Leak at intake manifold (1 Viewer)

[paulj]

My 1976 stock FJ 40 runs pretty crappily. The engine surges, and runs better when the choke is out after it's warmed up. It has a leak around the intake manifold at the gasket. I should say gaskets, as the PO sandwiched 2 of them under there. Being a newbie when I bought it, I didn't know the difference, and it ran fine for a while, but now it doesn't. When I spray starting fluid around the gasket the engine surges momentarily, so I know it's leaking. Question: What do I do to fix it? Should I take out the manifold and have it machined flat, or just try to get another one? Could the block be warped as well? If so, is that fixable? I probably won't do the work myself, but just want to know what my options would be.

 

[Fast Eddy]

I'm dealing with this myself right now. It is very unlikely that the head is warped. Take it apart and assess the situation. It only took me a couple hours to get it apart. I'm swapping the intake manifold not because of any warpage, but because I want it to be the original style for smog purposes.

You may find the manifolds need to be machined, or you may find the PO cobbled it and it just needs to be refreshed with new gaskets.

You want to separate the intake from the exhaust and replace those gaskets as well. SOR makes an "insulator" that completely blocks off the heat riser between the manifolds to be more sure the intake doesn't crack due to overheating. Mine's not cracked after this many years, so I'm going with the original heat plate, but still replacing the gaskets. My '78 has the CA Thermal Reactor exhaust, so I swapped in the SOR plate when I had it apart.

I'm not sure about other people's opinions, but I'm going to mount the two manifolds loosely together, snug them against the block, snug them together, then tighten against the block and only finally tighten them together. My exhaust manifold is a later model with the ends that move independently and have two bolt-holes each.

 

[sggoat]

Same situation here. Leak is somewhere around #5 cyl. Plan is to remove the manifolds, have them resurfaced(together). Pull the head and fix the low compression in #2 &#3, reinstall a rebuilt OEM carb(current weber) -with the proper heat shield, AND now(since I read this post) get an $OR 'insulator'. finally, regasket the manifolds. Whew!

 

[Pighead]

First, I'd check the torque on the bolts or nuts holding the manifold to the head...

 

[Gdubyacobb]

First, I'd check the torque on the bolts or nuts holding the manifold to the head...

Give this a shot.
I may have been the one in a million lucky guy, but I had a missing manifold bolt when I got my 40 and replacing it fixed every idle issue that I had.
Crossing my fingers for you!

 

[65swb45]

You haven't mentioned if your exhaust is stock cast iron or a header. It does make a difference.

 

[paulj]

Exhaust manifold is stock cast iron.

 

[Fast Eddy]

Mine's back in there with a bunch of fancy new Toyota gaskets, including the carby, but not the linkage, etc.

 

[sggoat]

I'm dealing with this myself right now. It is very unlikely that the head is warped. Take it apart and assess the situation. It only took me a couple hours to get it apart. I'm swapping the intake manifold not because of any warpage, but because I want it to be the original style for smog purposes.

You may find the manifolds need to be machined, or you may find the PO cobbled it and it just needs to be refreshed with new gaskets.

You want to separate the intake from the exhaust and replace those gaskets as well. SOR makes an "insulator" that completely blocks off the heat riser between the manifolds to be more sure the intake doesn't crack due to overheating. Mine's not cracked after this many years, so I'm going with the original heat plate, but still replacing the gaskets. My '78 has the CA Thermal Reactor exhaust, so I swapped in the SOR plate when I had it apart.

I'm not sure about other people's opinions, but I'm going to mount the two manifolds loosely together, snug them against the block, snug them together, then tighten against the block and only finally tighten them together. My exhaust manifold is a later model with the ends that move independently and have two bolt-holes each.

I've looked, but can't find the exhaust insulator you are talking about--I need one. Could you give more info on this, please?
Thanks, Gary

 

[kruisinkid]

SOR p/n 044-12C $33.89
http://www.sor.com/cat044.sor
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