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Unread 12-24-2012, 10:42 PM   #1
Eric_B_1984
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AMC 360 keeps blowing out intake seals.

I have an 87 Grand Wagoneer, and I decided to swap out the 2BBL intake for an Edelbrock 4BBL intake, if I remember right it was this one http://www.summitracing.com/parts/ed...merican-motors In the past year or so I have had the intake off at least 5 times. It keeps blowing the rear seal out. I first used the rubber piece that came with the valley pan kit as well as the valley pan. That time it didn't even last past 2 minutes. Later after someone pointed it out to me, I realized that there never was a PCV valve on the engine, so I put one one it in the port on the intake behind the Carb. This time as per the recommendation of Edelbrock I did not use the rubber end pieces, rather a very large bead of silicone front and back, and the Edelbrock gaskets between the intake and the valley pan, and let it set about 2 days before even cranking the engine. This time I got it to hold while I tuned the Carb and I drove it down the street, put about 4-5 miles on it and noticed smoke so limped it home and found that the rear silicone blew out. I had towed it to another friend who has built several of these engines we took it back apart he did everything without the valley pan we had it running again, and it blew out when I got it home pulling it off the trailer. I got pissed off and didn't even look in the direction of this thing for 3 months. I called Edelbrock again, they told me to not use gaskets or a valley pan, to use black silicone around every port and front and back (also I had been using Permatex ultra black through this whole process), I did that, ran great for about 3 or 4 months I took it on an off road trip and during that it started overheating, and leaking again. I am at a loss on this now. I have built several Chevy small blocks, did the same job, and never a problem. I just don't know what to do at this point.

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Unread 12-25-2012, 05:03 AM   #2
RockRollin
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Valley pan and silicon, no gasket over valley pan. Oil filler tube should have port in the cap hooked to the air cleaner, make sure it can breath (brake cleaner till it flows clean). Checked compression? Could be blow-by, or head gasket.
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Unread 12-25-2012, 05:18 AM   #3
Eric_B_1984
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That is how I have it now, valley pan with silicone, the oil fill tube does have a vented oil cap in fact the one time it blew out, there was no cap on it. I did do a compression test before the last time I did the job and if I recall they were all between 138 and 141psi. I can't see any typical signs of blow-by, or a blown head gasket for that matter. Because of the absurd hours I work I am half considering either having someone do the job, or commit a sin and get the conversion kit and put a Chevy small block in it.
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Unread 12-25-2012, 06:48 AM   #4
RockRollin
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Maybe this helps, I wonder if egr pressure is affecting your install. The one recommends letting sit for 24hrs before torque http://www.ifsja.org/forums/vb/showt...gasket+trouble
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Unread 12-25-2012, 06:57 AM   #5
Eric_B_1984
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Quote:
Originally Posted by RockRollin View Post
Maybe this helps, I wonder if egr pressure is affecting your install. The one recommends letting sit for 24hrs before torque http://www.ifsja.org/forums/vb/showt...gasket+trouble
I have the intake with no egr. All of the emissions crap has been removed except for a high flow cat without egr tube. The exhaust manifolds have the bypass caps in so all that tubing has also been eliminated as well as all the other random emissions vacuum tubing.
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Unread 12-25-2012, 08:06 AM   #6
RockRollin
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I have the same intake in the parts staging area. I have had my stock intake off a couple times, but have not had any issues with stock one. Are you getting oil coming through, and overheating? Which came first, if it overheated could have stretched the aluminium. I understand the egr delete, I'm wondering if there could still be a heat issue from the exhaust ports being blocked by the intake instead of gasket material. What I plan on doing is valley pan, and silicon at the ends placing and waiting for 24hrs before torque. Valley pan is necessary so as to not foul the pcv valve. Where did you place your pcv, any pics?
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Unread 12-25-2012, 08:15 AM   #7
Eric_B_1984
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If only I stayed 15 more minutes, I literally just left my mom's house where my jeep is, I could have taken a few pictures before I left. I may try to run up there later tonight, I need to sleep now (I work midnights). Honestly it never ran hot, except for the time it blew a rad hose on me, with the stock intake. I had seriously just started the engine for the first time with it, when it blew out the rear rubber seal, I didn't even have the oil tube in I was too eager to hear it run. I this last time, it was leaking oil first I am almost 100% sure.
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Unread 12-25-2012, 07:14 PM   #8
Eric_B_1984
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Quote:
Originally Posted by RockRollin View Post
I have the same intake in the parts staging area. I have had my stock intake off a couple times, but have not had any issues with stock one. Are you getting oil coming through, and overheating? Which came first, if it overheated could have stretched the aluminium. I understand the egr delete, I'm wondering if there could still be a heat issue from the exhaust ports being blocked by the intake instead of gasket material. What I plan on doing is valley pan, and silicon at the ends placing and waiting for 24hrs before torque. Valley pan is necessary so as to not foul the pcv valve. Where did you place your pcv, any pics?

