I have had my car running for several years and it I have never felt confident because of the engine temps really rise up when I come to a stop. My fans are controlled by the stock ECU and bring the temps down sometimes. Ifs its 100 degrees outside and I am in stop and go traffic the fans stay on constantly. Once traffis starts to move the temps start to come back to 180 degrees.

I was thinking of adding a petcock valve to the top of the top of the manifold. Or possibly add a small line to the top of the radiator fluid reservoir. Maybe I still have trapped air. If I ever have to open any radiator line it takes forever 4-6 hours for the engine not to overheat.

I am not sure if the bleeder line at the radiator is doing any good because the line runs under the car and then back to the radiator fluid reservoir

Anyone have any idea or suggestions. Any info would be appreciated.

i have a hose coming off the top radiator pipe on my MOTOR going to header tank . and the radiator is just a air bleed screw .

Try this my system is very simular drain down the system and the disconnct the radiator bleeder pipe at header tank put all coolant into bucket and onto van roof with long enough hose start syphon action and connect to bleeder pipe to the rad leaving header cap off.
Works for me but It never get's hot in the UK .

Gday Richard,

That bleed line from the radiator to the header tank isn't needed and probably isn't helping either.

I've got similar lay out in mine but rather than run the bleed line all the way back to the header tank I have a few foot of hose on it and when I'm filling the system from completly empty I just hook it up high so any air can bleed out then once the system is purged put a bolt in and seal it off.
Tied out of the way

Gerrelt does the same with his I think, works well.




Are your fan/s adequate?
they will cycle on and off every few mins in slow moving traffic escpecially at temps like 100f.

yeah mines like Joels but i dont have a hose just a srcew.
you still need a hose from top hose/housing on the MOTOR to header tank just like a subaru. just put a small fiting in to fit the ,i think its 10mm hose

I have a VW scirocco radiator with (2) 10 inch fans. I was thinking of building a alumn fan shroud for the fans. Just so when the fans cut on they are pulling heat from the entire surface of the radiator.

If I cut the bleeder line at the radiator what do I do with the opposite end that connects to the reservoir? Just plug it off? Or connect to the small radiator fluid hose the heats up the thhrottle body? Just curious?

Thanks,

Richard

the cut bleed line plumb that into where you was going to put a p valve. just use a srcew in brass fitting , done.

Agreed, all you need is a high point somewhere to bleed the air out.


A Scirocco radiator would be more than ample, are the fans staying off when you're on the move?
If they are then shrouding is what you need.
When stopped the fans just can't pull enough air through the entire core to get it below the fan shut off temp.

Also is the heat getting away from the radiator ok when your not moving?

Yes, when I start driving the fans cut off and the temps drop back to normal. Looks like I am going to add a fan shroud and add a bleeder line from the top of the coolant manifold to the coolant reservoir.

Thanks for all the suggestions. Will post the results..

Hi

Do you have room for the Scirocco shroud and fan, OEM fans & shroud usually work much better than after market fans.

I have an Audi 100 fan & shroud on my car, it works well, I previously used it on my WBX 1302, it has speed flaps that open up at speed and get sucked shut when the fan comes on.

Steve

I would have to move the radiator forward a little. I looked on ebay and couldnt locate a scricco shroud. I will have to search a while.

I went with the 12 inch fans for the MR2 radiator on my trike ea81. But then swapped the MR2 Rad for the Alfasud, somewhat smaller.

This meant the 12 inch fans were a little to large. BUT it is ok because it was easy to blank off the moon sections so really didnt need shrouds.

I also found with the ea81 with my radiaotr 2 metres away now up the frotn that air pockets still occur even if I take off the end of the small manifold coolant hose opposite the thermostat to bleed it. I have a bleed on the radiator also. I found that the main radiator hose into the water pump, if thats taken off and filled with coolant then air pockets dont occur. Think I might relocate the expansion bottle to that sid eof the engine so it drains towards the water pump a few inches away.

An idea I saw on a Mazda conversion bug:

Run a small diameter line from the top of the radiator, up the A-pillar, over the arch above the door and rear window, down the C-pillar to the pressurized header tank or swirl pot in the engine bay.

This allows any air in the top of the radiator to vent to the header tank without being trapped by fluid in a low spot.

The logic seems pretty good and the owner said that it worked well in purging air from the system.

A shroud is a necessity however the fact that your car cools when its moving means that the shroud will do little to solve your problem when stationary.

You will find most cars will have their fans on in traffic as there is no natural airflow and the water pump is at idle. I wouldnt worry too much.

As for bleeding the system, I have a ball bearing valve on the radiator that lets excess air out as the system fills up. I then tapped a brass fitting into the top coolant exit pipe that has a line running to the header tank. It bleeds the high point in the motor constantly and avoids the air-locks that can take a while to bleed.

My bloody radiator is too big and works too well. I struggle to get to operating temps and have blocked parts of the radiator off in an attempt to stay hot. Going to go back to the 2nd radiator set up i had, which was a little alpha 33 radiator 600mm x 310mm. Worked a treat!


Matt

Have to disagree Matt, the shroud is only really for stationary use, it makes sure the airflow is pulled from the radiator and not lost around it. Once you are moving, the shroud has no use at all and is detrimental to flow, that's why some have rubber flaps that blow open when moving..

The OP's problem is the thermostat, you need to ensure that it gets exposed to the engine coolant temperature, in our swaps, this gets too diluted with cold return coolant and this artificially lowers the thermostat temperature which is why the engine temperature rises. This obviously gets worse with a more efficient radiator!
My fix for this is to move the thermostat to the outlet and remove the original, it takes ZERO effort to bleed and gives an extremely stable temperature with fast warm up. An alternative fix is to space off the radiator return flow from the bypass flow using one of the spacers used by the Canadian vanagon guys.

Fitting a small bore bleed at the top of the radiator to the coolant reservoir will ensure you don't get any trapped air in the system.

Thsi is my system: