ST185 GT Four: Exhaust Leak

[Levin]

Hey people, I recently got my hands on a ST185 GT Four. I picked it up pretty cheap, because it needed a bit of work done on it (all new filters, oil change, basic maintenance, rear differential bush, new CV joints etc). I've pretty much got all that fixed now. But now comes the biggie..... there's an exhaust leak somewhere before the turbo. I recently hooked up a boost gauge, and she's only running a measly 5 pound (and obviously isn't pulling very hard). My question is how expensive is this leak likely to be to get fixed, my mechanic wouldn't quote me, he said that it was a "big job" and that he wouldn't know how much it would cost till he had fixed it. Any and all help would be much appreciated.

Cheers, Tom

[Dell'Orto]

It depends if its a cracked manifold or its just warped, or if its purely blown the exhaust gasket.
Whip it off (Its not that hard) and check for any obvious cracks, then have the face planed and a new gasket and nuts and it'll be good as gold.

[Levin]

...so basically what you're saying is that everything just unbolts. Sounds good. I'm about to get a boost controller. 10 pound sound safe to you? Cause she really isn't making me happy at the moment

[Dell'Orto]

Pretty much, there are 7 bolts that hold the manifold to the head, and 4 that hold the turbo to the manifold....bit of a wiggle and it comes off.
They ought to run about 10psi anyway, so once you fix that leak you'll see some more boost pressure.
About 15psi is about the max you'd want to go to...and do the intake and exhaust before you wind it up. It ought to have a boost cut at 12ish psi too.

[Levin]

Thanks for the advice. The other thing I need to do is take some weight out of the car, shes very heavy. Any ideas on what to take out. I was thinking of starting with the A/C

[Chickenman]

Make sure you get a ball and spring boost controller as well, so much better than a plain old bleed controller.

Even with it at it's lowest setting (after calibration) you'll notice a major difference (eliminates wastegate bleed).


And gut the catalytic converter.

[Levin]

Ok, next question, how do you disable boost cut (cause 12psi aint that high). Will cutting the VSV prevent boost cut?

[vvega]

boost cut on the 164 is load based
they have no map sensor so it works it out on flap position and tps signal
its very clkeaver and there is no way around it that i know of

the yank and uk versions have a map sensor

ifyou wanna get rid of it your gunna have to look to a new ecu
i.e 185 or mr2 and rewire the plugs to suit


v

[Al]

boost cut on the 164 is load based
they have no map sensor so it works it out on flap position and tps signal
its very clkeaver and there is no way around it that i know of

the yank and uk versions have a map sensor

ifyou wanna get rid of it your gunna have to look to a new ecu
i.e 185 or mr2 and rewire the plugs to suit


v

Re read the car in question old man

[vvega]

$&#$% me im going insane

just unplug the hose fromt he sensor marked boost sensor on the firwall
this will give you all the boost you want

bear in mind
it will go bang

unless your name is al and you fluke everthing

v

[Levin]

I have installed a boost gauge, and will be using a (fairly) accurate boost controller, I'm thinking of running about 13 (dont want her to go boom on me). 13 psi should be sweet?

[vvega]

well belive it or not our resadent fulke aretist runs 19 psi on occasion an his car ant dead
but to be honest i wouldt go over 1 bar(14psi) without look at a non ceramic wheel

not eveyone has al's luck with 3sgte's

v

[Levin]

Ha ha i'd never run 19psi without modifying the turbo and engine. Also is there anyway of telling if the turbo has been rebuilt? The car has done 126000k's so I'd assume it has, as most gt4 turbos give up after 100000ks. But i guess that with the exhaust leak the turbo hasnt been going very hard? My gauge never reads anything over 5psi, so i assume the wastegate never comes in to play.

[Malcolm]

as most gt4 turbos give up after 100000ks.

Who told you that?

[Adydas]

Mine was going strong at 194,000ks and is No on a ST185 without a rebuild.

[Levin]

as most gt4 turbos give up after 100000ks.

Who told you that?

I read it on some site on the net (cant quite remember where). BTW your site has some very good info Im probably going to look into this exhaust leak in the next few days.... I REALLY need to be running more than 5psi!

[Malcolm]

I think I might know the site you're talking about, did it go something like this?

The CT20, as you can see was the first Toyota turbo, and is far from perfect. It has relatively restrictive turbine housing even for the stock horsepower levels of its applications. Lag is also considerable. Maximum flow is enough for about 210hp. Also, it is reported to fail around 100000km no matter how religiously you cool-down after driving and use best oils possible

As you can see, it refers to the nasty old ct20, the ct26 is far better in terms of reliability, even the ceramic ones can last well over 150,000km

[Boosted_162]

Are you certain there actually a leak in the manifold or are you saying that because you are only running 5psi? Cos my old ST185 only ran stock boost of 5psi in 1st and 2nd, then got 6psi in 3rd and up cos of the boost restrictor...And my old CT26 was on 200000km, not sure if it was rebuilt but was still going good.

[sergei]

My turbo on ST165, 200000km, no play, no leaks. Goes fine. I doubt previous owner did anything as I grab it off his hand in a sad state... (cracked radiator, waterpump was leaking, oil seals leaking etc.)

[Levin]

I think I might know the site you're talking about, did it go something like this?

The CT20, as you can see was the first Toyota turbo, and is far from perfect. It has relatively restrictive turbine housing even for the stock horsepower levels of its applications. Lag is also considerable. Maximum flow is enough for about 210hp. Also, it is reported to fail around 100000km no matter how religiously you cool-down after driving and use best oils possible

As you can see, it refers to the nasty old ct20, the ct26 is far better in terms of reliability, even the ceramic ones can last well over 150,000km

Ahh yes that was the one I'm pretty sure its a exhaust leak, thats what the AA man told me and it runs 5psi in ALL gears, so yeah.....