Intake/exhaust manifold install … failed attempt #1 … need advice (1 Viewer)

[fyton2v]

Well, I learned 2 things. I did a fair job at rebuilding my carburetor. It works fine and I now know what it feels like to have a functional secondary. However, I have intake leaks (and probably some small leak(s) around the exhaust manifold, but I’m not certain about that. If it is leaking, it’s hard to notice.

So, as I prep for possible failed mounting attempt number #2, I realize I’m not sure if I should be securing the intake and exhaust manifolds together before or after mounting. What’s the proper method? I did it afterwards on try 1. Got to around 30 lbs on a torque wrench before I decided to give up.

Now that I have it all apart again, I see some things, and I’m not sure if I’m within flatness tolerances. My intake is pretty much dead flat. I thought the exhaust was flat, too, but after closer inspection it’s not exactly flat. From any direction it’s not off by more than .015mm, measured with a feeler gauge.

The gasket I used was the “aftermarket”, thick graphite option from SOR. Not sure if it was made by Remflex. I’ve ordered a Remflex gasket from Amazon for the next try.

Thanks in advance.

 

[bhsdriller]

When I took mine all apart I did not unbolt them which helped keep everything lined up. I've heard of this happening when you do.
Used a Remflex and it sealed perfect

Might have to get them bolted together and machined flat

 

[brian]

why not oem gasket?

 

[fyton2v]

I’m worried about leaks so I thought the thicker gasket would help. Not sure if my logic if flawed, however. I do know that the previous owner, and some point in the distant past messed with this because was some gasket sealer left behind. I figured the stock gasket didn’t work the last time.

 

[fyton2v]

When I took mine all apart I did not unbolt them which helped keep everything lined up. I've heard of this happening when you do.
Used a Remflex and it sealed perfect

Might have to get them bolted together and machined flat

They seem pretty flat. One thing I’m a little concerned about is that it’s only machined flat on the bottom. When the bolts press down at the point where the two manifolds form the bolt holes it’ll push them back out of alignment. But probably only by a tiny fraction of a mm. Since the whole thing is only off by a tiny fraction of a mm now do they really need more flattening?

 

[Steamer]

Here’s what I do. When I have my manifolds apart, I bolt them together loosely with the gasket between them. I then mount them on the head together without a gasket. I go back and forth drawing both mounting surfaces together gradually until the bolts holding them together are torqued. I then remove the pair bolted together to install the main gasket. I use a Toyota OEM gasket.

When I had them off together once the exhaust manifold was warped a tad so I had them surfaced. The only time I have had a leak was when I was given the wrong gasket.

 

[B y r o n]

Maybe this will help:

 

[fyton2v]

Didn’t try that method to measure warping, but I have a precision straightedge. Will check it out and see if it gives me a different look at the problem. I’m surprised 1/2 a mm is within tolerance. Thanks for that man page!

 

[77mustard40]

Gents I went through 3 installs when I found a vac leak as part of my conversion back to a stock Aisin carb. I have headers but solved this by measuring the depth of each opposing ear (intake and exhaust) on each bolt/stud location. IIRC Jim C told me that .010” was the max tolerance. Mine were all below that figure but I wanted to make sure that the torque at each location applied equal pressure to each manifold. I sourced some thick flat machine washers and used a file to remove the measured depth disparity at each location across 1/2 of the face of the washer. I’m marked the opposite side of the washer with a sharpie so I could see the orientation of the washer in relation to the manifolds as I assembled them. OEM gasket, dry, and torqued to spec. That was 10 years ago and I’ve had no issues.

 

[micruz60]

You should also verify that the mating surface on the cylinder head is flat; using studs instead of bolts will allow you to 'hang' the combo manifold on the head before tightening up the nuts and lock washers.

 

[Skreddy]

I use the remflex gaskets on everything. On a cruiser engine, I will snug the intake and exhaust nuts finger tight with the remflex gasket in there, then put on the head with gasket and snug all finger tight. After that, I tighten the nuts off the head all a turn or so, then the intake to exhaust nuts/bolt a turn or so, repeat until it seems like I’ve done enough. If the intake and exhaust aren’t snugged together enough, the mounting holes to the head between the two won’t line up, but a little wiggling will get them on. Remflex gaskets don’t need near as much torque as you’d think. I still overtorque them on everything but am yet to have one leak.

 

[fyton2v]

We’ll, I’ve confirmed that the intake is flat. Amazingly flat. The exhaust, not so much. The bottom parallel line of that manifold is OK, but the top parallel line has a warp. It’s a bit convex with 2nd port angled slightly down and away from the 3rd port. Along the top line, it’s off by a little over .5mm. I think I’ll see if I can find a machine shop.

