heat riser in split manifold 1964 fj40

[destin]

** updated

Ok so very soon i am going to sort out the heat riser.
However, since the manifold and intake etc are not leaking currently, and i rather not have them pulled off unless needed to avoid any potential cracking ( not sure if the cast iron is prone to cracking ).

Is there a way to access the state of the heat riser without removing the manifold, for example, could i simply remove the carb look down and see if the heat riser has a range of motion?
If so even possibly "unseize" or unstick the riser to it moves as it should?
My feeling is that it is stuck on the half open half close stage, or even possibly moving from open to half closed but not closed, judging by the behavior.

I have ordered all new gaskets / bolts and studs in case they need to come off.
But i was hoping one of you had messed with this in the past.

Also where exactly in the diagram is the heat riser located?
Between the intake and the exhaust manifold?

Thanks guys

 

[ocdbeetle]

If you have it...all the pieces....Keep it on.....If you're keeping an original engine that is.....

Not sure of the arguements for taking it off, I'm a firm believer in going with what the engineers had in place (with the few exceptions where the money spenders needed a lesser fix to the dismay of the engineers)...

When I got my '65, the PO had taken off the OG exhaust manifold, installed a MAF header and removed the heat valve.....I wish I still had the original parts instead of the header...

 

[destin]

If you have it...all the pieces....Keep it on.....If you're keeping an original engine that is.....

Not sure of the arguements for taking it off, I'm a firm believer in going with what the engineers had in place (with the few exceptions where the money spenders needed a lesser fix to the dismay of the engineers)...

When I got my '65, the PO had taken off the OG exhaust manifold, installed a MAF header and removed the heat valve.....I wish I still had them......

I am keeping it all stock... i was just wondering the wisdom of removing it as a solution. Seems like we both have a similar hesitation about removing it.

Alternately replacing, un-seizing it would be the other solution...
Any of you ever rebuild/ service the heat riser?

SOR no longer has it, i guess i should call toyota on monday and see if they can order it.

 

[wesintl]

I'm sure the oem parts are discon.

It's really not a big deal on the Siamese head since the intake is cast iron. If left open on the alum ones they can crack. It just takes a little longer to warm up if you weld them closed.

 

[destin]

I'm sure the oem parts are discon.

It's really not a big deal on the Siamese head since the intake is cast iron. If left open on the alum ones they can crack. It just takes a little longer to warm up if you weld them closed.

Makes sense.

What if it is seized open instead of closed?
Problematic?

Thanks again for your help and patience man

 

[destin]

** updated

Ok so very soon i am going to sort out the heat riser.
However, since the manifold and intake etc are not leaking currently, and i rather not have them pulled off unless needed to avoid any potential cracking ( not sure if the cast iron is prone to cracking ).

Is there a way to access the state of the heat riser without removing the manifold, for example, could i simply remove the carb look down and see if the heat riser has a range of motion?
If so even possibly "unseize" or unstick the riser to it moves as it should?
My feeling is that it is stuck on the half open half close stage, or even possibly moving from open to half closed but not closed, judging by the behavior.

I have ordered all new gaskets / bolts and studs in case they need to come off.
But i was hoping one of you had messed with this in the past.

Also where exactly in the diagram is the heat riser located?
Between the intake and the exhaust manifold?

 

[73FJ40]

The heat riser is baffle plate shown in your picture that I've marked up. The exploded view is shown OUTSIDE the exhaust manifold, which is probably why you're confused.

This whole assembly is properly located a couple inches below the surface on the exhaust manifold where gasket no. 8 sits. The heat riser is located inside the manifold, the torsion spring outside towards the front of the engine, the counterweight outside towards the rear of the engine. The shaft which connects the three, penetrates the front and rear walls of the exhaust manifold. Obivously, the spring and heat riser slide onto the pivot shaft, I think the counter weight is pressed or welded on.

The heat riser is a curved plate, like a tongue, and is illustrated in its 'cold' position. When cold, the curved 'tip' of the tongue at the bottom directs some of the exhaust gas upwards, to warm up the bottom of the intake manifold.

As the torsion spring heats up, it rotates the shaft counterclockwise (looking from the front) so the curved bottom of the tongue rotates out of the exhaust gas, towards the right side wall of the exhaust manifold.

To see if the heat riser is working, you could grab onto the counterweight (if it's still there) and see if it moves. Don't twist too hard, the shaft is likely rusted thin. If it is there and does move, then look at the spring. It's under the cover, item #57 on the illustration.

If you want to look at the heat riser inside the exhaust manifold, the 'easiest' way in is to drop the exhaust pipe and look up inside the exhaust manifold with a mirror and a bright flashlight.

I really doubt there are TOYOTA parts available, unless some dealer is stuck with them on his shelf. I've got some of these parts for my '73 F-Engine, if you want to see what they look like.

 

[destin]

this makes perfect sense
Thanks for explaining it so clearly, this is fantastic.
I tried to carefully move the counter weight, but it would not budge.

Here are a few photos.
I am thinking the riser is stuck in the open position...?
( open as in dumping heat into the intake manifold )

counter weight and counter weight stop:

spring:

hacky mount from previous owner? ( i have the original oil tower in my basement )

 

[destin]

Also, if i went the route of removing the intake and exhaust manifold and un-seizing the heat riser --possibly sand blasting and painting and reinstalling all the bits --, should I be terribly concerned about the intake and exhaust manifolds cracking?

The cast iron seems like pretty tough stuff, I am just checking

 

[73FJ40]

Thanks for the positive feedback on my explanation. Sometimes it's hard to explain, particularly when you already know it in detail.

You've got some great pictures! Regarding the riser plate's current position, if it isn't corroded away, I think you could gage it from the clearance to the 'stop' marked on your picture. I don't know if fully open is against the stop, or near it.

 

[destin]

Thanks man

Currently the counter weight is not touching the lower / bottom stop, but rather it is completely touching the upper part of the stop.

Assuming, as you mentioned that the riser plate is not corroded, I believe that this would mean the riser plate is stuck open?

Have you ever unseized a heat riser before?
I guess the next step would be to confirm that this is indeed wide open, and also see if the riser plate is in good condition.

Thanks again, I really appreciate it!

Thanks for the positive feedback on my explanation. Sometimes it's hard to explain, particularly when you already know it in detail.

You've got some great pictures! Regarding the riser plate's current position, if it isn't corroded away, I think you could gage it from the clearance to the 'stop' marked on your picture. I don't know if fully open is against the stop, or near it.

 

[IDave]

Your heat riser appears to be closed, not open. That said, it is when it is closed that it is directing heat to the bottom of the intake, and that's not what you want, as you are aware.

You can try Kroil, PB Blaster or something like that to try to loosen it, but I've tried on several exhaust manifolds and never gotten a seized one to open.

Unless you drive it in freezing weather, the heat riser is not critical, and having it open is far more important than having it closed. So, one option is to cut it out.

Other options: SOR has some used, or maybe someone who junked their's would be willing to part with it.

 

[destin]

Thanks IDave

Just ordered some penetrating oil.
Is this something that i have to soak the parts in, or can you just saturate it via spraying it on?
Should i be concerned about driving it after i saturated the areas the night before?

Thanks

 

[IDave]

Well, the more the merrier. You can start with spray and go from there.

 

[destin]

Well, the more the merrier. You can start with spray and go from there.

Thanks man

What about driving it, or heat cycling, during the saturation period?

bad?

 

[IDave]

I expect it might help.

 

[Trollhole]

For a 64 manifold heat riser yours looks to be in a lot better shape than most I have seen. From the looks of it it should come free fairly easily. Soak it where it needs it and no more. Start the engine and let it warm up with you inspecting it. Once the smoke clears drive it. Then reapply at night. Gently tapping the shaft should help also. Be aware the couterweight shouldn't be hit as it likes to fall apart.

How about some more pics of the engine. I love the big window SD-40's. I've been thinking of cloning them.

 

[destin]

For a 64 manifold heat riser yours looks to be in a lot better shape than most I have seen. From the looks of it it should come free fairly easily. Soak it where it needs it and no more. Start the engine and let it warm up with you inspecting it. Once the smoke clears drive it. Then reapply at night. Gently tapping the shaft should help also. Be aware the couterweight shouldn't be hit as it likes to fall apart.

How about some more pics of the engine. I love the big window SD-40's. I've been thinking of cloning them.

Thanks man

I have some penetrating oil ordered and will try to gently loosen this thing up.
I will take some more photos at lunch

 

[destin]

ok popped off the exhaust at lunch.

The metal flap is in prefect condition, still shiny even.
I figure if i spray some penetrating oil internally and externally, it will break free in no time

Sorry fro the not so high quality phone photos, did not have my camera with me.

 

[destin]

Update...

Been spraying with mousemilk ad tapping the front side ( non counter weight end ) periodically.
Still not loose, but i think it will eventually be sorted

I wanted to clean up the heat riser shield and the spiral spring while i have it off.
These were originally nickel coated?
Hard to tell.
Would soaking them in vinegar be bad for any of the plating?

Cheers!

Destin