Help with heat riser/exhaust manifold

[black95]

I am in the process of getting my 1978 FJ40 running, it has been sitting for around 6 years from the previous owner. Rebuilt the carb this week, went to put everything back together, but removed the carb spacer/heat shield before I did. Underneath it I found a HUGE crack in my exhaust manifold. Pulled the manifold tonight, figured I needed to check the heat riser anyway. Well, the cracks are worse than I thought, and the heat riser was stuck in the open position. Looking at how mangled the plate under the intake was, I would have thought it had been stuck closed at one time. I put a 10MM wrench on the heat riser shaft and it freed up more and more as I was turning it. So much so, that it now will not stay open, the spring tension snaps it closed in my 50 degree garage. Have not tried heating it yet to see what happens.

So here are the questions.

Does this manifold look like it is worth fixing? I do not want to go with headers. It looks like there is ceramic or something inside the manifold, what will welding do to this?

What is the standard method of dealing with the heat riser? I live in Colorado, so it seems it would be useful, but if it's going to be problematic and crack my intake, shouldn't it be cut out and the holes welded up? I do not want to go with a water heat riser setup. I would think there would be enough heat just based on the exhaust manifold's proximity to the intake, without the heat riser flap. That design falls under the WTF were they thinking area in the Toyota handbook, A movable part you can't grease and is subject to exhaust temps??? Wonder if you could put anti-seize on it?

Thanks guys, I love my support group

 

[black95]

And this, that's a big damn crack.

 

[3_puppies]

I'm thinking that needs to go to the scrap pile.

find a used one, you just need the center section, you can re-use your ends.
78 has the EGR off the main manifold?

I think I've got a few of those on the shelf, if you can't find one close by.

 

[black95]

I'll look around. I already own this one and might try to weld it back together just for the heck of it. I have read posts on the web were people are having pretty good luck MIG welding cast iron. I have a Hobart 175 that I'm pretty fluent with. Nice thing is there isn;t much structural need, I just want it quiet. It doesn't matter how cool your rig is when it has an exhaust leak making it sound like a junkpile.

I had 4k budgeted to build this rig, tires and lift took a major chunk of that....I'm getting very low.

A buddy from my local club is bringing me one out this weekend on our trail ride. His has a stuck heat riser too, which makes me think I should be cutting that thing out.

 

[Pin_Head]

Brazing them works. Welding not so much. They look like that whether the heat riser valve is stuck or not. Stuck valve tends to crack the intake manifold.

 

[black95]

Anyone live in cold weather and not have a heat riser anymore? Does it make a huge difference?

 

[RicardoJM]

Anyone live in cold weather and not have a heat riser anymore? Does it make a huge difference?

I live in Denver and have some experience to share. My truck has been running a header since last summer. I did not get a fluid heat riser installed until mid-December. Without the fluid heat riser, when the temps were in single digits and below zero, it would take a long (too long) time for the truck to warm up. After installing the fluid heat riser, the warm up times decreased dramatically. In my experience, it does make a huge difference on those really cold mornings.

 

[black95]

I was afraid that would be the answer I got. So what's a guy to do? do you stick a wrench under the truck and move the heat riser shaft every 6 months to keep the damn thing from locking up? I'm thinking about welding a more substantial nut on the end of the shaft if so.

 

[Pin_Head]

All you need to do is make sure that the flapper isn't stuck and turns a couple of times a year. It is remarkably reliable.

 

[black95]

So I checked the heat riser today, hit it with a torch for a second, nothing happened. Then I tapped it with a screwdriver and it snapped open. Doesn't seem very reliable to me. I guess the screwdriver tap could be simulated by road shock or bumps. I guess I'll leave the thing alone and check on it once in a while.

I went ahead and put the manifold in my giant vice and heated, cranked, heated, cranked, and heated until the crack closed up. Then I grooved it out with a grinder, heated it red with a oxy/actetylene torch, and threw a weld on it. Letting it stay in the vice until it cools. I just don't see why this won't hold. Like I said though, have another coming Saturday.

 

[black95]

That's one thing I just don't get about Ih8mud...

Some guy posts a question about what type of damn oil filter to use, he gets 500 hits and 127 answers.

Post up something you really need info on, like what's the best options for heat riser and manifold fixes.....you get nothing.

 

[Fast Eddy]

Some guy posts a question about what type of damn oil filter to use, he gets 500 hits and 127 answers.

Post up something you really need info on, like what's the best options for heat riser and manifold fixes.....you get nothing.

Everyone deals with oil filters. With manifolds, 75% of people just swap in a header. 90% of the remaining people either have a good manifold, or get a good one from someone else. Repairs on old cast iron are rare. I doubt that weld penetrated far enough to last. Once the butterfly valve is broken loose, it will continue to function as long as it doesn't sit for a long time. I've got two that work fine. One is even in the dreaded thermonuclear reactor manifold.

Get the heat riser insulator from SOR to go between the manifolds. It's expensive, but will save your intake manifold.

Specter Off-Road Land Cruiser Parts - Search On 044-12

 

[cruiser9]

I live in the North East so it can quite cold here. I had a header on mine ( po installed). Never had aan issue, other than warming up ( as stated earlier). From what I can gather, that is a common problem with the exults header which is why the header swap. This was told to me when i first got mine, which was a 78 also. I don't know how true it is.