So what would they do, just sand it down a bit on a belt sander?

 

[Blastservices]

So I’m currently having an issue with this as well. I am working on a F155 all stock components but on my head on the lower machined edge of the exhaust ports it was eroded from leaking for ever. The cylinder head shop welded but im afraid not enough.
The first gasket was the graphite one from SOR. The port holes are ovalized or not really squished tight to the ports. When it was tightened it just moved off the surface and had a terrible leak. The next gasket was a felpro and it has the metal crush rings around the port but also a little too ovalized around the port. I just ordered a Toyota one from the local dealer for Monday. We will see if it’s any better.

 

[fyton2v]

Yikes. I don’t feel so bad about my issues anymore. You’d think adding more metal and grinding it back a bit would be the way to go, but it sounds like your motor is back together. What a pain.

So I’m currently having an issue with this as well. I am working on a F155 all stock components but on my head on the lower machined edge of the exhaust ports it was eroded from leaking for ever. The cylinder head shop welded but im afraid not enough.
The first gasket was the graphite one from SOR. The port holes are ovalized or not really squished tight to the ports. When it was tightened it just moved off the surface and had a terrible leak. The next gasket was a felpro and it has the metal crush rings around the port but also a little too ovalized around the port. I just ordered a Toyota one from the local dealer for Monday. We will see if it’s any better.

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[Blastservices]

Yikes. I don’t feel so bad about my issues anymore. You’d think adding more metal and grinding it back a bit would be the way to go, but it sounds like your motor is back together. What a pain.

I guess I assumed the SOR graphite gasket was already a tried and true fix for these problems. I’m learning they aren’t the best solution for every detail.

 

[brian]

So I’m currently having an issue with this as well. I am working on a F155 all stock components but on my head on the lower machined edge of the exhaust ports it was eroded from leaking for ever. The cylinder head shop welded but im afraid not enough.
The first gasket was the graphite one from SOR. The port holes are ovalized or not really squished tight to the ports. When it was tightened it just moved off the surface and had a terrible leak. The next gasket was a felpro and it has the metal crush rings around the port but also a little too ovalized around the port. I just ordered a Toyota one from the local dealer for Monday. We will see if it’s any better.

View attachment 2847820

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thats horrible....i'd be pissed if i paid a shop for that "repair"...looks like they ground it by hand, in addition to not even building it back up enough.

 

[Chestcutter]

Here’s what I do. When I have my manifolds apart, I bolt them together loosely with the gasket between them. I then mount them on the head together without a gasket. I go back and forth drawing both mounting surfaces together gradually until the bolts holding them together are torqued. I then remove the pair bolted together to install the main gasket.

I second @Steamer 's method. Torque up the intake to exhaust connection with both tight to the head minus gasket, then put the gasket on and final install.

I used Remflex for both the inter-manifold gasket and the manifold to head gasket, on the advice of many here, mostly to compensate for rough surface on the exhaust manifold. So far so good on the leaks, although I plan to retorque this weekend after 500 or so miles. I know some folks don't think Remflex is as durable, however I know some mechanics around here who swear by them for race car engines...

Using studs instead of bolts makes the install much easier, with the exception of the fact that the newer studs are a little long and the manifold barely clears the firewall, and in my case didn't clear the steering box heat shield bracket.

It would be nice if Toyota started making these manifolds again as part of the FJ40 parts refresh...

 

[Blastservices]

So I ordered part number 17172-6020 from the local Toyota dealer. I got part number 17172-60031which also appears to availble on eBay as well. The major difference between it and the Felpro and SOR graphite gaskets are the port holes are super exact verse being sloppy and having lot of space around the port with no gasket contact. I’m all sealed up and no issues. Garbage fitting parts make a difference and hope this helps someone from wasting money and time like I just did…

 

[fyton2v]

Update.

I'm happy to report that try #2 was a home run. The Remflex gasket kit arrived from Amazon faster than I expected. I figured I'd give it a go and if I failed again, I'd pay a pro to resurface the manifold and then try an OEM gasket.

While the gasket definitely worked, and I'm happy, I'm unsure all the credit goes to Remflex. Some learning happened during the first failed attempt and I did a better job this time. Also, I followed @Skreddy 's torquing process. While everything was apart I rebuilt the carburetor and man the whole thing runs better.

Thanks for the advice, everyone.

EDIT: Followed Remflex's torquing recommendation. Tightened the manifold bolts down to approx. 23 lbs, and the riser to about 20 lbs.

 

[fyton2v]

And here’s an unnecessary pic of my truck.