Coolant flow around the engine - potential dumb question

[artois7 21]

Hi all,

 

I have a potentially dumb question to ask. I've done a lot of searching and can't find an answer.

 

On my old mi16, you could see coolant flowing back into the header tank when revving it, via the pipe on the right hand side.

 

Is itthe same on 8vs?

 

My 309 appears to be running hot. It had a reasonable air lock which resulted in it burping coolant all over the place (was running it with the cap off), I get a steady stream of coolant out of both bleed nipples, the fan comes on and I get nice hot and cold air in the cabin.

 

I suspect the radiator is gummed up and wants replacing, but just for peace of mind, does the coolant flow through the header tank on an 8v setup? Or just circulates around the engine, so there are no visual tells that the pump is working?

[Tom Fenton 1,542]

I have had a furred up rad give me problems before. 

 

Easy way to test is remove it from the car and put a hose pipe on full blast in one end. If a pretty keen blast comes out the other end then it’s probably ok. If you get a pretty feeble trickle of water at best then it’s probably furred up. Weight is also a giveaway. Radiators aren’t expensive so if in doubt swap for a new one.

[artois7 21]

I think I will replace the rad, the car was sat up for 17 years so it's highly likely to be pretty funky in there. Pattern parts from ECP/GSF suitable?

 

In terms of the header tank, should I be seeing coolant flowing back into it? The pipe on the right hand side of the tank stays cold. I'm not sure if I should see water flowing through it.

[boldy205 75]

GSF always used to do Nissins rads, which I and many others have used and should recommend. 

[jackherer 543]

14 hours ago, artois7 said:

In terms of the header tank, should I be seeing coolant flowing back into it? The pipe on the right hand side of the tank stays cold. I'm not sure if I should see water flowing through it.

Yes you should see flow into the header tank from the pipe you mention. It might only be a dribble at idle but it should flow more as you increase the revs.

[jackherer 543]

13 hours ago, boldy205 said:

GSF always used to do Nissins rads, which I and many others have used and should recommend. 

They're still available, it's spelt Nissens though. It should be under £60 posted.

[artois7 21]

1 hour ago, jackherer said:

Yes you should see flow into the header tank from the pipe you mention. It might only be a dribble at idle but it should flow more as you increase the revs.

Thanks, that's what I feared. I appear to have no flow even under revs.

 

Brand new water pump so maybe the pipes are blocked... Bugger.

 

[jackherer 543]

The only time I've seen that was with an Alfa Romeo that has a plastic water pump impellor which was loose and just spinning on the shaft. I've never seen 205 water pumps with plastic impellors but I guess something similar could happen with a metal impellor. As it's a new pump I'd definitely be looking at it.

[Ozymandis 97]

4 hours ago, jackherer said:

The only time I've seen that was with an Alfa Romeo that has a plastic water pump impellor which was loose and just spinning on the shaft. I've never seen 205 water pumps with plastic impellors but I guess something similar could happen with a metal impellor. As it's a new pump I'd definitely be looking at it.

i recently fitted a current production DAYCO belt/tensioner/water pump kit and the water pump supplied by DAYCO has a dark grey plastic impeller/ also VALEO pumps have plastic impellers.

[jackherer 543]

They must have changed them then, I've never seen a plastic impellor on a 205 GTI or Mi16 pump. Valeo is OE too I think so they've definitely changed.

 

If they have plastic impellors there is a very good chance they will start to spin on the shaft sooner or later and stop flowing water. Because it initially only fails at higher RPM the car will test fine on your driveway, the temp will gradually increase, the fan will cut in and the temp will come back down, the cycle will repeat a few times and you'll be convinced the coolant system is working perfectly but as soon as you drive it above 30 miles an hour it will rapidly over heat.

[Ozymandis 97]

Kieran,the DAYCO pumps  now in my scrap pile, my only experience of an impeller doing as you say, was on a v expensive genuine BMW pump.

 

 A load of opinions on this very thing on V A G forums, some right tosh being talked,e.g." the metal impellers are too heavy and impose massive strains on the drive system", or "its to stop the huge problem of failing water pumps destroying blocks as they thrash around!"

 

its bollocks, I think the basic reason is cheese paring, save a few grams, save a couple of pennies etc

 

DW8 original pumps were VALEO pumps and always plastic, they don't come loose and are always fine when examined at a timing belt system replacement. I think the manufacturers of other brands haven't always got it right though. Id use a VALEO one.

[jackherer 543]

10 hours ago, Ozymandis said:

my only experience of an impeller doing as you say, was on a v expensive genuine BMW pump.

The Alfa one I had trouble with was the original genuine part too. I agree it's definitely a money saving exercise.

[artois7 21]

All sorted. The water connections on the throttle body were absolutely blocked solid. Cleaned them out and all seems well, it's running hotter than I expect it to but that will probably be cured with another flush and a new rad.