V6 Cooling

[StuF215 1 1 Cars]

Hi, im having issues with the cooling system when the car is stationary, driving along its fine I get 80/85 degrees. Light traffic is more like 90. However once I have stopped for 3-4 mins the temp will rise to 105 degrees. The fan cuts in at around 90 but fails to cool the engine down enough to switch the fan off, it will stay at the 110 degrees mark and coolant will begin to flow through the overflow on the expansion tank (not loads). Cap is a 0.9 bar rating. 12" Pacet fan being used.

 

This is going to be my everyday car so im dreading my first traffic jam

 

Im trying to find ways of improving and have come up with the following ideas:

 

1* Bigger expansion tank -- Not enough room!

 

2* Bigger Rad -- Not enough room!!

 

3* Removing metal pipe underneath rear exhaust manifold -- Will attempt this asap.

 

4* Adding a booster pump from other side of rad -- Not sure where to plumb it in!??

 

5* Custom rad with larger capacity, like the heavy duty rads you can get for the gti td. Larger single veins rather than 2 smaller ones.

 

The Golf VR6 rad im using has the inlet and outlet on one side, could I gain extra cooling by relocating the bottom hose to the opposite end to the inlet?

 

 

Any other ideas I havn't thought of?

 

This is the current plan of my cooling system.

 

 

Thanks in advance

Stu

[StuF215 1 1 Cars]

I have moved the expansion tank btw

 

[DrSarty 90 1 Cars]

Firstly, Goliath's previous 'install' - which I think he would agree was a rushed bodge - had a much smaller fan and coped with some traffic jams on the EuroTrip, although I'm positive they did have some cooling issues like you.

 

These are purely suggestions, not in order and not definite fixes:

 

* relocate the fan to the inside face of the radiator. Make sure it 'pulls' when you do.

 

* try a wider/deeper/thicker radiator (on top of the above suggestion which is recommended even by the fan manufacturer) because it's simply a matter of heat transfer. Naturally more coolant and more surface area on the rad will help out.

 

* consider a larger diameter fan, although 12" really should be enough.

 

* consider triple checking for air locks in the system. Really bleed it and chase them out.

 

* consider 2 x 11" fans (both on the inside as above).

 

* bonnet vent(s)

 

I can't think of much else.

 

Beautiful looking install by the way.

Edited October 5, 2009 by DrSarty

[Goliath 94]

By the looks of it you have run the pipes slightly wrong, it looks like there is a pipe missing from your diagram though.

 

Here is a rather crap diagram showing how I have mine on my new setup, currently untested though. This is using a 205 GTI radiator. (I have cut out the black metal pipe that goes behind the exhaust.

 

[taylorspug 7]

Try a 20psi cap and more cooling from the fan(s). The cap will stop water jetting out the header tank if and when it does get hot, and it sounds like it just needs more cooling from the fans to keep hold of the temperature. I dont think you need a bigger rad, as the temperature is fine when you are on the move and obviously being controlled by the thermostat. So save your money for now on that score.

 

Id be careful with bonnet vents, unless they are well placed they can do more harm than good, especially when the car is on the move. Plus they look pony.

 

EDIT: Your install looks very nice too, i imagine you have used a servo bar style thing to get the servo and master cylinder over there?

Edited October 5, 2009 by taylorspug

[StuF215 1 1 Cars]

Been trying to get on here to reply but my net is past being pants!

 

Sarty thanks for your input and kind words, I cant get a fan any bigger than maybe 8" on the inside of the rad and it would have to go on the bottom right. The main issue with heating when stationary is the fact that the front exhaust manifold is about 5mm away from the back of the rad. I have made a heat shield to cover the front down pipe so I must have reduced heat transfer a little since my first post. Can't do much about the distance in between other than move the rad somewhere else. Rad core width is 30mm, I could squeeze it to 40mm with a bit more work on the front bumper and valance.

 

Bonnet vents are a last resort as I want the car looking standard, you can see the big silver rad behind the bumper already which is bugging me! Next time its off im going to spray it black so its a bit more descrete. Have thought about raising the back of the bonnet an inch.

