exhuast manifold replacement issues

Good evening!

Spent ~6 hours changing out my exhaust manifold today, am sunburned all to shit for it too! . This is the first time i have done one, and it went relatively smoothly for what it's worth. seems a lot more complicated when i read it in the haynes manual.

at any rate, got the old one off, the intake was FULL of nasty grimy carbon, which i cleaned out as best i could. was careful to rtv and mount up the new gasket and intake and exhaust manifold.

got everything connected and back in place. started it up and got some smoke where the manifold meets the exhaust and now i hear bit of a whistle (like air sneaking in) around the top of the engine ( i think the fuel injectors).

i assume the orings at least need to be changed on the injectors, they were relatively gummed up, but the actual spraying part was clean (ran seafoam through the tank last fill up), but im leaning towards getting some ford injectors off of ebay since they are cheap and i have heard good things about them from you guys.

for the exhaust connection to the manifold, anyone else have exhaust escaping there when they do the swap? what did you do to fix it? i thought i had it in pretty tight. maybe pull it apart, use some RTV and then put back together as tight as possible?

thanks in advance

Did you use a torque wrench and the proper sequence? If so, you can try re-torquing the bolts again.

I had a whistle sound on my 88 after replacing the exh manifold. I ended up having to remove it and reseal with hi-temp RTV.

Also check your throttle body and vacuum lines.

i did the proper sequence on the bolts to re-connect, but couldn't get the torque wrench in there to ensure i didn't over torque. used the 'feel right' method that may or may not have cut it... lol. i tried to be as careful about not over tightening as possible, maybe i can bust out the torque tomorrow and give it another try, most of those bolts are in at impossible areas to reach...

i RTV'd the gasket on both sides before putting the intake and exhaust on, and i feel that i got a good seal there (will check again tomorrow). i think it is the fuel injectors b/c i pushed on the one i thought that whistle was coming from and it almost went away, so i guess i need to redo the orings or replace all together (125K on them anyways). i cleaned out a LOT of gunk from the holes that the injectors go into, so now the o rings might not cut it....

but for exhaust leak where the manifold meets the exhaust, i didn't torque, just pushed until i thought it was in, so you think i could pull it off, RTV and then re-install the 2 bolts to see if i can get a better seal there.

Throttle body and vacuum lines are good, double checked them as soon as i heard the whistle i REALLY hope i got a good enough seal the first time, that was a lot of damn work.

btw this is a 1993 4.0 sport, bone stock AW4

Cheers

Hold on here. Slow down. I've never seen or used RTV for a intake or exhaust manifold. THe best stuff to use is the copper gasket cement. RTV is for valve covers or differentials, and personally, I don't like it for those either. Somebody else please feel free to correct me if this is wrong.

RTV won't hold there. Been there done that when I was 18. Make sure you have a new donut gasket in there and get it nice and tight. As for the manifolds to the head, I've Never used RTV there, Only metallic gasket material.

goodburbon said:

RTV won't hold there. .

Click to expand...

x2! Bad Idea!!

You got to take the air box out, no matter if it's an early or late model. I've had pretty good luck with one person guiding the socket from the bottom and another tightening from the top. It takes a selection of extensions and posibly a universal joint in a couple of locations. The bolts in my experience will take a good bit of torque, the end studs won't.
I've used OEM, graphite covered gaskets and Fel Pro with some kind of coating either silicon or Teflon. I can't ever remember using RTV.
Check the manifold for a bow or warpage. Even a new one can be flawed. I actually had to trim the bolt holes out on an OEM replacement exhaust manifold once.
I've heard of guys using high temp RTV on the intake exhaust manifold. I always figured it got way to hot even for the hight temp. types of RTV.

thanks guys, this is much appreciated!

i will pick up some gasket cement and taking out the air box is a great idea!

i might try some hi temp where the manifold connects to the exhaust so that i can create a better seal there as well, that was where the leak was yesterday.

in reality, it might just sit for a few days, my hands are cut to crap from yesterday! i need a good pair of mechanics gloves...

winterbeater said:

Hold on here. Slow down. I've never seen or used RTV for a intake or exhaust manifold. THe best stuff to use is the copper gasket cement. RTV is for valve covers or differentials, and personally, I don't like it for those either. Somebody else please feel free to correct me if this is wrong.

Click to expand...

What he said. Ive done three of these, and wouldn't dare trust ANY RTV in there. I always figured with that heat, it would melt and gum things up pretty bad. Copper spray - couple of coats on both sides of the gasket, and bolt it up. I think Torque spec is like 20 or 30lbs? I can never even get my bolts going without popping my Twrench, so I go a bit tighter. Good luck!

Please note the "RTV" in the product name.

http://www.permatex.com/products/Au...mum_Temperature_RTV_Silicone_Gasket_Maker.htm

I think most people are referring to the "Copper Spray" which is in an aerosol can- not the RTV goop.

Personally, I have not found the need for anything more than a small dab of gasket shellac about every three inches around the gasket to help "hold it in place" until I get everything aligned and "finger tight."