If the exhaust housing cracks how easy is it to see?

A mate is experiencing boost drop off 17psi - 9psi after only a few seconds and we have checked all his hoses, intercooler, actuator, etc.. I'm thinking maybe a cracked housing?
It's a stage 3 T3 on a stock RST engine with a bit of port work so should have no problem holding boost at all!

Cheers!

 

Is the wastegate penny sealing properly & is it any different with the pipe pulled off the actuator?

 

Dont know mate the arm moves freely so it should be but worth a look!
Pull the pipe off?!! That will just cause a massive boost spike and det! lol

 

i had a similar problem today, peaked at 23psi and dropped back to 12psi.
all my boost presets peaked at their set levels and dropped back to 12psi, was very odd.
however a boost hose then popped off and then put it back and tightened them all back up and it then held much better dropping 2 psi, but needed work on map and boost controller settings need tidying a bit.
a cracked housing can cause surge, but it would have to be a big crack to allow that sort of boost drop.

 

Yeah i've never actually seen a cracked housing but dont know what else to try.

 

i sent my turbo off for repair as i thought the bearings or whatever were shot..turned out to be a cracked housing..thing is, it was boosting perfectly just making a high pitched whistling noise and the repairer said that was the symptoms to a cracked housing.hth?

 

Yeah that would be the sound of the gasses escaping, but as it was boosting fine maybe this isnt the problem then

 

Very strange this one. Have you pressured the system for leaks?

 

No mate i havent, I did think about that but will need to make some sort of adapter up to fit on where the air filter goes I guess?

 

yes and you'll have to pop the rockers off to make sure all the valves are closed as some air will bypass the inlet butterfly otherwise.

 

Fuck that! Cant be arsed! lol

 

why not check the actuator first with a hand vacum pump and see what pressure the movement starts and what pressure it holds constant without leaking. Could be just as simple as an actuator before you start taking turbos apart for no reason. Chances are it is cracked as most of them are anyways so expect to see it cracked if you take it apart anyways. ?

 

I have Jano (see first post), you say most are cracked?? Does that mean it's not the problem?

 

I made a device to fit where my dump valve goes. I taped up the exhaust and sealed the airfilter with a plastic bag and tape. The device was a tube with a washer welded on top with a tire valve. I then hooked it up to the comprerssor and put a few pounds of pressure through. It showed leaks all over the place, sump gasket , roker gasket exhaust gasket ect. You will obviously have to keep adding air as it will leak out through leaks and exhaust joints but i was only topping it up every minute or so.

 

yes i have came across a cracked housing a few times in the past, they dont normally make a big drop in boost unless the crack is comming from the wastgate penny seat area, they normally crack in the exhaust gas inlet union around the turbine caseing and can be more noticable by being a very loud turbo (i can describe the sound to be like a hoover lol) Also another place to check is the seal between the compressor caseing to the backplate that bolts onto the bearing case, its only made of paper gasket type stuff and they are known to crack and leak, easy change by unbolting the compressor housing which can be done without removing the turbo from the car

 

The first post just says you have checked the pipes mate. Doesnt explain how? Just looking does not give everything away, although you should be able to spot the obvious.

Also yes most are crackd after 20+years of abuse and higher than std boost levels. It will of course make a difference depending on where the crack/s are and how big etc. It would be best to get one that isnt cracked but after abuse it will crack anyway, so its a no win situation. I norm use volvo .48 or saabs, as most of these have not been molested by the likes of us and run pretty safe levels of boost and heat etc.

 

Yeah i did exaclty as you described above and the actuator held 10psi all day long, all the boost pipes are new Samco's, and the IC is a new Airtec, I think a pressure test of some sort might have to be the way to go before we start changing the turbo about, but saying that he was previously on a stock T3 and that had no problem holding boost so it does point to it being the turbo as nothing else has changed (we were told it was a good one, but who really knows).

Interesting that all exhaust housings crack, didnt realise this was the case, trouble with a .48 housing is your adding lag
In this particular instance it is a .48 housing anyway and he wants to drop back to a .36 to gain some response so if it is cracked we'll be sure to find one thats not cracked....... at least not to start with! lol