New noise from olds 307 ticking/knocking/exhaust leak?

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Tz44

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Mar 24, 2012
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That exhaust diagram is totally whacked. I kept looking at it then just a few minutes ago, realized that something wasn't quite right.

I still don't get where there's an exhaust donut on the cross over pipe. I distinctly recall the crossover has flanged ends. There should not be a donut on the crossover. If there is, something doesn't seem right.

There should be 3 bolts/springs on the down pipe to the cat converter. THREE. The donut should be on top of the down pipe to the converter.

Here's what you should be seeing according to the 1987 Chassis service manual.


View attachment 122547
There were three spring bolts on top of the down pipe above the converter. That’s where I put the donut gasket and where the old one fell out. There are flanged ends on the crossover and as far as I could tell, no spring bolts. However it does kind of look like there’s another donut on the passengers side crossover. I’ll have to get it down to say for sure, I’m not able to see it well enough to say for sure. I can clearly see pieces of the flange gasket above the EFE on the driver side poking out from between the flanges.
I think to cover all the bases I’ll order another flange gasket and donut gasket before I drop the crossover. You’re right about that diagram; it seems like some things are out of place.
 

69hurstolds

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If the donut is replaced with the 3 spring bolts, you should be good there if nothing snapped off. Dorman makes a bolt/spring kit (1 bolt/1 spring) to replace them if ever needed under p/n 03137 available at most auto parts stores. There are no spring bolts on the crossover.

I apologize for the errors. It's been a while since I've fiddled with the exhaust manifolds and went from memory, which I should know better. I saw what I thought was a donut gasket and immediately thought of the spring bolts. If the cross over is stock should have a flange and taper seal on both ends on both driver and passenger side.

I'm only used to cast iron manifolds, so the "log" versions may appear different, but should seal the same way. The crossover pipe for Y and 9 engines are the same.

I found a picture of a passenger side exhaust manifold and the seal for the crossover pipe only LOOKS like a donut gasket the way the sealing surface looks. Notice where it bulges out a bit. So as long as any carbon is cleaned off and no holes, you should be good. It's just the integrity of the bolts that would worry me. They get real crusty and can snap off just looking at them. The crossover is obviously going to have to be removed anyway if you do the oil pan gasket.

 

Tz44

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Mar 24, 2012
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8
If the donut is replaced with the 3 spring bolts, you should be good there if nothing snapped off. Dorman makes a bolt/spring kit (1 bolt/1 spring) to replace them if ever needed under p/n 03137 available at most auto parts stores. There are no spring bolts on the crossover.

I apologize for the errors. It's been a while since I've fiddled with the exhaust manifolds and went from memory, which I should know better. I saw what I thought was a donut gasket and immediately thought of the spring bolts. If the cross over is stock should have a flange and taper seal on both ends on both driver and passenger side.

I'm only used to cast iron manifolds, so the "log" versions may appear different, but should seal the same way. The crossover pipe for Y and 9 engines are the same.

I found a picture of a passenger side exhaust manifold and the seal for the crossover pipe only LOOKS like a donut gasket the way the sealing surface looks. Notice where it bulges out a bit. So as long as any carbon is cleaned off and no holes, you should be good. It's just the integrity of the bolts that would worry me. They get real crusty and can snap off just looking at them. The crossover is obviously going to have to be removed anyway if you do the oil pan gasket.

That makes sense. I’ll just order another flange gasket. I’ll see if I can find some bolts to replace the stock ones (the ones I haven’t been able to crack loose yet) so that I won’t have to fight them as much if/when I replace the oil pan gasket. Hoping they’re not leaking against the heads but I’ll check once I get a chance. Hurricane Dorian might end up affecting us here so i might not be able to make much progress and shipping will be slow. I have a service manual and a quadrajet book to keep me occupied though.
 
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69hurstolds

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I suggest while you're under there, to check the tightness of the oil pan bolts before wholesale changing of the gasket. Many times, the bolts loosen causing a leak and tightening them can minimize or even stop the leak. Costs nothing but a little time and then if it still leaks, then get the gaskets. Most of the side bolts are 3/8" hex heads like the valve cover bolts. Motor mounts may get in the way of a couple, but most are accessible. The corners should be 1/2" head size if memory serves. Of course, don't believe my memory.

The bolts for the passenger crossover are 3/8" diameter, 16 pitch threads. Approximately 1-1/2" long. They need to be grade 8 to handle the heat and stress loads. Don't get stainless bolts. without proper lube they'll gall, and most of the time they're easier to twist off. Go by the recommended torque of 23 lbs-ft. No need to warp the flanges or strip something out.

And in my experience, if you clean all threads and put anti-seize on the bolts when you install them, you'll likely never have to replace them again because it always seems to go against whatever you try to do to make it easier on yourself should you have to do it again. But I'd put anti-seize on them anyway since you said you may do a transplant later.
 
