Zafira Z22SE 2001 cooling system, so confusing.

Daveinoz

Please, will anyone explain to me just how the coolant flows in this system, as the coolant pathway though the Thermostat seems most unusual, like backwards, compared to any other car engine.
The most unusual area is that Thermostat Housing, as the cool side of the Heater connection connects to where the hot coolant is supposed to flow around the Thermostat. What seems to be the outlet side of the thermostat connects to the hose going to the bottom of the radiator, which is called the Radiator Outlet Hose (just got Hose prices with descriptions from Holden Dealer).
It has got me baffled, just what goes on in that Thermostat Housing, and beyond.
Basically, why does the cooled coolant from the radiator, go to what is usually called the water outlet above the thermostat?

vocky

the thermostat is mounted on the inlet to the engine, not the outlet. So the warmest coolant comes from the top hose towards the radiator.
The warmer heater hose is nearest the exhaust manifold, it comes out and through the interior heater before returning to warm up the thermostat. The heater circuit is also used as the thermostat bypass circuit.

Daveinoz

Thanks for your explanation.
Sure is different, to any other engine I have seen.
What is the advantage/point of the coolant flowing backwards, through the thermostat? More stable engine coolant temperatures?

sandyc

I have no idea what the advantage is, however it's the way it has been designed and if you aren't having any cooling issues then leave it alone to do it's job.
It obviously works well because despite all the common problems we regularly discuss on here, Ive never come across a Z22 with a blown head gasket.

Daveinoz

Thanks, that is good news.
Now all I need to know is the part number for the 82 degrees C Thermostat, as GM dealer locally, claim that 94 is the one, which would likely wreck the engine, in our Summer conditions, and would have the cooling fans running fast, most of the time, so it definitely needs an 82. Suppose I should ask Matt, as he seems to be in charge of the shop, but if anyone else knows it would help me find price of it locally. Most Zafira parts here, are about twice the cost, including flying them out, from the UK. :sick:

Matt

http://www.courtenaysport.co.uk/buy-online/shop-by-category/cool-stats/cool-stat-thermostat-most-models/prod_30.html

Daveinoz

Thanks Matt.

vocky

it's to maintain the engine at 90 degrees for emission regs

Daveinoz

Thanks Vocky.
Having trouble with local GM parts person. All I want is to find out price and availability of the 82C thermostat, for this 2.2L Zafira, and all that is listed is the 94C one, but all I get is an argument, when I tell him the car won't tolerate that one, as when up to operating temperature, radiator fans will run continuously, and in Summer most likely full speed. Haynes Workshop Manual says to only use 82C in the Zafira, with this Z22SE engine, too.
Matt kindly gave me a source for what I need, in the UK, but I tend to go for genuine, first, and if not grossly overpriced, by it locally.
Please. I need some enlightened person, to give me the GM Part number for the 82C thermostat, which is original fitted in Zafira's in Australia, and likely in most other countries.

Daz

The ones that courtenay sport supply are genuine gm items. 🙂

Sent from my GT-I9100 using Tapatalk 2

Daveinoz

That is good to know, just wanting to buy near home, in Australia if possible, and not way overpriced.

guy_27

David for the savings its worth buying from the UK. Delivery is usually only 5 days. In most cases holden will take a couple of days if they don't have it in Stock.

Daveinoz

Thanks for that, good to see you here. And you are keen on Opel based vehicles.
Yes, here it is often more than two business days, to get the parts, then a trip into town.

I have to admit that it has been a rather disturbing issue, and have got a bit stressed, as I have done the big Chains job, with other unexpected difficulties, and Water Pump replacement, and so on. Took about 6 weeks to complete, from when ordering parts, 3-5 hours plodding on with the job, then 4 days or so to recover. I am on Disability Support, therefore it has been a major achievement, :thumbup: kind of repair which I long doubted I would ever again be able to do anything like. 😃
Hence the posting on two forums to find answers. Which has been a great help.

Maybe will go for the one at Courtenay Sport, as they seem to be clued up. Just for now will sleep on it.
Be glad when Zafira is on the road and running well, which it will be once the Temp Sensor (be here tomorrow), and correct Thermostat, is fitted.
I had put in the Tridon brand 88C one, so there probably isn't a rush to put the proper one in, but will find out after the new Temp Sensor is in.
I cannot thank folk on the forums enough, so thanks very much for your most valuable assistance.