FJ40 Exhaust Manifold Help

[NJFJ40]

My 02/80 FJ40 needs another exhaust manifold gasket as I have a recurring leak. I had the original leak repaired by a shop and 9 months later it needs fixed again (this time I plan to do it). My guess is warpage, the fact that they didn't use two OEM gaskets as people here suggest, the fact that one of the head bolts is broken and thus unusable, or a combo of the above.

Question (can you tell I am new at this?): Do I have to go in from the top to do this type of job or can you attack from underneath and avoid removing the air cleaner, carb, etc...?

Any other advice?

Regards

AT

 

[IDave]

My suggestion: go in from the top: remove the air cleaner and carb. Remove the manifold. Check it yourself for warpage with a straight edge, and make sure the manifolds are fairly lined up. A little warpage can be made up for by proper torquing, which you cannot do with the carb in place.

Replace that missing manifold stud (that's what you mean, not head bolt). This is critical.

I think that with the stock manifold you should need only one stock gasket. It is with headers that you may require two gaskets.

You will have to retorque (best you can) after a heat/cool cycle, and then again later.

 

[65swb45]

My suggestion: go in from the top: remove the air cleaner and carb. Remove the manifold. Check it yourself for warpage with a straight edge, and make sure the manifolds are fairly lined up. A little warpage can be made up for by proper torquing, which you cannot do with the carb in place.

Replace that missing manifold stud (that's what you mean, not head bolt). This is critical.

I think that with the stock manifold you should need only one stock gasket. It is with headers that you may require two gaskets.

You will have to retorque (best you can) after a heat/cool cycle, and then again later.

What he said. 1980 manifolds are the most forgiving when you torque. Also, while I am not defending your previous mechanic, the manifold bolts are something that need to be checked on a regular basis after replacing the gasket. Unfortunately, the heat shield makes it impossible to get to the top middle nuts without pulling the carb, which is why they often go without checking for too long.

 

[NJFJ40]

Thx for the input. So, do those top middle nuts/bolts need to be checked after some break-in period or is it routine to just re-tighten the end bolts only. I guess I am asking if I should consider taking off the carb a week or so after I replace to gasket so I can get at the middle section.

AT

 

[IDave]

Technically, yes. You should take off the carb and retorque. To be honest, I am able to get a regular wrench in and do it "by feel". But I am not having leaks.

 

[Trevor]

Thx for the input. So, do those top middle nuts/bolts need to be checked after some break-in period or is it routine to just re-tighten the end bolts only. I guess I am asking if I should consider taking off the carb a week or so after I replace to gasket so I can get at the middle section.

AT

It's a PITA, but yes, you should remove the carb and retorque the bolts. I was suprised at how loose they became after just 200 miles.