 

I have no bleed vents on any of the hoses as they are all of the shelf silicone jobbies

 

Goliath, im running the bottom rad hose to the bottom ally pipe on the engine then the top pipe to the top hose. Are you running them the other way then? Also the VR6 rad I have doesnt have the extra outlet for the smaller hose which goes to the exp. Thats why the pipe is missing on my diagram. This must contribute to air in the system...

 

I have yet to cut out the pipe that goes around the back of the engine due to weather, it wont stop raining! Looking at it inlet manifold will have to come off, noooooo.

 

Cheers taylorspug and a good suggestion about the cap you know where I could come across one with that rating? There is a 16psi one on fleabay i've just seen!

 

I have used the 406 linkage to move the original servo across, bit of a pain and isnt strictly necessary but playing with the brakes is alot easier if its on the n/s. I used a 1.9gti ready made brake pipe set but used the drivers side for the passenger pipe work and the same for the rear. Then extended out to the mastercylinder with braided hoses through a plate.

 

Same with the bulkhead you dont have to mod it but if you do things get alot easier. So I did that too!

[taylorspug 7]

Good stuff, very nice idea, and even though its not strictly needed, it makes the engine bay look alot more 'balanced' with it located over there.

 

The tank cap can be had from any decent motor factors, they will usually have a book with all the cars/caps/pressure ratings listed. I *think* they actually list a 205 that uses the higher pressure cap, a diesel IIRC.

[welshpug 1,661]

off the Turbo Diesel, the rest are 1bar

 

1306 84 RADIATOR CAP 1,4 BAR.

[StuF215 1 1 Cars]

I forgot to mention I had a Honda type cap fitted as its slightly lower clearance. I actually have a new high pressure Stant (think its called that) cap for a 205 with lever for pressure release without unscrewing cap. But its useless to me atm!

 

Pug parts will not fit

[hexhamstu 9]

heat wrap around the exhaust manifold?

[Goliath 94]

Sarty thanks for your input and kind words, I cant get a fan any bigger than maybe 8" on the inside of the rad and it would have to go on the bottom right. The main issue with heating when stationary is the fact that the front exhaust manifold is about 5mm away from the back of the rad. I have made a heat shield to cover the front down pipe so I must have reduced heat transfer a little since my first post. Can't do much about the distance in between other than move the rad somewhere else. Rad core width is 30mm, I could squeeze it to 40mm with a bit more work on the front bumper and valance.

How have you got the rad mounted? One of the reasons I have decided to change my vr6 rad for the 205 one is because I have managed to make it fit without having to alter any of the bumper or valence, it's all mounted normally without any cutouts and the grill fits in place too.

I am not using the fan cowling but will (probably) be running 2 10" or 12" slimline fans on the front and one 8" slimline fan on the back.

I know Ade ran just 2 8" fans on the front of a vr6 rad and had no problems.

 

I have no bleed vents on any of the hoses as they are all of the shelf silicone jobbies

That was the main problems I had at first, without the bleed points there will be a lot of air in the system as there are lots of high points that the air cannot escape from. I am now using some normal 205 pipes with bleed screws on them and it makes a big difference.

Goliath, im running the bottom rad hose to the bottom ally pipe on the engine then the top pipe to the top hose. Are you running them the other way then? Also the VR6 rad I have doesnt have the extra outlet for the smaller hose which goes to the exp. Thats why the pipe is missing on my diagram. This must contribute to air in the system...

No, I drew the diagram wrong! Top to Top, Bottom to Bottom is the correct way. Thats another reason I have gone with the 205 Rad, because it has the extra return pipe which really benefits it. Also there is no way to bleed the vr6 rad above the top intake as there is no bleed screw on the top IIRC.

Notice I also have another breather/bleed/return pipe coming from a T piece from the top Matrix pipe. Adding this in made the biggest difference of all.

