understanding the cooling system

V

vwchemist

Low Mileage
Hi, I'm installing this 850 engine in my 600 chassis, and I'm trying to understand the cooling system. What function does the bypass port on the water pump serve? I'm thought it gave the water somewhere to go before the thermostat opens, but it seems to be plumbed in below the thermostat.

Is there a downside to routing the bypass hose directly to the thermostat housing without going through the banjo temp sensor fitting? Or just blocking the bypass port altogether?
 
vwchemist,

Good question. Don't have the answer to that one.

Coeincidently, I am at that point in the circuit also. Just tested the values on the temperature sensor. Scratched my head when I didn't find a blind hole there. Stopped short of looking at the line drawing showing the flow run in the head.....and looking at a blank head to witness the porting.
Perhaps a convienient place to mount the sensor ?

Post here when you stumble onto the answer?

850 motor in a 600. Now that sounds like some conversion ! 843cc, 903cc ? Got pics?
 
The trusty manual answered my question. Water just recirculates from the head back to the pump until the thermostat opens, allowing water to go through the radiator and then to the pump. I guess that means there is some portion of hot water flowing directly back to the pump at all times, but it must be insignificant once the thermostat opens up.

1646198100219.png
 
Coolant is always pushed into the block by the pump, hot water (like hot air) rises - so the top of the engine is the hottest point, flow TO the pump and into the block come from the bottom of the radiator (the coolest point)

850 uses a different temp sender to a 127 (didn't you have a 100GL block?) Temp sender on an 850/600 has a hole thru the centre, so water flows thru it and into the banjo two way sender fitting, being pulled back into the pump - so that the pump isn't "dead heading" when the thermostat is closed, as this can lead to isolated hot spots in the system / cavitation at the pump.

You said in another post the engine came set up with a 127 type water pump, does it look like this one?
https://www.ebay.com.au/itm/332016045391 as this is the water pump style used on 127 and A112, three bolt unique shape mount at the block, no provision for an engine driven cooling fan.

CW rotation pump with a 4 bolt (same pattern as 850 903 coupe) style comes from a Seat 133, these do have provision for an engine driven cooling fan and looks like this https://www.ebay.com.au/itm/274109146953 disregard the sellers mention of this being the pump to use with A112 engine into 850, that's incorrect

I'm guessing the distributor drive spur gear of the engine you purchased matched the 600 type, with the correct helical cut for CW rotation of the engine?

SteveC
 
Yes, I have that 3 bolt style pump on my block, but I think the concept is the same. I might need to modify my thermostat housing or get a different one so the OD matches that of the water pump. I'm going to use an electric fan on the radiator.

I got my 127 cam installed in the block and the 600 spur gear. Seems like everything should be spinning the right way now, just need to get it in the car.
 
The fitting for the 5/8 size hose on the 127 pump is for a heater hose return, the feed to the heater is on the thermostat housing. Simplest fix would be to make / buy a T pipe that is 5/8 x 2 and 8mm - 5/16 inch on the third leg, and use that to bleed any air / recirculate coolant while the thermostat is closed ...

something a bit like this
www.ebay.com

5/8" x 5/8 x 5/16 Tee Aluminum Coolant Heater Hose Fitting Water Metal Connector | eBay

Heater Hose Fitting. Heater Hose Fitting in Various Sizes Material: Aluminum.
www.ebay.com

SteveC
 
You must log in or register to reply here.
Back
Top