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Greengti1

V6 overheating....

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Greengti1

Hi

 

first sorry if this is in the wrong section...

 

ok, so I brought a V6 205 project sometime ago.  One of the issues was overheating, after getting help on here I fitted a mk3 golf rad with two 11" Spal fans.  I also have the Volvo headertank mounted in the scuttle tray.

 

i have a bleed valve coming out of the top hose linked to the heater matrix and there are the two bleed screws on the V6 thermostat housing.

 

i have also brought a new thermostat.

 

i am using the bottle on top of the headertank trick to push the water through and clear any air.

 

i have had all bleed points free of air and purging coolant without any bubbles.

 

BUT!! Despite all this it is still overheating !! The fans kick on as they should but the temp goes up and up....

 

also very strange is coolant seems to vanish! As I said all bleed pint would run with fluid but gaffer it gets hot the coolant seems to vanish and gets replaced with air..

 

i am depressed about bout the situation, all I can think of in regard to possible issues are:

- I am not getting all the air out...

- the water pump is not working so the water is not circulating.

- head gasket.

 

some thought / help would be very much appreciated so I can get out of the current cycle of filling / bleeding / running / cooling / filling / bleeding / running / cooling I am in.....

 

thanks 

 

adam 

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jackherer

You should be able to see coolant flowing back to the expansion tank if the water pump is working. I had a similar issue with an Alfa V6 once, it would flow coolant at idle but as soon as you revved it up the flow stopped dead. It turned out the impeller was cracked and just span on the shaft.

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Greengti1

I must admit the expansion tank looks stagnant to me... I have been topping up with water since originally filling with antifreeze and the tank is staying clear water while some of the stuff in the engine is coming out a green / blue..

 

 

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jackherer

Unless it has been plumbed unusually/incorrectly that suggests the water pump isn't doing anything.

 

You should see at least a trickle of coolant going into the expansion tank at idle and if you rev the engine up it should turn into a torrent.

 

Have you tried revving it quite high while looking into the top of the expansion tank?

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Greengti1

With the cap off the water level in the expansion tank will swell when Reving the engine. There are also bubbles.  

 

With the expansion cap on the tank will look still and stay cold even when the rad and engine are boiling.  

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jackherer

Bubbles are a bad sign unfortunately. It's probably worth buying a sniff test kit to check for combustion gasses in the coolant.

 

It's probably worth describing exactly how it is plumbed in just in case there is something amiss there too.

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Greengti1

Yes I ordered one on Saturday so it should be with me for the weekend.

 

the plumbing setup:

 

header tank in scuttle tray in front of the driver, the main feed goes to the bottom left hand side (as you look at it from the front) of the engine block.

 

the top thermostat port at the front links to the top radiator outlet. (This has a overflow T back to the header tank)

 

the bottom thermostat port at the front links to the bottom radiator outlet.

 

the top thermostat port at the back links to the top heater matrix port. (This has a bleed valve)

 

the bottom thermostat port at the back links to the bottom heater matrix port

 

hope that makes sense.... 

 

adam

 

 

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Greengti1

I got out for another look and to try the head gasket tester this morning.

 

the head gasket tester is a blue liquid that sits in a curved tube which is placed over the headertank using a bung.  If there are exhaust gases being pushed through the system the liquid should turn yellow.  

 

The good news news is the liquid stayed blue after 10ish mins of running, so I am hoping the head is ok, either that or the eBay test was a dud....

 

other more positive news was the fans cut in and cooled it sufficiently to cut out again... only once though... maybe due to the cooler weather....

 

so the water in the expansion tank still does not appear to move (other then to swell and settle as revs increase and decrease and the engine temp builds) and the expansion tank water remains cold regardless of how hot the engine is.

 

it feels like an airlock - which I would like to think unlikely.  Or the water pump.....

 

thoughts would be very much  appreciated..

 

thanks very much

 

adam

 

 

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Goliath

Here is a picture of how my cooling system is routed:

23769025798_abe2caf1d2_z.jpg

 

I have had lots of trouble over the years getting these to run cool enough. Mine still gets hot very quickly when on track (I think an oil cooler would help).

 

I have found that almost always the problems seem to be caused by airlocks - which seem to be there even after hours of bleeding. I have found that taking out the green temp sensor (next to the bleed point) in the top aluminium pipe on the side of the engine and filling it up from there, as well as filling it up the normal way - works quite well for bleeding.

 

Also - has your engine ever been run without a thermostat? If so then the seal will corrode and expand meaning when you put a new thermostat in the seal will be so tight that the thermostat will not open.

 

p.s. I've never heard of the volvo expansion tank setup located in the scuttle - mine uses a standard ph2 205 expansion tank located in the normal place:

36951210993_414f5b9c19_z.jpg

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Goliath

p.p.s.

 

Perhaps your expension tank setup on the drivers side is because you still have the standard black metal pipe that goes around the back of the engine?

 

I have always cut the pipe at the point circled in the below photo and then just run a rubber coolant hose from there straight to the bottom outlet on the standard 205 expansion tank.

 

42230426670_a542f2470c_z.jpg

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Greengti1

Thanks very much for the suggestions. I will give filling from the temp sensor a go.

 

The person who started the conversion has positioned the brake mater cylinder where the standard header tank should be hence the Volvo tank in the scuttle...

 

 Thanks again. 

 

Adam

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