Sorry it's not the best picture but it's right there next to the heater hose on the rear left
forumrunner_20121225_201252.jpg
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Unread 12-26-2012, 06:56 AM   #9
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I wonder if the exhaust cross over is leaking in somehow and creating pressure. Did your manifold have a threaded hole in the bottom? Did you seal it?
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Unread 12-26-2012, 04:49 PM   #10
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It's the 2131 intake EGR delete so no x-over. It has to be building crankcase pressure somehow. That should be a non pressure seal at the back of the intake. Whatever crankcase venting there is, isn't enough. Still thinking blowby. Compression check, make sure bottom of PCV valve baffle is clear, then filler tube vent. Could check vacuum at PCV lint at valve
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Unread 12-28-2012, 12:52 PM   #11
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Quote:
Originally Posted by RockRollin View Post
It's the 2131 intake EGR delete so no x-over. It has to be building crankcase pressure somehow. That should be a non pressure seal at the back of the intake. Whatever crankcase venting there is, isn't enough. Still thinking blowby. Compression check, make sure bottom of PCV valve baffle is clear, then filler tube vent. Could check vacuum at PCV lint at valve
The egr (or egr delete) and exhaust cross over are mutually exclusive. The 2131 has a crossover. I looked at some on line pictures and it doesn't appear there is a plug in it so what I was thinking isn't your problem.

You are correct, the purpose of the seal is to keep oil in. It is not there to keep some kind of pressure. That area is not sealed off from the rest of the engine, there are oil drain holes. So he entire crank case must be pressurizing. THe PCV and breather seem like logical places to start. It's hard to tell from the pic, where do you have the hose from the PCV going to?
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Unread 12-28-2012, 04:16 PM   #12
Eric_B_1984
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I'll be honest I've never had to add a pcv system to an engine that didn't aleady have one. In the picture you can see where I put it, but I hooked it to the port on the back of the carb. One local mechanic recommends punching a hole in one of the valve covers and re plugging the port where it's at now, but he's a full blood Ford guy. I'm at the point with this thing where it seems more logical to this center bolt 350 in this thing.
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Unread 12-28-2012, 04:30 PM   #13
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If I recall, you should have the back of the carb plugged and either run the PCV to the front (center port) of the carb or into the air cleaner.
never had these issues once I ditched end seals with my Performer manifold and 1406 carb.
Also make sure you don't reuse the valley pan. It's a crush gasket and can give you issues. I've heard of some get away with it, but I wouldn't.
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Unread 12-28-2012, 04:38 PM   #14
RockRollin
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No. No x-over at all. I looked at the one I have in the staging area. Actually mine has a freeze plug in the PCV location that will be coming out
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Unread 12-28-2012, 06:04 PM   #15
Eric_B_1984
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Quote:
Originally Posted by CutterN55 View Post
If I recall, you should have the back of the carb plugged and either run the PCV to the front (center port) of the carb or into the air cleaner.
never had these issues once I ditched end seals with my Performer manifold and 1406 carb.
Also make sure you don't reuse the valley pan. It's a crush gasket and can give you issues. I've heard of some get away with it, but I wouldn't.
That is my same setup with the 1406 carb. I have the brake booster going to the one in the front, and the one in the back going to the pcv. I haven't been this confused in a very long time.
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