I have yet to cut out the pipe that goes around the back of the engine due to weather, it wont stop raining! Looking at it inlet manifold will have to come off, noooooo.

You shouldnt have to take the inlet off at all, the pipe is a lot below the inlet and doesn't interfere with it. I cut mine while the engine was out but it should be easy enough with the engine in the bay, there are 3x10mm bolts holding the pipe to the block, 2 on the back which will need to come off, the other one is on the side but that can stay on to hold the remainder of the pipe in place.

[marksorrento205 80]

Is there way you could safely put a bleed screw in the top of the rad, maybe on the top of the plastic side bits?

[StuF215 1 1 Cars]

How have you got the rad mounted? One of the reasons I have decided to change my vr6 rad for the 205 one is because I have managed to make it fit without having to alter any of the bumper or valence, it's all mounted normally without any cutouts and the grill fits in place too.

I am not using the fan cowling but will (probably) be running 2 10" or 12" slimline fans on the front and one 8" slimline fan on the back.

I know Ade ran just 2 8" fans on the front of a vr6 rad and had no problems.

 

 

That was the main problems I had at first, without the bleed points there will be a lot of air in the system as there are lots of high points that the air cannot escape from. I am now using some normal 205 pipes with bleed screws on them and it makes a big difference.

 

No, I drew the diagram wrong! Top to Top, Bottom to Bottom is the correct way. Thats another reason I have gone with the 205 Rad, because it has the extra return pipe which really benefits it. Also there is no way to bleed the vr6 rad above the top intake as there is no bleed screw on the top IIRC.

Notice I also have another breather/bleed/return pipe coming from a T piece from the top Matrix pipe. Adding this in made the biggest difference of all.

 

You shouldnt have to take the inlet off at all, the pipe is a lot below the inlet and doesn't interfere with it. I cut mine while the engine was out but it should be easy enough with the engine in the bay, there are 3x10mm bolts holding the pipe to the block, 2 on the back which will need to come off, the other one is on the side but that can stay on to hold the remainder of the pipe in place.

 

I have the rad as low down as possible so its level with the bottom of the valance, I have had to remove pieces of the bumper mainly for the fan, im going to install a 2nd fan and run it from a 2nd stat off of the rad. Hopefully this will prevent the exhaust from heating the rad too much before the thermostat even opens in the head. In fact do you know where the head stat is??

 

Will the gti rad be large enough for the 3.0l? The extra outlet is an advantage I could do with, i'd have to weld an extra inlet to my header tank, could be a pain in the butt cheeks. Let me know how you get on with yours.

 

I like Marks idea with the bleed screws, I have seen these extra outlets you can add to hoses demon tweeks sell them

Demon Tweeks

These look quite handy, I could just add a couple of these. I reckon I could even fix one to the top of the rad if I tried hard enough.

 

I have now removed the rear pipe but have yet to refill the system, removing the inlet helped loads I just couldn't get to it otherwise.

 

Stu, Exhaust manifolds have heat shields on already I actually have some and tried wrapping the downpies but I coulnt really get it on right and it looked pants. I think the stuff I have is too wide.

[Hilgie 16 2 Cars]

Initially I ran a Golf VR6 rad, but switched to a Golf 1.6 rad later on. Same size but has the top hose bleed connection and features the same threaded connection for the rad fan switch sensor. Also both inlet and outlet are on the same side. Never had issues with running stationary (and it has done that more than is has been driving!!!)

[StuF215 1 1 Cars]

Thanks hilgie, its your fault we're all doing these v6 conversions so im glad you have added your 2 pence

 

I didnt really want to mess around with a different sized rad so the 1.6 one sounds ideal I dont have to make new mounts

i'll have a look for one

 

Stu

[StuF215 1 1 Cars]

Hilgie do you know which model the rad came off of, I can't seem to find the right one

 

or nissens part number would be special

 

Stu

[Hilgie 16 2 Cars]

Golf II or III 1.6

 

I'll have a look for the partnumber.

[welshpug 1,661]

the Nissens website has an application guide with diagrams and measurements