My sud overheats

[streamz]

So I took my s3 sud out on its somewhat maiden voyage to a wedding 2 hours drive away after having installed the 1.7 twin carb motor last summer only to discover it was overheating and boiling over going up the hills. I changed the coolant and bled the system but it was still overheating. I discovered keeping it under 3k rpm would stop it from overheating completely. I have the fan connected to a switch on the dash because the thermoswitch has never worked so I know that's not the issue. I set the ignition timing before I left. Idle speed lined up with the I mark. Checked and still in time. (this is the 1.5 flywheel. they have the same timing marking as the 1.7 right?) Heater core was in the circuit and very hot though I couldn't get it to blow hot in cabin??. Top and bottom radiator hose was very hot. Replaced the thermostat with a known good one and still no change.

Only thing I can think of is a blockage but I have flushed the radiator out with a hose and it seemed fine. Any thoughts?

[KevJTD]

is the coolant flowing around ok? try pulling the return pipe off the heater bottle and see if it flows out the pipe when the engine is running.
not unknown for water pump impellers to fail but more on modern cars with plastic impellers
that should also tell if the circulation has a blockage anywhere.
i've also known the inlet pipe hole in the header tank to block up, that prevents water getting around. poke a small drill bit in there, it should go straight through into the tank.

they do tend to rise a bit in water temp going up hill but shouldn't go above 95 really
all the small bore stuff is where you need to check for any blockages, like the "T" piece

[streamz]

Ok i'll check the flow from the return on the header tank. I know before i put the engine in I spun the pump by hand and it felt good so I just left it. Could be the impellers are broken inside.

[streamz]

Am I right that the ignition timing marks on the 1.5 flywheel are the same as on the 1.7? Just want to make sure its not wrong timing thats causing it to overheat.

[KevJTD]

water pump is a long shot to be honest, they're all metal construction so are usually ok.
it's the modern ones with plastic impellers on a metal shaft that give issues when the plastic cracks allowing the shaft to spin without turning the impeller properly

[Kegsti66]

Is your fan running the right way? Mine was running backwards and needed re wiring so it sucked cool air in instead of trying to push it out.

[streamz]

this is a good point. Ill check that too.

[KevJTD]

a very good point. had forgot that one kieth.
it has the effect of making matters worse than if it doesn't work at all if you're travelling slowish in town as it stops any forward air-flow benefit

[streamz]

this makes alot of sense. Especially since i have the fan wired to a switch and keep it running all the time. Is it just a matter or reversing + and - wires?

[KevJTD]

this makes alot of sense. Especially since i have the fan wired to a switch and keep it running all the time. Is it just a matter or reversing + and - wires?

yes, simple as that

just do as kieth says, switch it on and see which way the wind blows.
if it's pushing it through the radiator out the front of the car it's going the wrong way.
it should pull air into the rad from through the grille

[streamz]

So i have done some tests.

The fan is sucking in air through the radiator.
Coolant does flow out of the return hose to the header tank from the radiator (a trickle at idle and reasonable flow under a few revs)
Re checked ignition timing. Seems to be ok was just very slightly retarded.

not sure what to check next.

[Kegsti66]

sudboy 1490 had similar problems with his car with a 1.7 fitted.
I think he fitted a re-cored radiator in the end but not sure if his actually over heated or just ran hot.
Are you sure your thermostat is ok and not stuck?
Sorry I can't suggest anything else.

[streamz]

Thanks. Im going to thoroughly flush it all out. Take off every hose and make sure they are clear and hose out the radiator. Hopefully i dislodge a blockage and it comes right.

[Kegsti66]

Don't forget, flush it both ways including the heater matrix. Hope you get a result.

[dralf1965]

When you have hot water in both radiator inlet and outlet pipes, check radiator surface all over for cool(blocked) areas.

[streamz]

Having a look today I could feel a mist of water in the engine bay. It seems the radiator has a few pinholes. I took it out and it looks very rusty inside.

Time to find a new radiator i suspect. Is it worth getting recored or replace with a new one?

[streamz]

photographic evidence

[KevJTD]

fins look a bit beat up too, that loses a fair amount of efficiency in the rad.

new ones are available readily from the likes of ebay.

http://www.ebay.co.uk/itm/NRF-58701-284 ... 19f81ae9b4

[streamz]

thanks Kev, I've ordered a new one. Apparently it will arrive sometime in November lol Hopefully that solves all my cooling problems. Cant wait to get out on the road this summer.

[streamz]

Well the rad arrived much sooner than expected. One strange thing. It has twisted plastic down the coolling tubes. Are they meant to be there or should they have been removed during manufacturing?

[justsuds]

They should be there, - they are to cause a bit of turbulance as the water flows through the tube, to help it transfer the heat into the tube wall and into the air flowing through.
John.

[streamz]

Ok that's a relief. Thought that might be the case bust wasn't sure. Can't wait to test it out

[KevJTD]

a few of us guys here in UK have seen decent improvemnts from fitting a new rad, got my fingers crossed for you

don't forget to stick with the same colour of anti-freeze mix, blue or green are ok to mix with each other but niether should be mixed with the new red organic stuff.

[streamz]

Well I got the new rad in on Saturday. Went in quite well. Just had to cut the rubber mounts in half as it sits higher than the old one. Also used one of the offcuts to space out the top mount. Filled it up with new green coolant and went for a drive.
Seems a good result. Didnt overheat once even with holding the revs above 4k.

[Kegsti66]

Spot on mate, sounds like a result.
As Kev posted, a few of us have had cooling issues and you can flush an old rad till it runs clear but it may still have a blockage in a few fins.
Well done.
Enjoy.

[Alfasud1978]

Sorry for not seen the post earlier. I had a similar problem with my 1978 Alfasud 1.3 Super and I have replaced the rad with a new one from Valeo. Best testing under summer Cyprus temperatures was done this year as I was participating in the Classic Cars Time Attack Meetings and temperature didn't go above 93C even after 8 hot laps.

BTW I have recently upgraded the carb system by installing a Weber 32/36 DGV, on a twin carb intake manifold from a 1.3Ti plus electric fuel pump. An upgrade I strongly recommend. The car feels and goes much faster.

[Kegsti66]

I love that shot of your sud kicking up the back wheel.

[streamz]

Sorry for not seen the post earlier. I had a similar problem with my 1978 Alfasud 1.3 Super and I have replaced the rad with a new one from Valeo. Best testing under summer Cyprus temperatures was done this year as I was participating in the Classic Cars Time Attack Meetings and temperature didn't go above 93C even after 8 hot laps.

BTW I have recently upgraded the carb system by installing a Weber 32/36 DGV, on a twin carb intake manifold from a 1.3Ti plus electric fuel pump. An upgrade I strongly recommend. The car feels and goes much faster.

Yeah my new rad is valeo too. Seems to be good quality although not quite the same as OEM fit it is close enough.

You weren't tempted to upgrade to twin carbs?

[Alfasud1978]

Not really as I would like to keep it as stock as possible. Tyres currently used are Toyo R888R 185/60/14.
Biggest problem is that I am participating in the up to 1500cc category with a 1286cc and 75bhp, against more powerful cars, but with 100% reliability and sensible but quick driving I managed to lock the category championship by the end of the 4th meeting of out of 6.