corrosion to exhaust system

[bigsi]

well had a sod of a job today, getting the stud off the aux manifold wastegate to exhaust feed flange.

the damn stud had siezed itself in there, so after loads of wd40 and some heat i gave in and welded a nice big nut over the stud, then put socket ona nd the thing finally started coming out, back and fore back and fore, then 3mm from the end it sheared.

to say i wasnt happy was an understatement and by this time my finger was killing me, neverless i got some bits out and drilled it out only for a small piece of the edge of the cast round the bolt hole to break away!!! aaarrgghh not my day and i hit vesuvius on the stress level.

so i thought about taking the whole aux manifold off.. no joy all bolts siezed also.

so after tidiying things up as it was now late, i have figured out what to do, i will square off the rounding cast to the flange and then i will use a nut and bolt on that side to compress the flanges and the new stud and nut the otherside. i am trying to get her ready to goto the openday event at the end of the month and let them take a look at her.

while under the car i took a picture of the inside of the aux manifold where the wastegate comes up, it looks like its stuck open (am i right?) picture attatched.

well tomorrows a whole new day and i still have more to do!!

Edited September 13, 2006 by bigsi

[WayneB]

Its shut, the valve face bares on the upper cast iron seat .

Boost pressure retracts it away from the seat face (via the wastegate diaphragm)

Edited September 9, 2006 by WayneB

[molemot]

All looks jolly familiar; studs always shear, so do the studs holding the wastegate to the manifold and the bolts holding the wastegate assembly together. As the valve is springloaded shut, if they stick or the diaphragm fails, they will stick shut and the boost goes stratospheric. If the valve is defective - test by applying about 10 psi to the pressure inlet, this should operate the valve; if the diaphragm has a hole, a hissing noise will be heard and air issues from the hole in the bottom of the wastegate - and you have to dismantle it, reassembly can be simpler if you rotate the alloy part of the wastegate and drill and tap new holes in the cast iron manifold. This is simpler than trying to drill out the old studs as you can get a decent centre for the drillings. A bit of oxyacetylene torch really does help undo stubborn exhaust threads; it was the only way to get the manifold of my old aeroplane for its' annual inspection without breaking studs and that meant taking the cylinder off with a Lycoming engine.....!!

[brado]

Not wanting to start a new topic for similar issue so I will post my experiance here. I tried fitting an exhaust and all turbo studs sheared, so thought best remove turbo, and manfold studs sheared, also wastegate exhaust pipe had to be removed and those sheared as well (good start). A colleague of mine drilled out the turbo studs and that has now been cleaned up and new studs fitted ready to back on.

Could possibly do the manifold studs in situ but as wastegate studs need coming out thought about removing the whole wastegate section of the manifold. Now scared these will shear and reading others experiances even more scared. Last thing I want to do is crack main manifold or remove it.

any one got the wastegate studs out in situ? whats likelyhood of wastegate manifold studs shearing?

Any advice? sounds like these are common issues.. Thanks

[bigsi]

i will be doing mine this week if i can get a clear day to get on with it.

i still cant see any crack in my manifold, and i am yet to check to see if its the flexi section in the two outlet pipes to the silencer.

this all in turn means that not only did i miss the sw lotus meet last week i am now not going to the hethel meet either, to say im dissapointed would be putting it lightly.

[bigsi]

GOOD NEWS FINALLY!!!!!!!!!!!

i have found the damn exhuast leak!!!!! its on the braided gator section on on of the silencer feed pipes.

when i took them off the other week and cleaned and re-painted them in aluminium high temp paint i also coated the braid over the flexi gator joint, took the wheel off and saw it was coated in black soot, ran engine while friend put hands on gator and bingo!!! its leaking right there.

i did intend to pressure test these two pipes , but i didnt get round to doing them and assumed they would be fine, needless to say that i wont be assuming anything anymore with this car!

so today im going to do a temp fix then send off for the pipe from sj sportscars.

going to speak to woman about going to hethel now, i may get there, not a certainty as the little man isnt settled yet and being 7 weeks old i dont like going to far.

but, at least i dont have to take the damn engine out... yet!

Edited October 2, 2006 by bigsi

[bigsi]

ok i have now picked up a replacement gator section, its a bit longer than the original but im hoping it will go in tomorrow.

i am going to my friends engineering place in the morning, removing the pipe, we will then jig it up so it locks in place and then cut a suitable section away, then weld the new section in place, thereby replacing the damaged section.

as you can see from the picture the original is coated in exhaust soot over the fresh aluminium paint i used.