JB Weld / Exhaust Mani Question!!!

[socal_eazye]

Ive been suffering from a MASSIVE exhaust leak so I decided to change both gaskets and holy crap they were on there hard so hard I snapped off the farthest bolt on the driver side connecting the mani to the head. My question is can I just JB weld the damn thing back on??? I know the mani get seriously hot but isn't JB Weld just steel resign will it hold up??? Thanks!!!

 

[xxraptor660xx]

Are you talking about the stud?

 

[Mr Peepers]

JB weld only holds up to ~500*F and will not like the hot/cold cycles too well(break loose). I'm not sure where you planned on using the JB weld, but if it's in place of a stud, I don't recommend it at all. If the stud broke off, use an easy-out and fix it the right way.

 

[pboglio]

The cylinder head is water cooled. Based on my experience using silicone gasket sealer between the head/exhaust manifold, the regular JB weld should be more than fine. Its good for 500 *F.

Edit: I just reread your post. Use a drill extractor to pull the broken stud out if you already didn't strip clean out of the hole. Then use a helicoil insert to fix it right.

 

[turboglenn]

If the stud snapped out of the head, or broke off into the head. Have amchine shop build up some aluminum weld, drill and tap it for teh correct repair.. JB weld on something like that is a total joke and waste of time. trust it if you want, but i wouldn't and i've been known to come up with some odd fixes for things when i'm in a hurry or don't have teh things with me to repair something right while at the track or broken down on the road...

have an exert fix it... JB weld is for small holes in radiators and little stuff like that, NOT for a stud in aluminum holding a cast iron manifold and being heat cycled everyday

 

[Locke]

Based on my experience using silicone gasket sealer between the head/exhaust manifold, [...]

Using silicone as a sealer for the manifold can shorten the life of your o2 sensors.

 

[NN4S]

Using silicon as a sealer for the manifold can shorten the life of your o2 sensors.

I'm guessing you are referring to any of the silicon-based gasket sealers/makers (including the copper hi-temp stuff)? If so, how long will it affect the system? Does it lose it's ability to kill off the O2 sensor as it cures over time, or is it a constant threat to the sensor? What about wideband sensors? I don't mean to hijack this thread, but this is the first that I've ever heard of Permatex RTV products doing harm to the O2 sensor.

To get back on topic: JB Weld will not hold up for any length of time on an exhaust manifold/stud/O2 housing; it will just melt away with a nasty smell to it. It also makes clean-up, welding in fresh material & repair more of a pain since it doesn't clean off as easily as the normal cruddy/grimey parts do. Been there, dealt with it, will beat my son if he ever tries it again!

 

[Locke]

I'm guessing you are referring to any of the silicon-based gasket sealers/makers (including the copper hi-temp stuff)? If so, how long will it affect the system? Does it lose it's ability to kill off the O2 sensor as it cures over time, or is it a constant threat to the sensor? What about wideband sensors? I don't mean to hijack this thread, but this is the first that I've ever heard of Permatex RTV products doing harm to the O2 sensor.

Silicone outgasses will coat the sensor, preventing it's potential exposure to oxygen.

See Oxygen sensor - Wikipedia, the free encyclopedia and silicone o2 sensor - Google Search

 

[NN4S]

Another common cause of premature failure of lambda probes is contamination of fuel with silicones (used in some sealings and greases) or silicates (used as corrosion inhibitors in some antifreezes). In this case, the deposits on the sensor are colored between shiny white and grainy light gray.

The probe then tends to report lean mixture, the ECU enriches the mixture, the exhaust gets rich with carbon monoxide and hydrocarbons, and the mileage worsens.

Thanks; that was extermely helpful. I've been fighting with an excessive rich condition for a bit now where the sensor has been that light grey color. The Wiki explained it well; now I've got to get a replacement sensor and scrape any remaining sealant off of the flanges and put a new gasket on it to try & correct the problem. I'd not considered the silicon in the hi-temp sealant as a possible cause for the problem... good to know!

 

[GS-T_Newboost]

if the bolt broke off in the head try some easy outs. you can get a good set a sears for cheap. good luck

ps. i have stoped a exhaust leak with jb weld on my mani.

 

[Eclipsegst2312]

I broke a stud off into my head from my exhaust manifold. It leaked and was very annoying. I just drilled out the broken stud, used an easy out from sears and fixed it the right way. Its alot better in the long run.

 

[whiteythepimp]

Well if this is any help.. I bought my 90 from some shop and the manifold was cracked between the 2nd and 3rd exhaust runner.. and long story short the dude jb welded it.. It lasted about 50 miles till i got home and the jb weld gave out.. IMO JB weld is a bad idea for anything to do with your motor