Plumbing right

[mmt 14]

Hi guys, 

my coolant temp is Way too high (130 c after only 2-3 short laps) 

 

could it be caused by wrong plumbing? Gti6 head, mi16 2.0 bottom, cabin heater. 
 

water pump new, no Air in the system, termostat  new and functioning, new radiator fully ducted.  New aftermarket temp sensor and instrument. 
 

Is there an exploded view of correct plumbing available please. 
 

it has been running lean- could that be the heat source? Believe that is fixed now - wanted to be sure that the coolant hoses are connected correctly. 
 

thanks. 

[welshpug 1,621]

Running lean will not help things,   the cooling system with a gti6 wont be much different to an 8 valve,  neatest way to do it is to use the BakerBM hoses.

 

Both heater hoses join the system near the thermostat housing,  metal pipe across the back of the block to the water pump.   Top hose and bottom hose.

 

Expansion tank tees off one of the heater hoses, one top port to the steam port on the radiator, other port blanked off.

[welshpug 1,621]

Could also be nothing wrong and your sensor is the wrong scaling for the gauge.

 

What gauge and sensor are you using?     The original 205 sensor fits in the 306 thermostat housing which is the easiest route to a reasonably accurate temperature reading.

[pug_ham 240 3 Cars]

Are you running the water / oil heat exchanger on your car?

 

I found with this still fitted that oil and water temps rose quickly and sat higher than I'd have preferred after a few laps.

 

g

[mmt 14]

Thanks guys. 
aftermarket sensor and gauge from VDO. The ecu reading confirms the gauge (with the labtop plugged in. )
 

running (Big) air/Oil cooler not the original one. 

could wrong plumbing cause water not to flow correctly? 
 

 

[welshpug 1,621]

probably, what does yours look like?

[mmt 14]

On 4/30/2023 at 12:11 PM, welshpug said:

probably, what does yours look like?

Here goes: 

From the back outlet: 1 hose to the heater matrix, 1 to the expansion tank, 1 to the metal tube into top inlet of termostat housing. 

 

Termostat housing to radiator, radiator into back og bottom, and one small hose to expansion tank. 

 

From heater matrix to bottom inlet of termostat housing. 
 

would it make any difference to put hose from heater to top inlet of termostat housing? 
 

thanks. 
/M

[Tom Fenton 1,524]

I have suffered similar before, car running hotter than it really should.

I would try the following, restrict the flow on the radiator bleed loop to a small hole say 5mm, it only needs to be able to get rid of the air, if a large volume is returning to the header tank all the time then you are losing cooling.

Similarly I would then try to restrict the flow to the heater matrix, if it is too large it is flow that isn't going through the radiator.

[mmt 14]

Thanks Tom. 
to be sure it is the thin hose which goes from the top og the radiator to the expansion tank? 
there is a constant flow of cooling through that thin hose. It is not a lot but you Can see the coolant flow constantly. 
 

could a rod with a 5 mm Hole inside the hose do the trick? 

[mmt 14]

Inserted a 4,5 mm restrictor- still constant coolant flow under load. ????

[mmt 14]

[Tom Fenton 1,524]

16 hours ago, mmt said:

Inserted a 4,5 mm restrictor- still constant coolant flow under load. ????

There should be a constant flow, it is about limiting the volume of it, as any percentage that is going that way isn't being cooled by the radiator. Same goes for the heater matrix, hence why I'd try restricting that as well.

[welshpug 1,621]

whilst I understand Tom's explanation of the theory, there really shouldn't be any need to restrict the pipes any more than they are already, its not like everything is non original,    its still an XU engine in an engine bay and cooling system laid out around an XU engine.

 

 

have you tried it after correcting the lean running?

[mmt 14]

Thanks guys. I Agree to your point, Graham. Desperate times and all that…
 

Inserted 2x restrictions in the hoses. It seems to work. With fan turned on it Can now idle at 85 c. They are quickly remowed if needed. 
 

thanks again ! 

[Tom Fenton 1,524]

Glad it has worked for you. Agree Mei i can't really explain it either, but it does work.

[petert 549]

In a 205 this hose doesn’t exist. I always delete it and run a single stage thermostat, so that all coolant has to pass through the engine. The hose is only there to bypass the heater matrix whilst warming up. 

[wicked 103 3 Cars]

That hose is not a bypass on the heater matrix, but on the radiator; the heater matrix is always open. The thermostat is a 2-way valve: if the exit toward the radiator is closed implies that the bypass is open. If the exit towards the radiator is open should imply that the exit towards the bypass is closed. This is to maintain a constant flow through the engine regardless the temperature. 

 

On my trackday car I removed the heater matrix and blocked that outlet, meaning that on low temperature all flow is going through the bypass and the engine heats up really quickly. Once on temperature all flow is force through the radiator and have maximum cooling capacity. 

 

 

 

[welshpug 1,621]

not on a gti6, its a simple single stage thermostat.

[mmt 14]

Hose goes from the back of the bottom to the termostat housing. 
 

heater matrix must be open at all times? When the termostat open at 82 c all coolant in engine, radiator and heater must be at the same temp. Open or close single stage termostat. 

 

the setup is from the mi16 engine. The gti6 engine has a different outlet with only 2 outlets. Heater matrix in from steel tube and out to the termostat housing.  I figure it makes difference. 
 

Want to keep the heater Unit. 

Edited May 8, 2023 by mmt

[mmt 14]

You can buy restrictors on-Line 

 

https://jagsthatrun.com/products/heater-hose-restrictor-splicers

 

[welshpug 1,621]

The Mi16 housing really fits the gti6 head??   Never heard of that before!

 

Would be inclined to make it all gti6 including the rear water housing and metal pipe

[mmt 14]

No - termostat housing is gti6. It is the water outlet on the bottom back which is mi16. 

[wicked 103 3 Cars]

On 5/8/2023 at 9:21 PM, welshpug said:

not on a gti6, its a simple single stage thermostat.

I assumed mi16, so ignore my comment. 

 

Maybe add some pictures of the thermostat housing and connections.