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Tz44

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Mar 24, 2012
47
8
I suggest while you're under there, to check the tightness of the oil pan bolts before wholesale changing of the gasket. Many times, the bolts loosen causing a leak and tightening them can minimize or even stop the leak. Costs nothing but a little time and then if it still leaks, then get the gaskets. Most of the side bolts are 3/8" hex heads like the valve cover bolts. Motor mounts may get in the way of a couple, but most are accessible. The corners should be 1/2" head size if memory serves. Of course, don't believe my memory.

The bolts for the passenger crossover are 3/8" diameter, 16 pitch threads. Approximately 1-1/2" long. They need to be grade 8 to handle the heat and stress loads. Don't get stainless bolts. without proper lube they'll gall, and most of the time they're easier to twist off. Go by the recommended torque of 23 lbs-ft. No need to warp the flanges or strip something out.

And in my experience, if you clean all threads and put anti-seize on the bolts when you install them, you'll likely never have to replace them again because it always seems to go against whatever you try to do to make it easier on yourself should you have to do it again. But I'd put anti-seize on them anyway since you said you may do a transplant later.
I’ll give tightening them a shot. I never even thought to check if they were loose. That would be great. I’ve been trying to prep for this damn hurricane so haven’t had much time to mess with it.
Also, any idea where I could get the flange gasket quickly? Parts stores? Amazon? The one I have is a felpro 60771 I believe but I assume there are others that will work. Thanks in advance, might get a chance to work on it this weekend as long as the storm passes quickly.
 

69hurstolds

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No other brand of gasket I can find other than the GM one. Which, you never know, COULD have been made by Felpro. Who knows for sure? NAPA, O'reilly's, Autozone, Advance, and Rockauto.com all sell the Felpro. So if you need one quick, just about any parts store should have one.

Well, O'reilly's sells a Nickson gasket. Their p/n EG24867. Have no idea what that's about. Same price as the Felpro.
 

69hurstolds

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While you're at it, keep this in mind- The oil pan gasket (same for ALL 260-455 Olds V8s) part number to keep in mind is Fel Pro OS30471C. This gasket is very similar (again, if not the same part) as the GM discontinued version ( GM p/n 22519181). From the people that has used them, the gasket is cork with a steel core in it just like the GM gasket. It helps prevent squeezing out the sides. As always with Olds V8s, if you DO replace the oil pan gasket, it is wise to put RTV at the corners where the front/rear rubber seals meet the cork.

Best price I've seen on these is ebay for around 10 and change shipped. But they have them at just about all the auto parts stores for around 18-20.

There are other part numbers, like OS30534TC, and they apparently have a steel core as well, but I don't have any personal experience with those.

As for torqueing the oil pan- The corners are actually 1/2" socket sized nuts on studs on your 307. These are torqued to 17 lbs-ft. The little 3/8" headed bolts are to be torqued to 10 lbs-ft. The heating/cooling cycles sometimes gets these to come loose. I do not recommend putting any type of thread lock on the bolts, however. Unless you have brass balls.
 
Oct 14, 2008
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Also be careful not to overtighten the gasket. I have used the Felpro exhaust donuts and they last long term, just don't over torque them. I personally think this exhaust setup is awful. Horrible as in restrictive with too many leak points. This exhaust system is part of the reason the 307 is seen as a joke. Even more criminal was having this on the HO motor, should have used the FE3X exhaust on production cars. And you know those stainless manifolds are restrictive when cast iron log manifolds, which are still terrible are chosen for the HO motor.
 
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Tz44

Not-quite-so-new-guy
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Mar 24, 2012
47
8
While you're at it, keep this in mind- The oil pan gasket (same for ALL 260-455 Olds V8s) part number to keep in mind is Fel Pro OS30471C. This gasket is very similar (again, if not the same part) as the GM discontinued version ( GM p/n 22519181). From the people that has used them, the gasket is cork with a steel core in it just like the GM gasket. It helps prevent squeezing out the sides. As always with Olds V8s, if you DO replace the oil pan gasket, it is wise to put RTV at the corners where the front/rear rubber seals meet the cork.

Best price I've seen on these is ebay for around 10 and change shipped. But they have them at just about all the auto parts stores for around 18-20.

There are other part numbers, like OS30534TC, and they apparently have a steel core as well, but I don't have any personal experience with those.

As for torqueing the oil pan- The corners are actually 1/2" socket sized nuts on studs on your 307. These are torqued to 17 lbs-ft. The little 3/8" headed bolts are to be torqued to 10 lbs-ft. The heating/cooling cycles sometimes gets these to come loose. I do not recommend putting any type of thread lock on the bolts, however. Unless you have brass balls.
I have Mahle oil pan gasket I found on rock auto. I can’t remember if it’s steel core or not I’ll have to check when I get home.
 
Oct 14, 2008
6,244
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Melville,Saskatchewan
I can't see the pan gasket being fun to do in car. I have been buying the Felpro conversion set. A bunch of gaskets for slightly more but just a regular cork pan gasket. I also used either the 292 Ford, the one Felpro sells as an Olds replacement or the AMC 6 or supposedly the AMC 360 seal. These are easy to install. What isn't easy to do is remove the rope seal. Too bad Olds didn't use these factory or changing the rear main would be doable with the pan off.
 
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