has two seals, one to seal against the inner part of the neck, and has a pressure relief, and an outer seal to seal against the top of the filler neck. Then stick a small bore pipe from the filler neck to the bottom of the expansion bottle which is open to the atmosphere (and partly full of water!)

The idea is that when the engine warms up, the air will be expelled into the expansion bottle. As the engine cools, water will be sucked back into the engine from the expansion bottle.

This automatically purges any air, and keeps the system topped up.

And it gives somewhere to fill it up right at the top!.

Note that the expansion bottle only has a single pipe, compared to a normal header tank which has to be at the top, and has two pipes, one from the highest point, and one to the bottom rad hose. The expansion bottle is open to atmosphere, whereas a header tank is pressurised.

Also the expansion tank system needs the right sort of radiator cap. If you use a normal one, it will probably suck air back into the system when it cools down.

Chris.

How does it suck water from the expansion bottle back into the system?, the rad cap wouldn't be open.

unstable load · Post by **unstable load** » Tue Jun 04, 2013 7:25 am

The expansion tank has an internal pipe that goes to the bottom of the tank. This allows the coolant to be drawn back into the engine via the same pipe that connects it to the radiator overboard drain.
The radiator is fitted with a blocking cap without the spring/pressure relief mechanism and the pressure cap goes onto the tank, allowing pressure bleed-off if required.
Daily top ups are done via the expansion tank and system filling is via the radiator cap, as normally done.

ChrisJC · Post by **ChrisJC** » Tue Jun 04, 2013 7:19 pm

The rad cap is not the normal type - I don't know what it is called.

But the important point is that it seals to the outer part of the neck (whereas a normal one doesn't seal that part). The inner part is normal, i.e. it is sealed to the inner part of the neck with a spring loaded seal. So excess pressure will pass the inner part, and will pass down the overflow pipe to the expansion tank. This only happens when the pressure exceeds the rating of the cap. When the engine cools, it will generate a vacuum, and suck water from the expansion tank back into the engine. A normal radiator cap will let air back in here because the outer part of the cap is not sealed, but this kind of radiator cap means the vacuum will definitely suck from the expansion bottle and draw in water.

So it temperature cycling will purge any air, and keep it purged.

Chris.