92spi

is there a better intake/exhaust manifold gasket than the felpro one? i'm tired of changing it every 2 yrs. or so. no missing studs/bolts and manifold face and head are true. this is on a '81 zxt. saw the sticky on the change of a n/a zx, and i always pull the head to do the job. might try it another way. maybe use the little spy cam i bought so i can see. pita.

NismoPick

Nope.

And it will burn through if you don't torque the nuts / bolts and re-torque them properly, ESPECIALLY on the L28ET turbo motor. About 100 miles into a new manifold gasket, you need to retorque them.

92spi

thanx. i wil be doing this AGAIN pretty soon. exhaust seems to be leaking from close to the front this time. makes the turbo lag even longer. should this retorque be done hot? i downloaded the factory manual (thank you so much); maybe it'll be in there. have just had the haynes(toilet paper edition)manual for all these years. nice to have some other reference source.

SHADY280

retourque when warm, if you do it hot you could pull the stud right out of the head, or break the stud. also make sure the turbo is supported, by hanging less weight off the manifold it will increase the service life of the studs and gasket. you can also use copper coat spray before installing the gasket to help the sealing and service life. you can also get better studs so none break, not just the standard steel ones.

92spi

ok, my learned brethren; got the manifolds off and gasket is burned thru at BOTH ends. i find no tighten sequence in the aforementioned fsm and the haynes refers to one that doesn't exist in their manual. i'm assuming start in the middle and work towards both ends and retighten after a few miles/hot/cold cycles. if someone could post and offer a little guidance, it would be much appreciated. also, about the pita heat shields. could they be left off? at least until the retorquing is completed? and more support for the turbo? it is dreadfully heavy;could definitely use it. any ideas for that? can the egr be deleted? sorry for all the questions-this job $uxx and don't want to do it again. oh, by the way the gasket was burned out the bottom on #'s 1&6. thanx gents, ron.

SHADY280

try getting the manifold machined straight. should cost about 25 bux. if its warped from heat that could be causing the same blow out spots. to support the turbo find somewhere on the block with a threaded set of holes and make a steel bracket of sorts. i cant remember whats there to attach to but i thought there was something. your right to start tightening at the center and work out. if you can get the heat sheild in later there is nothing wrong with leaving it out to retighten later. with the turbo your gonna want to put it back in.

92spi

exhaust manifold is at the machine shop as i speak (or type!) i was fortunate and didn't break any studs or bolts. will investigate a brace for the manifold/turbo. not a very fun job on a rainy day. i appreciate your quick post. ron

92spi

one more question to you guys; could the cat converter be creating some back pressure that hastens the failure of the gasket? car has 110k miles and has had free flow muffler and pipe from cat back for a while. never has run rich (no black smoking) and always seemed to idle and accelerate well (at least after turbo lag). just trying to dot t's and cross i's so to speak.

NismoPick

No. The turbocharger creates much more back pressure than a cat. You should check out the book "Maximum Boost". I have a hard copy as well as pdf. Maybe it's time I upload it.

As I said before, incorrect torque procedure is what causes manifold gasket failure.

92spi

makes sense. thanx.

92spi

ok, cutting manifold costed 65 bux (whew); 7 yrs. ago was $25; same place, same person. wish my wages had gone up accordingly! will be reassembling today. new grade 8 hardware except for 'thick, cupped washers'. now, do these particular washers fit 'external round side' in, or 'internal round side' in? hope you know what i mean, 'cuz i always had problems w/the concave and the convex terminology. found no place to brace up turbo; can possible add extra hanger to turbo outlet pipe to help alleviate weight on manifold flange. slow and steady wins the race; wish me luck.

SHADY280

i always put the cup side in. that way it creates a spring type lock and also the cup digs into the manifold a bit so nothing moves. if it moves it leaks. dont forget the lock washers

92spi

well, i've still got exhaust leaking. no time to fix right now. work calls. will have to wait for another day. will be posting about this again. thanx for the input.

92spi

update; success (i think). it appears that the cutting of the face of the exhaust manifold moved the outlet flange of the downpipe too close to the engine and was fouling on the transmission case. when i pulled the manifold off, it had been leaking under EVERY exhaust outlet. disassemble, grind, grind, grind until clearance was achieved. engine is reassembled now, no leaks for now, will run thru a coupla heat cycles and retorque. this re-do took about 4 hours (including grinding), so it appears i'm getting more proficient at the task, i'm sad to say. should have noticed clearance prob the first time. comment, tips, advice welcome; and thanks to those who posted.

92spi

retorqued manifolds today; some of the bolts were suprisingly loose. whoever said putting the heatshields on was the big PITA was right! ashamed to say a couple of the intake shield bolts were left off due to xtra large hands. put a test gage on the boost and it is only about 10psi w/manual controller. think i'll leave it alone.

MurphyEF

Think of concave making a cave, it curves inward like a cave or a bowl.