overflow issue

[AlanDITD]

Ok so car had been perfect, but a few days ago i lost power / throttle response. Turbo spool is poor to. Anyway cant find a leak in the air system. However today i was checking the cooolant whuch is green, but in the overflow tank its a different pink fluid.....
The pipe has been wrapped with tape so im assuming its leaking. If this was drawing air in the cooling system and the engine is a touch to hot would it pull the timing and leave me with a slug.

Ill fix it on monday anyway but hoping this will solve the problem. Does this sound plausible?

What you think?

[AlanDITD]

Ok scrap the above, seems the rad cap is an aftermarket one and its gone bad,

Also found a leak so thats good news, i think its the stock BOV! If the engine is reved up slowly then no leak, but if i rev to 3k then let off then rev up to 5k etc etc and try to build some pressure there is a massive pshhhh sound, which im assuming should be impossible with the recirc Dump valve.

If i remove the DV as i dont have a spare, how do i reconnect the pipes?

[Nick Mann]

That's what dump valves do? Have a google on how dump valves work and all should become clear.

[Nick Mann]

Oh, err.... unless I have mis-read your post? You mean holding the throttle steady at high revs you can hear air passing the dump valve?

[AlanDITD]

Its a recirc though nick, i thought they should be silent?

This one is making noise like a VTA, thats why im wondering is it leaking, it only happens when i let of the throttle!

PS im not 100% sure its the DV either, but theres definately a huge VTA sound coming from somewhere, which also coincides with a crap spool and definate loss in power! Im just hoping the two are linked!

[Nick Mann]

No, they aren't silent - they do the same job. They are a lot quieter though. At high boost the noise should still be easily audible with a recirc, exhaust and stereo notwithstanding. I guess as you have a bigger tub and a smaller block than the VR4 you'll be running higher boost pressure?

[AlanDITD]

Ahh sorry Nick i missed the part that says its doing this in nuetral just reving the engine. So no load and no boost!

[Nick Mann]

I don't have experience of your car to know for sure, but most dump valves don't need boost to operate, just a pressure difference accross the throttle body. I can make my atmospheric bov make a reasonable noise revving in neutral, although obviously not as much as when on boost under load.

[AlanDITD]

Ok nick thanks,

Well today i will make some investigations!

What do you think about the issue with expansion tank? The old owner has fitted a high pressure rad cap and im guessing it is stopping the fluid flowing to the expansion tank and causing the engine to run to hot. The pipe between the expansion tank and rad, has no leaks. Im struggling to find what the standard rad cap pressure should be, but 1.1bar seems to be about right. This is fitted with a 1.3bar cap!

[Subaru ETA]

I would have a look at my cap but my car isn't at home! It should be the same as Evo 7 tho

[AlanDITD]

Just caught it leaking. Cap is actually faulty

[Louis]

Standard cap is 0.9.

1.3 cap doesn't increase pressure as such, it actually lowers the boiling point of the fluid in the system.

Also, be very aware of mixing antifreeze types. You should stick to one kind, preferable the type that was in the engine. Most modern antifreeze is RED (pink)(organic), if your engine is filled with GREEN or BLUE and you add red to top it up, the chemical reaction will cause a brown sludge build up in the engine and all the rubber pipes and they will clog and burst or leak at the joins, this will cause the engine to over heat and cause major problems!.

[Nick Mann]

1.3 cap doesn't increase pressure as such, it actually lowers the boiling point of the fluid in the system.

No, but yes but.

Boiling point is actually increased because the pressure is increased. The cap rating is the point at which the cap opens and allows coolant into the overflow tank. Higher pressure is exactly that, but the reason for running it is to increase the boiling point of the coolant.

The rest of your reply was cock on!

[Louis]

Yes, your explanation is much clearer than mine lol! i knew it changrd the bioling point for the better

[AlanDITD]

why would you want to do that though? Surely it means the engine runs hotter?

So as an update, ive taken everything to bits down to the Turbo and it looks fine, no play and normal oil in the piping! Maybe feels a little better, cant hear a leak anymore. Still seems down on power though, im going to have to buy a boost gauage and hook it up to see what reading im getting, should be about 0.8bar.

If the Rad cap has leaked, then theres a chance im assuming, of air in the coolant system, what are the effects of that? Bad running? I can go through the bleep process again tomorow with a new rad cap, (need to find the bleep nipple to) Im sure theres nothing terminally wrong, also checked the wastegate in situ, didnt seem stuck but hard to tell, might make that the next port of call!

any more input from anyone who knows what there talking about

[Nick Mann]

I don't think it will make any significant difference to the engine temps - the thermostat and fans should still work the same way. It will allow the temp to get higher before boiling though, if you want a bit more headroom when giving the car beans for an extended period.

A dodgy rad cap could well let water out and air in. It means the pressure might not be held, so the coolant will boil at 100 (ish) rather than 120 (ish). That gives air in the system too, as the coolant boils and also worse cooling as there is air in there. Theoretically short journeys and topping up coolant shouldn't be too bad, but any sane person would get the problem sorted asap.

[AlanDITD]

Of course mate im going for a new rad cap in the morning ive just been trying to work it out for the last couple of days, then luckily i saw the leak happen when the system got alot hotter!

I have been reading about the late boost and potential could be a problem with the catalytic convertor or the WGA...for interest the metal pole from the WGA should i be able to pull and push this pretty easily or are they quite strong?

There seems to be a small nurling on the pole which stops it slipping inside the WGA to far...does that sound normal to?