assimilated420

ok i noticed this sound comin from my engine and i popped the hood and as i rev it i would hear this spitting sound and noticed ONCE AGAIN that the number 6 cylinder exhaust gasket is leaking AGAIN! what the hell.. irebuilt the top half of my motor and replaced the gaskets and such and shes frikin leaking again.. im losing performance and everything due to this.. is there any sort of bonding material or metal compound to repair this leak without having to rip the top half of the engine apart or am i gonna have to do it the long way.. im only speaking temporary that will hold until i can gather funds and time to fiz it AGAIN.. and also.. when i do fix it again.. what gasket should i use.. i never have had problems with fel-pro before but cmon the same leak in the same spot TWICE?? rediculous..

NismoPick

common prob that i've seen on the L28's. Is the last exhaust stud gone or still there? There's not much you can do, that won't be a potential damage to the head (meaning you could use exhaust pipe hole glue), but it only works for a short time & leaves a nasty hard residue.

jfairladyz

You could have some warpage at the mating surface. Have/had you been running without the end nut/bolt? If you're running without all the fasteners in the manifold you can very easily blow out the gasket there and, if you run it that way for long enough, warp the flange.

assimilated420

the last stud is there.. the gasket seems to leak in the very same spot.. is there any high temperature bonding agent that can withstand some amount of pressure.. im sure something of the sort exists.. besides welding the ****er...

NismoPick

post some pics! BTW... welding isn't really an option anyway cuz ya can't really weld aluminum to steel.

jfairladyz

Yeah there is stuff that will withstand extreme heat. I had a warped exhaust flange where the manifold bolts to the head pipe. It worked good for a while but eventually it started to break up and the exhaust pressure would just shoot it out from the seam. The stuff was supposed to withstand like 1200F but it's very brittle once it hardens and you'd have to take your manifold off anyways to do it. But it's not a permanent fix either. I'd pull the manifold off and check it with a straight edge as well as the gasket surface on the head for flatness. And make sure the bolts are all tightened properly too. If the manifold is warped you could get a new one, have the old one machined, or even try to bang the old one back to shape. It's not likely that the head would warp there but it is possible.

assimilated420

if i can get a hold of a digicam i would post pics.. to be more specific.. on the top of plunem of the exh. manifold... the gasket seems to have just burned away or something.. is it running too hot that the metal used cant suffice or ?

jfairladyz

If the flange is warped and the exhaust gas can force itself around the gasket it will burn the gasket up no problem at all. The gasket is meant to withstand heat while it is sealing with only the edges exposed. If the flange is warped and the gasket faces are exposed then the gasket can't stand up to that. If you've already checked for the tightness of the bolts then I'm pretty sure the maniflod flange is warped and your best bet is to get it repaired or replace it. Either way, it's gotta be pulled off because a sealer won't hold it for very long at all.

jfairladyz

Oh and just a thought that popped into my head right now. Before you pull the whole manifold off, try replacing the stud. It could be stretched or weakened so that it's stretching when it's heated enough. That would cause the same results as a warped manifold. You should be able to get the end stud out without having to remove the manifold.

assimilated420

ok heres some food for thought.. i talked with my dad(who used to work on cars alot) and he said the standard gaskets you buy come with the fiberboard material and metal insert.. he said that the way it is designed is for the material on the exhaust is to burn away and expose the metal and he said that after so long you need to REtorque the bolts as the material releases some torque on them and that the seal weakens but when you retorque them it presses the metal insert and creates an all metal seal. he said youre supposed to do it after a few heating or 100 miles whichever comes first. so im gonna go out there tomorrow and retorque them and make sure they are on there snug n tite. the leak is still very minute and young and prolly only due to this..

jfairladyz

You didn't check to make sure the bolts were tight?!? That shoulda been the first thing you did, I think I mentioned doing that above. But let us know how that goes and hopefully that'll fix your problem and save you a lot of work.

assimilated420

well i had torqued them down properly but i never knew that was the case with these gaskets.. i was like well i torqued them down when i put it on i didnt know they had to be REtorqued after so long.. and its not like theres a huge gap there... well i guess i know no for future reference

lww

assimilated, I'm sitting here going through my FSM and can't for the life of me find the torque specs for the intake/exhaust manifold bolts...

Do you know what they are?

P.S.
I'm asking the wife and kids for the FSM CD from Courtesy Nissan for Christmas... That should make searching a little easier!

NismoPick

According to the Haynes manual... 15 ft/lbs for the intake & 14 ft/lbs for the exhaust manifold. Which seems pretty low... I'd say 20.

assimilated420

i use my chiltons manual.. the bolts are to be tightened 25-33lbs for the 10mm bolts, 11-18lbs for the 8mm bolts and nuts 9-12lbs

assimilated420

and btw.. chiltons is better than haynes.. sorry

NismoPick

That's wonderful info, but too bad it won't help ya, cuz the exhaust studs use 12mm nuts & the intake manifold bolts are 14mm... hopefully you were reading the wrong part of the Chilton book, cuz that would suck if they were wrong!

jfairladyz

I'm pretty sure all those manuals use generic torque specifications for a good deal of their specs. As in they base their torque values upon the size of the bolt where as the FSM would have the torque value that Nissan engineers specified. Any of those numbers will work but that's the reason there's so much difference between torque values in the different values. Things like grade, heat and pressure have to be taken into consideration and for generic values things like this are usually not taken into account.

jfairladyz

Yeah but a Haynes will outlast any Chiltons or FSM. Hands down.
Why? you ask. Is it supperior materials or construction techniques? No that's not it. Then what is it you ask? It's simple really. How COULD the Hayne's ever be damaged or worn out since it JUST SITS ON A SHELF AFTER YOU OPEN IT AND REALIZE ITS ABOUT AS USELESS ON THESE CARS AS AN SAE SOCKET SET!!!!

I'm just playing. I got a Haynes manual and it's tattered and torn apart. I have to sift through all the loose pages just to find any info I need. Most of it has been trashed except for the wiring diagrams and any important specifications.

assimilated420

oh btw when they say 8 and 10mm they are talking the bolt size.. not the head size..

lww

Smack!

NismoPick

I guess it just depends on who's working on the car then, cuz I'd rather know what socket size is needed to remove the bolt (or identify it). Knowing what size the thread is, won't get it out of the car.

lww

I assume they took another seat after you re-torqued them?

lww

I hate it when they do that. Technically correct information that's completely useless is no help at all...

assimilated420

i wouldnt say completely useless at least it gives you an idea of why they give the torque settings for each bolt and besides.. if youre not smart enough to figure out the head size you shouldnt even be working on the car in my opinions..